STLED325QTR

STLED325 I²C interfaced, advanced LED controller/driver with keyscan, standby power management and real time clock (RTC) Features ■ LED controller driver with 13 outputs (8 segments/5 digits) ■ Standby power management to host ■ Integrated low-power, accurate RTC ■ Integrated remote control decoding: – Philips (RC5, RCMM) – Thomson (RCA, R2000) – NEC and R-STEP ■ Wake-up using front panel keys, remote control, real time clock (RTC), extra pin (AV or CEC) ■ Battery or super-cap back up mode for real time clock (RTC) ■ Keyscanning (8x2 matrix) ■ Low power consumption in standby mode ■ I2C serial bus interface (SCL, SDA) ■ 16-step dimming circuit to control the display brightness ■ 5.0 V (± 10%) for VCC ■ Built-in thermal protection circuit ■ External crystal with internal oscillator for real time clock (RTC) Applications ■ Set-top boxes ■ White goods ■ Home appliances ■ DVD players, VCRs, DVD-R Table 1. QFN32 (5 x 5 mm) Description The STLED325 is a compact LED controller/ driver that interfaces microprocessors to LED displays through serial I2C interface. It drives LEDs connected in common anode configuration and includes keyscanning for an 8 x 2 key matrix which automatically scans and de-bounces a matrix of up to 16 switches. Furthermore, the STLED325 provides standby power management to the host. It also integrates a low-power, highly-accurate RTC and a remotecontrol decoder. All functions are programmable using the I2C bus. Low power consumption during standby mode is achieved. The STLED325 controller/driver is ideal as a single peripheral device to interface the front panel display with a single-chip host IC like CPU. Device summary Order code Temp range (° C) Package Comments STLED325QTR -40 to +85 °C QFN32 250 parts per reel April 2011 Doc ID 17576 Rev 1 1/62 www.st.com 62 Contents STLED325 Contents 1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2 Functional and application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.1 Low power mode of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.2 I2C serial interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.3 Initial power up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.4 Display types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.5 Keyscan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.6 Timers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Guard timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.6.2 Watchdog timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.7 Power-on-reset and soft-start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.8 LED drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.9 Over temperature cut-off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.10 Standby mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.11 2/62 3.6.1 3.10.1 Cold boot up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.10.2 Entering standby mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.10.3 Wake-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Real time clock (RTC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 3.11.1 Reading the real time clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 3.11.2 Writing to the real time clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 3.11.3 Register table for RTC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 3.11.4 Setting alarm clock registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 3.11.5 Century bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 3.11.6 Initial power-on defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.11.7 Programmable display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 3.11.8 Lookup table with ppm against the calibration register values . . . . . . . . 24 3.12 Remote control decoder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 3.13 Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 3.14 Ready . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.15 Mute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Doc ID 17576 Rev 1 STLED325 Contents 3.16 GPIO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.17 Power sense circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.18 4 3.17.1 Switchover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3.17.2 Battery low warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 3.17.3 Different power operation modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Bus characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Electrical ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 4.1 Absolute maximum ratings (TA = 25 °C, GND = 0 V) . . . . . . . . . . . . . . . . 33 4.2 Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 4.2.1 DC electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 4.3 Power consumption estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 4.4 Oscillator and crystal characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 4.5 ESD performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 5 Display RAM address and display mode . . . . . . . . . . . . . . . . . . . . . . . 41 6 KEY matrix and key-input data storage RAM . . . . . . . . . . . . . . . . . . . . 42 7 Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 7.1 Configuration mode setting command . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 7.2 Data setting command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 7.3 Configuration data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 7.3.1 8 Interrupt flags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 7.4 Address setting command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 7.5 Display control and hotkey setting command . . . . . . . . . . . . . . . . . . . . . . 51 7.6 Keyscanning and display timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 8.1 Default state upon power-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 8.2 Initial state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 9 Remote control protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 10 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 10.1 Power supply sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Doc ID 17576 Rev 1 3/62 Contents STLED325 10.2 ISET variation with RSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 10.3 Application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 11 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 12 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4/62 Doc ID 17576 Rev 1 STLED325 List of tables List of tables Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. Table 11. Table 12. Table 13. Table 14. Table 15. Table 16. Table 17. Table 18. Table 19. Table 20. Table 21. Table 22. Table 23. Table 24. Table 25. Table 26. Table 27. Table 28. Table 29. Table 30. Table 31. Table 32. Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Register table for RTC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Alarm repeat modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Century bits examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Initial power-on defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 RTC display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 LUT with ppm against the calibration register values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Different power operation modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Absolute maximum ratings (TA = 25 °C, GND = 0 V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 DC electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Voltage drop estimation with RGB LED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Capacitance (TA = 25°C, f = 1 MHz) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Power supply characteristics (TA = -40 to 85°C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Dynamic switching characteristics (TA = -40 to +85 °C, VCC = 5.0V ± 10%, GND=0.0V, Typical values are at 25°C). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Timing characteristics (TA = -40 to +85 °C, VCC = 5.0 V ± 10%, GND=0.0 V, typical values are at 25 °C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Oscillator characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Crystal electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 ESD performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Battery range and battery detect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Power down/up AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Power down/up trip points DC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Thermal shutdown characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Bit map for segment 1 to segment 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Data write command. b5 b4: 00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Data Write 2 command. B5 b4: 01 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Data Read 1 command. b5 b4: 10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Data Read 2 command. b5 b4: 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Power-up defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 QFN32 (5 x 5 mm) mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 Doc ID 17576 Rev 1 5/62 List of figures STLED325 List of figures Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Figure 16. Figure 17. Figure 18. Figure 19. Figure 20. Figure 21. Figure 22. Figure 23. Figure 24. 6/62 Functional block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Pin configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Display types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Power-up condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Power down condition (normal behavior) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Standby condition (normal behavior) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Keyscan and digit mapping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Power sense circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Battery switchover waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Power down/up mode ac waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 VCC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 KEY matrix and key-input data storage RAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Data write command (b7 b6) for GPIO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Interrupt bit mapping in Byte 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Interrupt bit mapping in Byte 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Blanking time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Keyscanning and display timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Rext versus Iseg curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 QFN32 package dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 QFN32 carrier tape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Doc ID 17576 Rev 1 STLED325 1 Description Description The STLED325 is a compact LED controller/driver that interfaces microprocessors to LED displays through serial I2C interface. It drives LED connected in common anode configuration. The STLED325 drives up to 40 discrete LEDs in 8 segment/5 digit configuration while functioning from a supply voltage of 5 V. The maximum segment current for the display digits is set through a single external resistor. Individual digits may be addressed and updated without rewriting the entire display. Additionally it includes keyscanning for an 8 x 2 key matrix which automatically scans and de-bounces a matrix of up to 16 switches. Furthermore, it provides standby power management to the host. The STLED325 also integrates a low-power, highly-accurate RTC and a remote-control decoder. All functions are pro-grammable using the I2C bus. Low power consumption during standby mode is achieved. STLED325 supports numeric-type displays and reduces the overall BOM costs through high integration. Also it provides ESD protection of greater than 2 kV HBM. The LED controller/driver is ideal as a single peripheral device to interface the front panel display with a single-chip Host IC like CPU. Doc ID 17576 Rev 1 7/62 Functional and application diagram Functional and application diagram Functional block diagram ISET Current source Voltage regulator Vcc Output segments Internal core supply POR & Soft-start Internal reset Bandgap and UVLO VCC Detect Command Decoder I2C SPI Serial Seria lI/F I/F SCL SDA Display Mem (20 (5 x 8) 16) ThermalCtrl Remote protection Decoder & Guard timer Vbat Detect 8-bit 20- bit output Output latch Latch Timing Gen Key Scan & Dimming OSC OSC (Fixed Freq) GPIO2 VREG SEG1/KS1 8 WAKE_UP GPIO1 MUTE KeyData Mem (2 (2xx12) 8) KEY1-KEY2 IRQ_N Segment d rivers Figure 1. SEG8/KS8 165 - bit Shift Shift Register Register 5 Digit Grid Drivers d rivers 2 STLED325 DIG5 DIG4 DIG1 2 XIN XOUT RTC + 32KHz Osc IR_IN RC decoder VBAT READY Power management STDBY GND (0V) AM04143V1 8/62 Doc ID 17576 Rev 1 STLED325 Functional and application diagram Figure 2. Application diagram STLED325 SCL SDA Microcontroller or CPU LED 4-digit 7-segment (+dot-point) display panel READY 4 DIG1-DIG4 STBY IRQ_N SEG1/KS1SEG8/KS8 MUTE WAKE_UP 8 XIN External 32.768KHz crystal DIG5 XOUT PWR STBY REC MUTE VBAT From remote control sensor IR_IN ISET R GPIO1 From sensor/To LED GPIO2 From sensor/To LED VREG Connect to external capacitor KEY1-KEY2 2 Key scan (8x2 matrix) !-6 Doc ID 17576 Rev 1 9/62 Functional and application diagram MUTE IRQ_N GPIO1 READY STBY XOUT XIN GND VREG VBAT ISET 31 30 29 28 27 26 25 Pin configurations 32 Figure 3. STLED325 1 24 SEG1/KS1 2 23 SEG2/KS2 3 22 SEG3/KS3 GPIO2 4 21 SEG4/KS4 STLED325 14 15 16 VCC KEY2 KEY1 17 SEG8/KS8 13 WAKE_UP 8 DIG1 18 SEG7/KS7 12 7 DIG2 SCL 11 19 SEG6/KS6 DIG3 6 10 SDA DIG4 20 SEG5/KS5 9 5 DIG5 IR_IN !-6 10/62 Doc ID 17576 Rev 1 STLED325 3 Functional description Functional description The STLED325 is a common anode LED driver controller which can be used to drive red, green or blue LEDs as the current is adjustable through the external resistor. In the common anode configuration, the digit outputs source the current to the anodes while the segment outputs sink the current from the cathodes. The configurable output current can be used to drive LEDs with different current ratings (red, green or blue). The brightness can be controlled through the I2C interface as described later. The outputs can be connected together in parallel to drive a single LED. In this case, two parallel current sources of equal value drive a single LED. The external resistor value can be set accordingly to determine the desired output current. Soft-start limits the inrush current during power-up. The built-in thermal protection turns off the display when the temperature exceeds 140°C with a small hysteresis of 15°C. The display is blanked (LEDs are turned off or in high-Z state) on power-up. 3.1 Low power mode of operation When not used, the STLED325 goes into low power mode of operation wherein the current consumption drops to less than 1 mA. During this mode, the data configured is maintained as long as the supply voltage is still present (the contents of the internal RAM need the supply voltage to be present). Port configuration and output levels are restored when the STLED325 is taken out of shutdown. For minimum supply current in shutdown mode, logic inputs should be at GND or VCC. 3.2 I2C serial interface The interface is used to write configuration and display data to the STLED325. The serial interface comprises of a shift register into which SDA is clocked on the rising edge of the SCL after a valid start of communication. When communication is stopped, transitions on SCL do not clock in the data. During this time, the data are parallel-loaded into a latch. The 8-bit data is then decoded to determine and execute the command. For an overflow condition, if more bytes are written, then they are ignored whereas if more bytes are read, then the extra bytes are stuffed with 1’s. 3.3 Initial power up On initial power-up, all control registers are reset, the display is blanked and the STLED325 is in the low-power mode. All the outputs are in high-impedance state at initial power-up. The SDA is pulled high by an external pull-up resistor. The display driver has to be configured before the display can be used. Doc ID 17576 Rev 1 11/62 Functional description 3.4 STLED325 Display types Figure 4. Display types Seven segment display with dot point and common-anode LED panel 3.5 Keyscan The full keyscan is illustrated in the later section of the datasheet. One diode is required per key switch. The keyscan circuit detects any combination of keys being pressed during each de-bounce cycle. The keyscan matrix on the STLED325 passes command from the front panel to the host processor through the SDA pin on STLED325. The STLED325 can be programmed to wake-up the system from standby using any of the 16 keys pressed on the front panel. These wake-up keys are also referred to as hot-keys. 3.6 Timers 3.6.1 Guard timer For safety related applications, a guard timer is integrated in the STLED325. The guard timer gives enhanced reliability to the device. The guard timer can be used to detect an out of-control microprocessor. The user programs the guard timer by setting the desired amount of time-out into the Guard timer. This guard time has an initial de-fault value of 10s upon first power-up and subsequently can be configured from 1s to 15s during normal operation. If a time period of longer than 15s is desired, then the watchdog timer from RTC can be used. It can also be disabled after first power-up. If the processor does not clear the timer within the specified period, the STLED325 puts the system in the standby mode. This is only active from L to H transition on READY or WAKE_UP pin but it is not levelbased. The guard timer count is cleared by the guard timer clear/reset bit. While in normal mode, the count starts from the previously count value that was in the register. During the cold boot up or warm boot up, the count starts from the configured value. 12/62 Doc ID 17576 Rev 1 STLED325 3.6.2 Functional description Watchdog timer Another watchdog timer is present in the Watchdog timer register at address 09h of the RTC register map. This watchdog timer can be used to program timer values of greater than 15s. Bits BMB4-BMB0 store a binary multiplier and the three bits RB2-RB0 select the resolution where: 000 = 1/16 second (16 Hz); 001 = 1/4 second (4 Hz); 010 = 1 second (1 Hz); 011 = 4 seconds (1/4 Hz); and 100 = 1 minute (1/60 Hz). The Watchdog timer is programmed by setting the desired timeout into the Watchdog register, address 09h. The amount of timeout time is determined to be the multiplication of the 5-bit multiplier value with the resolution values depicted by the watchdog resolution bits. The Watchdog timer is disabled when its register is cleared by writing a value of 00h. Hence the Watchdog function is not enabled upon power on. It is enabled when a non-zero value is written into its register. The Watchdog timer is reset by performing a write to the watchdog register, then the time-out period starts over. If the processor does not reset the timer within the specified timeout period, and when the timeout occurs, the watchdog flag is set. The watchdog timer of RTC is cleared by writing a 00 value and starts again whenever any new value is written to it. The WatchDogEn Flag can be disabled or enabled by writing to the register bit and the reset of watchdog timer is done by writing to the register. 3.7 Power-on-reset and soft-start The device integrates two internal power-on-reset circuits which initialize the digital logic upon power up. One circuit is for the VCC power and the other is for the VBAT power. The soft-start circuit limits the inrush current and high peak current during power-up. This is done by delaying the input circuit’s response to the external applied voltage. During soft-start, the input resistance is higher which lowers the in-rush current when the supply voltage is applied. Doc ID 17576 Rev 1 13/62 Functional description 3.8 STLED325 LED drivers The constant current capability is up to 40 mA per output segment and is set for all the outputs using a single external resistor. When acting as digit drivers, the outputs source current to the display anodes. When acting as segment drivers, the LED outputs sink current from the display common cathodes. The outputs are high impedance when not being used as digit or segment drivers. Each port configured as a LED segment driver behaves as a digitally-controlled constant current sink. The LED drivers are suitable for both discrete LEDs and common anode (CA) numeric LED digits. When fully configured as a LED driver, the STLED325 controls up to 8 LED segments in a single digit with individual 8-step adjustment of the constant current through each LED segment. A single resistor sets the maximum segment current for all the segments, with a maximum of 40 mA per segment. The STLED325 drives any combination of discrete LEDs and common anode (CA) digits for numeric displays. The recommended value of RSET is the minimum allowed value, since it sets the display driver to the maximum allowed segment current. RSET can be a higher value to set the segment current to a lower maximum value where desired. The user must also ensure that the maximum current specifications of the LEDs connected to the drivers are not exceeded. 3.9 Over temperature cut-off The STLED325 contains an internal temperature sensor that turns off all outputs when the die temperature exceeds 140°C. The outputs are enabled again when the die temperature drops below 125°C. Register contents are not affected, so when a driver is over-dissipating, the external symptom will be the load LEDs cycling between on and off as the driver repeatedly overheats and cools, alternately turning the LEDs off and then back on again. This feature will protect the device from damage due to excessive power dissipation. It is important to have good thermal conduction with a proper lay-out to reduce thermal resistance. 3.10 Standby mode By utilizing the standby function, the host processor and other ICs can be turned off to reduce power consumption. The STLED325 is able to wake-up the system when programmed hotkeys are detected to signal that the full operation of the system is required. The hotkeys can be entered to the system through the front panel keys or through the infrared (IR) remote control or the Real Time Clock (RTC) alarm or through the wake-up pin. STLED325 supports multiple remote control protocols decoding by setting the appropriate register. The STLED325 is able to cut-off the power to the main board for standby operation for good power management. STBY will be set to high when READY signal goes from high to low, I2C command for standby is seen or when the guard timer has finished counting down to 0, whichever occurs first. In the normal mode of operation, the STBY is asserted only when the guard timer has finished counting down to 0. This is meant to put the system into stand-by even though standby command was not issued by the host or READY signal did not go low. This occurs as the guard timer register was not cleared before it finished counting down to 0. 14/62 Doc ID 17576 Rev 1 STLED325 3.10.1 Functional description Cold boot up When power is first applied to the system, the STLED325 is reset. It will then manage the power to the main board by bringing the STBY pin to a low level. This wakes up the main processor which asserts the READY pin to a high level to indicate to STLED325 of a proper boot-up sequence. If the microprocessor does not assert the READY pin to a high within 10s (default), the STLED325 cuts off the power to the Host by asserting the STBY pin. The high level on READY pin signifies that the processor is ready. After this, the processor can configure the STLED325 by sending the various I2C commands for configuration of display, RC protocol, RTC display mapping, hot-keys. The power-up behavior in 2 conditions is shown in Figure 5. Doc ID 17576 Rev 1 15/62 Functional description Figure 5. STLED325 Power-up condition 1a) Power-up condition (normal behavior ) VCC to STLED325I Internal POR Guard timer counts up to 10s STBY READY MUTE READY asserts within 10s which is the desired behavior, processor is active and not hung 1b) Power-up condition (processor not responding ) VCC to STLED325I Count over Internal POR Guard timer counts up to 10s STBY READY continues to remain low/high READY MUTE Due to abnormality in the processor, READY did not change state from low to high, leading to STBY assertion !-6 Note: 16/62 1 Guard timer is turned off by default upon READY assertion. 2 If Guard timer is to be kept on during READY high condition, the guard timer registers must be set accordingly by proper commands through I2C bus. 3 In this power-up condition, Guard timer is triggered by internal POR pulse. 4 During power-up, the Guard timer value is 10s. Doc ID 17576 Rev 1 STLED325 3.10.2 Functional description Entering standby mode The STLED325 controls the power to the main board using the STBY pin. During normal operation, the STBY pin is a low level which externally controls a Power MOS switch to enable power to the main board. The STLED325 asserts the STBY pin to a high when any one of the following conditions occur: – Processor fails to respond by enabling the READY pin within 10s upon first power-up (cold boot up) – Guard timer counts down to 0s – Processor makes the READY pin to low (can happen in various conditions such as user presses STBY key on front panel, STBY key on remote control, etc). Figure 6. Power down condition (normal behavior) 2a) Power-down condition (normal behavior ) READY MUTE STBY 2 us Guard timer is not required here 2b) Power-down condition (abnormal behavior of processor ) READY READY continues to remain high MUTE STBY In this case the READY remains high and as long as READY is high, the MUTE is low and STBY is low. !-6 – Guard timer can be kept on during normal condition when READY is high (depending on the user). – In this condition, the guard timer can be disabled or enabled. If the guard timer is enabled, the timer needs to be cleared before the programmed count of the timer is reached. If the programmed count is reached, the STBY will be asserted. – It is advisable not to enable the guard timer during normal operation. Doc ID 17576 Rev 1 17/62 Functional description 3.10.3 STLED325 Wake-up The STLED325 can wake-up from any one of the following sources: – Front-panel keys – Remote-control keys – Real time clock (RTC) in 3 conditions (alarm, watchdog timer, oscillator fail) – External wake-up pin (by a low to high transition on this pin) – GPIO status changes – READY pin goes from low to high Figure 7. Standby condition (normal behavior) 3a) Standby condition (normal behavior ) Hot key command from IR or Key pad or RTC or WAKE_UP for wake up Guard timer triggers STBY READY MUTE READY asserts within programmed timer value (1s-15s) 3b) Standby condition (abnormal behavior , processor is not responding) Hot key command from IR or Key pad or RTC or WAKE_UP for wake up Guard timer triggers Signals STBY after guard timer count is over STBY READY READY continues to remain low MUTE !-6 – When the hot-key is detected either from front-panel or remote control or RTC or from a transition (low to high transition) on WAKE_UP pin during stand-by, the STBY pin de-asserts. – The de-assertion of the STBY triggers the guard timer. – The timer value is the programmed value by the user (1-15s). If the user did not change the value before entering standby, then it remains 10s. – Also note that the guard timer is off when the STLED325 is in the standby mode. The guard timer is thus triggered by a de-assertion of the STBY signal or by internal power on reset signal. 18/62 Doc ID 17576 Rev 1 STLED325 3.11 Functional description Real time clock (RTC) The STLED325 integrates a low power Serial RTC with a built-in 32.768 kHz oscillator (external crystal controlled). Eight bytes of the SRAM are used for the clock/calendar function and are configured in binary coded decimal (BCD) format. An additional 12 bytes of SRAM provide status/ control of alarm and watchdog functions. Addresses and data are transferred serially via a two line, bi-directional I2C interface. The built-in address register is incremented automatically after each WRITE or READ data byte. Note that all 4 digits must be enabled before using the RTC display. Functions available to the user include a non-volatile, time-of-day clock/calendar, alarm interrupts and watchdog timer. The eight clock address locations contain the century, year, month, date, day, hour, minute, second and tenths/hundredths of a second in 24 hour BCD format. Corrections for 28, 29 (leap year - valid until year 2100), 30 and 31 day months are made automatically. The RTC operates as a slave device through the slave address of the STLED325 on the serial bus. Access is obtained by implementing a start condition followed by the correct device slave address. The 16 bytes contained in the device can then be accessed sequentially in the following order: – 1. Reserved – 2. Seconds register – 3. Minutes register – 4. Hours register – 5. Day register – 6. Date register – 7. Century/month register – 8. Year register – 9. Calibration register – 10. Watchdog register – 11 - 16. Alarm registers The RTC keeps track of the date and time. Once the date and time are set, the clock works when the STLED325 is in normal operation and standby operation. Wake-up alarm feature is also included in the RTC module. The accuracy of the RTC is approximately 20 ppm (±50secs/month). How-ever this much depends on the accuracy of the external crystal used. The wake-up alarm is programmed to wake up once the date and time set are met. This feature is present in normal and standby mode of operation. Only one date and time is available for setting. The real time clock (RTC) uses an external 32.768 kHz quartz crystal to maintain an accurate internal representation of the second, minute, hour, day, date, month, and year. The RTC has leap-year correction. The clock also corrects for months having fewer than 31 days. 3.11.1 Reading the real time clock The RTC is read by initiating a Read command and specifying the address corresponding to the register of the real time clock. The RTC registers can then be read in a sequential read mode. Alarms occurring during a read are unaffected by the read operation. Doc ID 17576 Rev 1 19/62 Functional description 3.11.2 STLED325 Writing to the real time clock The time and date may be set by writing to the RTC registers. The new RTC time can be updated by writing to the RTC registers. The new time only takes affect after a complete write cycle. If the write cycle is incomplete, the new time value is discarded. A single byte may be written to the RTC without affecting the other bytes. 3.11.3 Register table for RTC Table 2. Register table for RTC Addr D7 00h D6 D5 D4 D3 D2 Reserved D1 D0 Functional/range BCD format Reserved 01h OSC_S T 10 seconds Seconds Seconds 00-59 02h Rsvd 10 minutes Minutes Minutes 00-59 03h MD_HM_MS Hours (24 hours format) Hours 00-23 04h Rsvd Rsvd Day 01-7 05h Rsvd Rsvd Day of month Date 01-31 06h CB1 CB0 Month Century/month 0-3/01-12 Year Year 00-99 07h 10 hours Rsvd Rsvd Rsvd Day of week 10 date Rsvd 10M 10 years 08h 12/24 Rsvd Cal_sig n 09h RB2 BMB4 BMB3 BMB2 0Ah AFE Rsvd ABE AI 10M 0Bh RPT4 RPT5 0Ch RPT3 RPT6 0Dh RPT2 0Eh 0Fh Calibration BMB1 BMB0 Calibration RB1 Watchdog Alarm month Al month 01-12 AI 10 date Alarm date Al date 01-31 AI 10 hour AIarm hour AI hour 00-23 Alarm 10 minutes Alarm minutes Al min 00-59 RPT1 Alarm 10 seconds Alarm seconds Al sec 00-59 WDFEn Alarm: day of week Rsvd (bypass mode) Flags Legend: Cal_Sign = Sign bit OSC_ST = Oscillator Stop bit BMB0 – BMB4 = watchdog multiplier bits CB = Century bits ABE = Alarm in battery back up mode enable bit AFE = Alarm flag enable RB0 – RB2 = watchdog resolution bits RPT1 – RPT6 = alarm repeat mode bits 20/62 RB0 Doc ID 17576 Rev 1 STLED325 Functional description WDFEn = watchdog flag enable 12/24 = 12 hour or 24 hour format (‘0’ for 24-hour format and ‘1’ for 12-hour format). For 12 hour PM display, the 8th segment of last digit (digit 4) is driven to indicate PM mode through a dot on the last digit. It is recommended to fill the unused bits in the register map to 0 upon a cold boot up. The timekeepers and alarm store data in BCD format, while the calibration, watchdog bits are in binary format. The structure of the frame is shown below. For RTC, all the Dig1 to Dig4 must be configured to show the proper time. Figure 8. Keyscan and digit mapping Keyscan Digit 5 (used for discrete LED) Dig 1 Dig 2 Dig 3 Dig 4 AM08722V1 If the date programmed in the RTC exceeds a valid date value, then the RTC does not function as desired. So the invalid dates should never be programmed into the RTC. 3.11.4 Setting alarm clock registers Address locations 0Ah-0Eh contain the alarm settings. The alarm can be configured to go off at a prescribed time on a specific month, date, hour, minute, or second or repeat every year, month, day, hour, minute, or second. It can also be programmed to go off while the STLED325 is in the standby mode to serve as a system wake-up call. Bits RPT6-RPT1 put the alarm in the repeat mode of operation. Codes not listed in the table default to the once per second mode to quickly alert the user of an incorrect alarm setting. Note that by default, the alarm repeat mode is enabled and by default the repeat frequency is set to “once per year”. Address locations 0Ah to 0Eh contain the alarm settings. The alarm can be configured to go off at a prescribed time. The default repeat alarm mode is once per year. Programming the RPT[6:1] bits changes the repeat alarm mode. Doc ID 17576 Rev 1 21/62 Functional description Table 3. STLED325 Alarm repeat modes RPT5 RPT4 RPT3 RPT2 RPT1 RPT6 Repeat alarm mode 1 1 1 1 1 1 Once per week 1 1 1 1 1 0 Once per second 1 1 1 1 0 0 Once per minute 1 1 1 0 0 0 Once per hour 1 1 0 0 0 0 Once per day 1 0 0 0 0 0 Once per month 0 0 0 0 0 0 Once per year If the RPT value is other than the valid ones listed in the table, the default repeat alarm mode is once per second so as to quickly alert the user of an incorrect alarm setting. When the clock information matches the alarm clock settings based on the match criteria defined by RPT[6:1], then the alarm flag is set. Then if the alarm flag enable bit, is also set, this will activate the alarm interrupt. Interrupt is cleared by reading the Interrupt registers. 3.11.5 Century bits The clock shall include correction for leap years. The clock shall also correct for months fewer than 31 days. Corrections for 28, 29 (leap year –valid until year 2100), 30, 31 day months must be made automatically. The two Century bits increment in a binary fashion at the turn of the century, and handles all leap years correctly. See table for additional explanation. Table 4. Century bits examples CB[0] CB[1] Leap year? Example (1) 0 0 Yes 2000 0 1 No 2100 1 0 No 2200 1 1 No 2300 1. Leap year occurs every 4 years (for years evenly divisible by 4), except for years evenly divisible by 100. The only exceptions are those years evenly divisible by 400. (The year 2000 was a leap year, year 2100 is not.) 22/62 Doc ID 17576 Rev 1 STLED325 3.11.6 Functional description Initial power-on defaults Upon application of power to the device, the register bits in the RTC initially power-on in the state indicated in table below. Table 5. Initial power-on defaults OSC_ST AFE WDFEn 0 0 0 Initial power-on defaults value of the RTC registers. Note: All other control bits power-up in a default state of 0 unless otherwise specified. Doc ID 17576 Rev 1 23/62 Functional description 3.11.7 STLED325 Programmable display The default display of the RTC time is the 2 MSB digit for hour and the 2 LSB digit for minutes. However, if the MD_HM_MS bit is set, then the RTC display for the digits can be changed according to Table 6. Table 6. 3.11.8 RTC display MD_HM_MS RTC display 10 Date-month 00 Hour-minute (default and recommended) 01 Minute-second 11 Month-date Lookup table with ppm against the calibration register values The lookup table of the calibration register values for the equivalent ppm is shown in Table 7 below: Table 7. LUT with ppm against the calibration register values Sign bit 24/62 Counts/bit PPM 0 0 0 0 0 0 0 0 0 0 0 0 1 2 0 0 0 0 1 0 4 0 0 0 0 1 1 6 0 0 0 1 0 0 8 0 0 0 1 0 1 10 0 0 0 1 1 0 12 0 0 0 1 1 1 14 0 0 1 0 0 0 16 0 0 1 0 0 1 18 0 0 1 0 1 0 20 0 0 1 0 1 1 22 0 0 1 1 0 0 24 0 0 1 1 0 1 26 0 0 1 1 1 0 28 0 0 1 1 1 1 31 0 1 0 0 0 0 33 0 1 0 0 0 1 35 0 1 0 0 1 0 37 0 1 0 0 1 1 39 0 1 0 0 0 0 41 0 1 0 0 0 1 43 0 1 0 0 1 0 45 0 1 0 0 1 1 47 Doc ID 17576 Rev 1 STLED325 Functional description Table 7. LUT with ppm against the calibration register values (continued) Sign bit Counts/bit PPM 0 1 1 1 0 0 49 0 1 1 1 0 1 51 0 1 1 1 1 0 53 0 1 1 1 1 1 55 0 1 1 1 0 0 57 0 1 1 1 0 1 59 0 1 1 1 1 0 61 0 1 1 1 1 1 63 1 0 0 0 0 0 0 1 0 0 0 0 1 -4 1 0 0 0 1 0 -8 1 0 0 0 1 1 -12 1 0 0 1 0 0 -16 1 0 0 1 0 1 -20 1 0 0 1 1 0 -24 1 0 0 1 1 1 -28 1 0 1 0 0 0 -33 1 0 1 0 0 1 -37 1 0 1 0 1 0 -41 1 0 1 0 1 1 -45 1 0 1 1 0 0 -49 1 0 1 1 0 1 -53 1 0 1 1 1 0 -57 1 0 1 1 1 1 -61 1 1 0 0 0 0 -65 1 1 0 0 0 1 -69 1 1 0 0 1 0 -73 1 1 0 0 1 1 -77 1 1 0 0 0 0 -81 1 1 0 0 0 1 -85 1 1 0 0 1 0 -90 1 1 0 0 1 1 -94 1 1 1 1 0 0 -98 1 1 1 1 0 1 -102 1 1 1 1 1 0 -106 1 1 1 1 1 1 -110 1 1 1 1 0 0 -114 1 1 1 1 0 1 -118 1 1 1 1 1 0 -122 1 1 1 1 1 1 -126 Doc ID 17576 Rev 1 25/62 Functional description 3.12 STLED325 Remote control decoder The remote control (RC) decoder module decodes the signal coming from IR_IN pin. The IR remote control protocols recognized by STLED325 are Philips-RC-5, RCMM, Thomson RCA, R2000, NEC and R-STEP protocols. The selection of remote control protocol to use is done by setting the RC protocols register. The command from the remote control is used to wake-up from standby and resume normal operation. All RC keys can be programmed to act like RC hotkeys. Upon receiving any one of the designated hotkeys, wake-up operation begins. The address of the appliance (8-bit) is stored first into the internal RAM. Then, the command for the hotkeys is programmed into the internal RAM. Each hotkey memory address could accommodate one byte (8-bit). Usually one byte is reserved for one command. The hot-keys can be configured to wake-up the system by more than one RC device address (up to a maximum of 8 device addresses). 3.13 Interrupt The STLED325 interrupts the Host by pulling the IRQ_N pin to a low-level both in normal mode of operation and during wake-up. The interrupt is enabled by STLED325 when any of the conditions occur: – Front panel key press in normal operation or during system standby state – Remote control key press in normal operation or during system standby state (including the toggle bit changes for all RC protocols) – A low-to-high on the external pin, WAKE_UP – Real time clock triggers (alarm, watchdog timer, 32 kHz oscillator fails) – GPIO input changes – Low battery indication – Thermal shutdown The IRQ_N is an active low level signal and is cleared only after the Interrupt buffer is read. After reading the interrupt buffer, the Host will know the actual source of the interrupt. This allows the Host to exactly know the event which caused the interrupt (e.g STBY key on the Front Panel). The interrupt signal is used to inform the Host of any events detected by the STLED325. Note that the IRQ_N pin is an open-drain pin which requires an external pull-up resistor. Figure 9. Interrupt The interrupt output is of active low level type. 26/62 Doc ID 17576 Rev 1 STLED325 Functional description While the interrupt is being read by the MCU and a new GPIO or key data comes in, no new interrupt is generated but the register for GPIO and KEY data is updated so that the MCU does not miss the new KEY and GPIO data. 3.14 Ready The STLED325 supports cutting-off power to the main board for standby operation for good power management. STBY will be set to high when the READY transitions from high to low. During a cold boot up or wake up from standby, if the READY pin stays low, the STLED325 will assert the STBY when the guard timer has finished counting down to 0. When the READY drops to a low, MUTE goes high immediately and soon after (2µs minimum) the STBY is asserted. In the normal mode of operation, when READY is a high, the STBY is asserted only when the guard timer is enabled and has finished counting down to 0. This is meant to put the system into stand-by as the READY pin was stuck at high and the guard timer register was not cleared before it finished counting down to 0. It is advised to disable the guard timer during normal operation. 3.15 Mute The MUTE pin will be set to logic high to mute the audio output before power is cut to the host processor. In wake up mode, the MUTE pin will be set to logic low to enable the audio output immediately after the high assertion of the READY pin. In general, MUTE follows READY pin with an inverted polarity. This pin is used to prevent pop-up sound during powerup and power-down states. 3.16 GPIO The STLED325 supports 2 additional GPIOs that can be configured as inputs or outputs. As an input, the GPIO can be used to interface to a sensor or a switch or key and as an output, the GPIO can be used to drive individual indicator LEDs. 3.17 Power sense circuits The STLED325 has a built-in power sense circuit which detects power failures and automatically switches to the battery or super-cap supply when a power failure occurs. The energy needed to sustain the SRAM and clock operations can be supplied by small lithium button supply or a super-cap when a power failure occurs. When operating from the battery or super-cap, all the inputs and outputs are driven to a known state (generally L). Doc ID 17576 Rev 1 27/62 Functional description STLED325 Figure 10. Power sense circuit For the STLED325 itself, there is the normal operational mode where the supply is from the 5 V VCC. When the VCC drops below a pre-defined low level, the supply source is switched from the VCC to the battery or super-cap supply. To conserve power and maintain long battery life in this battery supply mode, only the RTC and the clock to the RTC remain operational. 1. The system will only go into battery mode while: Vcc < 3.5 V and Vcc < Vbat. So, it means that the system will only switch to battery mode when Vcc drop below 3.5V and Battery voltage is higher VCC voltage. 2. The system will enter back into Vcc mode from battery mode while: VCC > Vbat It means that the system will switch back to Vcc mode as soon as the VCC is higher than Vbat. The STLED325 continually monitors Vcc for an out-of-tolerance condition. Should VCC fall below the Switchover voltage (VSO = 3.5 V), the device goes into a low-power mode. Inputs to the device will not be recognized at this time to prevent any erroneous data or outcome from device. The device also automatically switches over to the battery and powers down into an ultra low current mode of operation to maximize the super-cap or battery duration. As system power returns and VCC rises above Vbat, the battery or super-cap is disconnected and the power supply is switched to the external VCC. During the battery or super-cap backup mode, the clock registers of RTC are maintained by the attached battery or super-cap. On power-up, when VCC returns to a nominal value, write protection continues for tREC (refer to timing diagram in later part of spec). Upon power-up, the device switches from battery to VCC when VCC > Vbat. When VCC rises above Vbat, it will recognize the inputs. 28/62 Doc ID 17576 Rev 1 STLED325 Functional description Figure 11. Circuit The minimum operating voltage of STLED325 is 2.5 V with a typical VBAT voltage of VCCVF (diode). Therefore, the typical delta voltage swing across the capacitor is ΔV = VCC – VF – VCCmin where VF is approximately 0.5 V. Therefore, ΔV = 5 – 0.5 – 2.5 = 2 V Since the typical battery current (IBAT) is limited to 7 µA, the capacitance and duration of power-out time can be calculated using the formula: I = CΔV/Δt Where I = 7µA, ΔV=2V, C= capacitance in Farads and Δt is power-out time in seconds. Using a 0.1F super-cap, for example, the equation would be: 7µA = 0.1F x 2V/Δt Solving for Δt, the typical power-down time is about 28,571 seconds = 8 hours. 3.17.1 Switchover During the period the VCC falls, in order for the battery switchover circuit to work reliably, the fall time of VCC from 5V to 0V should be at least 100µs. This is to allow the comparator to trigger and switch from VCC to VBAT mode should there be a need. During the VCC rise period from 0V to 5V, the rise time of VCC is not critical. This is indicated by the Figure 12. Figure 12. Battery switchover waveform Also note that for battery operation, there will be a current spike of 5mA in 10us into the battery when VCC to VBAT switchover happens. From VBAT to VCC switching, the current Doc ID 17576 Rev 1 29/62 Functional description STLED325 spike is very low into the battery. The battery must be protected against such spikes. This is not relevant for super-cap. During the switching from VBAT to VCC, the I2C is active after a minimum of 5ms. 3.17.2 Battery low warning The STLED325 automatically performs battery voltage monitoring upon power-up. If the interrupt for this condition (ABE) is enabled, the RTC will generate an interrupt pulse if the battery voltage is found to be less than a minimum of 2.5V. However, this condition is unlikely to go away very quickly as time is needed for the battery to be replaced, and it is not desirable to keep issuing an interrupt. Therefore when this bit is set, this condition is checked once every week. If the condition is still true, then interrupt is sent again. The ABE bit is an enable bit for battery status check. If the ABE bit was set and the battery low is generated during a power up sequence, this indicates that the battery is below approximately 2.5 V and may not be able to maintain data integrity. At this point, a fresh battery needs to be installed or the super-cap recharged. This situation only occurs when a battery is used but not with a super-cap as the super-cap re-charges when the supply is present. 3.17.3 Different power operation modes The device is capable to support the different power modes as shown in the Table 8. Table 8. 30/62 Different power operation modes VCC VBAT Condition Operation Present Present VCC > VBAT Normal operation of chip from VCC Present Absent (Float or 0V) VCC > VBAT and VCC > 3.5V Normal operation of chip from VCC until VCC is 3.5V Absent (Float or 0V) Present VBAT > 2.5V Chip operations from VBAT in a low power mode of operation VCC < 3.5V VBAT > VCC Absent (Float or 0V) Absent (Float or 0V) Doc ID 17576 Rev 1 Chip operations from VBAT in a low power mode of operation VCC < 3.5V and VBAT < 2.5V Chip does not function. Completely shutdown. STLED325 3.18 Functional description Bus characteristics The bus is intended for communication between different ICs. It consists of two lines: a bidirectional data signal (SDA) and a clock signal (SCL). Both the SDA and SCL lines must be connected to a positive supply voltage (typical voltage is 3.3 V) via a pull-up resistor (typical value is 10 K). The following protocol has been defined. - Data transfer may be initiated only when the bus is not busy. - During data transfer, the data line must remain stable whenever the clock line is High. - Changes in the data line, while the clock line is High, will be interpreted as control signals. Accordingly, the following bus conditions have been defined: Bus not busy: Both data and clock lines remain High. Start data transfer: A change in the state of the data line, from high to Low, while the clock is High, defines the START condition. Stop data transfer: A change in the state of the data line, from Low to High, while the clock is High, defines the STOP condition. Data valid: The state of the data line represents valid data when after a start condition, the data line is stable for the duration of the high period of the clock signal. The data on the line may be changed during the Low period of the clock signal. There is one clock pulse per bit of data. Each data transfer is initiated with a start condition and terminated with a stop condition. The number of data bytes transferred between the start and stop conditions is not limited. The information is transmitted byte-wide and each receiver acknowledges with a ninth bit. By definition a device that gives out a message is called “transmitter,” the receiving device that gets the message is called “receiver.” The device that controls the message is called “master.” The devices that are controlled by the master are called “slaves.” Acknowledge: Each byte of eight bits is followed by one Acknowledge Bit. This Acknowledge Bit is a low level put on the bus by the receiver whereas the master generates an extra acknowledge related clock pulse. A slave receiver which is addressed is obliged to generate an acknowledge after the reception of each byte that has been clocked out of the master transmitter. The device that acknowledges has to pull down the SDA line during the acknowledge clock pulse in such a way that the SDA line is a stable Low during the High period of the acknowledge related clock pulse. Of course, setup and hold times must be taken into account. A master receiver must signal an end of data to the slave transmitter by not generating an acknowledge on the last byte that has been clocked out of the slave. In this case the transmitter must leave the data line High to enable the master to generate the STOP condition. Note: Refer to Philips I2C specification or contact STMicroelectronics for more information on I2C. Doc ID 17576 Rev 1 31/62 Functional description Table 9. Pin description Pin number Symbol Type Name and function 1 MUTE OUT Output from the STLED325 to gracefully mute the audio before entering standby mode 2 IRQ_N OUT Interrupt output (active low level type) to interrupt the MCU under various conditions 3 GPIO0 IN/OUT GPIO0 that can be configured as an input or output 4 GPIO1 IN/OUT GPIO1 that can be configured as an input or output 5 IR_IN IN 6 SDA IN/OUT 7 SCL IN 8 WAKE_UP Input Wake-up pin (can be used for wake-up on detecting a low to high transition). AV wake-up or CEC wake-up. 9 DIG5 OUT Digit output pin. Can be used in conjunction with 8 segment outputs to control 8 discrete LEDs on the front panel. 10 - 13 DIG4 –DIG1 OUT Digit output pins 14 VCC PWR 5.0 V ± 10% main supply voltage. Bypass to GND through a 0.1 µF capacitor as close to the pin as possible. 15, 16 KEY2-KEY1 IN 17 - 24 SEG8/KS8 to SEG1/KS1 OUT 25 ISET IN 26 VBAT Input 27 VREG Output 28 GND PWR 29 XIN IN 30 XOUT OUT Output of the external crystal. Open when external clock 31 STBY OUT Hardware pin to control the power to the Host 32 READY IN EPAD 32/62 STLED325 Remote control data input I2C compatible serial data I/O I2C compatible serial clock input Input data to these pins from external keyboard are latched at end of the display cycle (maximum keyboard size is 8 x 2). 5V digital input. Segment output pins (dual function as key source) Current sense input. Connect resistor to ground to set constant current through LEDs. Connect to GND through a resistor to set the peak segment current. Battery power supply for the RTC when there is no supply to the chip 1.8V regulator output. Connect to an external capacitor. Connect this pin to system GND Connect to an external crystal or apply external clock Input to the device from the Host to indicate that Host is ready Exposed pad. Connect to PCB GND. Doc ID 17576 Rev 1 STLED325 Electrical ratings 4 Electrical ratings 4.1 Absolute maximum ratings (TA = 25 °C, GND = 0 V) Absolute maximum ratings are those values above which damage to the device may occur. Functional operation under these conditions is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. All voltages are referenced to GND. Table 10. Symb ol Absolute maximum ratings (TA = 25 °C, GND = 0 V) Value Uni t Supply voltage to ground -0.5 to +7.0 V VI Logic input voltage (KEY1, KEY2 inputs) -0.5 to +7.0 V VI Logic input voltage (all input pins except KEY1, KEY2) -0.5 to +3.6 V PD Power dissipation1 1200 mW TA Operating ambient temperature -40 to 85 °C TJ Junction temperature 150 °C TSTG Storage temperature -65 to +150 °C 300 °C -2 to +2 kV VCC Parameter Lead temperature (10 sec) TL VESD Electrostatic discharge voltage on all pins2 Table 11. Human body model Thermal data Symbol Parameter QFN 32 Unit RTj-c Thermal resistance junction-case TBD °C/W Doc ID 17576 Rev 1 33/62 Electrical ratings STLED325 4.2 Recommended operating conditions 4.2.1 DC electrical characteristics (TA = -40 to +85 °C, VCC = 5.0 V ± 10%, GND = 0 V) Table 12. DC electrical characteristics Symbol Parameter Min Typ Max Uni t VCC External supply voltage 4.5 5.0 5.5 V VREG Internal logic supply voltage and regulator output 1.62 1.8 1.98 V VIH HIGH level input voltage (all digital pins except KEY1 and KEY2) High level guaranteed 1.35 1.98 V VIL LOW level input voltage (all digital pins except KEY1 and KEY2) Low level guaranteed 0 0.45 V VIH HIGH level input voltage (KEY1 and KEY2 pins) High level guaranteed 3 5.5 V VIL LOW level input voltage (KEY1 and KEY2 pins) Low level guaranteed 0 2 V VIN = VIH or VIL -2 2 µA IIH, IIL Input current (all pins) VHYS Hysteresis voltage (digital pins) VOL Low level output voltage (Digital output pins) IOLEAK 0.2 Driver leakage current V IOL2 = 4 mA 0.4 V Drivers off -150 µA ISEG Segment drive LED sink current VLED = VF = 2.5 V VDIGIT = VCC – 1.0 -30 -40 -50 mA IDIG Digit drive LED source current VDIGIT = VCC – 1.0 240 320 400 mA ±4.0 % ITOLSEG RSET 34/62 Test conditions Segment drive current matching VCC=5.0 V, TA=25°C VLED=2.5V; LED current = 40 mA External current setting reference resistor (precision = ±1% tolerance) Doc ID 17576 Rev 1 ISEG = 40 mA 360 Ω STLED325 4.3 Electrical ratings Power consumption estimation Each port of the STLED325 can sink a maximum current of 40 mA into an LED with a 3.4 V forward voltage drop when operated from a supply voltage of 5.0 V. The minimum voltage drop across the internal LED drivers is thus 5.0 - 3.4 = 1.6 V. The STLED325 can sink 8 x 40 = 320 mA when all outputs are operating as LED segment drivers at full current. On a 5.0 V supply, a STLED325 dissipates (5.0 V-3.4 V) x 320 mA = 512 mW when driving 8 of these 3.4 V forward voltage drop LEDs at full current. If the application requires high drive current, consider adding a series resistor to each LED to drop excessive drive voltage offchip. If the forward voltage of the LED is lesser than 4.4 V (say 2.4 V), then the maximum power dissipation of STLED325 when all segments are turned on will be (5 - 2.4) V x 320 mA = 832 mW. To lower the power dissipation, consider adding a small series resistor in the supply. Another alternative is to in-crease the value of the RSET to lower the current of the LEDs from 40 mA to say 30 or 20 mA. The efficiency will be the power consumption in the LEDs divided by the input power consumed. Equation 1 Efficiency = Vdiode x Idiode / VCC x ICC As an example, consider LED with forward voltage of VF = 2.4 V, Ipeak = 40 mA, VCC (max) = 5.5 V, N=number of segments=8(max), D=duty cycle=15/16, Power dissipation, PD (max) = 5 mA x 5.5 V + (5.5-2.4) V x (15/16) x 40 mA x 8 = 27.5 + 780 = 807.5 mW. To lower this value, add a series resistor with the supply. Table 13. Voltage drop estimation with RGB LED LED Typical forward voltage VF Typical current Red 2.2 V 40 mA 5V Green 2.5 V 40 mA Blue 3V 40 mA External VF Segment driver drop 1V 2.2 V 1.8 5V 1V 2.5 V 1.5 5V 1V 3V 1V Typical supply Digit driver voltage drop Note that the above analysis is for a typical condition. If the VF is higher and the supply voltage is lower than 5V, then it is recommended to operate the LED at a lower current than 40mA in order to have enough headroom for the digit and segment drivers so as not to affect the brightness and matching. Table 14. Capacitance (TA = 25°C, f = 1 MHz) Symbol Parameter Test conditions CIN Input capacitance (all digital pins) Doc ID 17576 Rev 1 Min Typ Max Unit 15 pF 35/62 Electrical ratings STLED325 Power supply characteristics (TA = -40 to 85°C) Table 15. Symbol Parameter Test conditions ICC Operating power supply current ICC(Q) Quiescent supply current ) Table 16. 36/62 Typ Max Unit All blocks of chip ON except that no display load VCC = 5.5V TBD mA Display OFF VCC = 5.5V 2 mA Dynamic switching characteristics (TA = -40 to +85 °C, VCC = 5.0V ± 10%, GND=0.0V, Typical values are at 25°C) Symbol Note: Min Parameter Min Typ Max Units 400 kHz fSCL SCL clock frequency tLOW Clock low period 1.3 µs tHIGH Clock high period 600 ns 0 tR SDA and SCL rise time 300 ns tF SDA and SCL fall time 300 ns tHD:STA START condition hold time (after this period the first clock pulse is generated) 600 ns tSU:STA START condition setup time (only relevant for a repeated start condition) 600 ns tSU:DAT Data setup time* 100 ns tHD:DAT Data hold time 0 µs tSU:STO STOP condition setup time 600 ns tBUF Time the bus must be free before a new transmission can start 1.3 µs trec Watchdog output pulse width 96 98 ms The transmitter must internally provide a hold time to bridge the undefined region (300ns max) of the falling edge of the SCL. Doc ID 17576 Rev 1 STLED325 Electrical ratings Table 17. Timing characteristics (TA = -40 to +85 °C, VCC = 5.0 V ± 10%, GND=0.0 V, typical values are at 25 °C) Parameter Propagation delay time Symbol Min Typ Max Unit tPLZ 300 ns tPZL 100 ns tTZH1 2 µs tTZH2 0.5 µs tTHZ 120 µs CI 15 pF Rise time Fall time Input capacitance Mute active to standby active TM-S GPIO edge to interrupt trigger Tirq 2 Test conditions CLK -> SDA CL = 15 pF, RL = 10 kΩ Seg1 to Seg12 CL = 300 pF Grid1 to Grid8, Seg13/Grid16 to Seg20/Grid9 CL = 300 pF, Segn, Dign µs 8 Doc ID 17576 Rev 1 µs 37/62 Electrical ratings 4.4 STLED325 Oscillator and crystal characteristics Table 18. Oscillator characteristics Symbol Parameter Conditions Min VSTA Oscillator start voltage ≤10 seconds 1.5 tSTA Oscillator start time VCC = 3.0 V CL1 CL2 Typ Max Unit V 1 s XIN 25 pF XOUT 25 pF +20 Ppm IC-to-IC frequency variation(1) -20 1. Reference value. TA = 25 deg C, VCC = 3.0 V, CFM-145 (CL = 6 pF, 32.768 KHz) manufactured by Citizen. Table 19. Crystal electrical characteristics Symbol Parameter Conditions Min Typ fo Resonant frequency(1) 32.768 Rs Series resistance(2) 35 CL Load capacitance 12.5 Max Unit KHz 40(3) kΩ pF 1. Externally supplied. ST recommends the Citizen CFS-145 (1.5 x 5 mm) and the KDS DT-38 (3 x 8 mm) for thru-hole, or the KDS DMX-26S(3.2x8mm) for surface-mount, tuning fork-type quartz crystals. KDS can be contacted at kouhou@kdsj.co.jp or http://www.kdsj.co.jp. Citizen can be contacted at csd@citizenamerical.com or http://www.citizencrystal.com 2. Circuit board layout considerations for the 32.768KHz crystal of minimum trace lengths and isolation from RF generating signals should be taken into account. Note: 38/62 1 Oscillator is not production tested. 2 Externally supplied. ST recommends the Citizen CFS-145 (1.5 x 5 mm) and the KDS DT-38 (3 x 8 mm) for thru-hole, or the KDS DMX-26S(3.2x8mm) for surface-mount, tuning forktype quartz crystals. KDS can be contacted at kouhou@kdsj.co.jp or http://www.kdsj.co.jp Citizen can be contacted at csd@citizen-americal.com or http://www.citizencrystal.com 3 Circuit board layout considerations for the 32.768KHz crystal of minimum trace lengths and isolation from RF generating signals should be taken into account. 4 Guaranteed by design. Doc ID 17576 Rev 1 STLED325 4.5 Electrical ratings ESD performance Table 20. ESD performance Symbol Parameter Test conditions ESD MIL STD 883 method 3015 (all pins) HBM Table 21. Typ Max ±2 Unit kV Battery range and battery detect Symbol Parameter VBAT(1) Battery supply voltage IBAT Min Conditions Min Typ Max Unit 2.5 3 3.5(2) V 7 10 uA TA= 25 C, Battery supply current VCC= 0 V, Oscillator ON, VBAT=3 V 1. STMicroelectronics recommends the RAYOVAC BR1225 or BR1632 (or equivalent) as the battery supply. 2. For rechargeable back-up, VBAT(max) may be considered VCC. Figure 13. Power down/up mode ac waveforms Table 22. Power down/up AC characteristics Symbol Parameter (1)(2) Min tpD SCL and SDA at VIH before power down 0 ns trec SCL and SDA at VIH after power-up 10 µs Typ Max Unit 1. VCC fall time should not exceed 5mV/µs. 2. Valid for ambient operating temperature: TA=-40 to 85, VCC = 2.5V to 5.5V (except where noted) Table 23. Power down/up trip points DC characteristics Symbol Parameter(1)(2) VSO Battery back-up switchover voltage (from VCC to VBAT) VCC < 3.5V and VCC < VBAT V VSO Battery back-up switchover voltage (from VBAT to VCC) VCC > VBAT V Doc ID 17576 Rev 1 Min Typ Max Unit 39/62 Electrical ratings STLED325 1. All voltages are referenced to GND. 2. Valid for ambient operating temperature: TA=-40 to 85, VCC = 2.5V to 5.5V (except where noted) Table 24. Symbol TSD THYS Thermal shutdown characteristics(1) Parameter Conditions Typ Max Unit Thermal shutdown threshold VCC=5V 140 Deg C Hysteresis VCC=5V 15 Deg C 1. Thermal shutdown is not production tested. Figure 14. VCC characteristics 40/62 Min Doc ID 17576 Rev 1 STLED325 5 Display RAM address and display mode Display RAM address and display mode The display RAM stores the data transmitted from an external device to the STLED325 through the serial interface. The addresses are as follows, in 8-bits unit: Table 25. Bit map for segment 1 to segment 8 Seg1 Seg4 Seg8 10 HL 10 HU Dig1 11 HL 11 HU Dig2 12 HL 12 HU Dig3 13 HL 13 HU Dig4 14 HL 14 HU Dig5 b0 b3 b4 XX HL b7 XX HU “0” in memory means GND on outpu; ‘1” in memory means VCC on output. Doc ID 17576 Rev 1 41/62 KEY matrix and key-input data storage RAM 6 STLED325 KEY matrix and key-input data storage RAM The key matrix is of 8x2 configuration, as shown below: Figure 15. KEY matrix and key-input data storage RAM The data of each key are stored as illustrated below, and are read by the appropriate read command, starting from the least significant bit. Key 1 Key 2 Key 1 Key 2 Key 1 Key 2 Key 1 Key 2 Seg1 KS1 Seg2 KS2 Seg3 KS3 Seg4 KS4 Seg5 KS5 Seg6 KS6 Seg7 KS7 Seg8 KS8 b0 b1 b2 b3 b4 b5 b6 b7 All the front panel keys can be configured as hot keys using the “configuration mode setting command”. Alternatively, any number of keys out of 16 keys can be programmed for hot key functions by using the hot-key setting command. It is recommended to read the hot key values immediately upon STBY de-assertion. If they are not read within the guard preset timer value, the hot key data are cleared. It is recommended to have 10 KΩ pull down resistors on the KEY1 and KEY2 input pins and the output SEG/KS pins can see a maximum load of 300pF. This load condition is important for the key dis-charge cycle time. 42/62 Doc ID 17576 Rev 1 STLED325 7 Commands Commands A command sets the display mode and status of the LED driver. The first 1 byte input to the STLED325 through the SDA pin after the slave address is regarded as a command. If slave address is not transmitted before the commands/data are transmitted, the commands/data being transmitted are invalid (however, the commands/data already transmitted remain valid). 7.1 Configuration mode setting command This command initializes the STLED325 and performs any one of the following functions: i) Selects the duty factor (1/8 to 1/16 duty factor). When this command is executed, display is turned off. To resume display, the display ON command must be executed. If the same mode is selected, nothing is performed. ii) Selects the remote control protocol to use. iii) Sets the guard timer. The guard timer is configurable from 1 to 15s or turned off completely. iv) Sets the guard timer action to perform when the guard timer counts. Two actions are allowed: no action or set STBY to high level. MSB 0 LSB 0 b5 b4 b3 b2 b1 b0 Bits b7-b6 = 00 is decoded as a configuration mode setting command. The subsequent bits are de-coded as follows: b5: enables wake-up from the external WAKE_UP pin b4: enable for the display configuration setting change (number of digits) b3: allows display of RTC (during normal or STBY modes) b2: enables all RC keys as hot-keys b1: enables all FPK keys as hot-keys b0: enables the Guard Timer to issue STBY once the timer expires Note: When displaying the RTC during normal mode, if the µP is writing data to STLED325 using I2C bus, the RTC display on LED momentarily turns off. The first byte after the configuration command is in the following format: MSB b7 LSB b6 b5 b4 B3 b2 b1 b0 Remote control protocol setting (bits b6-b4) 000: RC Disabled (default) Doc ID 17576 Rev 1 43/62 Commands STLED325 001: Philips RC-6 (optional only enabled for Philips) 010: Philips RC-5 011: Philips RCMM 100: NEC 101: R-STEP 110: Thomson R2000 111: Thomson RCA When b7=‘0’, incoming RC data is output on SDA in decoded format where the Device Address, Start Bit, Toggle Bit and Data Bits are sent. Note that the default location is 0x00 for the first device address. This order of the bits sent is in the same format as the incoming RC data. When b7=‘1’, incoming raw data (no header information) is output on SDA. Address decoding is still performed to decode the corresponding RC protocol. The format of the data on SDA corresponds to the format of the respective RC frame. For details, refer to the RC protocol section of the datasheet. GUARD TIMER SETTING (bits b3-b0) 0000: Turned off (guard timer disabled) 0001: 1 seconds 0010: 2 seconds 1111: 15 seconds The second byte after the configuration command is in the following format: MSB b7 LSB b6 b5 b4 b3 b2 b1 b0 7-Segment display mode setting (bits b1-b0) 00: 1 digit, 8 segments (Digit 1 pin output is enabled) 01: 2 digits, 8 segments (Digit 1 and Digit 2 pin outputs are enabled) 10: 3 digits, 8 segments (Digit 1, Digit 2 and Digit 3 outputs are enabled) 11: 4 digits, 8 segments (Digit 1, Digit 2, Digit 3 and Digit 4 outputs are enabled) b2: configuration for the digital outputs of the chip b2 = 1 will enable the outputs of the chip to be push pull type to 1.8V b2 = 0 will enable the outputs of the chip to be open-drain (can be externally pulled up to 3.3V) b3: configuration for the GPIO0 44/62 Doc ID 17576 Rev 1 STLED325 Commands b3 = 0 enables the GPIO0 as input b3 = 1 enables the GPIO0 as output b4: configuration for the GPIO1 b4 = 0 enables the GPIO1 as input b4 = 1 enables the GPIO1 as output b5 = interrupt enable register bit for GPIO (applies to both GPIO0 and GPIO1) b5 = 0 disables the interrupt generation from any of the two GPIOs b5 = 1 enables the interrupt generation from any of the two GPIOs inputs change b6 = configuration of the edge trigger for GPIO0 (works only when b5 is enabled) b6 = 0 sends interrupt when GPIO0 triggers from a high to a low b6 = 1 sends interrupt when GPIO0 triggers from a low to a high b7 = configuration of the edge trigger for GPIO1 (works only when b5 is enabled) b7 = 0 sends interrupt when GPIO1 triggers from a high to a low b7 = 1 sends interrupt when GPIO1 triggers from a low to a high The minimum pulse width for a valid GPIO detection must be 8us minimum. Upon power application, the following modes are selected: Display mode setting: the 4-digit, 8-segment mode is selected (default: display off and keyscan on). Remote control protocol setting: RC-5. Guard timer setting: turned on with 10s. After the first command is processed by STLED325, the guard timer is turned off until it is turned on by the host. Guard timer action: Issue Standby. Doc ID 17576 Rev 1 45/62 Commands 7.2 STLED325 Data setting command This command sets the data-write and data-read modes. MSB LSB 0 Description: 1 b5 b4 b3 b2 b1 b0 Bits b7-b6 = 01 is decoded as a data setting command. The subsequent bits are decoded as follows: b5 b4 = 00: data write command (see bits b1-b0) b5 b4 = 01: data write 1 command (see bits b1-b0) b5 b4 = 10: data read 1 command (see bits b1-b0) b5 b4 = 11: data read 3 command (see bits b1-b0) b3: clear the guard timer (no change in guard time) b2: when set to a 1, the guard timer is forced to enable and starts the count again. While in normal mode, the count starts Table 26. Data write command. b5 b4: 00 b1-b0 00 Write memory (display or RTC) – Address range: 0x00-0x0F. Start address pointer location is 0x00. 01 Write memory (display). Address range: 0x10-0x13. Start ad-dress pointer location is 0x10. 10 Write memory (discrete LED). Address: 0x14. 11 Write data into GPIOs if they are configured as outputs (see note 1) Note 1: The following byte with MSB7 and MSB6 corresponds to GPIO[1:0] for data to be written into GPIO1 and GPIO0 when they are configured as outputs. Figure 16. Data write command (b7 b6) for GPIO MSB LSB MSB7 MSB6 GPIO1 GPIO0 RSVD RSVD RSVD RSVD RSVD RSVD When b7 is 1, it drives logic 1 on GPIO1 output and when it is 0, it drives logic 0 on GPIO1 output. When b6 is 1, it drives logic 1 on GPIO0 output and when it is 0, it drives logic 0 on GPIO0 output. 46/62 Doc ID 17576 Rev 1 STLED325 Commands Table 27. Data Write 2 command. B5 b4: 01 B1-b0 00 Reserved 01 Reserved (RC6 disable) 10 Reserved (RC6 enable) 11 Enter standby mode Any subsequent data bytes in this case will be ignored. Table 28. Data Read 1 command. b5 b4: 10 b1-b0 00 Read Key (following 2 bytes will contain key data) 01 Read GPIO register (following 1 byte will contain the GPIO data with MSB7: GPIO1 data and MSB6: GPIO0 data). This is the input monitor for GPIO[1:0] for reading purpose. When b7 of subsequent byte is low, it means that GPIO1 input is low and when it is high, it means that GPIO1 input is high. When b6 of subsequent byte is low, it means that GPIO0 input is low and when it is high, it means that GPIO0 input is high. 10 Read RC data (following four bytes are the address + command bytes from RC) 11 Read Interrupt status register (refer to the Interrupt Flag section for detailed description) Table 29. Data Read 2 command. b5 b4: 11 b1-b0 00 Reserved 01 Read configuration byte values (see section on configuration bytes) 10 Read LED display memory 11 Read RTC memory. Address command must be issued prior to reading. On power application, the normal operation mode and address increment mode is set with the default display memory address set to 0x10 (start of display memory address location). Refer to the display memory section. In the auto increment address mode, the address command is sent once followed by the data bytes. Alternatively, the data command can be sent followed by the data bytes. In this case, when new display data is to be written, the last value of the address will be used and then incremented. Upon reaching the last display memory address, the address jumps to 0x10, as it represents the first address location of the display memory. Doc ID 17576 Rev 1 47/62 Commands STLED325 In fixed address mode, the address command has to be sent followed by the display data. When next byte of data is to be written, address command has to be sent again before new display data byte. When the user wants to read the RTC data from the specified memory location of RTC, the user must first set the address of the RTC location using “Address Setting Command” after which send the “Read RTC Register” command. If the address pointer was located in the display memory location and user issues a “Read RTC Register” command without sending the “Address Setting Command”, the RTC data is read from the address location of the previous value of the RTC address pointer. Thus before reading the RTC register data, the user must set the proper address for RTC using “Address Setting Command”. Prior to writing data to the RTC registers, the address of the RTC must be set using the Address Setting command. Else, if the address pointer happens to be pointing at the LED display memory, then the data will be written to the address location of the previous value in the RTC address pointer. This is vice-versa true for the LED display memory. 7.3 Configuration data Up to a maximum of 5-bytes are sent from LSB to MSB as configuration data. The 29-bytes represent the following configuration information: MSB (b7) LSB (b0) Byte1 B7 B6 Decoded/Raw RC setting B5 B4 B3 RC Protocol setting B2 B1 B0 Guard timer setting Byte 2 B7 Interrupt config for GPIO1 B6 Interrupt config for GPIO0 B5 B4 B3 B2 Interrupt enable config for GPIOs GPIO1 configuration (input or output) GPIO0 configuration (input or output) Digit 5 discrete LED config B1 B0 7-segment LED display configuration setting Byte 3 B7 B6 Not used B5 B4 B3 For display enable B2 B1 B0 For display dimming setting Byte 4 Front Panel Hot Key Bank 1 Byte 5 Front Panel Hot Key Bank 2 On power application, the normal operation mode and address increment mode is set with the default display memory address set to 0x10 (start of display memory address location). Refer to the display memory section. In the auto increment address mode, the address command is sent once followed by the data bytes. Alternatively, the data command can be sent followed by the data bytes. In this case, when new display data is to be written, the last value of the address will be used and then 48/62 Doc ID 17576 Rev 1 STLED325 Commands incremented. Upon reaching the last display memory address, the address jumps to 0x10, as it represents the first address location of the display memory. In fixed address mode, the address command has to be sent followed by the display data. When next byte of data is to be written, address command has to be sent again before new display data byte. When the user wants to read the RTC data from the specified memory location of RTC, the user must first set the address of the RTC location using “Address Setting Command” after which send the “Read RTC Register” command. If the address pointer was located in the display memory location and user issues a “Read RTC Register” command without sending the “Address Setting Command”, the RTC data is read from the ad-dress location of the previous value of the RTC address pointer. Thus before reading the RTC register data, the user must set the proper address for RTC using “Address Setting Command”. Prior to writing data to the RTC registers, the address of the RTC must be set using the Address Setting command. Else, if the address pointer happens to be pointing at the LED display memory, then the data will be written to the address location of the previous value in the RTC address pointer. This is vice-versa true for the LED display memory. 7.3.1 Interrupt flags The interrupt is sent on the IRQ_N pin when any one of the event occurs (FP key pressed, RC key pressed or preset value of RTC/guard timer is triggered or activity on WAKE_UP pin or GPIO pins). Simultaneously, the interrupt flags are set. The micro-processor can read the interrupt flags by send-ing the read interrupt flag register command. The following 16-bit data is read by the processor after sending this command. This enables the microprocessor to know what caused the interrupt to occur. If the host sees an interrupt issued from first byte, it is not necessary to read the second byte. Figure 17. Interrupt bit mapping in Byte 1 Byte 1: MSB &0+ LSB 2#+ '0)/;= '0)/;= &0 HOTKEY DURING WAKE UP 20 HOTKEY DURING WAKE UP 4HERMAL SHUT DOWN "ATTERYLOW !-6 Doc ID 17576 Rev 1 49/62 Commands STLED325 Figure 18. Interrupt bit mapping in Byte 2 Byte 2: MSB LSB 2ESERVED 24# WATCHDOG TIMER 24# ALARM 24# FAIL 7AKE UP PIN 7ATCHDOG /SCILLATOR ,TO( TIMER OR(TO, b7-b4 = Normal operation 24#ALARM 24# FAIL /SCILLATOR b3-b0=Wake up operation !-6 In the normal mode of operation, when any FP or RC key is pressed or when alarm/watchdog is triggered, the STLED325 sets the flags in the above interrupt flag register and asserts the IRQ_N pin. The data which caused the interrupt to assert remains in the buffer until it is changed by another key-press. It is up to the micro processor to issue the read interrupt command to ascertain what caused the interrupt. If the micro processor does not issue the interrupt within a specific time, the old data is lost and only the latest data is reflected in the Interrupt Flag register. In the standby mode of operation, only the hot-key will cause the interrupt flag to be set and the IRQ_N pin will be asserted. The micro processor should then read the interrupt to know what caused the wake-up operation before proceeding with the normal data communication or asserting STBY again if there is no action to be performed. Upon the first read of the hotkey data, the data in the buffer is cleared. When the b4 of the above interrupt flag is set, then the µP should read the address 0x0F from the RTC register space to determine if the alarm was triggered. Only after determining this, the interrupt flag is cleared and the IRQ_N pin de-asserted. The IRQ_N pin will only be de-asserted once the interrupt flags have been read. The chip will continue to send the interrupt periodically (approximately every 40us) to the main Host chip if the oscillator is down signifying to the Host chip that the frequency is out of spec. 7.4 Address setting command This command sets an address of the display memory or the address of the RTC register map. MSB 1 LSB 1 x b4 b3 b2 b1 b0 The address range from 00h-0Fh represents the RTC register map. For writing data to RTC registers, initially the address command is sent followed by the RTC data. 10h-14h represents the 7-segment and discrete LED display correspondence. On power application, the address is set to 10h. In the auto-increment mode, when the address reached 0x14, the next ad-dress will be 0x10. 50/62 Doc ID 17576 Rev 1 STLED325 7.5 Commands Display control and hotkey setting command 1 0 b5 b4 b3 b2 b1 b0 Bits b7-b6 = 10 is decoded as a display control and hotkey setting command. The subsequent bits are decoded as follows: b5 = 0: sets display control for dimming setting as shown in the table below. Display control and dimming setting when b5 = 0 b3.b0: sets dimming quantity. 0000: sets pulse width to 1/16. 0001: sets pulse width to 2/16. 0010: sets pulse width to 3/16. 0011: sets pulse width to 4/16. 0100: sets pulse width to 5/16. 0101: sets pulse width to 6/16. 0110: sets pulse width to 7/16. 0111: sets pulse width to 8/16. 1000: sets pulse width to 9/16. 1001: sets pulse width to 10/16 (default and recommended) 1010: sets pulse width to 11/16. 1011: sets pulse width to 12/16. 1100: sets pulse width to 13/16. 1101: sets pulse width to 14/16. 1110: sets pulse width to 15/16. 1111: sets pulse width to 16/16. Figure 19. Blanking time b4: Turns on/off display Doc ID 17576 Rev 1 51/62 Commands STLED325 0: Display off (keyscan continues) 1: Display on When b5 = 1, the decoding is based on bits b1-b0 as illustrated below: b1 b0 = 01: IR hot-key configuration of ADR and DATA. After this 3 bytes are sent which are in the form ADR+DATA to configure the hot-key for a particular device address. A maximum of 8 hot keys can be configured from a single device address or 4 hot-keys from two device addresses and so on. If more than 24 bytes in the form of ADR+DATA are sent, then the pointer moves back to the first ADR+DATA location. b1 b0 = 10: FP hot-key configuration. Any of the 16 keys can be configured as hot-keys. 2 bytes of key data command are sent following this command to configure the front-panel hotkeys. b4, b3 b2: Reserved b1b0: 00 or 11 are treated as invalid commands and subsequent data bytes are ignored. Remote control hot keys when b5 = 1 b1 b0: 01 Following 8-bit is sent to indicate the address for RC and subsequent 16-bit indicates the RC hot key value itself. So a total of 3 bytes are sent for one hot-key configuration. A total of 24 bytes are re-served for RC hot key configuration. Note that the customer code is programmable for the RC hotkey for both RCMM and R-STEP RC protocol. Front Panel Hot Keys when b5 = 1 b1 b0: 10 Front panel hot keys can be configured by sending 2 bytes of key data to configure any key as hot-key from any of the 2 banks. Any number of keys can be configured as hot-keys. When input key code matches any one of the predefined key codes stored in the internal RAM, the STLED325 de-asserts the STBY output. 52/62 Doc ID 17576 Rev 1 STLED325 7.6 Commands Keyscanning and display timing Figure 20. Keyscanning and display timing Grid Outputs DIG1 DIG2 DIG3 DIGn ----------- Key Scan DIG1 tDISP=500us SEG1 SEG2 t=1/16 of tDISP SEG3 SEGn tFRAME=tDISP * (n+1) n = number of digits AM04168V1 The value is fixed by the internal clock from the oscillator. One cycle of keyscanning consists of one frame, and data of 8x2 matrices are stored in the RAM. Note that the keyscan is only at the end of the frame when the display is ON. When the display is OFF, the keyscan takes place continuously. The grid/digit is turned off during the keyscan. Doc ID 17576 Rev 1 53/62 State STLED325 8 State 8.1 Default state upon power-up Table below shows the default state of the STLED325 upon power-up. Table 30. Power-up defaults Serial number 8.2 Function Default state 1 Display OFF 2 Key-scan ON 3 IR Disabled 4 Display mode 8 segment/1 digit 5 Display address 10H with address increment mode 6 RC protocol Disabled 7 Dimming 10/16 duty factor 8 Hot keys (IR and FP) Disabled 9 Guard timer 10s Initial state On power application, the 10/16-pulse width is set and the display shows the value configured in the LED display RAM before entering the standby mode. Thus if TUNE is required to be shown on the LED upon wake-up, then the user must write the corresponding digit and segments locations in the LED display memory before going into the standby mode of operation. The value of the display changes only after user configuration. If the user wishes to display the RTC value during standby, then the user must configure the STLED325 by sending the appropriate command. If the user does not configure the STLED325 to display the RTC in standby, the LED shows the same value as was written previously in the LED display memory location. Note that all the hot keys are disabled on power-up. Only the hot-keys (FP or RC) can be detected to wake-up the system from standby condition. 54/62 Doc ID 17576 Rev 1 STLED325 9 Remote control protocols Remote control protocols Contact STMicroelectronics for more information on RC protocols or refer to separate document (TBD). Doc ID 17576 Rev 1 55/62 Application information STLED325 10 Application information 10.1 Power supply sequencing Proper power-supply sequencing is advised for all CMOS devices. It is recommended to always apply VCC before applying any signals to the input/output or control pins. 10.2 ISET variation with RSET The graph of ISET variation with RSET is shown in Figure 21. Figure 21. Rext versus Iseg curve 56/62 Doc ID 17576 Rev 1 STLED325 Application diagram C2 R3 GND R2 R1 VBAT VREG C1 G P IO 2 Figure 22. Application schematic G P IO 1 10.3 Application information C reg VCC W A K E _U P IR Q _N D IG 5 S TB Y READY M ain C P U SCL SDA M U TE IR rem ote control sensor C L1 LE D 4 -D igit 7 -segm ent (+ dot -point) S T LE D 325 IR _IN XI XO IS E T RSET GND C rystal (32.768K H z) 4 D IG 1-D IG 4 D isplay panel S E G 1/K S 1 -S E G 8/K S 8 W ith som e individual LE D s D1 D2 D3 D4 D5 D6 D7 D8 K E Y 1-K E Y 2 R4 C L2 R5 K eyscan (8x2 m atrix) GND AM08725V1 Resistors: RSET = external resistor for current setting R1 = 1-10 KO SDA external pull-up resistor R2 = 1-10 KO SCL external pull-up resistor R3 = 1-10 KO IRQ_N external pull-up resistor R4-R5 = 10 KO external key-matrix pull-down resistors Capacitors: C1 = 33 µF (25 V) electrolytic C2 = 0.01-0.1µF (25V) ceramic Creg=0.1 uF CL1 = CL2 = 25pF Diodes D1-D8 = 1N4148 Supply voltage VCC = 5 V ± 10% Doc ID 17576 Rev 1 57/62 Package mechanical data 11 STLED325 Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK is an ST trademark. Table 31. QFN32 (5 x 5 mm) mechanical data Millimeters Symbol Min Typ Max A 0.80 0.90 1.00 A1 0 0.02 0.05 A3 0.20 b 0.18 0.25 0.30 D 4.85 5.00 5.15 D2 3.35 3.45 3.55 E 4.85 5.00 5.15 E2 3.35 3.45 3.55 e L 0.50 0.30 ddd 58/62 0.40 0.50 0.08 Doc ID 17576 Rev 1 STLED325 Package mechanical data Figure 23. QFN32 package dimensions Doc ID 17576 Rev 1 59/62 Package mechanical data STLED325 Figure 24. QFN32 carrier tape 60/62 Doc ID 17576 Rev 1 STLED325 12 Revision history Revision history Table 32. Document revision history Date Revision 27-Apr-2011 1 Changes Initial release. Doc ID 17576 Rev 1 61/62 STLED325 Please Read Carefully: Information in this document is provided solely in connection with ST products. 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The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners. © 2011 STMicroelectronics - All rights reserved STMicroelectronics group of companies Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Philippines - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America www.st.com 62/62 Doc ID 17576 Rev 1