SM8133BW

SM8133B White LED Driver IC OVERVIEW The SM8133B is a charge pump type white LED driver. It can drive 1 to 6 backlight white LED connected in parallel and 1 flash white LED. The output voltage circuit has a 3.0V LDO (Low Dropout Regulator), making the device ideal for camera-equipped cellular phones. The charge pump switches between ×1 to ×1.5 boost mode in response to LED drive current requirements to extend battery life to the maximum. The boost switching occurs in response to the drive current of all the connected LED and thus supports variations in LED forward-bias voltage drop (VF). Each LED drive current is controlled by a 7-channel LED drive current control circuit. The 6 backlight channels can be subdivided into 2 groups, with each group having independent dimming and lighting control. The backlight grouping, backlight LED drive current and ON/OFF control, flash LED drive current and ON/OFF control, and LDO output ON/OFF control are all set by 3-wire serial interface data input. Also, the RESETB pin can be connected to the microcontroller supply for a system-wide shutdown function. FEATURES I I I I I I I I I I I Noise reduction due to charge pump boost circuit Automatic charge pump switching to conserve power Drives 1 to 6 backlight white LED (30mA/ch at maximum setting) Drives a flash white LED (150mA at maximum setting) Backlight and flash white LED brightness adjustment Group settings for 2-group backlight lighting control 3-wire serial input interface for all setting and control 3.0V output LDO circuit built-in Shutdown function by RESETB pin Soft start circuit built-in Thermal protection circuit built-in I I I I I I I I I I I Input voltage range • No-load current (IOUT = 0mA): 2.7 to 4.6V • Load current (IOUT = 80mA): 3.0 to 4.6V • Load current (IOUT = 200mA): 3.3 to 4.6V Quiescent current • LDO only: 0.3mA (typ) • Not -switching (×1.0 mode): 0.5mA (typ) • Switching (×1.5 mode): 2.5mA (typ) Standby current: 0.01µA (typ) Operating frequency: 750kHz (typ) Backlight LED current: 30mA/ch (typ) Flash LED current: 150mA (typ) All LED total maximum current: 200mA (typ) Backlight LED current matching (ILED = 30mA) : ± 3% Flash LED current accuracy (ILED = 150mA) : ± 5% LDO (Low Dropout Regulator) output voltage : 3.0V ± 2% Packages: 20-pin QFN WL-CSP (under development) APPLICATIONS I I I I ORDERING INFORMATION Device SM8133BB SM8133BW Package 20-pin QFN WL-CSP Cellular phone Digital still camera PDA Portable games SEIKO NPC CORPORATION —1 SM8133B PACKAGE DIMENSIONS (Unit: mm) QFN-20 4.20 ± 0.20 4.00 ± 0.10 4.20 ± 0.20 4.00 ± 0.10 20 1 0.50 0.60 ± 0.10 0.05 0.22 ± 0.05 0.05 M 1.00MAX WL-CSP (under development) Top view Bottom view 0.48 ± 0.03 0.68 ± 0.03 B D C B A 12345 2.56 ± 0.03 0.4 + 0.03 0.02 − 0.02 20 − φ0.2 ± 0.03 A 0.22 2.56 ± 0.03 0.09 ± 0.007 0.55 ± 0.02 φ0.05 M S AB S 0.08 ± 0.03 0.4 0.06 S SEIKO NPC CORPORATION —2 SM8133B PINOUT (Top view) QFN-20 SDA SCK RESETB VOUT LDOUT WL-CSP (under development) 15 14 13 12 11 EN DIN7 DIN6 DIN5 GND 16 17 18 19 20 12345 10 9 8 7 6 VIN C2P C2M C1M C1P D C B A 54321 PIN DESCRIPTION Number Name QFN-20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 WL-CSP D1 C1 B1 B2 A2 A1 A3 B3 B4 A4 A5 B5 C5 C4 D5 D4 C3 D3 D2 C2 DIN4 DIN3 DIN2 DIN1 PGND C1P C1M C2M C2P VIN LDOUT VOUT RESETB SCK SDA EN DIN7 DIN6 DIN5 GND O O O O – – – – – – O O I I I I O O O – LED drive current control output 4 (connect to ground when not used) LED drive current control output 3 (connect to ground when not used) LED drive current control output 2 (connect to ground when not used) LED drive current control output 1 (connect to ground when not used) Charge pump ground connection Charge pump capacitor connection 1P Charge pump capacitor connection 1M Charge pump capacitor connection 2M Charge pump capacitor connection 2P Voltage supply LDO output (leave open circuit when not used) LED drive voltage output Reset signal input (internal reset when RESETB is LOW) Serial data clock input Serial data input Serial interface enable input LED drive current control output 7 (connect to ground when not used) LED drive current control output 6 (connect to ground when not used) LED drive current control output 5 (connect to ground when not used) Ground I/O Description DIN4 DIN3 DIN2 DIN1 PGND SEIKO NPC CORPORATION —3 SM8133B BLOCK DIAGRAM C1M C1P C2M C2P VIN Charge pump 1/ 1.5 VOUT Mode control & Output voltage control & Protection Current control & Under current detector DIN1 DIN2 DIN3 DIN4 DIN5 DIN6 Thermal shut down RESETB SCK SDA EN Control logic DIN7 LDO 3V & Protection LDOUT GND PGND SEIKO NPC CORPORATION —4 SM8133B SPECIFICATIONS Absolute Maximum Ratings GND = PGND = 0V Note. The device may suffer breakdown if any one of these parameter ratings is exceeded. Parameter Supply voltage range Input voltage range Output voltage range VOUT output current LDO output current Power dissipation Junction temperature Storage temperature range Symbol VIN VEN, VSCK, VSDA VDIN1 to 7 VOUT IOUT ILDO PD TJMAX Tstg Rating −0.3 to 5.5 –0.3 to VIN + 0.3 –0.3 to VIN + 0.3 5.5 500 200 1429 (Ta = 25°C)*1 +125 −55 to +125 Unit V V V V mA mA mW °C °C *1. When mounted on a 34 × 40 × 1.6mm glass epoxy board, the power dissipation is related to the operating temperature by the following equation. I I I Maximum junction temperature: TMAX = 125°C Operating temperature: Ta [°C] Thermal resistance: θJ = 70°C/W Power dissipation [mW] 1600 1429 1200 1143 857 800 571 PD = (TMAX − Ta) θJ 400 0 25 35 45 55 65 75 85 Operating temperature [°C] Recommended Operating Conditions GND = PGND = 0V Rating Parameter Pin Symbol VIN1 Supply voltage range VIN VIN2 VIN3 Input voltage range Ambient temperature range EN, SCK, SDA, RESETB − VES Ta Conditions min ×1.0 mode, IOUT = 0mA ×1.5 mode, IOUT = 80mA ×1.5 mode, IOUT = 200mA Each logic-level pin 2.7 3.0 3.3 0 −30 typ 3.6 3.6 3.6 − − max 4.6 4.6 4.6 VIN +85 V V V V °C Unit SEIKO NPC CORPORATION —5 SM8133B Electrical Characteristics DC Characteristics GND = PGND = 0V, VIN = 3.6V, Ta = 25°C unless otherwise noted. Rating Parameter Standby current Pin VIN Symbol ISTB IDD1 Quiescent current VIN IDD2 IDD3 Maximum output voltage Maximum output current Operating frequency Internal circuit power-ON reset time*1 Soft start time LED drive pin leakage current LED drive current matching LED maximum drive current 1 LED drive pin voltage 1 LED maximum drive current 2 LED drive pin voltage 2 LDO output voltage LDO maximum output current LDO input stability LDO load stability LDO overcurrent protection circuit operating current Thermal protection circuit operating temperature*1 Thermal protection circuit hysteresis*1 VOUT VOUT C1M VIN DIN1 to 7 DIN1 to 7 DIN1 to 6 DIN1 to 6 DIN1 to 6 DIN7 DIN7 LDOUT LDOUT LDOUT LDOUT LDOUT – – EN, SCK, SDA, RESETB EN, SCK, SDA, RESETB VOUT IOUT fOSC TPOR TSS ILEAK1 to 7 ∆ILED ILED1 to 6 VDIN1 to 6 ILED7 VDIN7 VLDO ILDO ∆VOUT1 ∆VOUT2 IOS TSD TSDHYS VIH VIL VIHYS IIL IIH Standby mode LDO-only operating, no load ×1.0 mode, no load ×1.5 mode, no load ×1.5 mode VOUT maximum voltage ×1.5 mode ×1.5 mode switching frequency Time from when power is applied until internal circuit reset Time between EN signal falling edge and LED turning ON Standby mode, VDIN1 to 7 = 5.0V ×1.0 mode, matching between channels with ILED1 to 6 maximum setting ×1.0 mode, ILED1 to 6 maximum setting ILED1 to 6 maximum setting ×1.5 mode, ILED7 maximum setting IDIN7 maximum setting VIN = 3.6V, ILDO = 100mA VIN = 3.0V, VLDO = 2.85V 3.3V ≤ VIN ≤ 4.6V, ILDO = 30mA VIN = 3.6V, 10µA ≤ ILDO ≤ 80mA VIN = 3.6V Not in test mode Not in test mode HIGH-level input voltage range LOW-level input voltage range Hysteresis voltage width EN = SCK = SDA = RESETB = VIN EN = SCK = SDA = RESETB = GND Condition min – – – – 4.8 200 650 – – – –3.0 27.0 80 142.5 225 2.94 100 – – 120 – – 1.8 – – – –1.0 typ 0.01 0.3 0.5 2.5 5.0 – 750 0.02 1.3 0.01 – 30.0 120 150.0 300 3.00 – – – 230 180 20 – – 0.3 – – max 1.00 0.7 1.0 4.0 5.2 – 850 0.10 3.0 1.00 +3.0 33.0 150 157.5 375 3.06 – 1.0 100 360 – – – 0.6 0.5 1.0 – µA mA mA mA V mA kHz ms ms µA % mA mV mA mV V mA %/V mV mA °C °C V V V µA µA Unit Logic-level input voltage Logic-level input current *1. Design guaranteed value SEIKO NPC CORPORATION —6 SM8133B AC Characteristics GND = 0V, VIN = 3.6V, Ta = 25°C unless otherwise noted. Rating Parameter SCK clock cycle SCK HIGH-level pulse width SCK LOW-level pulse width EN setup time EN hold time EN recovery time Write data setup time Write data hold time Symbol tSCK tWH tWL tCS tCH tCR tDS tDH Condition min 2000 800 800 1000 800 1000 600 600 typ – – – – – – – – max DC – – – – – – – ns ns ns ns ns ns ns ns Unit EN tCS SCK tWH tSCK tDH tWL tCR tCH tDS SDA Data input timing diagram SEIKO NPC CORPORATION —7 SM8133B VOUT EFFICIENCY 100 90 VOUT power efficiency [%] 80 VF = 3.2V VF = 3.4V VF = 3.6V VF = 3.8V 70 60 50 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 VIN [V] Efficiency of PIN vs. POUT Backlight LED × 6pcs, ILED1 to 6 = 20mA, Flash LED × 1pc, ILED7 = 0mA, IOUT = 120mA, ILDO = 0mA 100 90 VOUT power efficiency [%] 80 VF = 3.2V VF = 3.4V VF = 3.6V VF = 3.8V 70 60 50 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 VIN [V] Efficiency of PIN vs. POUT Backlight LED × 3pcs, ILED1 to 6 = 15mA, Flash LED × 1pc, ILED7 = 0mA, IOUT = 45mA, ILDO = 0mA SEIKO NPC CORPORATION —8 SM8133B 100 90 VOUT power efficiency [%] 80 VF = 3.2V VF = 3.4V 70 VF = 3.6V VF = 3.8V 60 50 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 VIN [V] Efficiency of PIN vs. POUT Backlight LED × 6pcs, ILED1 to 6 = 20mA, Flash LED × 1pc, ILED7 = 80mA, IOUT = 200mA, ILDO = 0mA 100 90 VOUT power efficiency [%] 80 VF = 3.2V VF = 3.4V 70 VF = 3.6V VF = 3.8V 60 50 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 VIN [V] Efficiency of PIN vs. POUT Backlight LED × 3pcs, ILED1 to 6 = 15mA, Flash LED × 1pc, ILED7 = 150mA, IOUT = 195mA, ILDO = 0mA SEIKO NPC CORPORATION —9 SM8133B 100 90 VOUT power efficiency [%] 80 VF = 3.2V 70 VF = 3.4V VF = 3.6V VF = 3.8V 60 50 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 VIN [V] Efficiency of PIN vs. POUT Backlight LED × 6pcs, ILED1 to 6 = 20mA, Flash LED × 1pc, ILED7 = 80mA, IOUT = 200mA, ILDO = 100mA 100 90 VOUT power efficiency [%] 80 70 VF = 3.2V VF = 3.4V VF = 3.6V VF = 3.8V 60 50 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 VIN [V] Efficiency of PIN vs. POUT Backlight LED × 3pcs, ILED1 to 6 = 15mA, Flash LED × 1pc, ILED7 = 150mA, IOUT = 195mA, ILDO = 100mA SEIKO NPC CORPORATION —10 SM8133B FUNCTIONAL DESCRIPTION Serial Interface The SM8133B uses a 3-wire serial interface to control each setting. Input data on SDA is input MSB first in an 8 clock pulse cycle structure, with the first 4 cycles of data setting the mode and the next 4 the corresponding mode data. Data bits on SDA are read as received data on the rising edges of the SCK clock after EN goes HIGH. Only the leading 8 bits on SDA are read after EN goes HIGH and all subsequent input data bits are ignored, but the received data is reflected in SM8133B operation with timing almost simultaneous with the EN falling edge. Conversely, if less than 8 bits are input on SDA, the data is ignored to prevent incorrect operation. All registers are write-only, and their status cannot be read. After power is applied, an internal power-ON reset circuit initializes all registers to logic level LOW in standby mode. However, the possibility exists that there may be insufficient reset time, depending on the VIN input voltage rise time and fall time, so reset mode (0H or EH) should be expressly invoked after power is applied. There is no restriction in the input sequence when setting parameters. However, since the parameters are set in the same order as the data input sequence and the time taken from LED ON/OFF data input to LED dimming data input can exceed the soft start time, it is highly advisable to enter the LED dimming data first. The charge pump circuit, that supplies the LED drive voltage, starts whenever any parameter in address 5H (LED ON register) is set to 1, with the LED drive voltage output on VOUT. Conversely, when all parameters in address 5H are set to 0, all other parameter data settings input after reset are retained in standby mode. The serial interface pins EN, SDA, CSK, and RESETB are CMOS inputs, thus the input voltage on VIN must be a logic-level voltage and should not be left open circuit (floating). Control Data Mode selection data M1 MSB M2 Data 1 M3 Data 2 M4 Data 3 D1 Data 4 D2 Data 5 Setting data D3 Data 6 D4 LSB EN SCK SDA M1 M2 M3 M4 D1 D2 D3 D4 Control data input sequence I Mode selection Mode data Mode M1-M2-M3-M4 Mode data Mode M1-M2-M3-M4 0H Reset L-L-L-L 5H LED ON L-H-L-H 1H Grouping L-L-L-H 6H System settings L-H-H-L 2H A group dimming L-L-H-L EH Reset H-H-H-L 3H B group dimming L-L-H-H FH Serial input test H-H-H-H 4H DIN7 dimming L-H-L-L Other NPC test − SEIKO NPC CORPORATION —11 SM8133B Mode data “0H”: Reset register Mode data “EH”: Reset register Setting data High Low D1 D2 All system data reset System standby D3 D4 Reset mode is selected if EN goes LOW 4 clock cycles after 0H or EH mode select data is input, regardless of when power is applied or the parameter set data bits. When reset mode is selected, all data input previously is reset, thus grouping, dimming, and control data must be reentered. Mode data “1H”: Grouping register Setting data High Low D1 LED3 = B group LED3 = A group D2 LED4 = B group LED4 = A group D3 LED5 = B group LED5 = A group D4 LED6 = B group LED6 = A group LED1 and LED2 are always assigned to A group. When a setting data bit is LOW, A group is selected. When HIGH, B group is selected. Mode data “2H”: A group dimming register Mode data “3H”: B group dimming register Mode data “4H”: DIN7 dimming register Setting data 0H 1H 2H 3H 4H 5H 6H 7H 8H 9H AH BH CH DH EH FH D1 Low Low Low Low Low Low Low Low High High High High High High High High D2 Low Low Low Low High High High High Low Low Low Low High High High High D3 Low Low High High Low Low High High Low Low High High Low Low High High D4 Low High Low High Low High Low High Low High Low High Low High Low High Selected dimming value 0/15 1/15 2/15 3/15 4/15 5/15 6/15 7/15 8/15 9/15 10/15 11/15 12/15 13/15 14/15 15/15 D1 to D4 setting data bits control the each group LED current in 15 steps. See “LED drive current”. SEIKO NPC CORPORATION —12 SM8133B Mode data “5H”: LED ON register Setting data High Low D1 A group ON A group OFF D2 B group ON B group OFF D3 DIN7 ON DIN7 OFF D4 LDO ON LDO OFF This register controls the A group, B group, DIN7, and LDO ON/OFF state. Each state is ON when the corresponding bit is HIGH, and OFF when LOW. Each circuit starts when the corresponding bit in address 5H is set HIGH, transferring from standby mode. It is recommended that these 4 data settings be held LOW when possible to control current consumption. Mode data “6H”: System register Setting data High Low D1 A group maximum current = 15mA A group maximum current = 30mA D2 B group maximum current = 15mA B group maximum current = 30mA D3 DIN7 maximum current = 75mA DIN7 maximum current = 150mA D4 − − Note. Target values only. Current rating accuracy is not guaranteed. This register sets the maximum current drive for each group. For A and B group, LOW sets 30mA as the maximum, HIGH sets 15mA. For DIN7, LOW sets 150mA, HIGH sets 75mA as the maximum. LED drive current (Hexadecimal) A group Dimming register value 0H 1H 2H 3H 4H 5H 6H 7H 8H 9H AH BH CH DH EH FH A group max. current = 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 A group max. current = 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 B group B group max. current = 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 B group max. current = 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 DIN7 max. current = 0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 DIN7 DIN7 max. current = 1 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 Unit mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA Note. “H”: Hexadecimal Note. Target values only. Current rating accuracy is not guaranteed. SEIKO NPC CORPORATION —13 SM8133B LDO (Low Dropout Voltage Regulator) Operation is controlled using the LDO register (LSB in address “5H”). When the LDO register is set to 1, a regulated stable voltage is output from LDOUT. If the overcurrent protection circuit connected to LDOUT detects a continuous overcurrent condition for approximately 200µs, the LDO output stops and then restarts after a delay of approximately 1.4 seconds. At this point, if an overcurrent condition is detected again, the LDO output stops. If the overcurrent condition is detected a total of 12 successive times (approximately 16.8 seconds), the LDO load is deemed to be abnormal and the LDO output stops completely. The abnormal load condition is released only by selecting reset mode operation. Thermal Shutdown Circuit (Overheating Protection) The thermal shutdown circuit operates whenever the IC temperature exceeds approximately 180°C for whatever reason. VOUT output recommences when the IC temperature falls below approximately 160°C. RESETB Input (Internal Circuit Reset Signal) If the microcontroller, which drives the serial data inputs, stops, the SM8133B logic-level signal inputs are left floating and the SM8133B will most likely not transfer to standby mode normally. However, the RESETB pin can be connected to the microcontroller supply pin, so that the SM8133B is reset automatically whenever the voltage on RESETB drops. A pull-down resistor should be connected between RESETB and GND to avoid a floating RESETB input with voltage applied to the VIN pin. VOUT Output Circuit Mode Switching The SM8133B switches between 3 output states: power-save mode (standby state), ×1.0 mode (VIN through mode), and ×1.5 mode (×1.5 charge pump boost). This automatically adjusts the VOUT output to match the drive LED characteristics and reduces the total power dissipation. Switching to and from ×1.0 and ×1.5 mode occurs automatically in an internal circuit, and cannot be controlled using an external input. Switching to standby mode The internal circuit operating mode switches from ×1.0/×1.5 mode to standby mode when Reset resistor (mode data “0H”, “EH”) was input, suppressing current consumption. SEIKO NPC CORPORATION —14 SM8133B Switching from ×1.0 mode to ×1.5 mode If the LED drive current set by serial interface can be driven without boosting the VIN input voltage, the VOUT output operates in ×1.0 mode. In other words, if sufficient current flows even with the LED forward-direction voltage drop “VF”, then VOUT is less than 5.0V. Operation in the more efficient ×1.0 mode reduces the total power dissipation and extends the battery drive time. And if low “VF” LEDs are used or the LED drive current setting is LOW, the operating time in ×1.0 mode is also extended. 1.0 mode (high efficiency) High VF LED 1.5 mode (low efficiency) 1.0 mode (high efficiency) Low VF LED High VIN input 1.5 mode (low efficiency) Low VOUT mode switching time comparison due to drive LED “VF” variation If the VIN voltage falls or LED drive current set by serial interface increases such that the LED drive current is too low in ×1.0 mode, then the LED drive circuit low-current detector operates, the VOUT output is automatically switched to ×1.5 mode, and the charge pump boosts the output voltage. This occurs even if only one LED low-current condition is detected among the 7-channel LED drive circuits, thus it is recommended that LEDs have small “VF” variation to optimize the total efficiency. VIN input voltage 1.0 1.5 threshold Low ILED detector Low ILED detected (1) VOUT mode (2) 1.0 mode 1.5 mode VOUT output voltage 5.0V (3) VIN voltage drop and VOUT output voltage (1) When VIN falls, VOUT cannot overcome the LED “VF” rating, causing insufficient current flows and the ILED low-current signal becomes active. (2) When the ILED low-current condition is detected, the VOUT output circuit switches to ×1.5 mode (charge pump mode). (3) Prior to switching to ×1.5 mode, the VOUT voltage may be lower than 5.0V but sufficient current is supplied to the LED. If after startup, the LED connected to a DIN pin is switched, the LED connection detector circuit flags an error, and correct mode switching may not occur. If the DIN pin does not control the LED drive current, the low-current detector does not operate and the device cannot switch to ×1.5 mode. SEIKO NPC CORPORATION —15 SM8133B Switching from ×1.5 mode to ×1.0 mode VF increases immediately after the LED current starts to flow, and then decreases as the LED temperature increases due to the heating effect of the current flow. It can take about 10 seconds for the LED temperature to stabilize and for VF to reach equilibrium, and VF may fluctuate more than 200mV. The VF fluctuation is affected by the ambient temperature and LED current setting, and has a large affect on the automatic mode switching voltage tolerances. To counter the effects of VF fluctuation, the SM8133B outputs a mode reset signal once every 1.4 seconds which automatically switches the output mode to ×1.0, and then a determination is made whether to make the ×1.0 → ×1.5 mode switch. 1.4sec/cycle Mode reset (1) VOUT mode (2) 1.5 mode 1.0 mode Mode hold L: hold min 80µs max 200µs ILED detector ignore (3) VOUT output voltage 5.0V (4) Low ILED detector (5) Switching from ×1.5 to ×1.0 mode due to the mode reset signal (1) Mode reset signal is output once every 1.4 seconds. (2) Switching from ×1.5 to ×1.0 mode due to the mode reset signal pulse. (3) The mode hold time of 200µs (max) starts when output switches to ×1.0 mode. During this interval, the mode is not switched even if an ILED undercurrent condition is detected. (4) If VIN is low, the VOUT voltage momentarily drops because the boost function stops as a result of switching to ×1.0 mode. (5) The ILED undercurrent signal is ignored during the mode hold time, and the mode only switches in response to the detector output after the mode hold time expires. SEIKO NPC CORPORATION —16 SM8133B For example, if the VIN voltage is low and the VOUT output voltage in ×1.0 mode does not provide sufficient drive current, then the mode reset will cause a LED undercurrent condition. The LED undercurrent detector circuit will output an LED undercurrent signal immediately after the switch to ×1.0 mode, but the output will stay in ×1.0 mode and not return to ×1.5 mode for the duration of the mode hold time. Consequently, the VOUT output is not boosted during the 85µs (min) to 200µs (max) mode hold time and the voltage drops and the LED brightness is reduced. However, the LEDs are OFF for a maximum of 200µs only, and this is not discernible to the naked eye and thus is not a problem. 1.0 VIN input voltage 1.5 threshold Mode reset (1.4sec/cycle) Mode hold (H: hold) VOUT mode (H: 1.5, L: 1.0) 1.4sec max 200µS VOUT output voltage Low ILED detector (H: low ILED) 5.0V VOUT drop due to the mode reset single SEIKO NPC CORPORATION —17 SM8133B STARTUP SEQUENCE After power is applied to the SM8133B or when a reset input occurs (active-LOW input on RESETB or reset register mode setting), the internal power-ON reset circuit initializes all registers to their default value of 0. Consequently, all required data for LED drive operation must be input using the serial interface. The registers can be addressed in arbitrary sequence. Note that the registers are set in the same sequence as they are addressed. Example 1. Set LED1 to LED6 to 30mA drive without group setting Set EN HIGH, input “2FH” using the serial interface, set EN LOW (A group current setting 30mA), set EN HIGH, input “58H”, set EN LOW (A group ON), LED1 to LED6 turn ON after the soft start ends. Set A group current: 30mA (2FH) EN 1 SCK 2 3 4 5 6 7 8 1 2 A group ON (58H) 3 4 5 6 7 8 SDA Approx. 30mA ILED1 to 6 Soft start time Example 1 input waveform Example 2. Set LED1 to LED4 to A group, LED5 and LED6 to B group, and individual group brightness Input “13H” using the serial interface (group setting), input “25H” (A group current setting 10mA), input “3AH” (B group current setting 20mA), input “5CH” (A and B groups ON) on successive EN cycles. LED1 to LED6 turn ON after the soft start ends. Set grouping (13H) LED1 to LED4 A group LED5 to LED6 B group EN 1 SCK 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 Set A group current: 10mA (25H) Set B group current: 20mA (3AH) A group, B group ON (5CH) SDA ILED1 to 4 Soft start time Approx. 10mA Approx. 20mA ILED5 to 6 Example 2 input waveform SEIKO NPC CORPORATION —18 SM8133B Example 3. Set LED1 to LED6 to 30mA drive, temporarily turn OFF, turn ON again, and reset using RESETB input without group setting Input “2FH”(A group current setting 30mA) and “58H” (A group ON) from the serial interface. LED1 to LED6 turn ON after the soft start ends. While the LEDs are ON, input “50H” (A group OFF) to turn the LEDs OFF and transfer the SM8133B to standby mode. The internal register setting “2FH” (A group current setting 30mA) data is retained during standby mode, so you need to input “58H” (A group ON) only to turn the LEDs ON again. At this point, the charge pump soft start circuit operates again, taking a soft start time of approximately 1.3ms from when the data is input to when the LEDs turn ON. If RESETB is connected to the microcontroller power supply and the supply goes LOW, the SM8133B is reset, the LEDs turn OFF, and operation transfers to standby mode. RESETB Reset LED mode Reset mode Set A Group current : 30mA (2FH) A group ON (58H) LED ON mode A group OFF (50H) A group ON (58H) Reset mode EN 1 SCK 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 SDA ILED1 to 6 Soft start time Approx. 30mA Soft start time Approx. 30mA Example 3 input waveform SEIKO NPC CORPORATION —19 SM8133B TYPICAL APPLICATION CIRCUIT If the RESETB input is connected to the microcontroller power supply, the SM8133B is reset when microcontroller power supply stops, and operation transfers to standby mode. In circuits where the SM8133B logic-level inputs would become open circuit (floating) when the microcontroller supply stops, pull-down resistors should be connected to each logic-level signal input. C1 1.0µF C1M C1P C2 1.0µF C2M C2P 2.7 to 4.6V VIN C4 2.2µF Battery Charge pump 1/ 1.5 VOUT C3 2.2µF Back Light Max 30mA DIN1 6ch LDO for microcontroller power source Mode control & Output voltage control & Protection Current control & Under current detector DIN2 DIN3 DIN4 DIN5 DIN6 Thermal shut down RESETB VDD Pull down SCK Microcontroller SDA EN Control logic DIN7 Flash Max 150mA Pull down LDO 3V & Protection LDOUT 3V ± 2% (VIN ≥ 3.2V) Max 100mA C5 1.0µF GND PGND Note. If the driving LEDs are less than 7 pcs, the unused DIN pins should be connected to GND. If the LDO is not used, LDOUT pin should be left open circuit. SEIKO NPC CORPORATION —20 SM8133B PERIPHERAL PARTS About the External Capacitors The best capacitors for use with the SM8133B are multi-layer ceramic capacitors. When selecting a multi-layer ceramic capacitor, only X5R and X7R dielectric types are strongly recommended, since the loss of capacitance in various conditions is less than other types such as Z5U and Y5V. The much loss of capacitance in various conditions may cause the output voltage unstable. Table. The EIA three digit "TC" code Lower temperature limit X = −55°C Y = −30°C Z = +10°C High temperature limit 5 = +85°C 6 = +105°C 7 = +125°C 8 = +150°C Maximum allowable capacitance change from + 25°C (0V DC) F = ± 7.5% P = ± 10% R = ± 15% S = ± 22% T = +22%/−33% U = +22%/−56% V = +22%/−82% For example : X5R About the Input Capacitor "C4" The parts layout of PCB may merely cause the “VOUT” output voltage unstable. In this case, increasing the “C4” input capacitance value or adding another capacitor on the VIN input line is effective to solve the unstable output voltage. QFN-20 Package Package corner metals are not IC I/O pins. Don’t connect any lines to these corner metals. Bottom view SEIKO NPC CORPORATION —21 SM8133B FOOTPRINT PATTERN The optimum footprint varies depending on the board material, soldering paste, soldering method, and equipment accuracy, all of which need to be considered to meet design specifications. (Unit: mm) Package QFN-20 HE 4.2 HD 4.2 e 0.5 b3 0.30 ± 0.05 l1 0.20 ± 0.05 l2 0.70 ± 0.05 b3 e HE b3 e l1 l2 l2 l1 HD /2 HD HE /2 SEIKO NPC CORPORATION —22 SM8133B Please pay your attention to the following points at time of using the products shown in this document. The products shown in this document (hereinafter “Products”) are not intended to be used for the apparatus that exerts harmful influence on human lives due to the defects, failure or malfunction of the Products. Customers are requested to obtain prior written agreement for such use from SEIKO NPC CORPORATION (hereinafter “NPC”). Customers shall be solely responsible for, and indemnify and hold NPC free and harmless from, any and all claims, damages, losses, expenses or lawsuits, due to such use without such agreement. NPC reserves the right to change the specifications of the Products in order to improve the characteristic or reliability thereof. NPC makes no claim or warranty that the contents described in this document dose not infringe any intellectual property right or other similar right owned by third parties. Therefore, NPC shall not be responsible for such problems, even if the use is in accordance with the descriptions provided in this document. Any descriptions including applications, circuits, and the parameters of the Products in this document are for reference to use the Products, and shall not be guaranteed free from defect, inapplicability to the design for the mass-production products without further testing or modification. Customers are requested not to export or re-export, directly or indirectly, the Products to any country or any entity not in compliance with or in violation of the national export administration laws, treaties, orders and regulations. Customers are requested appropriately take steps to obtain required permissions or approvals from appropriate government agencies. SEIKO NPC CORPORATION 15-6, Nihombashi-kabutocho, Chuo-ku, Tokyo 103-0026, Japan Telephone: +81-3-6667-6601 Facsimile: +81-3-6667-6611 http://www.npc.co.jp/ Email: sales@npc.co.jp NC0503CE 2006.04 SEIKO NPC CORPORATION —23