ST763ABN

ST763A series 3.3V Step down current mode PWM DC-DC converters Features ■ Output voltage 3.3V ■ Supply voltage range from 3.3V to 11V ■ Guaranteed output current: 500mA ■ Typical operation frequency: 200KHz ■ Very low quiescent current: 0.6mA on mode 0.2µA OFF MODE ■ Switch ON/OFF control ■ Typical efficiency: 90% ■ Operating temperature range: -40°C to 85°C ■ Available in SO-8 package Description The ST763A is a step-down switching regulator. It operates from 3.3V to 11V giving a fixed 3.3V output voltage, delivering up to 500mA. The mainly features are typical efficiency of 90%, quiescent current of 0.6mA, and only 0.2µA in shut-down. The PWM current mode control provides precise output regulation and very good transient response. Output voltage accuracy is guaranteed to be ±5% over line, load and temperature SO-8 variations. A minimum number of external components is used and the fixed frequency switching allows easy filtering of output ripple and noise. Other features of this device are cycle-by-cycle current limiting, overcurrent limiting, under voltage lockout and programmable soft-start protection. A 22µH inductor works in most applications, so no sophisticated design is necessary. Package available is SO-8. Typical application are in 5V to 3.3V converters, cellular phones, portable instruments, hand-held computers, and peripherals. Order code May 2007 Part number Packaging ST763AC ST763ACDTR Rev. 3 1/14 www.st.com 14 ST763A series Contents 1 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2/14 ST763A series 1 Diagram Figure 1. Schematic diagram Diagram 3/14 Pin configuration ST763A series 2 Pin configuration Figure 2. Pin connections (top view) Table 1. Pin description Pin N° Symbol Name and function 1 SHDN Shutdown control (active low): If connected to GND the IC is in shutdown. Connect to VCC for normal operation (ON MODE). 2 REF 3 SS Soft start: a capacitor between SS and GND provides soft-start and short-circuit protections. 4 CC Compensation capacitor input: externally compensates the outer (voltage) feedback loop. Connect to OUT with 330pF capacitor 5 OUT Output voltage sense input: provides regulation of feedback sensing. Connect to 3.3V output. 6 GND Ground 7 LX 8 VCC 4/14 Reference output voltage: (1.25V): Bypass to GND with 47nF capacitor. Switch output. Drain of internal P-channel power MOSFET Supply voltage input. Bypass to GND with 1μF ceramic capacitance and large value electrolytic capacitor in parallel. The 1μF capacitor must be as close as possible to the GND and VCC pins. ST763A series Maximum ratings 3 Maximum ratings Table 2. Absolute maximum ratings Symbol Parameter Value Unit -0.3 to 12 V VCC DC input voltage VLX Switch pin voltage -0.3 to (VCC + 0.3) V VSHDN Shutdown voltage (SHDN) -0.3 to (VCC + 0.3) V VS,VC Soft start (SS) and compensation capacitor (CC) pins voltage -0.3 to (VCC + 0.3) V 2 A 2.5 mA 344 mW -40 to +150 °C 0 to +70 °C ILX Switching peak current IREF Reference current PTOT Continuous power dissipation at TA = 70°C Tstg Storage temperature range Top Operating junction temperature range SO-8 AC series Note: Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied Table 3. Thermal data Symbol RthJA Parameter Thermal resistance junction-ambient (1) SO-8 Unit 160 °C/W 1. This value depends from thermal design of PCB on which the device is mounted. 5/14 Typical application 4 Typical application Figure 3. Application circuit 6/14 ST763A series ST763A series Electrical characteristics 5 Electrical characteristics Table 4. Electrical characteristics (VCC = 5V, IO = 0mA, TA = TMIN to TMAX, unless otherwise specified). Symbol Parameter VCC Input voltage VO Output voltage ΔVO Line regulation ΔVO Load regulation η Power efficiency ISUPPLY Supply current VIH SHDN Input high threshold VIL SHDN Input low threshold ISHDN Shutdown input leakage current VLOCK Under voltage lockout RDS(on) LX On resistance Test conditions Unit 11 V 3.135 3.3 3.465 V VCC = 4.75 to 11V, IO = 0 to 500mA 3.135 3.3 3.465 V IO = 0 to 500mA 0.13 %/V 0.005 %/mA IO = 300mA 88 IO = 100mA 90 ON Mode (Including switch current) 0.6 2.5 mA OFF Mode 0.2 100 μA % 2 V 0.25 V 1 μA 3 V VCC Falling 2.7 ILX = 500mA 1 Ω 10 nA VCC = 12V, VLX = 0V VREF Reference voltage TA = 25°C ΔVREF Temperature reference drift TA = TMIN to TMAX Switching frequency TA = 25°C Compensation pin impedance Max. VCC = 4 to 11V, IO = 0 to 300mA LX Leakage current RC Typ. 3.3 ILEAK fOSC Min. 1.18 1.25 1.32 50 159 200 7500 V ppm/°C 212.5 KHz Ω 7/14 Typical performance characteristics ST763A series 6 Typical performance characteristics Figure 4. (Unless otherwise specified TJ = 25°C) Output voltage vs temperature Figure 5. Output voltage vs input voltage Figure 6. Reference voltage vs temperature Figure 7. Efficiency vs temperature Figure 8. Efficiency vs output current Figure 9. LX leakage current vs temperature 8/14 ST763A series Figure 10. LX ON Resistance vs temperature Typical performance characteristics Figure 11. Shutdown input threshold vs temperature Figure 12. Shutdown input leakage current vs Figure 13. Oscillator frequency vs temperature temperature Figure 14. Oscillator frequency vs input voltage Figure 15. Switching waveform, continuous conduction VI = 6V, IO = 250mA 9/14 Package mechanical data 7 ST763A series Package mechanical data In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a Lead-free second level interconnect. The category of second Level Interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com. 10/14 ST763A series Package mechanical data SO-8 MECHANICAL DATA DIM. mm. MIN. TYP inch MAX. MIN. TYP. MAX. A 1.35 1.75 0.053 0.069 A1 0.10 0.25 0.04 0.010 A2 1.10 1.65 0.043 0.065 B 0.33 0.51 0.013 0.020 C 0.19 0.25 0.007 0.010 D 4.80 5.00 0.189 0.197 E 3.80 4.00 0.150 0.157 e 1.27 0.050 H 5.80 6.20 0.228 0.244 h 0.25 0.50 0.010 0.020 L 0.40 1.27 0.016 0.050 k ddd 8˚ (max.) 0.1 0.04 0016023/C 11/14 Package mechanical data ST763A series Tape & Reel SO-8 MECHANICAL DATA mm. inch DIM. MIN. A MAX. MIN. 330 13.2 TYP. MAX. 12.992 C 12.8 D 20.2 0.795 N 60 2.362 T 12/14 TYP 0.504 22.4 0.519 0.882 Ao 8.1 8.5 0.319 0.335 Bo 5.5 5.9 0.216 0.232 Ko 2.1 2.3 0.082 0.090 Po 3.9 4.1 0.153 0.161 P 7.9 8.1 0.311 0.319 ST763A series Revision history 8 Revision history Table 5. Revision history Date Revision Changes 26-May-2006 2 Add TA row fOSC on table 4 and new template. 29-May-2007 3 Order code has been updated. 13/14 ST763A series Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. 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