Switching Type Regulator SI-3201S External Dimensions (unit: mm) Features ● Output current of 3A (Ta = 25ºC, VIN = 8 to 18V) ● High efficiency of 82% (VIN = 14V, I O = 2A) ● Requires 5 external components only ● Built-in reference oscillator (60kHz) ● Phase internally corrected ● Output voltage internally corrected ● Built-in overcurrent and thermal protection circuits ● Built-in soft start circuit 3.2 ±0.2 4.2 ±0.2 2.8 ±0.2 (17.9) 16.9 ±0.3 7.9 ±0.2 4.0 ±0.2 0.5 10.0 ±0.2 a 2.6 ±0.1 5.0 ±0.6 (2.0) b 0.95 ±0.15 Symbol Ratings Unit +0.2 Input voltage VIN 35 V Output voltage IO 3 A VO, SQ –1 V PD1 22 W With infinite heatsink Stand-alone 0.85 –0.1 Conditions (8.0) Parameter (Ta=25ºC) (4.6) Absolute Maximum Ratings +0.2 –0.1 0.45 SQ terminal voltage with respect to ground 3.9 ±0.7 P1.7 ±0.7 •4 = 6.8 ±0.7 1 2 3 4 1. VIN 2. SWOUT 3. GND 4. VOS 5. SS 5 Power Dissipation PD2 1.8 W Junction temperature Tj –40 to +150 ºC Storage temperature Tstg –40 to +125 ºC Junction to case thermal resistance j-c 5.5 ºC/W Junction to ambient-air thermal resistance j-a 66.7 ºC/W Standard Circuit Diagram SI-3201S 1 VIN Recommended Operating Conditions min typ max Unit C1 Input voltage VIN 8 18 V Output current IO 0.5 3 A Operating temperature Top –40 d +85 ºC VO CQ b e f Conditions L1 2 SW Tr a c Ratings Symbol a: Type No. b: Lot No. (Forming No. 1101) VIN Parameter (4.3) 8.2 ±0.7 D1 + g + 5 SS h C3 GND i 3 Ta—PD characteristics GND Electrical Characteristics Parameter Output voltage (VIN = 14V, I OUT = 2A, Tj = 25ºC unless otherwise specified) Ratings Symbol VO Unit min typ max 4.80 5.00 5.20 V Conditions Line regulation VO LINE 100 mV VIN = 8 to 18V Load regulation VO LOAD 50 mV IO = 0.5 to 3A 60 70 kHz 5 10 mA Efficiency * 1 Oscillation frequency Quiescent circuit current Iq Overcurrent protection starting current IS Soft * 3 start terminal % 82 f OSC Low level voltage VSSL Source current when low I SSL Discharge resistance RDIS 50 A 3.1 15 25 0.2 V 35 µA 4 kΩ IO = 0A *2 VSSL = 0.2V Notes: *1. Efficiency is calculated by the following equation: VO • I O = • 100 (%) VIN • I IN *2. A drooping-type overcurrent protection circuit is built in the IC. *3. An external voltage may not be applied to the soft start terminal. As shown in the diagram to the right, use this IC in the soft start mode with a capacitor or in the open-collector drive mode with a transistor. Leave the soft start terminal open when not using it since it is already pulled up in the IC. GND C1: 1000µF C2: 1000µF L 1: 250µH D1: RK46 (Sanken) a: Internal power supply b: Thermal protection c: Reference oscillator d: Reset e: Latch & driver f : Comparator g: Overcurrent protection h: Error amplifier i : Reference voltage Cautions: (1) A high-ripple current flows through C1 and C2. Use high-ripple type 1000µF or higher capacitors with low internal resistance. Refer to the respective data books for more information on reliability and electrical characteristics of the capacitor. (2) C3 is a capacitor used for soft start. (3) L1 should be a choke coil with a low core loss for switching power supplies. (4) Use a Schottky barrier diode for D1 and make sure that the reverse voltage applied to the 2nd terminal (SQ terminal) is within the maximum ratings (–1V). If you use a fast-recovery diode, the recovery voltage and the ON forward voltage may cause a reversed-bias voltage exceeding the maximum ratings to be applied to the 2nd terminal (SQ terminal). Applying a reversed-bias voltage exceeding the maximum rating to the 2nd terminal (SQ terminal) may damage the IC. (5) The 4th terminal (VS) is an output voltage detection terminal. Since this terminal has a high impedance, connect it to the positive (+) terminal of C2 via the shortest possible route. (6) Leave the 5th terminal (soft start terminal) open when not using it. It is pulled up internally. (7) To ensure optimum operating environment, connect the highfrequency current line with minimum wiring length. SI-3201S 5 SS C3 18 C2 VS 4 SI-3201S 5 SS SI-3201S 5 SS C3 ■ Load Regulation 5.10 5.00 Output voltage VO (V) Io = 0A = 1A = 2A = 3A 4.95 4.90 6 5.10 5 5.05 4 5.00 VIN =18V = 10V = 7V 4.95 4.90 4.85 4.85 0 5 10 15 20 25 30 0 35 0.5 6 80 5 V IN = 18V = 10V = 7V Output voltage VO (V) (%) 90 Efficiency 2.0 2.5 50 40 0.5 1.0 1.5 2 1 0 2 2.0 2.5 3.0 Output current IO (A) 4 6 8 10 Input voltage VIN (V) ■ Overcurrent Protection Temperature Characteristics 6 5 VIN =18V = 10V = 7V 4 3 2 1 4 TC = +100, 25, --20ºC 3 2 1 0 0 0 3 0 3.0 ■ Overcurrent Protection Characteristics ■ Efficiency Curve 60 1.5 Io = 0A = 1A = 2A = 3A Output current IO (A) Input voltage V IN (V) 70 1.0 Output voltage VO (V) Output voltage VO (V) 5.05 ■ Rise Characteristics 5.15 Output voltage VO (V) ■ Line Regulation 0 1.0 2.0 3.0 Output current IO (A) 4.0 5.0 0 1.0 2.0 3.0 4.0 5.0 Output current IO (A) ■ Ta—PD Characteristics 25 With silicone grease Heatsink: aluminum With infinite heatsink Power Dissipation PD (W) 20 15 10 5 0 –40 0 40 80 120 160 Operating temperature Ta (ºC) 19