1-1-3 DC/DC Converter ICs SI-8400L/8500L Series Separate Excitation Step-down Switching Mode with Coil ■Features ■Lineup • Switching ICs/Coil combined type Part Number SI-8401L SI-8501L VO(V) 5.0 5.0 IO(A) 0.5 1.0 • Requires only 2 discrete components • Low switching noise • No heatsink required • Built-in overcurrent and thermal protection circuits ■Absolute Maximum Ratings • Built-in soft start circuit (Output ON/OFF available)...SI-8500L Series Parameter ■Applications Ratings Symbol DC Input Voltage VIN Power Dissipation PD SI-8400L Unit SI-8500L 35 V 1.25 3 W Junction Temperature Tj +100 °C Storage Temperature Tstg –25 to +85 °C • Telephone power supplies • Onboard local power supplies ■Recommended Operating Conditions Parameter Ratings Symbol Unit SI-8401L DC Input Voltage Range VIN 7 to 33 Output Current Range IO 0 to 0.5 A Operating Temperature Range Top –20 to +85 °C Parameter V Ratings Symbol Unit SI-8501L DC Input Voltage Range VIN 7 to 33 Output Current Range IO 0 to 1.0 V A Operating Temperature Range Top –20 to +85 °C ■Electrical Characteristics (Ta=25°C) Ratings Parameter Symbol SI-8401L min. Output Voltage VO 4.80 Conditions Line Regulation Load Regulation Temperature Coefficient of Output Voltage Switching Ripple Voltage (C2=470µF) Overcurrent Protection Starting Current 5.20 V % VIN=20V, IO=0.3A f 60 Conditions kHZ VIN=20V, IO=0.3A 80 ∆VOLINE Conditions 100 mV VIN=10 to 30V, IO=0.3A 30 ∆VOLOAD Conditions 40 mV VIN=20V, IO=0.1 to 0.4A ∆VO/∆Ta mV/°C ±0.5 20 ∆Vr Conditions IS1 5.00 80 Conditions Oscillation Frequency max. VIN=20V, IO=0.3A η Efficiency Unit typ. 40 mVp-p VIN=20V, IO=0.3A 0.55 Conditions A VIN=10V (Ta=25°C) Ratings Parameter Symbol SI-8501L min. Output Voltage 4.80 Line Regulation Load Regulation Temperature Coefficient of Output Voltage Switching Ripple Voltage (C2=470µF) Overcurrent Protection Starting Current ICs V % 60 Conditions kHZ VIN=20V, IO=0.5A 70 ∆VOLINE Conditions 130 mV VIN=10 to 30V, IO=0.5A 30 ∆VOLOAD Conditions VIN=20V, IO=0.2 to 0.8A ∆VO/∆Ta ±0.5 55 mV mV/°C 45 ∆Vr Conditions Conditions 5.20 VIN=20V, IO=0.5A f IS1 5.00 83 Conditions Oscillation Frequency max. VIN=20V, IO=0.5A η Efficiency 56 VO Conditions Unit typ. VIN=20V, IO=0.5A mVp-p 1.1 VIN=18V A SI-8400L/8500L Series ■External Dimensions (Non-package type [EI-12.5 core/EI-19 core]) (Unit : mm) SI-8400L SI-8500L LIN r VIN y e LIN 26 ±0.1 12±0.5 VIN r w GND 14.5 Not encapsulated in a plastic package Product Mass: Approx. 5.1g ±0.5 (2.17) q w e VOUT SS GND ±0.1 26 Pin1 marking (10.16) (7.62) (2.19) 18 φ 0.8max. Not encapsulated in a plastic package Product Mass: Approx. 14.5g SK 4.7 ±0.6 10±0.2 13.2±0.6 Pin 1 marking 3.7 Vo q φ 0.6 4 2 18 ■Block Diagram SI-8400L SI-8500L 3 4 LIN 4 L1 MIC1 VIN Reg. 1 6 VO VIN Comp. 1 VO Reg. Latch & Drive Reset L1 MIC1 OCP OSC LIN OCP OSC Reset Comp. TSD Latch & Drive TSD Di1 Di1 Amp. Amp. VREF VREF 2 GND 2 S.S. 3 GND ■Typical Connection Diagram VIN 4 VIN SI-8400L GND 2 + C1 220µF VOUT LIN 3 N.C VO 1 + VIN + C1 470µF C2 470µF GND GND VIN SI-8500L 6 S.S 2 GND 3 C3 VOUT LIN 4 VO 1 + C2 470µF N.C GND GND C3 is necessary only for using soft start function. ■Ta-PD Characteristics 3.0 1.5 1.0 0.5 0 0 25 50 75 Ambient Temperature Ta (°C) PD=VO•IO SI-8500L Power Dissipation PD (W) Power Dissipation PD (W) SI-8400L 100 VO : Output voltage IO : Output current ηχ : Efficiency (%) 2.0 1.0 0 0 100 –1 ηχ 25 50 75 100 The efficiency depends on the input voltage and the output current. Therefore, obtain the value from the efficiency graphs and substitute the percentage in the formula above. Ambient Temperature Ta (°C) ICs 57