SI-8000SD_11

1-1-3 DC/DC Converter ICs SI-8000SD Series ■Features • Surface-mount package (TO263-5) • Output current: 3.0A Surface Mount, Separate Excitation Step-down Switching Mode ■Lineup Part Number VO (V) IO (A) SI-8033SD 3.3 3 SI-8050SD 5.0 • High efficiency: 79% typ. (SI-8033SD), 84% typ. (SI-8050SD) • Requires only 4 discrete external components • Internally-adjusted phase correction and output voltage • Built-in reference oscillator (60kHz) • Built-in overcurrent and thermal protection circuits • Output ON/OFF available • Soft start available by S.S pin ■Absolute Maximum Ratings Parameter DC Input Voltage Power Dissipation*2 Junction Temperature Storage Temperature Thermal Resistance (Junction to Case) Thermal Resistance (Junction to Ambient Air) Symbol VIN PD Tj Tstg Ratings 43*1 3 +125 –40 to +125 3 33.3 Unit V W °C °C °C/W °C/W When mounted on glass-epoxy board 40 × 40 mm (copper area: 100%) When mounted on glass-epoxy board 40 × 40 mm (copper area: 100%) Conditions θ j-c θ j-a ■Applications • Power supplies for telecommunication equipment • Onboard local power supplies *1: 35V for SI-8033SD *2: Limited by thermal protection circuit. ■Recommended Operating Conditions Ratings Parameter DC Input Voltage Range Output Current Range* Operating Junction Temperature Range Operating Temperature Range* Symbol VIN1 IO Tjop Top SI-8033SD 5.5 to 28 0 to 3.0 –30 to +125 –30 to +125 SI-8050SD 7 to 40 Unit V A °C °C *: Limited by Ta-PD characteristics. ■Electrical Characteristics Ratings Parameter Symbol min. Output Voltage Efficiency Oscillation Frequency Line Regulation Load Regulation Temperature Coefficient of Output Voltage Overcurrent Protection Starting Current Soft Start Pin* Low-Level Voltage Outflow Current at Low Voltage VO Conditions 3.17 SI-8033SD typ. 3.3 VIN=15V, IO=1A 79 VIN=15V, IO=1A 60 VIN=15V, IO=1A 25 VIN=8 to 28V, IO=1A 10 VIN=15V, IO=0.5 to 1.5A ± 0.5 3.1 VIN=15V 0.2 20 30 40 VSSL=0.2V 20 3.1 VIN=20V 0.2 30 40 30 80 max. 3.43 min. 4.8 SI-8050SD typ. 5.0 VIN=20V, IO=1A 84 VIN=20V, IO=1A 60 VIN=20V, IO=1A 40 VIN=10 to 30V, IO=1A 10 VIN=20V, IO=0.5 to 1.5A ± 0.5 40 100 max. 5.2 (Ta=25°C) Unit V % kHZ mV mV mV/ °C A V η Conditions f Conditions ∆VOLINE Conditions ∆VOLOAD Conditions ∆VO/∆Ta IS1 Conditions VSSL ISSL Conditions µA * Pin 5 is a soft start pin. Soft start at power on can be performed with a capacitor connected to this pin. The output can also be turned ON/OFF with this pin. The output is stopped by setting the voltage of this pin to VSSL or lower. Soft-start pin voltage can be changed with an open-collector drive circuit of a transistor. When using both the soft-start and ON/OFF functions together, the discharge current from C3 flows into the ON/OFF control transistor. Therefore, limit the current securely to protect the transistor if C3 capacitance is large. The ON/OFF pin is pulled up to the power supply in the IC, so applying the external voltage is prohibited. If this pin is not used, leave it open. SI-8000SD SI-8000SD SI-8000SD 5 ON/OFF 5 ON/OFF C3 5 ON/OFF C3 VOUT. ON/OFF Soft start Soft start +VOUT. ON/OFF 20 ICs SI-8000SD Series ■External Dimensions (TO263-5) Case temperature measurement point (0.40) ±0.2 (Unit : mm) 10.0 ±0.2 (8.0) (4.4) 3-R0.3 1.3 +0.10 –0.05 (1.75) 1.2 (15°) 4.5 ±0.2 (6.8) ±0.2 9.2± ±0.3 15.3 (3°) ±0.1 0.10 (3°) ±0.15 15.30 ±0.3 9.2 ±0.2 φ1.5 Dp: ±0.2 (3°) (2×R0.45) Pin Assignment q VIN w SWOUT e GND r VOS t S.S Plastic Mold Package Type Flammability: 94V-0 Product Mass: Approx. 1.48g (4.6) 2.4 (R0.3) ±0.3 ±0.2 ±0.2 2.0 (0.75) 4.9 0.88 ±0.10 (R0.3) 2.54 0 to 6° (0.5) ±0.1 (1.7 ±0.25 ) 1 2 3 9.9 4 ±0.2 0.8 ±0.25 ) (1.7 5 (3°) ±0.1 (1.7 ±0.25 ) 0.8 ±0.25 (1.7 ) (3°) 2-R0.3 10.0 ±0.02 ■Block Diagram ■Reference Data Copper Laminate Area on Glass Epoxy Board vs. thermal resistance (junction to ambient air) (Typical Value) 1 VIN Internal power supply SWOUT Overcurrent protection 2 Thermal resistance (junction to ambient air) θ j-a (°C/W) 55 50 With glass epoxy board of 40 × 40 mm 45 40 35 30 0 Oscillator Reset Latch & driver Comparator Thermal protection VOS Error amplifier 4 4.9 ±0.2 Reference voltage 200 400 600 800 1000 1200 1400 1600 1800 Copper Laminate Area (mm2) S.S 5 3 GND ■Typical Connection Diagram L1 VIN 1 VIN SWOUT 2 4 + D1 VOUT SI-8000SD C1 + S.S 5 C3 GND GND 3 VOS C2 C1 : 50V/1000µF C2 : 50V/1000µF C3 : 0.01µF (only when soft start function is used) L1 : 150µH D1 : SPB-G56 (Sanken) GND Diode D1 • Be sure to use Schottky-barrier diode as D1. If other diodes like fast recovery diodes are used, ICs may be destroyed because of the reverse voltage generated by the recovery voltage or ON voltage. Choke coil L1 • If the winding resistance of the choke coil is too high, the efficiency may drop below the rated value. • As the overcurrent protection starting current is about 3.5 A, take care concerning heat radiation from the choke coil caused by magnetic saturation due to overload or short-circuited load. Capacitors C1, C2, and C3 • As large ripple currents flow through C1 and C2, use high-frequency and low-impedance capacitors aiming for switching-mode-power-supply use. Especially when the impedance of C2 is high, the switching waveform may become abnormal at low temperatures. For C2, do not use a capacitor with an extremely low equivalent series resistance (ESR) such as an OS capacitor or a tantalum capacitor, which may cause an abnormal oscillation. • C3 is a capacitor for soft start. Leave pin 5 open if the soft start function is not used. This pin is pulled up with a pull-up resistor inside the ICs. To create the optimum operating conditions, place the components as close as possible to each other. ICs 21