SC4431

SHUNT REGULATOR WITH OPEN COLLECTOR OR OUTPUT PRELIMINARY - September 11, 2000 SC4431 TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com DESCRIPTION The SC4431 is a four terminal device for regulating an isolated power supply with very low output voltage. It is intended to be used as a replacement for three terminal shunt regulators such as SC431L where the output voltage is too low for them to function in conjunction with an opto-isolator. It achieves this by having seperate supply and output pins, allowing the output to sink current at voltages as low as 0.2V, while the supply pin still has sufficient voltage for the device to function. In this way, allowing for a 1.6V drop through an opto-isolator diode, regulation down to 1.8V out can be achieved. The SC4431 shunt regulator is available with three initial reference voltage accuracies (0.5%, 1.0% and 2.0%) in the space saving 5-lead SOT-23 package. The three voltage tolerances allow the designer the opportunity to select the proper cost/tolerance for their application. FEATURES •= Trimmed bandgap design - initial accuracies to •= •= •= •= + 0.5% 40mA drive capability Wide supply voltage range - 1.5V to 15V Low supply current - typically 110µA Full industrial temperature range APPLICATIONS •= Opto driver for very low output voltage isolated power supplies ORDERING INFORMATION Part Number (1)(2) Package SOT-23-5 SC4431CSK-X.TR Notes: (1) Where “-X” denotes initial reference voltage tolerance. Available options are ±0.5% (-.5), ±1% (-1) and ±2% (-2). (2) Only available in tape and reel packaging. A reel contains 3000 devices. TYPICAL APPLICATION CIRCUIT T1 VIN Primary Side Controller Secondary Side Rectification and Filtering R1 R2 C1 2V OUT U1 5.1k U2 5 OUT 1 VCC REF 33nF R3 6.34k SC4431 4 R4 10k 4N25 C2 22nF NC GND 2 3 2V Output Isolated Power Supply 1 © 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 SHUNT REGULATOR WITH OPEN COLLECTOR OR OUTPUT PRELIMINARY - September 11, 2000 SC4431 ABSOLUTE MAXIMUM RATINGS Parameter Input Supply Voltage Output Voltage Reference Voltage Continuous Output Current Reference Input Current Operating Ambient Temperature Range Operating Junction Temperature Range Storage Temperature Range Thermal Impedance Junction to Ambient Thermal Impedance Junction to Case Power Dissipation at TA = 25°C Lead Temperature (Soldering) 10 seconds ESD Rating (Human Body Model) Symbol VCC VOUT VREF IOUT IREF TA TJ TSTG θJA θJC PD TLEAD ESD Maximum -0.5 to +16 -0.5 to VCC -0.5 to +4 40 5 -40 to +85 -40 to +150 -65 to +150 256 81 475 300 2 Units V V V mA mA °C °C °C °C/W °C/W mW °C kV ELECTRICAL CHARACTERISTICS Unless specified, TA = 25°C, VCC = 2V, IOUT = 2mA. Values in bold apply over full operating temperature range. Parameter VCC Input Supply Voltage Input Supply Current Off State Input Supply Current Symbol Test Conditions MIN TYP MAX Units VCC ICC ICC(OFF) VREF = VOUT VREF = 1.187V, VOUT = 2V 1.5 110 65 15 200 100 150 V µA µA REF Reference Voltage VREF SC4431-.5, VREF = VOUT SC4431-1, VREF = VOUT SC4431-2, VREF = VOUT Change in VREF due to change in VCC Change in VREF due to change in IOUT dVREF dVCC dVREF dIOUT 1.219 1.224 1.231 1.207 1.243 V 1.212 1.224 1.236 1.200 1.250 V 1.200 1.224 1.250 1.187 1.261 8 15 20 V VCC = 1.5V to 15V IOUT = 0.1mA to 40mA mV 8 28 36 mV 2 © 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 SHUNT REGULATOR WITH OPEN COLLECTOR OR OUTPUT PRELIMINARY - September 11, 2000 SC4431 ELECTRICAL CHARACTERISTICS (Cont.) Unless specified, TA = 25°C, VCC = 2V, IOUT = 2mA. Values in bold apply over full operating temperature range. Parameter REF (Cont.) Reference Input Current Symbol Test Conditions 0.1mA ≤ IOUT ≤ 10mA MIN TYP MAX Units IREF 0.3 0.5 1.0 µA OUT Saturation Voltage VOUT(SAT) IOUT = 5mA, ICC = 500µA VREF = 1.261V, IOUT = 40mA Off State Output Current IOUT(OFF) VREF = 1.187V, VOUT = 2V 50 75 100 275 300 400 0.5 1 10 µA mV mV 3 © 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 SHUNT REGULATOR WITH OPEN COLLECTOR OR OUTPUT PRELIMINARY - September 11, 2000 SC4431 BLOCK DIAGRAM PIN CONFIGURATION SOT-23 -5 Lead (Top View) PIN DESCRIPTION Pin 1 2 3 4 5 Pin Name Pin Function VCC GND NC REF OUT This is the input supply pin for the IC. Logic and power ground. No connection. This is connected to the non-inverting input of the error amplifier. This is the output pin of the device, essentially an open collector. 4 © 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 SHUNT REGULATOR WITH OPEN COLLECTOR OR OUTPUT PRELIMINARY - September 11, 2000 SC4431 DEVICE OUTLINE - SOT-23-5 LAND PATTERN - SOT-23-5 ECN 00-1315 5 © 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320