The is a monolithic control circuit containing the primary functions required for DC-to-DC converters. These devices consist of an internal temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. This series was specifically designed to be incorporated in Step-Down and Step-Up and Voltage-Inverting applications with a minimum number of external components.

FEATURES FUNCTIONAL BLOCK DIAGRAM· Operation from 40 V Input Low Standby Current Limiting Output Switch Current 1.5 A Output Voltage Adjustable Frequency Operation to 100 kHz Precision 2% Reference

Rating Power Supply Voltage Comparator Input Voltage Range Switch Collector Voltage Switch Emitter Voltage (Vpin 40 V) Switch Collector to Emitter Voltage Driver Collector Voltage Driver Collector Current (Note 1) Switch Current Power Dissipation and Thermal Characteristics Ceramic Package, U Suffix = +25°C Thermal Resistance Plastic Package, P Suffix = +25°C Thermal Resistance SOIC Package, D Suffix = +25°C Thermal Resistance Operating Junction Temperature Operating Ambient Temperature Range Storage Temperature Range Symbol VCC VIR VC(switch) VE(switch) VCE(switch) IC(driver) ISW PD RJA PD RJA PD RJA

5.0 V, TA= to +70oC unless otherwise specified.) Characteristics Symbol OSCILLATOR Frequency (V Pin = 1.0 nF, = 25°C) fosc Charge Current = 25°C) Ichg Discharge Current = 25°C) Idischg Discharge to Charge Current Ratio (Pin7 to Vcc, TA=25°C) Idischg/Ichg Current Limit Sense Voltage (Ichg = Idischg, = 25°C) Vlpk(sense) OUTPUT SWITCH (Note 3) Saturation Voltage, Darlington Connection (ISW 1.0 A, VCE(sat)

Saturation Voltage (ISW 1.0 A, RPin 82 to VCC. VCE(sat) Forced 20) DC Current Gain (ISW 1.0 A, VCE = 25°C) hFE Collector Off-State Current = 40V) IC(off) COMPARATOR Threshold Voltage (TA = 25°C) Vth

(TA = TLOW to THIGH) Threshold Voltage (TA = 25°C) Threshold Voltage Line Regulation (VCC 40 V) Input Bias Current (Vin=0V)

1. Maximum package power dissipation limits must be observed. 2.Low duty cycle pulse techniques are used during test to maintain Junction temperature as close to ambient temperature as possible 3.If the output switch is driven into hard saturation (non Darlington configuration) at low switch currents 300 mA) and high driver currents (>30 mA), it may take µs to come out of saturation This condition will shorten the off' time at frequencies > 30 kHz, and is magnified at high temperatures This condition does not occur with a Darlingto n configuration, since the output switch cannot saturate If a non Darlington configuration is used, the following output drive condition is recommended Forced of output switch = IC, output/(Ic, driver -7.0 mA*) > 10 *The 100 . resistor in the emitter o f the driver device requires about 7.0 mA before the output switch conducts **Possible version for shipment