The UC1846/7 family of control ICs provides all of the necessary features to implement fixed frequency, current mode control Programmable Pulse-by-Pulse Current schemes while maintaining a minimum external parts count. The Limiting superior performance of this technique can be measured in imAutomatic Symmetry Correction in Push-pull proved line regulation, enhanced load response characteristics, and Configuration a simpler, easier-to-design control loop. Topological advantages include inherent pulse-by-pulse current limiting capability, automatic Enhanced Load Response Characteristics symmetry correction for push-pull converters, and the ability to parParallel Operation Capability for Modular allel "power modules" while maintaining equal current sharing. Power Systems Protection circuitry includes built-in under-voltage lockout and proDifferential Current Sense Amplifier with grammable current limit in addition to soft start capability. A shutWide Common Mode Range down function is also available which can initiate either a complete shutdown with automatic restart or latch the supply off. Double Pulse Suppression 500mA (Peak) Totem-pole Outputs ±1% Bandgap Reference Under-voltage Lockout Soft Start Capability Shutdown Terminal 500kHZ Operation Other features include fully latched operation, double pulse suppression, deadline adjust capability, and a ±1% trimmed bandgap reference. The UC1846 features low outputs in the OFF state, while the UC1847 features high outputs in the OFF state.

Supply Voltage (Pin 15). +40V Collector Supply Voltage (Pin 13). +40V Output Current, Source or Sink (Pins 14). 500mA Analog Inputs (Pins -0.3V to +VIN Reference Output Current (Pin 2). -30mA Sync Output Current (Pin 10). -5mA Error Amplifier Output Current (Pin 7). -5mA Soft Start Sink Current (Pin 1). 50mA Oscillator Charging Current (Pin 9). 5mA Power Dissipation TA=25°C. 1000mW Power Dissipation TC=25°C. 2000mW Storage Temperature Range. to +150°C Lead Temperature (soldering, 10 seconds). +300°C Note 1. All voltages are with respect to Ground, Pin 13. Currents are positive into, negative out of the speficied terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages. Pin numbers refer to DIL and SOIC packages only.

DIL-16, SOIC-16 (TOP VIEW) or N Package, DW Package PLCC-20, LCC-20 (TOP VIEW) Q, L Packages

PACKAGE PIN FUNCTION PIN 1 N/C C/L SS 2 VREF 3 C/S4 C/S+ 5 N/C 6 E/A+ 7 E/A8 Comp CT 10 N/C RT 12 Sync 13 A Out 14 Gnd 15 N/C 17 B Out 18 VIN 19 Shutdown 20

ELECTRICAL CHARACTERISTICS (Unless otherwise stated, these specifications apply for to +125°C for

UC1846/UC1847 PARAMETER Reference Section Output Voltage Line Regulation Load Regulation Temperature Stability Total Output Variation Output Noise Voltage Long Term Stability to 10mA Over Operating Range, (Note 2) Line, Load, and Temperature (Note 10kHz, TJ=25°C (Note TJ=125°C, 1000 Hrs. (Note TEST CONDITIONS UC2846/UC2847 MIN. TYP. MAX.

to +85°C for the UC2846/7; and to +70°C for the RT=10k, CT=4.7nF, TA=TJ.) UC3846/UC3847 MIN. TYP. MAX. UNITS V mV mV/°C mV mA

(Unless otherwise stated, these specifications apply for to +125°C for UC1846/7; ELECTRICAL CHARACTERISTICS (cont.) to +85°C for the UC2846/7; and to +70°C for the RT=10k, CT=4.7nF, TA=TJ.) UC1846/UC1847 PARAMETER Oscillator Section Initial Accuracy Voltage Stability Temperature Stability Sync Output High Level Sync Output Low Level Sync Input High Level Sync Input Low Level Sync Input Current Error Amp Section Input Offset Voltage Input Bias Current Input Offset Current Common Mode Range Open Loop Voltage Gain Unity Gain Bandwidth CMRR PSRR Output Sink Current Output Source Current High Level Output Voltage Low Level Output Voltage Current Sense Amplifier Section Amplifier Gain Maximum Differential Input Signal (VPIN 4-VPIN 3) Input Offset Voltage CMRR PSRR Input Bias Current Input Offset Current Input Common Mode Range Delay to Outputs Current Limit Adjust Section Current Limit Offset Input Bias Current Shutdown Terminal Section Threshold Voltage Input Voltage Range Minimum Latching Current (IPIN 1) (Note mA VIN mV V VPIN 3=0V, VPIN 4=0V, Pin 7 Open (Note 3) VPIN 5=VREF, VPIN µA TJ=25°C, (Note 2) VPIN 3=0V, Pin 1 Open (Notes & 4) Pin 1 Open (Note 3) RL (Pin 7)=15kW VPIN 1=0.5V, Pin 7 Open (Note to 40V VPIN 1=0.5V, Pin 7 Open (Note 3) VPIN 1=0.5V, Pin 7 Open (Note VCM=2V TJ=25°C (Note to -5V, VPIN to 5V, VPIN 7=2.5V RL=(Pin V dB MHz mA V Pin 8=0V Pin 8=0V Sync Voltage=3.9V, Pin to 40V Over Operating Range (Note kHz mA TEST CONDITIONS UC2846/UC2847 MIN. TYP. MAX.