TL3843B Datasheet | Texas Instruments

FEATURES - Low Start-Up Current (<0.5 m A) - Trimmed Oscillator Discharge Current - Current Mode Operation to 500 k Hz - Automatic Feed-Forward pensation - Latching PWM for Cycle-by-Cycle Current Limiting - Internally Trimmed Reference With Undervoltage Lockout - High-Current Totem-Pole Output Undervoltage Lockout With Hysteresis - Double-Pulse Suppression D (SOIC) OR P (PDIP) PACKAGE (TOP VIEW) P VFB ISENSE RT/CT 1 2 3 4 8 VREF 7 VCC 6 OUTPUT 5 GND D (SOIC) PACKAGE (TOP VIEW) P NC VFB NC ISENSE NC RT/CT 1 2 3 4 5 6 7 14 VREF 13 NC 12 VCC 11 VC 10 OUTPUT 9 GND 8 POWER GROUND - No internal connection DESCRIPTION /ORDERING INFORMATION The TL284x B and TL384x B series of control integrated circuits provide the features that are necessary to implement off-line or dc-to-dc fixed-frequency current-mode control schemes, with a minimum number of external ponents. Internally implemented circuits include an undervoltage lockout (UVLO) and a precision reference that is trimmed for accuracy at the error amplifier input. Other internal circuits include logic to ensure latched operation, a pulse-width modulation (PWM) parator that also provides current-limit control, and a totem-pole output stage designed to source or sink high-peak current. The output stage, suitable for driving N-channel MOSFETs, is low when it is in the off state. The TL284x B and TL384x B series are pin patible with the standard TL284x and TL384x with the following improvements. The start-up current is specified to be 0.5 m A (max), while the oscillator discharge current is trimmed to 8.3 m A (typ). In addition, during undervoltage lockout conditions, the output has a maximum saturation voltage of 1.2 V while sinking 10 m A (VCC = 5 V). Major differences between members of these series are the UVLO thresholds and maximum duty-cycle ranges. Typical UVLO thresholds of 16 V (on) and 10 V (off) on the TLx842B and TLx844B devices make them ideally suited to off-line applications. The corresponding typical...