TL3845B description
The TL284xB and TL384xB series control ICs provide the features necessary to implement off-line or dc-to-dc frequency current control schemes with minimal external components.Internal implementation circuitry includes a leg of low-voltage lockout (UVLO) and a precision reference book clipping error amplifier for accurate inputs.Other internal circuitry including logic operation ensures a pulse-width modulation (PWM) comparator, which also provides current-limit control, and a totem-pole output stage or pump design high-peak source current.The output stage, suitable for driving N-channel mosfet, is low when it is in the off state.
The TL284xB and TL384xB series are standard TL284x pins and TL384x with the following improvements.The start-up current is specified as 0.5 Master (maximum), while the oscillator discharge current is trimmed to 8.3% Master (current).In addition, under dynamic conditions, the low voltage lock on the output branch has a maximum of 1.2 V while the saturation voltage sinks 10 masters (VCC = 5 volts).
The main difference between the members of this series is the UVLO threshold and the maximum process range.Typical UVLO thresholds of 16 V (up) and 10 V (off) in TLx842B and TLx844B units make them ideal for off-line applications.The corresponding typical thresholds are 8.4 V (on) and 7.6 V (off) for TLx843B and TLx845B devices.The units of the TLx842B and TLx843B can operate with a liability cycle close to 100%.A procedure ranges from 0 to 50%, and the TLx844B obtained by TLx845B is output with an internal switching trigger to put everything else within the blank clock cycle.The TL284xB-series unit features -40°C operation from up to 85°C.The TL384xB-series unit features operation from 0°C to 70°C.