UC2843B

DESCRIPTION

The  UTC  UC2843B  provides  off-line  or  DC-DC

fixed-frequency current-mode control design with minimum

external components. Internally-implemented circuits include an

under-voltage lockout (UVLO) and a precision reference with

accuracy at the error amplifier input. The UTC UC2843B also

contain internal circuits which include a pulse width modulation

(PWM) comparator providing current-limit control, logic ensuring

latched operation, and a totem-pole output stage designed to

source or sink high-peak current. The output stage is low when it

is in off-state condition and suitable for N-channel MOSFETs

driving.

The UTC UC2843B also has following advantages: the

start-up current lower than 0.5mA while the oscillator discharge

current is specified to 8.3mA (Typ.). In UVLO conditions, the

output has a maximum saturation voltage of 1.2V when sinking

10mA @ V CC = 5V.

The typical UVLO threshold of the UTC UC2843B is 8.4V

(on) and 7.6V (off) and can operate to duty cycles approximately

100%.

FEATURES

* Current mode operation:500 kHz

* Low start-up current value<0.5mA

* Latching PWM for cycle-by-cycle current limiting

* Trimmed oscillator discharge current

* Automatic feed-forward compensation

* Internally trimmed reference with UVLO

* High-current totem-pole output UVLO with hysteresis

* Double-pulse suppression

规格书UC2843B