Datasheet

UCC2800/2801/2802/2803/2804/2805-EP
LOW-POWER BICMOS CURRENT-MODE PWM
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SGLS135F − SEPTEMBER 2002 − REVISED OCTOBER 2010
9
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PARAMETER MEASUREMENT INFORMATION
Figure 1
Oscillator
The UCC3800/1/2/3/4/5 oscillator generates a sawtooth waveform
on RC. The rise time is set by the time constant of R
T
and C
T
. The
fall time is set by C
T
and an internal transistor on-resistance of
approximately 125. During the fall time, the output is off and the
maximum duty cycle is reduced below 50% or 100% depending on
the part number. Larger timing capacitors increase the discharge
time and reduce the maximum duty cycle and frequency.
Fi
g
ure 2
Error Amplifier
Gain/Phase Response
Figure 3
UCC1803/05 V
REF
vs V
CC
; I
LOAD
= 0.5 mA
Fi
g
ure 4
UCC1800/01/02/04 Oscillator Frequency
vs R
T
and C
T