Datasheet

GT Drv
(Pin 16) (gate drive): The output of the PWM is a
totem pole MOSFET gate driver on GT Drv. This output is
internally clamped to 15V so that the IC can be operated
with V
CC
as high as 35V. Use a series gate resistor of at
least 5 ohms to prevent interaction between the gate im-
pedance and the GT Drv output driver that might cause
the GT Drv output to overshoot excessively. Some over-
shoot of the GT Drv output is always expected when driv-
ing a capacitive load.
TYPICAL CHARACTERISTICS at T
A
= T
J
= 25
°
C
UC1854
UC2854
UC3854
Load Capacitance, µF
ns
0
100
200
300
400
500
600
700
0 0.01 0.02 0.03 0.04 0.05
Rise Time
Fall Time
R SET , k Ω
Duty
Cycle
70%
75%
80%
85%
90%
95%
100%
1 10 100
I,A AC µ
Multiplier
Output
µA
0
100
200
300
400
500
600
0 100 200 300 400 500 600 700
800
Mult Out=1
Mult Out=2V
Mult Out=3V
Mult Out=0V
V =2V, VA Out=5V RMS
R,k SET Ω
Frequency
kHz
10
100
1000
1
10
100
100pF
200pF
5nF
10nF
3nF
500pF
2nF
1nF
Frequency
kHz
Phase
Margin
degrees
Open-Loop
Gain
dB
-20
0
20
40
60
80
100
120
0.1 1 10 100 1000 10000
Frequency
kHz
Phase
Margin
degrees
Open-Loop
Gain
dB
-20
0
20
40
60
80
100
120
0.1 1 10 100 1000 10000
PIN DESCRIPTIONS (cont.)
Voltage Amplifier Gain and Phase vs Frequency Current Amplifier Gain and Phase vs Frequency
Gate Drive Rise and Fall Time Gate Drive Maximum Duty Cycle
Multiplier Output vs Voltage on Mult
Oscillator Frequency vs R
SET
and C
T
5