Philips Semiconductors Linear Products
Product specification
Current-mode PWM controller
UC3842
CURRENT SENSE CIRCUIT
ERROR
AMP
I
S
2R
CURRENT
SENSE
COMPARATOR
R
1V
1
COMP
R
3
CURRENT
SENSE
R
S
5
GND
NOTE:
Peak current (I
S
) is determined by the formula:
I
S
MAX
+
1.0V
Rs
A small RC filter may be required to suppress switch transients.
TYPICAL PERFORMANCE CHARACTERISTICS
Output Saturation Characteristics
4
100
SATURATION VOLTAGE (V)
VOLTAGE GAIN (dB)
80
0
60
40
20
0
–20
0
0.01
0.03 0.05 0.1
0.3 0.5 1.0
OUTPUT CURRENT, SOURCE OR SINK (A)
10
100
1k 10k 100k 1M
FREQUENCY (Hz)
PHASE (DEG)
Av
–45
–90
–135
–180
–225
10M
Error Amplifier Open-Loop
Frequency Response
45
0
3
2
1
August 31, 1994
1104
PHILIPS [ NXP SEMICONDUCTORS ]
