UC3844, 45 UC2844, 45
Figure 1. Timing Resistor versus
Oscillator Frequency
Figure 2. Output Deadtime versus
Oscillator Frequency
100
50
75
70
65
V
T
= 15 V
= 25°C
CC
A
1.0 nF
2.0 nF
20
5.0 nF
C
= 10 nF
T
10
60
55
50
5.0
2.0
100 pF
200 pF
NOTE: Output switches
at one–half the oscillator
frequency.
500 pF
1.0
10 k
20 k
50 k
100 k
200 k
500 k
1.0 M
10 k
20 k
50 k
100 k
200 k
500 k
1.0 M
f
, OSCILLATOR FREQUENCY (Hz)
f
osc
, OSCILLATOR FREQUENCY (Hz)
osc
Figure 3. Error Amp Small Signal
Transient Response
Figure 4. Error Amp Large Signal
Transient Response
V
= 15 V
= –1.0
V
= 15 V
CC
CC
A = –1.0
V
A
V
A
2.55 V
3.0 V
2.5 V
2.0 V
T
= 25
°C
T = 25°C
A
2.5 V
2.45 V
0.5
µs/DIV
1.0 µs/DIV
Figure 5. Error Amp Open Loop Gain and
Phase versus Frequency
Figure 6. Current Sense Input Threshold
versus Error Amp Output Voltage
100
80
60
40
20
1.2
0
V
V
R
= 15 V
= 2.0 V to 4.0 V
= 100 K
CC
O
L
V
= 15 V
CC
1.0
0.8
0.6
0.4
0.2
0
30
Gain
T
= 25°C
A
60
T
= 25°C
A
90
T
= 125°C
Phase
1.0 M
A
T
= –55
4.0
°C
120
A
0
150
180
– 20
10
100
1.0 k
10 k
100 k
10 M
0
2.0
6.0
8.0
f, FREQUENCY (Hz)
V
, ERROR AMP OUTPUT VOLTAGE (V)
O
4
MOTOROLA ANALOG IC DEVICE DATA
MOTOROLA [ MOTOROLA ]
