UC3844B, UC3845B, UC2844B, UC2845B
A VOL , OPEN LOOP VOLTAGE GAIN (dB)
100
80
Gain
60
40
Phase
20
0
− 20
10
V
CC
= 15 V
V
O
= 2.0 V to 4.0 V
R
L
= 100 k
T
A
= 25°C
0
φ
, EXCESS PHASE (DEGREES)
Vth , CURRENT SENSE INPUT THRESHOLD (V)
1.2
V
CC
= 15 V
1.0
0.8
T
A
= 25°C
0.6
T
A
= 125°C
0.4
T
A
= − 55°C
0.2
0
30
60
90
120
150
180
10 M
100
1.0 k
10 k
100 k
f, FREQUENCY (Hz)
1.0 M
0
2.0
4.0
6.0
V
O
, ERROR AMP OUTPUT VOLTAGE (V
O
)
8.0
Figure 6. Error Amp Open Loop Gain and
Phase versus Frequency
Figure 7. Current Sense Input Threshold
versus Error Amp Output Voltage
ISC , REFERENCE SHORT CIRCUIT CURRENT (mA)
∆
Vref , REFERENCE VOLTAGE CHANGE (mV)
V
CC
= 15 V
− 4.0
− 8.0
− 12
T
A
= 125°C
− 16
− 20
T
A
= 25°C
− 24
0
20
40
60
80
100
I
ref
, REFERENCE SOURCE CURRENT (mA)
120
T
A
= −55°C
90
70
50
− 55
− 25
0
25
50
75
T
A
, AMBIENT TEMPERATURE (°C)
Figure 8. Reference Voltage Change
versus Source Current
Figure 9. Reference Short Circuit Current
versus Temperature
∆
V , OUTPUT VOLTAGE CHANGE (2.0 mV/DIV)
V
CC
= 15 V
I
O
= 1.0 mA to 20 mA
T
A
= 25°C
∆
V , OUTPUT VOLTAGE CHANGE (2.0 mV/DIV)
V
CC
= 12 V to 25 V
T
A
= 25°C
2.0 ms/DIV
2.0 ms/DIV
Figure 10. Reference Load Regulation
Figure 11. Reference Line Regulation
http://onsemi.com
6
ÄÄÄÄ
ÄÄÄÄ
V
CC
= 15 V
R
L
≤
0.1
W
100
125
0
110
O
O
ONSEMI [ ON SEMICONDUCTOR ]
