LT1956 LINER [Linear Technology], LT1956 Datasheet - Page 4

• Manufacturer Part Number: LT1956
• Description: High Voltage, 1.5A, 500kHz Step-Down Switching Regulators
• Manufacturer: LINER [Linear Technology]

LT1956/LT1956-5
TYPICAL PERFOR A CE CHARACTERISTICS
4
2.5
2.0
1.5
1.0
2.4
2.0
1.6
1.2
0.8
0.4
2500
2000
1500
1000
500
0
–50
0
Switch Peak Current Limit
0
Lockout and Shutdown
Thresholds
–50
Error Amplifier Transconductance
–25
–25
JUNCTION TEMPERATURE ( C)
20
GUARANTEED MINIMUM
JUNCTION TEMPERATURE
0
DUTY CYCLE (%)
0
40
TYPICAL
LOCKOUT
START-UP
SHUTDOWN
25
25
50
60
50
75
75
W
80
100
100
1956 G01
1956 G04
1956 G07
U
100
125
125
1.234
1.229
1.214
1.204
1.224
1.219
1.209
3000
2500
2000
1500
1000
500
–50
100
40
35
30
25
20
15
10
Error Amplifier Transconductance
FB Pin Voltage and Current
5
0
ERROR AMPLIFIER EQUIVALENT CIRCUIT
V
R
0
Shutdown Supply Current
FB 2 • 10
LOAD
–25
V
SHDN
JUNCTION TEMPERATURE ( C)
1k
= 50
10
= 0V
–3
0
GAIN
FREQUENCY (Hz)
INPUT VOLTAGE (V)
PHASE
20
10k
25
CURRENT
VOLTAGE
R
200k
50
30
OUT
100k
75
40
1M
C
12pF
100
OUT
1956 G02
V
50
1956 G08
C
1956 G05
10M
125
2.0
1.5
1.0
0.5
0
200
150
100
50
0
–50
60
250
200
150
100
300
250
200
150
100
625
500
250
125
50
375
12
6
0
0
–50
0
SHDN Pin Bias Current
0
Shutdown Supply Current
0
Frequency Foldback
CURRENT REQUIRED TO FORCE SHUTDOWN
(FLOWS OUT OF PIN). AFTER SHUTDOWN,
CURRENT DROPS TO A FEW A
–25
AT 2.38V STANDBY THRESHOLD
(CURRENT FLOWS OUT OF PIN)
0.1
0.2
JUNCTION TEMPERATURE ( C)
SHUTDOWN VOLTAGE (V)
V
0
IN
0.4
= 60V
0.2
25
V
FB
0.6
50
(V)
V
0.3
IN
= 15V
FREQUENCY
SWITCHING
0.8
75
CURRENT
0.4
FB PIN
100
1.0
1956 G03
1956 G06
1956 G09
1956f
125
0.5
1.2