Datasheet

2
LT1268B/LT1268
A
U
G
W
A
W
U
W
ARB
S
O
LU
T
EXI T
I
S
Supply Voltage ....................................................... 30V
Switch Output Voltage............................................ 60V
Feedback Pin Voltage (Transient, 1ms) ................ ±15V
Operating Junction Temperature Range
Operating...............................................0°C to 125°C
Short-Circuit......................................... 0°C to 140°C
Storage Temperature Range................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)..................300°C
ORDER PART
NUMBER
WU
U
PACKAGE
/
O
RDER I FOR ATIO
ORDER PART
NUMBER
T
JMAX
= 125°C, θ
JC
= 2°C/W, θ
JA
= 50°C/W
LT1268CT
LT1268BCT
T
JMAX
= 125°C, θ
JC
= 2°C/W, θ
JA
= See Notes 5 and 6
Q PACKAGE
5-LEAD DD
FRONT VIEW
V
IN
V
SW
GND
FB
V
C
5
4
3
2
1
LT1268CQ
LT1268BCQ
T PACKAGE
5-LEAD TO-220
V
IN
V
SW
GND
FB
V
C
FRONT VIEW
5
4
3
2
1
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
REF
Reference Voltage Measured at LT1268B 1.235 1.244 1.253 V
Feedback Pin (Note 4)
● 1.224 1.244 1.264 V
Reference Voltage LT1268 1.224 1.244 1.264 V
● 1.214 1.244 1.274 V
I
B
Feedback Input Current V
FB
= V
REF
350 750 nA
● 1100 nA
g
m
Error Amplifier Transconductance ∆I
C
= ±25µA 3000 4400 6000 µmho
● 2400 7000 µmho
Error Amplifier Source or Sink Current V
C
= 1.5V 150 200 350 µA
● 120 400 µA
Error Amplifier Clamp Voltage Hi Clamp, V
FB
= 1V 1.80 2.30 V
Lo Clamp, V
FB
= 1.5V 0.25 0.38 0.52 V
Reference Voltage Line Regulation 3V ≤ V
IN
≤ V
MAX
, V
C
= 0.8V ● 0.03 %/V
A
V
Error Amplifier Voltage Gain 0.9V ≤ V
C
≤ 1.4V 500 800 V/V
Minimum Input Voltage ● 2.8 3.0 V
I
Q
Supply Current 3V ≤ V
IN
≤ V
MAX
, V
C
= 0.6V 7 10 mA
Control Pin Threshold Duty Cycle = 0 0.7 0.9 1.08 V
● 0.5 1.25 V
BV Output Switch Breakdown Voltage 3V ≤ V
IN
≤ V
MAX
, I
SW
= 1.5mA ● 60 75 V
V
SAT
Output Switch-ON Resistance T
J
≤ 100°C 0.12 0.18 Ω
(Note 1, 3) T
J
≤ 125°C 0.22 Ω
Control Voltage to Switch 12 A/V
Current Transconductance
I
LIM
Switch Current Limit (Note 3, 6) Duty Cycle = 50%, T
J
≤ 100°C ● 7.50 15 A
Duty Cycle = 65%, T
J
≤ 100°C ● 6.50 14 A
V
IN
= 15V, V
C
= 0.5V, V
FB
= V
REF
, switch pin open, unless otherwise noted.
E
LECTR
IC
AL C CHARA TERIST
ICS
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