LT1074/LT1076
ELECTRICAL CHARACTERISTICS
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
To calculate maximum switch “on” voltage at currents between
low and high conditions, a linear interpolation may be used.
Note 3:
A feedback pin voltage (V
FB
) of 2.5V forces the V
C
pin to its low
clamp level and the switch duty cycle to zero. This approximates the zero
load condition where duty cycle approaches zero.
Note 4:
Total voltage from V
IN
pin to ground pin must be
≥
8V after start-
up for proper regulation.
Note 5:
Switch frequency is internally scaled down when the feedback pin
voltage is less than 1.3V to avoid extremely short switch on times. During
testing, V
FB
is adjusted to give a minimum switch on time of 1µs.
Note 6:
I
LIM
≈
R
LIM
– 1k
R – 1k
(LT1074), I
LIM
≈
LIM
(LT1076).
5.5k
2k
Note 7:
Switch to input voltage limitation must also be observed.
Note 8:
V
MAX
= 40V for the LT1074/76 and 60V for the LT1074HV/76HV.
Note 9:
Does not include switch leakage.
BLOCK DIAGRA
INPUT SUPPLY
10
µ
A
0.3V
+
µ
-POWER
SHUTDOWN
–
6V
REGULATOR
AND BIAS
6V TO ALL
CIRCUITRY
CURRENT
LIMIT
COMP
C2
–
–
500
Ω
2.35V
+
SHUTDOWN*
2.21V
*AVAILABLE ON PACKAGES WITH PIN
COUNTS GREATER THAN 5.
4
W
LT1074
320
µ
A
CURRENT
LIMIT
SHUTDOWN
+
250
Ω
0.04
I
LIM
*
4.5V
10k
FREQ SHIFT
100kHz
OSCILLATOR
SYNC
3V(p-p)
V
IN
+
+
A1
ERROR
AMP
Z
ANALOG
X MULTIPLIER
XY
Z
Y
C1
–
PULSE WIDTH
COMPARATOR
400
Ω
15
Ω
R
R/S
S
Q
LATCH
R
G1
–
SWITCH
OUTPUT
(V
SW
)
LT1076
FB
V
C
24V (EQUIVALENT)
0.1
Ω
100
Ω
SWITCH
OUTPUT (V
SW
)
LT1074 • BD01
LINER [ LINEAR TECHNOLOGY ]
