■ 5A Onboard Switch (LT1074)
■ Operates Up to 60V Input
■ 100kHz Switching Frequency
■ Greatly Improved Dynamic Behavior
■ Available in Low Cost 5 and 7-Lead Packages
■ Only 8.5mA Quiescent Current
■ Programmable Current Limit
■ Micropower Shutdown Mode
■ Buck Converter with Output Voltage Range of 2.5V
■ Tapped-Inductor Buck Converter with 10A Output
■ Positive-to-Negative Converter
■ Negative Boost Converter
■ Multiple Output Buck Converter
The LT®1074 is a 5A (LT1076 is rated at 2A) monolithic
bipolar switching regulator which requires only a few
external parts for normal operation. The power switch, all
oscillator and control circuitry, and all current limit com-
ponents, are included on the chip. The topology is a classic
positive “buck” configuration but several design innova-
tions allow this device to be used as a positive-to-negative
converter, a negative boost converter, and as a flyback
converter. The switch output is specified to swing 40V
below ground, allowing the LT1074 to drive a tapped-
inductor in the buck mode with output currents up to 10A.
The LT1074 uses a true analog multiplier in the feedback
loop. This makes the device respond nearly instanta-
neously to input voltage fluctuations and makes loop gain
independent of input voltage. As a result, dynamic behav-
ior of the regulator is significantly improved over previous
On-chip pulse by pulse current limiting makes the LT1074
nearly bust-proof for output overloads or shorts. The input
voltage range as a buck converter is 8V to 60V, but a self-
boot feature allows input voltages as low as 5V in the
inverting and boost configurations.
The LT1074 is available in low cost TO-220 or DD packages
with frequency pre-set at 100kHz and current limit at 6.5A
(LT1076 = 2.6A). A 7-pin TO-220 package is also available
which allows current limit to be adjusted down to zero. In
addition, full micropower shutdown can be programmed.
See Application Note 44 for design details.
A fixed 5V output, 2A version is also available. See LT1076-5.
, LTC and LT are registered trademarks of Linear Technology Corporation.
10V TO 40V
Basic Positive Buck Converter
5A * USE MBR340 FOR LT1076
** COILTRONICS #50-2-52 (LT1074)
PULSE ENGINEERING, INC.
HURRICANE #HL-AK147QQ (LT1074)
C1 † RIPPLE CURRENT RATING ≥ IOUT/2
Buck Converter Efficiency
VOUT = 12V, VIN = 20V
VOUT = 5V, V IN = 15V
L = 50µH TYPE 52 CORE
DIODE = MBR735
1 234 5 6
OUTPUT LOAD CURRENT (A)