LT1076-5
5V Step-Down
Switching Regulator
FEATURES
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DESCRIPTIO
Fixed 5V Output
2A On-Board Switch
100kHz Switching Frequency
2% Output Voltage Tolerance Over Temperature
Greatly Improved Dynamic Behavior
Available in Low Cost 5-Lead Package
Only 9.5mA Quiescent Current
Operates Up to 60V Input
APPLICATI
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5V Output Buck Converter
Tapped Inductor Buck Converter with 4A Output
at 5V
Positive-to-Negative Converter
The LT1076-5 is a 2A fixed 5V output monolithic bipolar
switching regulator which requires only a few external
parts for normal operation. The power switch, all oscillator
and control circuitry, all current limit components, and an
output monitor are included on the chip. The topology is
a classic positive 鈥渂uck鈥?configuration but several design
innovations 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 LT1076-5 to drive a
tapped inductor in the buck mode with output currents up
to 4A.
The LT1076-5 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
designs.
On-chip pulse by pulse current limiting makes the LT1076-
5 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 LT1076-5 is available in a low cost 5-lead TO-220
package with frequency pre-set at 100kHz and current
limit at 2.6A. See Application Note 44 for design details.
TYPICAL APPLICATI
8V TO 40V
Basic Positive Buck Converter
100碌H**
鈥?/div>
V
IN
LT1076-5
SENSE
GND
V
C
R3
1.5k
V
SW
MBR340*
5V
鈮?.8A
* MBR330P MAY BE USED
FOR V
IN
鈮?/div>
25V
** COILTRONICS #100-1-52
HURRICANE #HL-AG210LL
鈥?/div>
+
C3
200碌F
C2
0.033碌F
+
C1
500碌F
25V
LT1076-5 TA01
U
VALUE MAY BE REDUCED TO 50碌H
FOR OUTPUT LOADS BELOW 1.5A
UO
UO
1
1
2
3
4
