1
LT1676
Wide Input Range,
High Efficiency, Step-Down
Switching Regulator
■
Wide Input Range: 7.4V to 60V
■
700mA Peak Switch Current Rating
■
Adaptive Switch Drive Maintains Efficiency at High
Load Without Pulse Skipping at Light Load
■
True Current Mode Control
■
100kHz Fixed Operating Frequency
■
Synchronizable to 250kHz
■
Low Supply Current in Shutdown: 30µA
■
Available in 8-Pin SO and PDIP Packages
■
Automotive DC/DC Converters
■
Telecom 48V Step-Down Converters
■
Cellular Phone Battery Charger Accessories
■
IEEE 1394 Step-Down Converters
The LT
®
1676 is a wide input range, high efficiency Buck
(step-down) switching regulator. The monolithic die in-
cludes all oscillator, control and protection circuitry. The
part can accept input voltages as high as 60V and contains
an output switch rated at 700mA peak current. Current
mode control offers excellent dynamic input supply rejec-
tion and short-circuit protection.
The LT1676 contains several features to enhance effi-
ciency. The internal control circuitry is normally powered
via the V
CC
pin, thereby minimizing power drawn directly
from the V
IN
supply (see Applications Information). The
action of the LT1676 switch circuitry is also load depen-
dent. At medium to high loads, the output switch circuitry
maintains high rise time for good efficiency. At light loads,
rise time is deliberately reduced to avoid pulse skipping
behavior.
The available SO-8 package and 100kHz switching fre-
quency allow for minimal PC board area requirements.
Figure 1
, LTC and LT are registered trademarks of Linear Technology Corporation.
39µF
63V
1676 F01
V
IN
V
CC
V
SW
LT1676
FB
V
C
SHDN
SYNC
2
5
4
3
7
8
1
6
GND
+
100µF
10V
+
MBR160
36.5k
1%
5V
400mA
12.1k
1%
22k
220µH*
2200pF
V
IN
8V TO 50V
100pF
*65T #30 ON MAGNETICS
MPP #55030
I
LOAD
(mA)
1
60
EFFICIENCY (%)
70
80
90
10 100 1000
1676 TA01
50
40
30
20
V
IN
= 12V
V
IN
= 24V
V
IN
= 36V
V
IN
= 48V
Efficiency vs V
IN
and I
LOAD
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U