FeaTures
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LTC3703
100V Synchronous
Switching Regulator
Controller
DescripTion
The LTC
®
3703 is a synchronous step-down switching
regulator controller that can directly step down voltages
from up to 100V, making it ideal for telecom and automo-
tive applications. The LTC3703 drives external N-channel
MOSFETs using a constant frequency (up to 600kHz),
voltage mode architecture.
A precise internal reference provides 1% DC accuracy.
A high bandwidth error amplifier and patented line feed-
forward compensation provide very fast line and load
transient response. Strong 1Ω gate drivers allow the
LTC3703 to drive multiple MOSFETs for higher current ap-
plications. The operating frequency is user programmable
from 100kHz to 600kHz and can also be synchronized to
an external clock for noise-sensitive applications. Cur-
rent limit is programmable with an external resistor and
utilizes the voltage drop across the synchronous MOSFET
to eliminate the need for a current sense resistor. For ap-
plications requiring up to 60V operation with logic-level
MOSFETS, refer to the LTC3703-5 data sheet.
PARAMETER
Maximum V
IN
MOSFET Gate Drive
V
CC
UV
+
V
CC
UV
–
LTC3703-5
60V
4.5V to 15V
3.7V
3.1V
LTC3703
100V
9.3V to 15V
8.7V
6.2V
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High Voltage Operation: Up to 100V
Large 1Ω Gate Drivers
No Current Sense Resistor Required
Step-Up or Step-Down DC/DC Converter
Dual N-Channel MOSFET Synchronous Drive
Excellent Line and Load Transient Response
Programmable Constant Frequency: 100kHz to
600kHz
±1% Reference Accuracy
Synchronizable up to 600kHz
Selectable Pulse-Skip Mode Operation
Low Shutdown Current: 50µA Typ
Programmable Current Limit
Undervoltage Lockout
Programmable Soft-Start
16-Pin Narrow SSOP and 28-Pin SSOP Packages
applicaTions
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48V Telecom and Base Station Power Supplies
Networking Equipment, Servers
Automotive and Industrial Control
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT and No R
SENSE
are trademarks of Linear Technology Corporation. All other trademarks
are the property of their respective owners. Protected by U.S. Patents, including 5408150,
5055767, 6677210, 5847554, 5481178, 6304066, 6580258.
Typical applicaTion
V
CC
9.3V TO 15V
+
MODE/SYNC V
IN
30k
10k
1000pF
470pF
15k
8.06k
1%
0.1µF
100
2200pF
113k
1%
BOOST
LTC3703
TG
COMP
FB
I
MAX
INV
RUN/SS
GND
SW
VCC
DRV
CC
BG
BGRTN
10
f
SET
22µF
25V
BAS19
V
IN
15V TO 100V
Efficiency vs Load Current
100
V
IN
= 25V
V
IN
= 50V
V
IN
= 75V
90
+
Si7456DP
0.1µF
8µH
68µF
95
V
OUT
12V
5A
EFFICIENCY (%)
270µF
16V
Si7456DP
+
85
10µF
1µF
MBR1100
80
0
1
3
2
LOAD (A)
4
5
3703 F01b
3703 F01
Figure 1. High Efficiency High Voltage Step-Down Converter
3703fc
1
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
