LTC3703
100V Synchronous
Switching Regulator
Controller
FeaTures
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.
n
High Voltage Operation: Up to 100V
n
Large 1Ω Gate Drivers
n
No Current Sense Resistor Required
n
Step-Up or Step-Down DC/DC Converter
n
Dual N-Channel MOSFET Synchronous Drive
n
Excellent Line and Load Transient Response
n
Programmable Constant Frequency: 100kHz to
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
LTC3703todrivemultipleMOSFETsforhighercurrentap-
plications.Theoperatingfrequencyisuserprogrammable
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
utilizesthevoltagedropacrossthesynchronousMOSFET
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.
600kHz
n
1% Reference Accuracy
n
Synchronizable up to 600kHz
n
Selectable Pulse-Skip Mode Operation
n
Low Shutdown Current: 50µA Typ
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Programmable Current Limit
n
Undervoltage Lockout
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Programmable Soft-Start
n
16-Pin Narrow SSOP and 28-Pin SSOP Packages
applicaTions
n
48V Telecom and Base Station Power Supplies
n
Networking Equipment, Servers
PARAMETER
Maximum V
LTC3703-5
60V
LTC3703
100V
n
Automotive and Industrial Control
IN
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT and No R
MOSFET Gate Drive
4.5V to 15V
3.7V
9.3V to 15V
8.7V
are trademarks of Linear Technology Corporation. All other trademarks
SENSE
+
V
CC
V
CC
UV
UV
are the property of their respective owners. Protected by U.S. Patents, including 5408150,
5055767, 6677210, 5847554, 5481178, 6304066, 6580258.
–
3.1V
6.2V
Typical applicaTion
V
CC
9.3V TO 15V
+
V
22µF
25V
IN
Efficiency vs Load Current
BAS19
0.1µF
15V TO 100V
100
95
MODE/SYNC
V
IN
+
30k
68µF
V = 25V
IN
f
BOOST
TG
SET
V
= 50V
LTC3703
Si7456DP
IN
10k
COMP
8µH
1000pF
470pF
15k
V
= 75V
IN
V
12V
5A
OUT
FB
SW
90
+
270µF
16V
I
V
CC
MAX
8.06k
1%
10Ω
INV
DRV
CC
85
0.1µF
Si7456DP
MBR1100
RUN/SS
GND
BG
113k
1%
10µF
100Ω
2200pF
80
BGRTN
0
1
2
3
4
5
1µF
LOAD (A)
3703 F01b
3703 F01
Figure 1. High Efficiency High Voltage Step-Down Converter
3703fc
1