LTC3703IGN Datasheet, PDF (1/34 Pages) Linear Integrated Systems – 100V Synchronous Switching Regulator

Features
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}
600kHz
n _{±1% Reference Accuracy}
n _{Synchronizable up to 600kHz}
n _{Selectable Pulse-Skip Mode Operation}
n _{Low Shutdown Current: 50µA Typ}
n _{Programmable Current Limit}
n _{Undervoltage Lockout}
n _{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}
n _{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.
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
Typical Application
V_CC
9.3V TO 15V
100Ω
2200pF
30k
10k
1000pF 470pF
8.06k
1%
15k
0.1µF
113k
1%
MODE/SYNC V_IN
f_SET
BOOST
LTC3703
COMP
TG
FB
SW
I_MAX
VCC
INV
DRV_CC
RUN/SS
BG
GND BGRTN
+ _22µF
25V
BAS19
0.1µF
10Ω
10µF
1µF
V_IN
15V TO 100V
+
68µF
Si7456DP
8µH
270µF ⁺
16V
Si7456DP
MBR1100
V_OUT
12V
5A
3703 F01
Figure 1. High Efficiency High Voltage Step-Down Converter
Efficiency vs Load Current
100
V_IN = 25V
95
V_IN = 50V
V_IN = 75V
90
85
80
0
1
2
3
4
5
LOAD (A)
3703 F01b
3703fc
1