LTC3703-5_15 Datasheet, PDF (8/32 Pages) Linear Technology – 60V Synchronous Switching Regulator Controller

LTC3703-5
W
FU CTIO AL DIAGRA
RSET
FSET
2
4µA
RUN/SS
5
C_SS
3.2V
MODE/SYNC 1
COMP
3
R2 R1
0.8V
FB
4
V_IN 16
–
1V ⁺
UVSD OTSD
CHIP
SD
EXT SYNC
SYNC
DETECT
OSC
FORCED CONTINUOUS
INV
–
+
+ FB
–
÷
% DC
LIMIT
PWM
+
+MIN–
+MAX–
V_CC
(<15V)
12
OVER
TEMP
BANDGAP
0.76V
0.84V
V_CC
UVLO
OT SD
0.8V
REFERENCE
INTERNAL
3.2V V_CC
UV SD
V_CC
C_VCC
OVERCURRENT
12µA
50mV
±
I_MAX
5
R_MAX
±
INV
REVERSE
CURRENT
DRIVE
LOGIC
V_CC
D_B
BOOST
15
TG
C_B
14
SW
13
DRV_CC
11
BG
10
BGRTN
9
6 INV
V_IN
M1
M2
L1
8 GND
C_OUT
V_OUT
GN16
U
OPERATIO (Refer to Functional Diagram)
The LTC3703-5 is a constant frequency, voltage mode
controller for DC/DC step-down converters. It is designed
to be used in a synchronous switching architecture with
two external N-channel MOSFETs. Its high operating volt-
age capability allows it to directly step down input voltages
up to 60V without the need for a step-down transformer.
For circuit operation, please refer to the Functional
37035 FD
Diagram of the IC and the circuit on the first page of this
data sheet. The LTC3703-5 uses voltage mode control in
which the duty ratio is controlled directly by the error
amplifier output and thus requires no current sense resis-
tor. The V_FB pin receives the output voltage feedback and
is compared to the internal 0.8V reference by the error
amplifier, which outputs an error signal at the COMP pin.
37035fa
8