LTC3812-5_15 Datasheet, PDF (1/34 Pages) Linear Technology – 60V Current Mode Synchronous Switching Regulator Controller

FEATURES
n _{High Voltage Operation: Up to 60V}
n _{Large 1Ω Gate Drivers}
n _{No Current Sense Resistor Required}
n _{Dual N-Channel MOSFET Synchronous Drive}
n _{Extremely Fast Transient Response}
n _{±0.5% 0.8V Voltage Reference}
n _{Programmable Soft-Start}
n _{Generates 5.5V Driver Supply}
n _{Selectable Pulse-Skipping Mode Operation}
n _{Power Good Output Voltage Monitor}
n _{Adjustable On-Time/Frequency: tON(MIN) < 100ns}
n _{Adjustable Cycle-by-Cycle Current Limit}
n _{Undervoltage Lockout On Driver Supply}
n _{Output Overvoltage Protection}
n _{Thermally Enhanced 16-Pin TSSOP Package}
APPLICATIONS
n _{48V Telecom and Base Station Power Supplies}
n _{Networking Equipment, Servers}
n _{Automotive and Industrial Control Systems}
LTC3812-5
60V Current Mode
Synchronous Switching
Regulator Controller
DESCRIPTION
The LTC3812-5 is a synchronous step-down switching
regulator controller that can directly step down voltages
from up to 60V input, making it ideal for telecom and
automotive applications. The LTC3812-5 uses a constant
on-time valley current control architecture to deliver very
low duty cycles with accurate cycle-by-cycle current limit
without requiring a sense resistor.
A precise internal reference provides 0.5% DC accuracy.
A high bandwidth (25MHz) error amplifier provides very
fast line and load transient response. Large 1Ω gate driv-
ers allow the LTC3812-5 to drive large power MOSFETs
for higher current applications. The operating frequency
is selected by an external resistor and is compensated for
variations in V_IN. A shutdown pin allows the LTC3812-5 to
be turned off reducing the supply current to <230μA.
Integrated bias control generates gate drive power from
the input supply during start-up and when an output short-
circuit occurs, with the addition of a small external SOT23
MOSFET. When in regulation, power is derived from the
output for higher efficiency.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 5481178, 5847554, 6304066, 6476589, 6580258,
6677210, 6774611.
TYPICAL APPLICATION
High Efficiency High Voltage Step-Down Converter
R_ON
110k
100k
PGOOD
1000pF
47pF
200k
5pF
I_ON
NDRV
PGOOD
BOOST
LTC3812-5
V_RNG
TG
FCB
RUN/SS
SW
EXTV_CC
INTV_CC
I_TH
BG
V_{FB SGND} PGND
100k
M3
ZXMN-
10A07F
0.1μF
1μF
V_IN
+
6V TO 60V
C_IN
22μF
M1
Si7850DP
L1
4.7μH
M2
Si7850DP
D1
10k ₊
MBR1100
1.89k
V_OUT
5V
5A
C_OUT
270μF
38125 TA01
Efficiency vs Load Current
100
V_IN = 12V
95
V_IN = 42V
90
V_IN = 24V
85
80
0
1
2
3
4
LOAD CURRENT (A)
5
6
38125 TA01b
38125fc
1