LT3692A_15 Datasheet, PDF (1/42 Pages) Linear Technology – Monolithic Dual Tracking 3.5A Step-Down Switching Regulator

LT3692A
Monolithic Dual Tracking
3.5A Step-Down Switching Regulator
Features
n _{Wide Input Range:}
– Operation from 3V to 36V
– OVLO Protects Circuit Through 60V Transients
n _{Independent Supply, Shutdown, Soft-Start, UVLO,}
Programmable Current Limit and Programmable
Power Good for Each 3.5A Regulator
n _{Die Temperature Monitor}
n _{Adjustable/Synchronizable Fixed Frequency}
Operation from 250kHz to 2MHz with Synchronized
Clock Output
n _{Independent Synchronized Switching Frequencies}
Optimize Component Size
n _{Antiphase Switching}
n _{Outputs Can Be Paralleled}
n _{Flexible Output Voltage Tracking}
n _{Low Dropout: 95% Maximum Duty Cycle}
n _{5mm × 5mm QFN Package}
n _{FMEA Compliant 38-Pin Exposed Pad TSSOP Package}
Applications
n _{Automotive Supplies}
n _{Distributed Supply Regulation}
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Description
The LT^®3692A is a dual current mode PWM step-down
DC/DC converter with two internal 3.8A switches. Independent
input voltage, shutdown, feedback, soft-start, UVLO current
limit and comparator pins for each channel simplify complex
power supply tracking and sequencing requirements.
To optimize efficiency and component size, both convert-
ers have a programmable maximum current limit and are
synchronized to either a common external clock input, or
a resistor settable fixed 250kHz to 2MHz internal oscillator.
A frequency divider is provided for channel 1 to further
optimize component size. At all frequencies, a 180° phase
relationship between channels is maintained, reducing volt-
age ripple and component size. A clock output is available
for synchronizing multiple regulators.
Minimum input to output voltage ratios are improved by
allowing the switch to stay on through multiple clock cycles
only switching off when the boost capacitor needs recharg-
ing. Independent channel operation can be programmed
using the SHDN pin. Disabling both converters reduces
the total quiescent current to <10µA.
The LT3692A is an improved version of the LT3692 with
reduced minimum on-time.
Typical Application
3.3V and 1.2V 2-Stage Dual Step-Down Multi-Frequency Converter
Independent Synchronized Switching Frequencies
Extend Full Frequency Input Range
V_IN1
5.5V TO 36V
4.7µF
V_IN1
SHDN1
BST1
V_OUT1
V_IN2
SHDN2
BST2
SW1
SW2
V_OUT1
3.3V
2.5A
550kHz
PG
0.1µF
100k
100k
0.22µF
47µF
8.06k
33pF 680pF
13k
4.7µH
24.9k
IND1
IND2
LT3692A
V_OUT1
V_OUT2
FB1
FB2
CMPI1
CMPI2
CMPO1 CMPO2
SS1
ILIM1
V_C1
RT/SYNC
SS2
ILIM2
V_C2
CLKOUT
DIV
GND
T_J
68.1k 102k
0.1µF
0.5µH
4.02k 100p
FB1
8.06k
47µF
V_OUT2
1.2V
1A
2.2MHz
CLKOUT
2.2MHz
10nF
220pF
40.2k
22pF
33.2k
0.1µF
V_IN = 30V
CH1:
550kHz
CH2:
2.2MHz
3692A TA01b
3692a TA01a
For more information www.linear.com/3692A
3692a TA01c
3692afc
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