LTC3864
60V Low IQ Step-Down
DC/DC Controller with
100% Duty Cycle Capability
Description
Features
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Wide Operating VIN Range: 3.5V to 60V
Wide VOUT Range: 0.8V to VIN
Low Operating IQ = 40µA
Very Low Dropout Operation: 100% Duty Cycle
Strong High Voltage MOSFET Gate Driver
Constant Frequency Current Mode Architecture
Verified FMEA for Adjacent Pin Open/Short
Selectable High Efficiency Burst Mode® Operation or
Pulse-Skipping Mode at Light Loads
Programmable Fixed Frequency: 50kHz to 850kHz
Phase-Lockable Frequency: 75kHz to 750kHz
Accurate Current Limit
Programmable Soft-Start or Voltage Tracking
Internal Soft-Start Guarantees Smooth Start-Up
Power Good Output Voltage Monitor
Low Shutdown IQ = 7µA
Available in Small 12-Pin Thermally Enhanced MSOP
and DFN Packages
The LTC®3864 is a robust, high voltage step-down DC/DC
controller optimized for automotive and industrial applications. It drives a P-channel power MOSFET switch allowing
100% duty cycle operation. The wide input and output voltage ranges cover a multitude of applications. This device
has been verified with the failure mode and effects analysis
(FMEA) procedure for operation during failure conditions.
The LTC3864 offers excellent light load efficiency, drawing only 40µA quiescent current in a user programmable
Burst Mode operation. Its peak current mode, constant
frequency PWM architecture provides for good control of
switching frequency and output current limit. The switching frequency can be programmed from 50kHz to 850kHz
with an external resistor and can be synchronized to an
external clock from 75kHz to 750kHz.
The LTC3864 offers programmable soft-start or output
tracking. Safety features include overvoltage protection,
overcurrent and short-circuit protection including frequency foldback and a power good output signal.
Applications
The LTC3864 is available in thermally enhanced 12-Pin
MSOP and 3mm × 4mm DFN packages.
Industrial and Automotive Power Supplies
Telecom Power Supplies
n Distributed Power Systems
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L, LT, LTC, LTM, OPTI-LOOP Linear Technology, Burst Mode and the Linear logo are registered
,
trademarks and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks
are the property of their respective owners. Protected by U.S. Patents including 5731694.
Typical Application
5.2V to 60V Input, 5V/2A Output, 350kHz Step-Down Converter
10µF
0.47µF
RUN
3.3nF
9.09k
90
VIN
25mΩ
PLLIN/MODE
SS
100
SENSE
LTC3864
GATE
ITH
FREQ
10µH
VOUT*
5V
2A
100k
422k
SGND
47µF
×2
PGOOD
PGND
*VOUT FOLLOWS VIN
WHEN 3.5V ≤ VIN ≤ 5.2V
EFFICIENCY (%)
350kHz
CAP
Efficiency
VIN*
5.2V TO 60V
80
PULSE-SKIPPING
70
60
50
0.01
VFB
80.6k
Burst Mode
OPERATION
VIN = 12V
VOUT = 5V
0.1
LOAD CURRENT (A)
1
3864 TA01b
3864 TA01a
3864fa
For more information www.linear.com/LTC3864
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