LTC3870-1
Features
PolyPhase Step-Down
Slave Controller for Digital
Power System Management
Description
nn LTC3887-1 Phase Extender
nn Operates with Power Blocks, DrMOS or External
Gate Drivers and MOSFETs
nn Cascade with Multiple Chips for Very Large Current
Applications
nn Accurate PolyPhase Current Sharing
nn EXTVCC Capable of 5V to 14V Input
nn Wide VIN Range: 4.5V to 60V
nn Wide Output Voltage Range : 0.5V to 14V
nn Wide SYNC Frequency Range: 100kHz to 1MHz
nn Pin Programmable CCM/DCM Operation
nn Pin Programmable Phase-Shift Control
nn Available in a 24-Pin (4mm × 4mm) QFN Package
Applications
nn High Power Distributed Power Systems
nn Telecom Systems
nn Industrial Applications
The LTC®3870-1 is a PolyPhase® step-down slave control-
ler specially designed for multiphase operation with LTC's
digital power system management DC/DC controllers. It
provides a small and cost effective solution for supply-
ing very large currents by cascading it with a LTC3887-1
controller. A peak current mode architecture provides the
LTC3870-1 with excellent current sharing from phase to
phase and from chip to chip.
Coherently working with the LTC3887-1, the LTC3870-1
does not require additional I2C addresses, and it supports
all programmable features as well as fault protection.
The constant switching frequency can be synchronized
to an external clock from the LTC3887-1 over a range of
100kHz to 1MHz.
L, LT, LTC, LTM, PolyPhase, 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, 5705919, 5929620, 6144194, 6177787,
6580258, 5408150
Typical Application
VIN
7V TO 14V
22µF
4.7µF
VOUT0
3.3V, 30A
1.0µH
530µF
2.15k
0.2µF
DrMOS
LTC3887-1
RUN0
3.3V
RUN1
VSENSE0+ GPIO0
1.8V
GPIO1
VSENSE1+ ITH0
ITH1
SYNC
* REFER TO LTC3887-1 DATA SHEET
FOR MASTER SETUP
VIN INTVCC
VCC0
VCC1
LTC3870-1
PWM0
PWM1
DrMOS
ISENSE0+ ISENSE1+
ISENSE0- ISENSE1-
RUN0
RUN1
FAULT0
FAULT1
ITH0
ITH1
SYNC
EXTVCC
FREQ
PHASMD
ILIM
MODE0
MODE1
GND
82.5k
0.56µH
1.74k
0.2µF
Load Transient Response of a
2-Phase Master (3887-1)/Slave
(3870-1) Converter
ILOAD
20A/DIV
10A TO 20A TO 10A
VOUT1
1.8V, 40A
530µF
IL LTC3887–1
(CH0)
10A/DIV
IL LTC3870–1
(CH0)
10A/DIV
VOUT
200mV/DIV
AC–COUPLED
VIN = 12V
VOUT = 1.8V
100µs/DIV
38701 TA01b
38701 TA01a
For more information www.linear.com/LTC3870-1
38701f
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