MAX1875 Datasheet, PDF (1/21 Pages) Maxim Integrated Products – Dual 180° Out-of-Phase PWM Step- Down Controllers with POR

19-2431; Rev 0; 7/02
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Dual 180° Out-of-Phase PWM Step-
Down Controllers with POR
General Description
The MAX1875/MAX1876 dual, synchronized, step-down
controller generates two outputs from input supplies
ranging from 4.75V to 23V. Each output is adjustable from
sub-1V to 18V and supports loads of 10A or higher. Input
voltage ripple and total RMS input ripple current are
reduced by synchronized 180° out-of-phase operation.
The switching frequency is adjustable from 100kHz to
600kHz with an external resistor. Alternatively, the con-
troller can be synchronized to an external clock gener-
ated to another MAX1875/MAX1876 or a system clock.
One MAX1875/MAX1876 can be set to generate an in-
phase, or 90° out-of-phase, clock signal for synchro-
nization with additional controllers. This allows two
controllers to operate either as an interleaved two- or
four-phase system with each output shifted by 90°.
These devices also feature soft-start and soft-stop.
The MAX1875/MAX1876 eliminate the need for current-
sense resistors by utilizing the low-side MOSFET’s on-
resistance as a current-sense element. This protects
the DC-DC components from damage during output-
overload conditions or when output short-circuit faults
without requiring a current-sense resistor. Adjustable
foldback current limit reduces power dissipation during
short-circuit conditions. The MAX1876 includes a
power-on reset output to signal the system when both
outputs reach regulation.
The MAX1875/MAX1876 are available in a 24-pin QSOP
package. An evaluation kit is available to speed designs.
Applications
Network Power Supplies
Telecom Power Supplies
DSP, ASIC, and FPGA Power Supplies
Set-Top Boxes
Broadband Routers
Servers
Typical Operating Circuit appears at end of data sheet.
Features
o Two Independent Output Voltages
o 180° Out-of-Phase Operation
o 90° Out-of-Phase Operation
(Using Two MAX1875/MAX1876s)
o Foldback Current Limit
o 4.75V to 23V Input Supply Range
o 0 to 18V Output-Voltage Range (Up to 10A)
o >90% Efficiency
o Fixed-Frequency Pulse-Width Modulation (PWM)
Operation
o Adjustable 100kHz to 600kHz Switching
Frequency
o External SYNC Input
o Clock Output for Master/Slave Synchronization
o Soft-Start and Soft-Stop
o RST Output with 140ms Minimum Delay (MAX1876)
o Lossless Current Limit (No Sense Resistor)
Ordering Information
PART
MAX1875EEG
MAX1876EEG
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
24 QSOP
24 QSOP
Pin Configuration
TOP VIEW
COMP2 1
FB2 2
ILIM2 3
OSC 4
V+ 5
REF 6
GND 7
CKO 8
SYNC 9
ILIM1 10
FB1 11
COMP1 12
MAX1875/
MAX1876
QSOP
24 EN
23 DH2
22 LX2
21 BST2
20 DL2
19 V_L
18 PGND
17 DL1
16 BST1
15 LX1
14 DH1
13 RST
(MAX1876 ONLY)
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.