MAX1876EEG+ Datasheet MAX1876EEG+, MAX1875EEG+, MAX1876EEG+T | P1-P3

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

Features

♦ Two Independent Output Voltages

♦ 180° Out-of-Phase Operation

♦ 90° Out-of-Phase Operation

(Using Two MAX1875/MAX1876s)

♦ Foldback Current Limit

♦ 4.75V to 23V Input Supply Range

♦ 0 to 18V Output-Voltage Range (Up to 10A)

♦ >90% Efficiency

♦ Fixed-Frequency Pulse-Width Modulation (PWM)

Operation

♦ Adjustable 100kHz to 600kHz Switching

Frequency

♦ External SYNC Input

♦ Clock Output for Master/Slave Synchronization

♦ Soft-Start and Soft-Stop

♦ RST Output with 140ms Minimum Delay (MAX1876)

♦ Lossless Current Limit (No Sense Resistor)

MAX1875/MAX1876

Dual 180° Out-of-Phase PWM Step-

Down Controllers with POR

________________________________________________________________ Maxim Integrated Products 1

LX2

DH2

BST2OSC

ILIM2

FB2

COMP2

TOP VIEW

DL2

PGND

DL1CKO

GND

REF

V+

BST1

DH1

LX1

COMP1

FB1

ILIM1

SYNC

QSOP

MAX1875/

MAX1876

RST

(MAX1876 ONLY)

Pin Configuration

Ordering Information

19-2431; Rev 0; 7/02

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.

EVALUATION KIT

AVAILABLE

PART TEMP RANGE PIN-PACKAGE

MAX1875EEG -40°C to +85°C 24 QSOP

MAX1876EEG -40°C to +85°C 24 QSOP

Typical Operating Circuit appears at end of data sheet.

MAX1875/MAX1876

Dual 180° Out-of-Phase PWM Step-

Down Controllers with POR

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional

operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to

absolute maximum rating conditions for extended periods may affect device reliability.

V+ to GND ..............................................................-0.3V to +25V

PGND to GND .......................................................-0.3V to +0.3V

to GND ..................-0.3V to the lower of +6V and (V+ + 0.3V)

BST1, BST2 to GND ...............................................-0.3V to +30V

LX1 to BST1..............................................................-6V to +0.3V

LX2 to BST2..............................................................-6V to +0.3V

DH1 to LX1 ..............................................-0.3V to (V

BST1

+ 0.3V)

DH2 to LX2 ..............................................-0.3V to (V

BST2

+ 0.3V)

DL1, DL2 to PGND........................................-0.3V to (V

+ 0.3V)

CKO, REF, OSC, ILIM1, ILIM2,

COMP1, COMP2 to GND ..........................-0.3V to (V

+ 0.3V)

FB1, FB2,

RST, SYNC, EN to GND...........................-0.3V to +6V

VL to GND Short Circuit .............................................Continuous

REF to GND Short Circuit ...........................................Continuous

Continuous Power Dissipation (T

= +70°C)

24-Pin QSOP (derate 9.4mW/°C above +70°C)...........762mW

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

ELECTRICAL CHARACTERISTICS

(V+ = 12V, EN = ILIM_ = V

, SYNC = GND, I

= 0mA, PGND = GND, C

REF

= 0.22µF, C

= 4.7µF (ceramic), R

OSC

= 60kΩ,

compensation components for COMP_ are from Figure 1, T

= -40°C to +85°C (Note 1), unless otherwise noted.)

PARAMETER CONDITIONS

MIN TYP MAX

UNITS

GENERAL

(Note 2)

4.75

V+ Operating Range

= V+ (Note 2)

4.75

5.5

V+ Operating Supply Current V

unloaded, no MOSFETs connected 3.5 6 mA

V+ Standby Supply Current EN = LX_ = FB_ = 0V R

OSC

= 60kΩ 0.3 0.6 mA

Thermal Shutdown Rising temperature, typical hysteresis = 10°C

160

°C

ILIM_ = V

100

125 mV

ILIM_

= 100kΩ 32 50 62 mV

Current-Limit Threshold PGND - LX_

ILIM_

= 600kΩ

225 300

375 mV

REGULATOR

Output Voltage 5.5V < V+ < 23V, 1mA < I

LOAD

< 50mA

4.75

5.25

Undervoltage Lockout

Trip Level

4.4

4.55

4.7 V

REFERENCE

Output Voltage I

REF

= 0µA

1.98 2.00 2.02

Reference Load Regulation 0µA < I

REF

< 50µA 0 4 10 mV

SOFT-START

Digital Ramp Period

Internal 6-bit DAC for one converter to ramp from 0V to

full scale (Note 3)

1024

DC-DC

Clocks

Soft-Start Steps 64

Steps

FREQUENCY

0°C to +85°C 84

100

115

Low End of Range R

OSC

= 60kΩ

-40°C to +85°C 80

100

120

kHz

High End of Range R

OSC

= 10kΩ

540 600

660 kHz

DH_ Minimum Off-Time R

OSC

= 10kΩ

250

303 ns

MAX1875/MAX1876

Dual 180° Out-of-Phase PWM Step-

Down Controllers with POR

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(V+ = 12V, EN = ILIM_ = V

, SYNC = GND, I

= 0mA, PGND = GND, C

REF

= 0.22µF, C

= 4.7µF (ceramic), R

OSC

= 60kΩ,

compensation components for COMP_ are from Figure 1, T

= -40°C to +85°C (Note 1), unless otherwise noted.)

PARAMETER CONDITIONS

MIN TYP MAX UNITS

SYNC Range

Internal oscillator nominal frequency must be set to half

of the SYNC frequency

200

1200

kHz

High

100

SYNC Input Pulse Width (Note 3)

Low

100

SYNC Rise/Fall Time (Note 3) 100 ns

ERROR AMPLIFIER

FB_ Input Bias Current 250 nA

0°C to +85°C

0.985 1.00 1.015

FB_ Input Voltage Set Point

-40°C to +85°C

0.98 1.00 1.02

0°C to +85°C

1.25

1.8

2.70

FB_ to COMP_ Transconductance

-40°C to +85°C 1.2 1.8 2.9

DRIVERS

DL_, DH_ Break-Before-Make Time

LOAD

= 5nF 30 ns

Low 1.5 2.5

DH_ On-Resistance

High 3 5

Ω

Low 0.6 1.5

DL_ On-Resistance

High 3 5

Ω

LOGIC INPUTS (EN, SYNC)

Input Low Level Typical 15% hysteresis, V

= 4.75V 0.8 V

Input High Level V

= 5.5V 2.4 V

Input High/Low Bias Current V

= 0 or 5.5V -1 0.1 +1 µA

LOGIC OUTPUTS (CKO)

Output Low Level V

= 5V, sinking 5mA 0.4 V

Output High Level V

= 5V, sourcing 5mA 4.0 V

COMP_

Pulldown Resistance During

Shutdown and Current Limit

17 Ω

RST OUTPUT (MAX1876 ONLY)

Output-Voltage Trip Level

Both FBs must be over this to allow the reset timer to

start; there is no hysteresis

0.87

0.9

0.93

= 5V, sinking 3.2mA 0.4

Output Low Level

= 1V, sinking 0.4mA 0.3

Output Leakage V+ = V

= 5V, V

RST

= 5.5V, V

= 1V 1 µA

Reset Timeout Period V

FB_

= 1V

140 315

560 ms

FB_ to Reset Delay FB_ overdrive from 1V to 0.85V 4 µs

Note 1: Specifications to -40°C are guaranteed by design and not production tested.

Note 2: Operating supply range is guaranteed by V

line regulation test. Connect V+ to V

for 5V operation.

Note 3: Guaranteed by design and not production tested.

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21

MAX1876EEG+

Mfr. #:

Buy MAX1876EEG+

Manufacturer:

Maxim Integrated

Description:

Switching Controllers Dual 180 Out PWM Step-Down

Lifecycle:

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MAX1876EEG+

MAX1876EEG+

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