Dual 36V Input Voltage, 8A

Synchronous Buck Converters with

Multiphase Capability and ASIL B

Safety Level

MAX25254/MAX25255

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Analog Devices | 13

11

LX1

Buck1 Inductor Connection. Connect an inductor from LX1 to the Buck1 output. LX1 is high impedance

when Buck1 is disabled.

12

BST1

Integrated High-Side MOSFET Gate Drive Supply. Connect a 0.1µF ceramic capacitor between BST2

and LX2 for proper operation.

13

EN1

Enable Input for Buck1. Drive EN1 high/low to enable/disable Buck1. EN1 can be connected directly to

the battery for always-ON applications.

14

SYNCOUT

90° Out-of-Phase Clock Output. Connect SYNCOUT of the primary IC to SYNC of the secondary IC for

quad-phase operation. Multiphase operation is designed for PWM mode. No clock is present on

SYNCOUT in skip mode or with external clock synchronization.

15

PGOOD1

Buck1 Open-Drain Power-Good Output. Connect PGOOD1 to BIAS or an external voltage rail with a

pull-up resistor. PGOOD1 is pulled to ground during startup, Buck1 output undervoltage, or overvoltage.

16

OUT1/FB1

Buck1 Output Sense/Feedback Input. In the fixed output version, connect OUT1 to the Buck1 output to

set the fixed output voltage. In the adjustable output version, connect FB1 to a resistor-divider between

the Buck1 output and AGND to program the output voltage between 0.8V and 14V. FB1 is regulated to

0.8V (typ) in the adjustable version.

17

TEMP

Die Temperature Monitoring Node. The voltage at TEMP is proportional to the IC die temperature.

18

VEA

Error Amplifier Output for Multiphase Operation. When two MAX25255 ICs are used in parallel for 4-

phase operation, tie both VEA nodes together for phase balancing. Leave VEA open in single-IC

operation.

19

AGND

Analog Ground. All of the sensitive analog signals are internally referenced to analog ground. Care must

be taken during layout to ensure that AGND is routed in the quiet section of the PCB.

20

BIAS

Internal Linear Regulator Output. Bypass BIAS with a 4.7µF (min) capacitor to AGND. BIAS supplies the

internal gate drive circuitry and is not for external use.

21

EXTVCC

Switchover Input. When valid voltage is present at EXTVCC, EXTVCC supplies the internal BIAS LDO

after soft-start is complete. If the EXTVCC voltage is not valid, or it is tied to ground, the BIAS LDO is

supplied by SUP1. Bypass EXTVCC with a 2.2µF ceramic capacitor.

22

OUT2/FB2

Buck2 Output Sense/Feedback Input. In the fixed output version, connect OUT2 to the Buck2 output to

set the fixed output voltage. In the adjustable output version, connect FB2 to a resistor-divider between

the Buck2 output and AGND to program the output voltage between 0.8V and 14V. FB2 is regulated to

0.8V (typ) in the adjustable output version.

23

PGOOD2

Buck2 Open-Drain Power-Good Output. Connect PGOOD2 to BIAS or an external voltage rail with a

pull-up resistor. PGOOD2 is pulled to ground during startup, Buck2 output undervoltage, or overvoltage.