MAX8688 Просмотр технического описания (PDF) - Maxim Integrated

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MAX8688

Digital Power-Supply Controller/Monitor with PMBus Interface

Maxim Integrated 

Digital Power-Supply Controller/Monitor

with PMBus Interface

Since the reference voltage input is provided by the

MAX8688, the REFIN mode provides complete control

of the POL in terms of soft-start, soft-stop, and margin-

ing transitions. It may be noted that the slew rates dur-

ing soft-start (tON_RISE) and during margining

(VOUT_TRANSITION_RATE) should be programmed

with POL current-limit consideration. An excessively

fast slew rate causes the POL to trip due to overcurrent.

A general guideline for setting the output-voltage slew

rate is as follows:

SLEW RATE ≤ (ILIMIT − ILOAD)

COUT

where COUT is the output capacitance on the POL out-

put, ILOAD is the load current being delivered by the

POL, and ILIMIT is the current-limit setting of the POL.

On receipt of either an OPERATION OFF command or a

turn-off signal from A3/ONOFF, the MAX8688 com-

mences the shutdown operation that has been pro-

grammed for the POL being controlled. After the

programmed tOFF_DELAY time, the MAX8688 ramps

down the output voltage to zero precisely in the pro-

grammed tOFF_FALL time, and deasserts its open-drain

ENOUT output.

3.3V

0.1µF

A1/SCLE

A2/SDAE

A3/ONOFF

SCL

SDA

RST

SYSTEM

CONTROLLER

IRQ

CLKOUT

FLT

CLKIO

DVDD

DGND

MAX8688

POWER MONITOR

AVDD

AGND

ADC

SMBus

CONTROLLER

TEMP SENSOR

INTERNAL REFERENCE

PMBus COMMAND AND

STATUS REGISTERS

DAC

MAXQ µC

200Ω

RS-

RS+

RS_C

200Ω

ISN-

ISN+

ISN_C

REFO

S1

DACOUT

ENOUT

0.1µF

LOAD

RSENSE

VO+

1µF

REFIN

POL

EN

VO-

VIN+

VIN-

Figure 3. Typical System Application—REFIN Mode

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