Maxim-integrated MAX15303 PMBus Command Set Manuel d'utilisateur télécharger pdf (Page 18)

MAX15303 PMBus Command Set User’s Guide

Page 18 of 52

TOFF_FALL

Reference:

Standard Command

Lockable:

Yes

Command Code:

0x65

Format:

Linear

Data Bytes:

Units:

Transfer:

Read/Write Word

Factory Value:

0xCA80 (5ms)

Description/Notes:

See Section 16.6 of the PMBus Specification Part II.

The TOFF_FALL command sets the ramp-down time from regulation at VOUT_COMMAND to 0V. The

nominal factory value is 5ms.

The MAX15303 achieves shutdown dV

OUT

/dt control by decrementing the loop setpoint by one 12-bit

step every time a certain number of ramp-controller clock cycles have elapsed in an 8-bit counter.

This results in a setpoint that decreases at a controlled rate, in turn creating a constant dV

OUT

/dt

during shutdown.

Because the MAX15303

must calculate the ramp control timer setting based upon the value of

VOUT_COMMAND, the possible range and resolution of TOFF_FALL will vary significantly.

The desired value of TOFF_FALL is retained in memory, regardless of ramp-timer limitations, but the

read-back value is based on actual hardware register settings.

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Maxim-integrated MAX15303 PMBus Command Set Manuel d'utilisateur Page 18