ADP1053ACPZ-R7 datasheet(22/84 Pages) AD

22 / 84 page

ADP1053

Data Sheet

Rev. A | Page 22 of 84

The unregulated Channel C can be programmed to be always

on, or it can be programmed to be on when either PSON_A

or PSON_B is on. This option is configured using Bit 4 of

Software Reset

The user can reset the ADP1053 power supply by writing the

GO command to Register 0xFE88 (Bit 0 for Channel A; Bit 1

for Channel B). When the GO bit is written, the power supply

for Channel A or Channel B is immediately turned off, and the

channel is restarted with a soft start after a preset delay. The

delay can be programmed to 0 ms, 500 ms, 1 sec, or 2 sec using

Bits[3:2] of Register 0xFE88.

PSON Sequencing

For both the regulated Channel A and Channel B and the

unregulated Channel C, the turn-on delay, turn-off delay,

and ramp rate can be independently configured. The register

settings can be used to set up the sequencing of the channels.

Figure 21 shows a typical sequencing diagram.

•

The turn-on delays (tDON_A, tDON_B, and tDON_C) are the delay

times between the activation of the PSON_A/PSON_B

pins or commands that trigger the turn-on signal and the

start of the output ramp-up.

•

The turn-off delays (tDOFF_A, tDOFF_B, tDOFF_C) are the delay

times between the activation of the PSON_A/PSON_B

pins or commands that trigger the turn-off signal and the

start of the output shutdown.

The turn-on and turn-off delays for Channel A, Channel B,

and Channel C can be set to 0 ms, 50 ms, 250 ms, or 1 sec

using Register 0xFE79, Register 0xFE7A, and Register 0xFE7B,

respectively.

tDON_A

tDOFF_C

tDON_B

tDON_C

PSON_A/

PSON_B

VOUTA

VOUTB

VOUTC

tSS_A

tSS_B

tSS_C

tDOFF_A

tDOFF_B

Figure 21. PSON Sequencing Diagram

The PGOOD signal of a master controller can be configured to

trigger the PSON signals of multiple slave controllers.

The ADP1053 also has fault link functionality; that is, the part

can be configured to shut down an output after another output

is shut down.

Soft Start Ramp

For either regulated channel of the ADP1053, the VS_A/VS_B

reference voltage increases from 0 V to the regulated reference

voltage after the PSON signal is received and after the turn-on

delay. The ramp rate for the reference voltage is set in Register

0xFE2A for Channel A and Register 0xFE2B for Channel B. The

first column of Table 8 shows the possible ramp rates for the

VS_A and VS_B references.

A non-zero prebias may result in a longer turn-on delay and

shorter rise time.

Table 8. Soft Start Ramp Timing

VS_A/VS_B

Reference Ramp Rate

Channel C

Duty Cycle Ramp Rate

1 V/1.75 ms

40 ns/1 switching cycle

1 V/10.5 ms

40 ns/2 switching cycles

1 V/21.0 ms

40 ns/4 switching cycles

1 V/40.2 ms

40 ns/8 switching cycles

For the unregulated Channel C, the duty cycle can be pro-

grammed to increase or decrease at a rate set by Bits[5:4] of

per one, two, four, or eight switching cycles. The soft start time

for Channel C is usually faster than the soft start time for the

regulated channels.

Two variation values are used for Channel C soft start:

tSS_C1 = |tF1 − tR1|

tSS_C2 = |tF2 − tR2|

where:

tR1 and tR2 are the timing values for the rising edges of OUT1

and OUT2, respectively.

tF1 and tF2 are the timing values for the falling edges of OUT1

and OUT2, respectively.

tSS_C1 sets the variation for OUT1, OUT3, OUT5, and OUT7

if these PWM outputs are assigned to Channel C.

tSS_C2 sets the variation for OUT2, OUT4, OUT6, and OUT8

if these PWM outputs are assigned to Channel C.

Both edges of a PWM signal assigned to Channel C can implement

modulation during soft start. At the initiation of soft start, a

modulated edge assigned to Channel C behaves as follows:

•

If the edge is configured for positive modulation, the edge

timing is the preset value plus the variation value. During

soft start, the edge moves to the left until it reaches the

preset value.

•

If the edge is configured for negative modulation, the edge

timing is the preset value minus the variation value. During

soft start, the edge moves to the right until it reaches the

preset value.

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