Power-Up Sequencer - Analog Devices ADP50460008 Owner's Manual

ADI Confidential

POWER-UP SEQUENCER

The sequencer block controls the activation and turn-on order
of the regulators (see the timing diagram in Figure 37, but note
that this timing diagram is just an example).
The activation delays of the regulators are programmable via
the following: Register EN_DLY12 (Address 4), Bits[7:4] for
Channel 1 and Bits[3:0] for Channel 2; Register EN_DLY36
(Address 5), Bits[7:4] for Channel 3 and Bits[3:0] for Channel 6;
and Register EN_DLY8 (Address 6), Bits[7:4] for Channel 8.
The delay time ranges from 0 ms to 30 ms in 2 ms steps. When
the internal oscillator is used, either the Channel 3 enable delay
(EN_DLY3) or the disable delay function must be set to 0 ms.
Each regulator has a programmable soft start; Register SFTTIM
(Address 2) controls the soft start for Channel 1 to Channel 7.
2.6V
VBATT
10ms TO 20ms
UVLO_SYS
2.8V
VREGO
POCO
EN
CHANNEL 1_ON
CHANNEL 3_ON
CHANNEL 2_ON
CHANNEL 6_ON
PWM1_ON
CHANNEL 4_ON
CHANNEL 5_ON
CHANNEL 7_ON
CHANNEL 8_ON
VOLTAGE
5V
3.6V
3.3V
2.5V
1V
NOTES
1. THE DELAY TIMES FOR THE CHANNELS CAN BE PROGRAMMED INDEPENDENTLY.
3.9ms
t
EN_DLY3
t
EN_DLY2
t
EN_DLY6
t
EN_DLY8
CH 1
(PSM)
Figure 37. Power-Up/Power-Down Sequence
The soft start of each regulator can be programmed to two levels
(see Table 17 to Table 21). The soft start circuit limits the inrush
current when a regulator turns on and the output capacitors are
charged. Excessive inrush current can create too much stress on
the main battery and decrease the input or battery voltage. The
activation for Channel 1 pulse-width modulation (PWM)
mode, Channel 4, Channel 5, Channel 6, Channel 7, and
Channel 8 is software controlled.
Register PWMCONT (Address 14), Bit 0 (PWM1) is the mode
select for Channel 1 PWM/PSM. The on/off controls for Channel 4
to Channel 8 are found in Register PCTRL (Address 32): Bit 4
(CH6_ON) is for Channel 6, Bit 3 (CH8_ON) is for Channel 8,
Bit 2 (CH7_ON) is for Channel 7, Bit 1 (CH4_ON) is for
Channel 4, and Bit 0 (CH5_ON) is for Channel 5.
CH 7
CH 1
(PWM)
CH 2
CH 8
CH 4
CH 5
CH 6
CH 3
Rev. Sp0 | Page 21 of 60
ADP50460008
t
OFFDLY
CH 1
(PSM)
DISCHARGE SWITCH FOR CHANNEL 2
DISCHARGE SWITCH FOR CHANNEL 6
DISCHARGE SWITCH FOR CHANNEL 8
DISCHARGE SWITCH FOR CHANNEL 4
DISCHARGE SWITCH FOR CHANNEL 5