PM6681A STMicroelectronics, PM6681A Datasheet - Page 28

• Manufacturer Part Number: PM6681A
• Description: Dual synchronous step down controller with adjustable LDO
• Manufacturer: STMicroelectronics

Device description
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Power up sequencing and operative modes
Let ’ s consider SHDN, EN1 and EN2 low at the beginning. The battery voltage is applied as
input voltage. The device is in shutdown mode.
When the SHDN pin voltage is above the shutdown device on threshold (1.5 V typ.), the
controller begins the power-up sequence. All the latched faults are cleared. LDO5
undervoltage control is blanked for 4 ms and the internal regulator LDO5 turns on. If the
LDO5 output is above the UVLO threshold after this time, the device enters in standby mode
and the adjustable internal linear regulator LDO is turned on.
The switching outputs are kept to ground by turning on the low side MOSFETs. When EN1
and EN2 pins are forced high the switching sections begin their soft-start sequence.
Table 9.
Shutdown
Standby
Mode
Run
Operative modes
SHDN is high,
EN1/EN2 pins are high
Both EN1/EN2 pins are low
and SHDN pin is high
SHDN is low
Conditions
Switching regulators are enabled; internal linear
regulators outputs are enabled.
Internal linear regulators active (LDO5 is always on). In
Standby mode LGATE1/LGATE2 pins are forced high
while HGATE1/HGATE2 pins are forced low.
All circuits off.
Description
PM6681A