PM6685TR View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
PM6685TR
STMicroelectronics
'PM6685TR' PDF : 48 Pages View PDF
Device description
PM6685
V5SW pin allows to keep the 5V linear regulator always active or to enable the internal
bootstrap-switch over function: if the 5V switching output is connected to V5SW, when the
voltage on V5SW pin is above 4.8V, an internal 3.0 Ω max p-channel MOSFET switch
connects V5SW pin to LDO5 pin and simultaneously LDO5 shuts down. This configuration
allows to achieve higher efficiency. V5SW can be connected also to an external 5V supply.
LDO5 regulator turns off and LDO5 is supplied externally. If V5SW is connected to ground,
the internal 5V regulator is always on and supplies LDO5 output.
Table 7. V5SW multifunction pin
V5SW
Description
GND
The 5V linear regulator is always turned on and supplies LDO5 output.
Switching 5V
output
External 5V
supply
The 5V linear regulator is turned off when the voltage on V5SW is above 4.8V
and LDO5 output is supplied by the switching 5V output.
The 5V linear regulator is turned off when the voltage on V5SW is above 4.8V
and LDO5 output is supplied by the external 5V.
The 3.3V linear regulator is supplied by LDO5 output.
LDO3_SEL pin allows to keep 3.3V linear regulator always enabled, always disabled or to
enable the internal bootstrap-switch over function. According to Table 7:
● If LDO3_SEL is connected to VREF pin, when the power good signal of the 3.3V
switching output voltage PGOOD3(see related sections) is high, the internal linear
regulator is turned off and LDO3 output is connected directly to OUT3 pin through an
internal 3Ω max p-channel MOSFET switch.
● If LDO3_SEL is connected to 5V, the internal 3.3V regulator is always on and supplies
LDO3 output.
● If LDO3_SEL is connected to ground, the internal 3.3V regulator is always off and
LDO3 output is clamped to ground.
Table 8. LDO3_SEL multifunction pin
LDO3_SEL
Description
GND
VREF
LDO5
The 3.3V linear regulator is always turned off.
The 3.3V linear regulator is turned off when PGOOD3 is high. LDO3 output is
supplied by the switching 3.3V output.
The 3.3V linear regulator is always turned on and supplies LDO3 output.
7.11
Power up sequencing and operative modes
Let’s consider SHDN, EN5 and EN3 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(1.5V 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. The switching outputs are kept to ground by turning on the low side MOSFETs.
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