The EN/PB/VSENSE pin is used to enable
the PMIC. The pin can be configured in three ways:
Device Enable (EN)
When configured as EN, this pin needs
to be pulled high to generate an ON-request. Pulling this pin low generates an
OFF-request.
- The deglitch-time of the
EN-pin is configured by EN_PB_VSENSE_DEGL in MFP_2_CONFIG register.
- The power-up sequence starts
if the EN input is above the VIL-threshold low for the configured
tDEGL_EN_Rise.
- To signify the power-up based
on an EN/PB/VSENSE pin-event, the device sets bit POWER_UP_FROM_EN_PB_VSENSE
in POWER_UP_STATUS_REG register. This bit does not assert the nINT pin.
Write W1C to clear the bit.
- The power-down sequence
starts if the EN input is below the VIH-threshold for
tDEGL_EN_Fall.
- In case of a shut-down fault,
no renewed on-request is required. The device automatically executes the
power-up sequence if EN input is still above the VIH-threshold.
(EN considered level-sensitive)
- In case of a cold reset
(regardless if by RESET-pin or I2C-request), no renewed on-request is
required. The device automatically executes the power-up sequence if EN
input is still above the VIH-threshold. (EN considered
level-sensitive)
- In case EN is pulled low
after entering SLEEP state, the pin must be pulled high again to enter the
INITIALIZE state. EN must remain high for tEN_PB_WAKEUP to
continue to the ACTIVE state. If EN is pulled low before
tEN_PB_WAKEUP elapses, the device re-enters the SLEEP state.
Push-Button (PB)
When configured as PB, a CMOS-type input used to power-up the PMIC. Typically, the PB
pin is connected to a momentary switch to ground and an external pullup resistor.
- The hold-time of the
push-button is configured by EN_PB_VSENSE_DEGL in MFP_2_CONFIG
register.
- The power-up sequence starts
if the PB input is below the VIL-threshold low for the configured
tPB_ON.
- To signify the power-up based
on an EN/PB/VSENSE pin-event, the device sets bit POWER_UP_FROM_EN_PB_VSENSE
in POWER_UP_STATUS_REG register. This bit does not assert the nINT pin.
Write W1C to clear the bit.
- The PB pin has a rising-edge
deglitch tDEGL_PB_RISE to filter bouncing of the switch
- The power-down sequence
starts if the PB input is held low for tPB_OFF-time (not
configurable).
- In case of a shut-down fault,
no renewed on-request is required. The device automatically executes the
power-up sequence without a PB-press.
- In case of a cold reset
(regardless if by RESET-pin or I2C-request), no renewed on-request is
required. The device automatically executes the power-up sequence without a
PB-press.
- In case the device is in
SLEEP state, a falling edge on PB transitions to the INITIALIZE state. PB
must remain low for tEN_PB_WAKEUP to continue to the ACTIVE
state. If PB is is released before tEN_PB_WAKEUP elapses, the
device re-enters the SLEEP state.
- A push-button press is only
recognized after VSYS is above VSYS_POR-threshold or the PB must be held
long enough after VSYS is above VSYS_POR-threshold.
- Following bits in the signify
the PB-press events:
- PB_FALLING_EDGE_DETECTED: PB was pressed for for a time-interval
longer than tDEGL_PB_INT since the previous time this bit
was cleared. This bit when set, does assert nINT pin (if config bit
MASK_INT_FOR_PB='0'). Write W1C to clear.
- PB_RISING_EDGE_DETECTED: PB was released for a time-interval longer
than tDEGL_PB_INT since the previous time this bit was
cleared. This bit when set, does assert nINT pin (if config bit
MASK_INT_FOR_PB='0'). Write W1C to clear.
- PB_REAL_TIME_STATUS:
Deglitched (tDEGL_PB_INT) real-time status of PB pin.
Valid only when EN/PB/VSENSE pin is configured as PB. This bit does
not assert the nINT pin.
Power-Fail Comparator Input (VSENSE)
When configured as VSENSE, this pin can be used to sense the supply-voltage of the
pre-regulator. Connect a resistor divider from the pre-regulator output to configure
the sense voltage.
- The deglitch-time of the
VSENSE-pin is configurable by EN_PB_VSENSE_DEGL in MFP_2_CONFIG
register.
- Power-up is gated by VSYS
being above the VSYSPOR_Rising-threshold and the VSENSE input is
above the VVSENSE-threshold (not deglitched)
- The power-up sequence starts
if the VSENSE input rises above VVSENSE.
- To signify the power-up based
on an EN/PB/VSENSE pin-event, the device sets bit POWER_UP_FROM_EN_PB_VSENSE
in POWER_UP_STATUS_REG register. This bit does not assert the nINT pin.
Write W1C to clear the bit.
- The power-down sequence
starts if the VSENSE input falls below the VVSENSE-threshold for
tDEGL_VSENSE_Fall, to avoid an un-sequenced power-off due to
the loss of VSYS-supply-voltage.
- In case of a shut-down fault,
no renewed on-request is required. The device automatically executes the
power-up sequence if VSENSE input is still above the
VVSENSE-threshold.
- In case of a cold reset
(regardless if by RESET-pin or I2C-request), no renewed on-request is
required. The device automatically executes the power-up sequence if VSENSE
input is still above the VVSENSE-threshold.
- In case the device is in
SLEEP state, VSENSE cannot be used to transition directly to the INITIALIZE
state. The device can only enter INITIALIZE following the OFF state.