DFE252012P-2R2M datasheet(17/44 Pages) MICROCHIP

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 2020 Microchip Technology Inc.

DS20006388A-page 17

MCP16501

FIGURE 4-1:

Illustration of Start-up Mechanisms for Various MPU Configurations.

Applications With a Backup Supply

Applications Without a Backup Supply

The application starts when VIN ramps up because of the capacitor C,

which delays the rise of nSTRT with respect to VIN and causes nSTRT

to appear low as soon as the MCP16501 is powered.

Note that PWRHLD (= SHDN from MPU) was set to ‘1’ at the time the

battery was mounted on the PCB (i.e., at the time of manufacturing).

The power channels of MCP16501 are turned off by the MPU by setting

SHDN = 0. The MPU is then in Backup mode.

If supported, the DDR can also be placed in Backup Self-Refresh

(BSR) mode by setting LPM = 1 before SHDN = 0.

To wake up the application from Backup mode, a wake-up event must

be generated for the SHDWC (Shutdown and Wake-up Controller) of

the MPU. This can be an internal event (e.g., RTC, RTT alarm,

TAMPER detection) or an event on an I/O of the SHDWC

(e.g., wake-up from a wireless module). The MPU will then set

SHDN = 1 and the low-to-high transition of PWRHLD will cause the

MCP16501 to restart.

If VIN is cycled while the MPU is in Backup mode (SHDN = 0), the

MCP16501 restarts automatically and sends a wake-up event to the

MPU on nSTRTO (WKUP).

If this wake-up event was not enabled in the MPU SHDWC

configuration, SHDN will stay low and the MCP16501 will turn off at the

end of the start-up sequence, because PWRHLD has not been set

high. If this wake-up event is enabled, SHDN will immediately go high,

thus confirming the start-up sequence for the MCP16501 and the

application will restart.

The application starts when VIN ramps up because of the capacitor C, which

delays the rise of nSTRT with respect to VIN and causes nSTRT to appear low

as soon as the MCP16501 is powered.

PWRHLD (= SHDN from MPU) is set to ‘1’ as soon as VBAT (= VDDIO) is above

its internal POR threshold (around 1.5V).

The power channels of MCP16501 are turned off by the MPU by setting

SHDN = 0. In this case, the MPU is not in Backup mode; it is simply completely

off. LPM cannot be used, nor can SHDN be set to ‘1’ because the supply voltage

of the SHDWC controller is missing. From the OFF state, the application can

only be restarted by cycling power on VIN.

The application does not immediately start when VIN ramps up.

The button must be pressed (nSTRT = Low) to start the MCP16501.

Note that PWRHLD (= SHDN from MPU) was set to ‘1’ at the time the

battery was mounted on the PCB (i.e., at the time of manufacturing).

The power channels of MCP16501 are turned off by the MPU by setting

SHDN = 0. The MPU is then in Backup mode.

If supported, the DDR can also be placed in backup self-refresh mode

(BSR) by setting LPM = 1 before SHDN = 0.

To wake up the application from Backup mode, a wake-up event must

be generated for the SHDWC (Shutdown and Wake-up Controller) of

the MPU. This can be an internal event (e.g., RTC, RTT alarm,

TAMPER detection) or an event on an I/O of the SHDWC

(e.g., wake-up from a wireless module). The MPU will then set

SHDN = 1 and the low-to-high transition of PWRHLD will cause the

MCP16501 to restart.

If VIN is cycled while the MPU is in Backup mode (SHDN = 0), the

MCP16501 does not restart automatically.

To restart the application, the button must be pressed and nSTRTO

(WKUP) be an enabled wake-up event.

The DDR supply loss, due to an input power loss while in BSR mode, will

be managed by software (i.e., by reloading the contents of the DDR).

The application does not immediately start when VIN ramps up. The button must

be pressed to start the MCP16501.

PWRHLD (= SHDN from MPU) is set to ‘1’ as soon as VBAT (= VDDIO) is above

its internal POR threshold (around 1.5V).

The power channels of MCP16501 are turned off by the MPU by setting

SHDN = 0. In this case, the MPU is not in Backup mode; it is simply completely

off. LPM cannot be used, nor can SHDN be set to ‘1’ because the supply voltage

of the SHDWC controller is missing.

To restart the application, the push button must be pressed.

MCP16501

MPU

VDDIO

VDDCORE

VDDIODDR

VIN

SHDN

LPM

WKUP

PWRHLD

LPM

nSTRTO

VBAT

nSTRT

PVINx,

VIN

MCP16501

MPU

VDDIO

VDDCORE

VDDIODDR

VIN

SHDN

LPM

WKUP

PWRHLD

LPM

nSTRTO

VBAT

nSTRT

PVINx,

VIN

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