PM6670AS datasheet(34/54 Pages) STMICROELECTRONICS

34 / 54 page

Device description

PM6670AS

34/54

7.1.8

VDDQ output discharge

Active discharge of VDDQ output occurs when PM6670AS enters the Suspend-To-Disk

system state (S3 and S5 tied to GND) and DSCG pin has been properly set.

Figure 37. DSCG pin connection for discharge mode selection

The PM6670AS allows the user to choose between fast discharge (Tracking Discharge), soft

discharge (Non-Tracking Discharge) or no discharge modes. Voltage on DSCG multilevel

pin determines discharge mode as shown in Table 2 on page 6.

Tracking discharge allows the fastest discharge of all outputs but requires the LDOIN to be

self-supplied from VDDQ output voltage. When an external supply rail is connected to

LDOIN, it must be taken into account to avoid damage to the device. Discharge current (1 A)

flows through the LDOIN pin until the output has reached approximately 400 mV and then a

soft discharge completes the process by discharging the output with an internal 22

Ω switch.

Figure 38. Fast discharge and soft discharge options

Table 2. Discharge mode selection

DSCG voltage

Soft-end type

Description

VDSCG >4.2V

No Discharge

All outputs left floating.

1V< VDSCG <3.5V

Fast (Tracking)

VDDQ and VTT actively discharged by LDO trough

LDOIN and VTT pins;

VDSCG <0.5V

Soft (Non-Tracking)

All outputs discharged by dedicated internal MOS.

PM6670

DSCG

+5V

VREF

PM6670

DSCG

+5V

VREF

PM6670AS

VDDQ

VTT

400mV

Fast discharge

VDDQ

VTT

Soft discharge

VDDQ

VTT

400mV

Fast discharge

VDDQ

VTT

Soft discharge

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