UM1685 datasheet(28/31 Pages) STMICROELECTRONICS

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How to change the supply configuration of the board

UM1685

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DocID025458 Rev 2

How to change the supply configuration of the board

The configuration of the supply voltages can be changed through the jumpers from J1 to J6

as listed in Table 11, Table 12 and Table 13.

Note:

When the VCC voltage of 7.5 V is used, the charge pump diodes should be replaced with

low-drop ones (suggested part BAR43SFILM). Otherwise the resulting boot voltage could

be lower than the respective UVLO threshold and the device is not operative.

When the VSREG pin is not shorted to the VS (JP1 is open) particular care must be taken in

order to avoid that the VBOOT voltage falls below the VSREG one (e.g. VS is floating and

VSREG is supplied). In this case the internal ESD diode is turned on and the device could

be damaged.

Adding a low drop diode between the VSREG and VS protects the internal ESD diode from

this event (the diodes of the charge pump must also be low drop type).

When the VCCREG pin is not shorted to the VCC (JP3 is open) particular care must be

taken in order to avoid that the VCC voltage falls below the VCCREG one. In this case the

internal ESD diode is turned on and the device could be damaged.

Adding a low drop diode between the VCCREG and VCC protects the internal ESD diode

from this event.

Table 11. VCC supply configurations

Configuration

JP1

JP2

VSREG range

Notes

Internally generated from

Closed

Open

VCC + 3 V ÷ 85 V

Default.

VCC value is determined by the internal regulator

configuration.

Internally generated from

a voltage source different

from VS

Open

VCC + 3 V ÷ VS

VCC value is determined by the internal regulator

configuration.

External protection diode could be required

(see following text below table).

Externally supplied

(equal to VSREG)

Open

Closed

7.5 V ÷ 15 V

External protection diode could be required

(see following text below table).

Table 12. VREG supply configurations

Configuration

JP3

JP4

VCCREG range

Notes

Internally generated from

VCC

Closed Open

VCC

Default.

Internally generated from

a voltage source different

from VCC

Open

6.3 V ÷ VCC

External protection diode could be required

(see following text below table).

Externally supplied

(equal to VCCREG)

Open Closed

3.3 V

External protection diode could be required

(see following text below table).

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