Figure 10. VDS diagnostic enabling signal

Every time hot swap driver is turned ON, the VDS comparator is masked until Hotswap_VDS mask_soft_start_flt

is expired (and the other masking conditions disappear).

Table 15. Hot swap and pre-driver parameters

Symbol

Parameter

Test condition

Min Typ Max Unit

Hotswap_ΔVHG1_4V

HGATE gate drive, (VHGATE −

VSOURCE)

Drive voltage at VB = 4.5 V

CP = VB + 5.3, VB + 6

5

-

-

V

Hotswap_ΔVHG1_12V

HGATE gate drive, (VHGATE −

VSOURCE)

Drive voltage at VB = 14 V,

CP = VB + 15, VB + 9

9

-

13

V

Hotswap_IHG,PU

GATE pull-up Current

-

20

37

55

μA

Hotswap_IHG,PD

GATE pull-down Current

-

50

80

120

mA

Hotswap_VDS

VDS on soft start MOS. A fault

is generated if detection happens

after ENOUT set

-

0.8

1

1.2

V

Hotswap_VDS_flt

VDS detection filter time

Guaranteed by scan

0.8 0.9

1

ms

MASK_VDS_rising_flt

Masking diag on filter time after

ENOUTrising edge

Guaranteed by scan

80 100 120

μs

MASK_VDS_falling_flt

Masking diag on filter time after

ENOUTfalling edge

Guaranteed by scan

1

1.2

1.4

ms

Hotswap_VDS_mask_soft_start_flt Soft start blanking time

Guaranteed by scan

80

90

100

ms

4.1.9

Oring pre-driver

The pre-driver for Oring MOSFET is an ideal diode regulator. When the load current creates more than

Oring_Full_ON of drop across the MOSFET (Oring_Full_ON comparator), the DGATE pin is pulled high by an

internal charge pump current source and clamped to Oring_ΔVDG2_12V above the SOURCE pin.

When the load current is small enough, the DGATE pin is actively driven to maintain Oring_VREG across the

MOSFET by actively regulating DGATE, thus implementing ideal diode function. In case of reverse voltage of

more than Oring_VREV across the MOSFET (SOURCE - VSENSE voltage drop), the oring MOSFET is turned

off, thus preventing reverse current from flowing from OUT to VB.

During normal operating condition, VGS of oring external FET is driven to allow the correct current load ( VSense

- VSource = Oring_VREG). For fast turning on and off condition, (when Vsense - Vsource > Oring_Full_ON) an

internal comparator activates a strong pullup current on DGATE pin.

Oring reverse and full on comparators are also used to quickly turn on and off the oring MOSFET, in order to

withstand with AC ripple disturbances (standard ISO 16750) and preventing AC noise from being transferred on

VOUT line.

This pre-driver implements same diagnosis and masking of hot swap pre-driver, such as VDS detection, shown in

Figure 10.

STPM801

Functional behavior in detail

DS13990 - Rev 2

page 18/38