L99MH98 datasheet(21/147 Pages) STMICROELECTRONICS

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3.2

Operation modes

Figure 5. Main operating modes

RESET

POWERUP

(300us max)

CHARGE

PUMP

ENABLING

ACTIVE

DIAGOFF

MULTI FAIL

SAFE

EN = 0 || POR = 0

EN = 1 && POR = 1

CP_READY &&

NO FAULT

Charge pump on

OUTE and OUTEx control

bits set to 1

Gate drivers working

according to

configuration HB_MODE

Charge pump on

Drivers OFF

OUTEx = 1 &&

HB_MODEx = 00

OUTEx = 0 ||

HB_MODEx != 00

VDD OV || CP UV ||

VDH_OV || VDH_UV ||

THERM_SD || WDG

Drivers off except for VDH_OV that the

reaction is configurable according to

GENMODE

Charge pump off according to the fault

VDD OV || CP UV ||

VDH_OV || VDH_UV ||

THERM_SD || WDG

NO FAULT &&

ChargePump ON

VDD OV || CP UV(after blank) ||

VDH_OV || VDH_UV ||

THERM_SD || WDG

NO FAULT &&

ChargePump OFF

3.2.1

Reset

The device gets out of reset mode to get into a power-up state as soon as the EN pin is high and the VDD is

above VDDPOR_OFF (increasing phase). If either the VDD falls below VDDPOR_ON (decreasing phase) with the EN

pin still high, the device experiences a power-on-reset and enters in reset mode.

Besides, the content of all the registers is reset to the default value. Once out of reset mode the global status

RSTB bit will be set indicating that all the device registers have been reset to the default value. This bit will be

automatically cleared by any valid SPI communication frame (after power-up state).

When the EN input pin is left floating, due of the internal pull-down resistor, the device enters (if not already done)

in reset mode minimizing its current consumption. When the device is in reset mode, to have the minimum current

drawn by VDH, less than IDD_SDN for CSN = high (SDO in tristate), the EN input pin must be low. In reset mode

the gate drivers together with the charge pump are switched off, all the MOSFETs are passively switched off by

the internal resistive link between gate and source present at each MOSFET and all the registers are reset to

default values.

3.2.2

Power-up state and charge pump enabling

When L99MH98 exits the reset state, before reaching the active state, the device passes through an intermediate

state, called power-up state, with the aim of loading all the configurations necessary for the device to function.

During this state it is not possible to guarantee the communication by SPI for a duration of tSTART.

When the charge pump is out from the start up phase, the device will automatically exit from the charge pump

enabling state to go to the active state. The start up phase duration is tCP_start.

3.2.3

Active mode

In active mode the diagnostic device is available. In active mode, with no faults, the charge pump is enabled if

VDH > VDHUV, the gate drivers are enabled if the OUTEx, x = 1...8, one for each half-bridge, control bits are set

and the OUTE bit (one generic for all the gate drivers) is set. If the OUTEx control bits are reset, or the OUTE bit

is reset, all the gate drivers are disabled and all the MOSFETs are switched off passively through the internal

resistive connection between gate and source present at each MOSFET.

L99MH98

Functional description

DS14611 - Rev 3

page 21/147

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