L99MH98 datasheet(20/147 Pages) STMICROELECTRONICS

20 / 147 page

Functional description

3.1

Power supply

The device has two supply input pins. VDH is the supply input of the charge pump for the MOSFET gate drivers. It

must be connected to the battery through a reverse battery protection. VDD is the supply input of the internal

voltage regulator for the logic, of the I/Os and of the current sense amplifiers output stage. This voltage has to be

the same as the application microcontroller supply (for example, 3.3 V or 5 V). When both VDD and VDH are

provided to the device, the power supply for the internal regulators for logic is taken from the VDD power pin.

None of the supply input pins are internally protected against negative voltage. The VDD supply input can

withstand a short to battery up to VDD absolute maximum rating. The decoupling capacitors on the VDD and VDH

pins must be placed in the PCB as close as possible.

3.1.1

VDH overvoltage (VDHOV)

An overvoltage diagnostic is present in L99MH98. The levels of the overvoltage diagnostic are described in the

Section 2.4.1: Supply, supply monitoring and current consumption. The overvoltage functionality is described in

the Section 3.2.4: Multi fail-safe mode.

3.1.2

VDH undervoltage (VDHUV)

When the VDH supply input voltage falls below the undervoltage protection threshold (VDHUV) for a time longer

than tUV_FILT, then the corresponding undervoltage flag (VDHUV) is set, and (in order to protect the external

power stage) the external MOSFETs are switched off. In particular, the LS MOSFETs gate drivers are forced to

switch off actively the LS MOSFETs with the maximum available current, regardless of the programmed gate

discharge current, whereas the HS MOSFETs gate drivers are forced, as long as VCP > VDH + 3 V, to switch off

actively the HS MOSFETs with the maximum available current, after that the HS MOSFETs gate drivers will be

disabled and the HS MOSFETs are passively switched off through the internal resistive connection between gate

and source. The gate drivers come out of forced disabled mode, once the undervoltage flag VDHUV is cleared.

The undervoltage flag VDHUV can be cleared by an SPI “read and clear” command only if the VDH undervoltage

condition is no longer present, namely if VDH > VDHUV for a time longer than the corresponding filtering time

tovuv_filt.

3.1.3

VDD overvoltage (VDDOV)

When the VDD exceeds the VDDOV threshold for a time longer than tOV_FILT, then the corresponding overvoltage

flag (VDDOV) is set, and (in order to protect the application) all the gate drivers are forced to switch off actively all

the MOSFETs with the maximum available current, regardless of the programmed gate discharge current. The

gate drivers come out of forced disabled mode, once the overvoltage flag VDDOV is cleared. The VDD

overvoltage protection aims at making the application robust against VDD short to battery.

The overvoltage flag VDDOV can be cleared by an SPI “read and clear” command only if the VDD overvoltage

condition is no longer present, namely if VDD < VDDOV for a time longer than the corresponding filtering time

tOV_FILT.

L99MH98

Functional description

DS14611 - Rev 3

page 20/147

L99MH98 датащи(PDF) 20 Page - STMicroelectronics

L99MH98 датащи(HTML) 20 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL