L9026 datasheet(22/60 Pages) STMICROELECTRONICS

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Figure 9. Switching resistive loads

OUTn driving

signal

Tdelay(ON)

Tdelay(OFF)

Vds

90%

10%

7.1.2

Inductive output clamp

Due to the fact that inductance still drives the current the voltage across the power switch increases until reaching

VDS(CL) in case of switching off inductive loads.

The voltage clamping is necessary to prevent device destruction and protects the device in all operative modes.

The maximum allowed load inductance is limited by the max energy.

The clamping structure protects the device in all operative modes (Sleep, Idle, Active, Limp Home).

Figure 10. Output clamp concept

7.1.3

Maximum load inductance

The device needs to dissipate energy when the inductive loads are switched. Eq. (1) and Eq. (2) compute

respectively the energy for low side and high side MOSFET.

E=VDSCL⋅ VS−VDSCL

RL ⋅In⋅ 1− RL⋅IL

VS−VDSCL +IL ⋅ LRL

(1)

E= VS−VDSCL ⋅ VOUTSCLRL ⋅In⋅ 1− RL⋅IL

VOUTSCL +IL ⋅ LRL

(2)

The maximum energy that can be dissipated is constrained by the device package. the ear listed in Table 15

consider that all channels dissipate the same energy switching off at the same time.

L9026

Power stages

DS13397 - Rev 9

page 22/60

L9026 数据表(PDF) 22 Page - STMicroelectronics