33988 Datasheet, PDF(18/34 Page) Freescale Semiconductor, Inc – Dual Intelligent High-current Self-protected Silicon High Side Switch (8.0mΩ)

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33988 Datasheet, PDF (18/34 Pages) Freescale Semiconductor, Inc – Dual Intelligent High-current Self-protected Silicon High Side Switch (8.0mΩ)

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FUNCTIONAL DESCRIPTION

FUNCTIONAL INTERNAL BLOCK DESCRIPTION

MCU

INTERFACE

POWER SUPPLY

MCU INTERFACE AND

OUTPUT CONTROL

SPI INTERFACE

PARALLEL CONTROL

INPUTS

SELF-PROTECTED

HIGH SIDE SWITCH

HS [0:1]

Figure 9. Functional Internal Block Diagram

POWER SUPPLY

The 33988 is designed to operate from 4.0V to 28V on the

VPWR pin. Characteristics are provided from 6.0V to 20V for

the device. The VPWR pin supplies power to internal

regulator, analog, and logic circuit blocks. The VDD supply is

used for Serial Peripheral Interface (SPI) communication in

order to configure and diagnose the device. This IC

architecture provides a low quiescent current sleep mode.

Applying VPWR and VDD to the device will place the device in

the Normal mode. The device will transit to Fail-safe mode in

case of failures on the SPI (watchdog timeout).

HIGH-SIDE SWITCH: HS[0:1]

Those pins are the high side outputs controlling multiple

automotive loads with high inrush current, as well as motors

and all types of resistive and inductive loads. This N-channel

MOSFET with 8mÎ© RDS(ON), is self-protected and each N-

channel presents extended diagnostics in order to detect

load disconnections and short-circuit fault conditions. The

HS[0:1] outputs are actively clamped during a turn-off of

inductive loads.

MCU INTERFACE AND OUTPUT CONTROL

In Normal mode, the loads are controlled directly from the

MCU through the SPI. With a dedicated SPI command, it is

possible to independently turn on and off several loads that

are PWMâd at the same frequency, and duty cycles with only

one PWM signal. An analog feedback output provides a

current proportional to each load current. The SPI is used to

configure and to read the diagnostic status (faults) of the high

side output. The reported fault conditions are: open load,

short-circuit to ground (OCLO-resistive and OCHI-severe

short-circuit), thermal shutdown, and under/over-voltage.

In Fail-safe mode, the loads are controlled with dedicated

parallel input pins. The device is configured in default mode.

33988

Analog Integrated Circuit Device Data

Freescale Semiconductor

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