L9949

12/20

Figure 7. Functional Block Diagram

FUNCTIONAL DESCRIPTION OF THE SPI

Serial Peripheral Interface (SPI)

This device uses a standard SPI to communicate with a microcontroller. The SPI can be driven by a microcontroller

with its SPI peripheral running in either of the two following modes: CPOL = CPHA = 0 or CPOL = CPHA = 1.

For these two modes, input data is sampled by the low to high transition of the clock CLK, and output data is

changed from the high to low transition of CLK.

The difference of these two modes is the standby polarity of the CLK. For CPOL = 0 the CLK remains low and

for CPOL = 1 the CLK remains high.

This device is not limited to microcontrollers with a build-in SPI. Only three CMOS-compatible output pins and

one input pin will be needed to communicate with the device. A fault condition can be detected by setting CSN

to low. If CSN = 0, the DO-pin will reflect the status bit 0 (fault condition) of the device which is a logical-or of all

bits in the status registers 0 and 1. The microcontroller can poll the status of the device without the need of a

full SPI-communication cycle.

Note: In contrast to the SPI-standard the least significant bit (LSB) will be transfered first (see. FIGURE 8).

Chip Select not (CSN)

The input pin is used to select the serial interface of this device. When CSN is high, the output pin (DO) will be

in high impedance state. A low signal will activate the output driver and a serial communication can be started.

Serial Data In (DI)

The input pin is used to transfer data serial into the device. The data applied to the DI will be sampled at the

DI (pin 7)

DO (pin 17)

CLK (pin 6)CSN (pin 14)

HS

LS

VS (pin5)

HS

LS

VS (pin5)

HS

LS

VS (pin5)

VS (pin13)

VS (pin13)

VS (pin8)

VS (pin8)

VS (pin18)

ESD

OUT6

(pin19)

HS

A-driver

HS

B-driver

HS

A-driver

LS

A-driver

HS

A-driver

LS

A-driver

HS

B-driver

LS

B-driver

HS

B-driver

LS

B-driver

Chargepump

Temperature

Protection

Driver Interface

Diagnostic

Power-On-Reset

SPI

Voltage and

Current

Reference

Current

Monitor

VCC

OUT3

(pin2)

OUT4

(pin3)

OUT5

(pin4)

OUT1

(pin9)

OUT2

(pin12)

VS

(pins 5,8,13,18)

GND

(pins 1,10,11,20)

CM

(pin 16)

VCC

(pin 15)

VS (pin18)

ESD