Data Sheet AS8446

Revision 1.8, Date 2005-03-17

Page 26 of 35

•

charge pump voltage Vpump - Vbat is too low:

The charge pump OK signal VPok is set and reset by the charge pump

(VPok = low )

monitor.

The threshold values of these parameters are programmable (see section Summary of all programmable registers

(parameters, functions)).

•

the calibration of the motor current measurement unit is not yet finished: Mcalib = low. The motor current must be zero

This calibration is done after the start up of the system including the ready signal of the charge pump: power on reset signal

nPOR and Vpok = high starts the calibration. The calibration procedure needs about 200

µs (see figure 4).

Summary of logic driver function: OUT = PWM and /Poverc and /PVunder and /PVover and VPok and Mcalib

Second by the analog motor voltage to regulate the slew rate during the rising and falling edge of the motor voltage (EMC

available at the pin Vmo. The characteristics (parameters) of this slew rate regulation can be programmed via the Three-Wire

Interface independently for the falling and rising edge of the motor voltage and can therefore be adapted to a specific

application (motor and its environment).

This programming of the output current characteristics (gate current of the external power FET) in both directions is shown in

section Summary of all programmable registers (parameters, functions).

PARAMETER

SYMBOL

MIN

TYP

MAX

UNIT

NOTE

Tolerances of driver

output current (pin

OUT), sourcing

IOUTon

-50%

+50%

The relative tolerances between adjacent

programming steps of the driver current are less

than 10%.

Tolerances of driver

output current (pin

OUT), sinking

IOUToff

-50%

+50%

The relative tolerances between adjacent

programming steps of the driver current are less

than 10%.

-

max. pulse duration = 1

µs @ 20 kHz or max. external charge to load: 250 nC @ 20 kHz

-

-

Programmable by the registers R1 to R6