BLOCK DESCRIPTION

POWER AMPLIFIERS

The two power amplifiers are connected in bridge

configuration working in AB class.

SENSE AMPLIFIER

This stage senses the voltage drop across the

Rsense.

The input stage is supplied by the charge pump

voltage to have an high dynamic, while the other

sections of the amplifier are supplied by the volt-

age of 10.5V internally regulated to have an high

power supply rejection (this voltage, supplies also

the error amplifier, the input amplifier and the op-

erational amplifier which generates the Vcc/2 volt-

age).

The open loop gain is around 80dB and the band-

with is more than 1MHz.

The voltage gain is fixed internally at 10 V/V.

ERROR AMPLIFIER

This is the stage which compares the input volt-

age and the sense voltage, generating the control

voltage for the power section.

The open loop gain and bandwith of this amplifier

are similar to the sense amplifier.

The negative input and the output of the error am-

plifier are accessible externally in order to have

the current loop compensation user configurable.

The dynamic of the output is limited at +/- 2Vbe to

have a faster response of the output voltage.

INPUT AMPLIFIER

The inputs and the output pins are externally ac-

cessible to have the possibility to configure the

transconductance gain of the current control loop

selecting the voltage gain of this amplifier.

The open loop gain and bandwith of this amplifier

are similar to the sense amplifier.

REFERENCE VOLTAGE GENERATOR

This block generates the two reference voltage

Vcc/2 and +5VREF.

The Vcc/2 voltage is used as reference by the

current control loop.

The +5VREF is a very stable voltage generator

that can be used as reference voltage of an exter-

nal DAC.

ELECTRICAL CHARACTERISTICS (continued)

Symbol

Parameter

Test Condition

Min.

Typ.

Max.

Unit

POWER AMPLIFIER

Rdson

DMOS on resistance

at 25

°C

0.3

Ω

Gdv

Differential voltage gain

32

V/V

Iol

Output current leakage

500

µA

SR

Output slew rate

0.4

V/

µs

Tsr

Saturation recovery time

5

µs

GBW

Gain bandwidth product

100

KHz

RETRACT

Vr

Max. retract voltage

Vcc shorted to GND

300

mV

Vr

Max. retract voltage

Vcc Normal

1

V

CHARGE PUMP

Cs

Storage capacitor

1

µF

Vs

Storage voltage

Vcc +4

V

Cp

Pump capacitor

0.2

µF

RETRACT TRUTH TABLE

Input

Input

Output

Output

-Retract

+Enable

Bridge Enable

+Retract

Brake and Retract

0

X

0

1

Run

1110

Disable

1000

L6246

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