H-Bridge Load Switching

Receiver

OUTP

OUTM

VDD (vbat)

AVSS

OUTPM

OUTMP

OUTPP

OUTMM

VDD ( vbat)

AVSS

OUTPM

OUTMP

OUTPP

OUTMM

Inverting Phase

OUTP

OUTM

Noninverting Phase

Load

Receiver

Load

AIC111

SLAS382A – JUNE 2003 – REVISED NOVEMBER 2005

www.ti.com

H-BRIDGE OUTPUT DRIVER

Function: An H-bridge output driver efficiently converts the delta sigma DAC modulator output signals. The

external load provides the low-pass filtering that recovers the differential analog signal from the H-bridge.

Characteristics: Standard H-bridge configuration with transistors sized to differentially drive the load impedance.

The load impedance is complex and a function of frequency.

A.

VDD does not necessarily have to be connected to the same potential as AVDD, it could be connected to a higher

potential than AVDD, equal to AVDD, but not less than AVDD.

Figure 5. Definition of Phase and Output Switching Current Polarity

Table 4. SPECIFICATIONS AT 25°C, HB_VDD = 1.3 V

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Block Parameters

DC offset

Idle channel; Differential across VOUT_P and VOUT_M

-5

0

5

mV

Fixed Q

33

Idle channel, measured at output of channel,

Broadband noise

μVrms

BW = 100 Hz-10 kHz, HB_VDD = 1.3 V, A-weighted

Adaptive Q

12

THD

BW = 100 Hz-10 kHz

0.03%

Switching frequency

640

kHz

3/4

Fixed Q

HB_VDD

Maximum output swing

Adaptive Q

HB_VDD

MICROPHONE POWER SUPPLY

Function: The microphone power supply circuit provides a constant power supply voltage and bias current for

the microphone preamp or sensor bias, provides a low-noise voltage reference (ac ground) for the PGAC,

provides regulated PGAC comparator threshold levels, provides bandgap regulated POR comparator trip voltage

levels, and provides a bandgap regulated current for the biases generator circuit.

Characteristics: The low-dropout regulator configuration or single stage, single-pole amplifier drives an external

0.1-

μF capacitor. The regulator does not oscillate under no-load or loaded conditions. The circuit supplies up to

50-

μA of continuous current.

Table 5. SPECIFICATIONS AT 25°C, AVDD = 1.3 V

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

MIC_VSUP

0.87

0.94

0.97

V

VMID_FILT

0.59 × AVDD

0.78

V

PSRR

0.1-

μF external bypass cap from MIC_VSUP to AVSS2.

55

dB

10

Copyright © 2003–2005, Texas Instruments Incorporated