Tr i p ath Technol ogy, I n c. - Techni cal In fo rma t io n

15

TK2150 – Rev. 1.0/12.02

Application Information

Figure 1 is a simplified diagram of one channel (Channel 1) of a TK2150 amplifier to assist in

understanding its operation.

Figure 1: Simplified TK2150 Amplifier

TK2150 Basic Amplifier Operation

The audio input signal is fed to the processor internal to the TC2001, where a switching pattern is

generated. The average idle (no input) switching frequency is approximately 700kHz. With an

input signal, the pattern is spread spectrum and varies between approximately 200kHz and

1.5MHz depending on input signal level and frequency. Complementary copies of the switching

pattern is output through the Y1 and Y1B pins on the TC2001. These switching patterns are input

to the TP2150 where they are level-shifted by the MOSFET drivers and then output to the gates

(HO1 and LO1) of external power MOSFETs that are connected as a half bridge. The output of

the half bridge is a power-amplified version of the switching pattern that switches between VPP

and VNN. This signal is then low-pass filtered to obtain an amplified reproduction of the audio

input signal.

The TC2001 processor is operated from a 5-volt supply. In the generation of the switching

patterns for the output MOSFETs, the processor inserts a “break-before-make” dead time

between the turn-off of one transistor and the turn-on of the other in order to minimize shoot-

through currents in the external MOSFETs. The dead time can be programmed by setting the

break-before-make control bits, BBM1 and BBM0. Feedback information from the output of the

half-bridge is supplied to the processor via FBKOUT1.

Additional feedback information to

account for ground bounce is supplied via FBKGND1.

HMUTE

OAOUT1

INV1

C

I

22

23

8

+

Analog

Ground

Power Ground

V5

AGND

MUTE

24

5V

V5

15

REF

R

REF

42

VNN

R

VPP1

VPP

VNN

19

VPPSENSE

17

VNNSENSE

C

SW

VN10

41,43

VNN

Offset Trim

Circuit

-

+

R

VNN1

R

VPP1

V5

V5

R

VNN2

Processing

&

Modulation

C

B

0.1uF

C

BAUX

R

B

VN10

D

B

VN10

FBKOUT1

6

FBKGND1

7

+

R

L

C

HBR

LO1

44

R

G

Q

O

HO1

48

R

G

Q

O

LO1COM

45

HO1COM

47

OCS1LP

54

OCS1LN

53

VBOOT1

57

OCS1HP

51

OCS1HN

50

R

S

R

S

C

S

VPP

VNN

R

OFA

V5

R

OFB

C

OF

R

F

R

I

VNN

R

FBB

R

FBB

R

FBC

R

FBC

C

FB

C

OCR

R

OCR

OCR1

16

C

S

R

FBA

R

FBA

V5

OUTPUT

FILTER

BIASCAP

C

A

1

2.5V

C

S

21

20

V5

AGND

5V

OVER

CURRENT

DETECTION

OVER

CURRENT

DETECTION

OVER/

UNDER

VOLTAGE

DETECTION

25

BBM 1

26

BBM0

F. BEAD

VN10

TC2001

TP2150

OVER

CURRENT

DETECTION

OCR1

Y1

Y1B

9

10

17

16

7

C

S

6

5

V5

AGND

5V