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

22

TK2150 – Rev. 1.0/12.02

= 1.0V typically

As high-wattage resistors are usually only available in a few low-resistance values (10m

Ω, 25mΩ

and 50m

expected range of loads to be driven well into clipping without current limiting while still protecting

the output MOSFETs in case of a short circuit condition.

Auto Recovery Circuit for Overcurrent Fault Condition

If an overcurrent fault condition occurs the HMUTE pin (pin 8 of the TC2001) will be latched high

and the amplifier will be muted. The amplifier will remain muted until the MUTE pin (pin 24 of the

TC2001) is toggled high and then low or the power supplies are turned off and then on again.

The circuit shown below in Figure 4 is a circuit that will detect if HMUTE is high and then toggle

the mute pin high and then low, thus resetting the amplifier. The LED, D1 will turn on when

HMUTE is high. The reset time has been set for approximately 2.5 seconds. The duration of the

reset time is controlled by the RC time constant set by R306 and C311. To increase the reset,

time increase the value of C311. To reduce the reset time, reduce the value of C311. Please

note that this circuit is optional and is not included on the RB-TK2150 evaluation boards.

R311

R307

R308

R311

R306

R309

R310

C311

10uF, NP

Q303

2N7002

R311

D1

LED

Q302

2N3904

Q304

2N3904

Q305

2N3906

HMUTE

Pin 8

MUTE

Pin 24

V5

AGND

Jumper

remove jumper to

enable mute

Figure 4: Overcurrent Autorecovery Circuit

Over- and Under-Voltage Protection

The TC2001 senses the power rails through external resistor networks connected to VNNSENSE

and VPPSENSE. The over- and under-voltage limits are determined by the values of the resistors

in the networks, as described in the table “Test/Application Circuit Component Values”. If the

supply voltage falls outside the upper and lower limits determined by the resistor networks, the

TC2001 shuts off the output stages of the amplifiers. The removal of the over-voltage or under-

voltage condition returns the TK2150 to normal operation. Please note that trip points specified in

the Electrical Characteristics table are at 25

°C and may change over temperature.

The TC2001 has built-in over and under voltage protection for both the VPP and VNN supply

rails. The nominal operating voltage will typically be chosen as the supply “center point.” This

allows the supply voltage to fluctuate, both above and below, the nominal supply voltage.