Tripath Technology, Inc. – Preliminary Technical Information

10

TPS4100 – KL/Rev. 2.5/02.05

PROTECTION CIRCUITS

The TPS4100 is guarded against over-current, over/under voltage, and over-temperature conditions. If

the device goes into one of the various protection states, the FAULT pin goes to a logic HIGH state

indicating a fault condition. When this occurs, all amplifier outputs are TRI-STATED and will float to VDD.

OVER-CURRENT PROTECTION

An over-current fault occurs if more than approximately 9.5 amps (typical) of current flows from any of the

amplifier output pins. This can occur if the speaker wires are shorted together, if one side of the speaker

is shorted to ground, or if an output is connected to VPP.

OVER AND UNDER VOLTAGE PROTECTION

An over-voltage fault occurs if the supply voltage is increased above 28.0 volts (typical), 26.0 volts

(minimum). This fault puts the amplifier into mute and resets automatically once the supply voltage is

reduced below the hysteresis band. The TPS4100 also has built-in load dump protection. This circuit

puts the amplifier into sleep mode if the supply voltage is increased above 30V. The TPS4100 is able to

survive power supply spikes to 60V if the duration is less than 50mS.

The TPS4100 is also equipped with under voltage protection. This circuit is activated if the supply voltage

goes below 8.1 volts (typical) and causes the output to mute. Increasing the supply voltage above the

hysteresis band (typically 9.5V) will bring the amplifier out of mute mode.

OVER-TEMPERATURE PROTECTION

An over-temperature FAULT occurs if the junction temperature of the part exceeds 160

°C (typical). The

thermal hysteresis is approximately 30

°C, therefore the fault will automatically clear when the junction

temperature drops below 130

°C.

SLEEP PIN (ACTIVE LOW)

The SLEEPB (SLEEP) pin is a logic input that when pulled low puts the TPS4100 into a low quiescent

current mode. This pin must be pulled up to an external 3.3V or 5V supply to activate (disable sleep

mode) the TPS4100. The sleep pin cannot be pulled up to VPP due to internal circuitry limitations. The

amplifier takes approximately 500mS to come out of sleep. This period of time allows the input capacitor

to charge fully assuming a value of 0.47uF. If the input capacitor size is increased, then additional time

will be required to allow for the input capacitor to fully charge. To ensure that turn on is pop-free, the

input capacitor must be fully charged before MUTEB is pulled high.

MUTEB PIN

The MUTEB pin is a logic input that mutes the TPS4100. Pulling this pin low activates the mute circuitry.

Pulling the pin high enables output switching and amplification. Please note that the input stage is still

versa, which eliminates turn-on/off pops. Please note that DC calibration is done every time MUTEB

transitions from low to high. The DC calibration takes approximately 6mS.