TPS9104

CELLULAR SUBSCRIBER TERMINAL

POWER SUPPLY/AUDIO SYSTEM

SLVS133A – AUGUST 1996 – REVISED APRIL 1998

7

POST OFFICE BOX 655303

is cycled on or off. The microphone amplifier needs only two resistors to set the gain, and one capacitor for dc

blocking (see Figure 47). Regulator A is the analog supply for the microphone amplifier, and EN_A must be

asserted for correct operation.

undervoltage lockout

Undervoltage lockout (UVLO) prevents operation of the functions in the TPS9104 until the supply voltage

exceeds the threshold voltage, eliminating abnormal power-up conditions internally and externally, and

providing an orderly turn-on.

overtemperature shutdown

If the die temperature exceeds 160

°C, the thermal protection circuit shuts off the TPS9104. When the die

temperature drops below 150

°C, the device can be restarted with the ON input.

charge pump driver

An unregulated inverting or doubler charge pump is implemented (see Figure 44) by connecting a network of

two capacitors and two diodes to CP. In the inverting configuration, the charge pump can power an LCD or

provide gate bias for a GaAs power amplifier. A 5-V supply for flash-memory programming or powering the

subscriber identity module (SIM) European applications can be achieved using the doubler configuration and

an external LDO. A logic-low input to the charge-pump enable, EN_CP, turns on the oscillator and driver; a logic

high turns them off. EN_CP input is disabled when RESET is asserted. The EN_CP has a 10-

µA internal pullup.

DISSIPATION RATING TABLE 1 – Free-Air Temperature

PACKAGE

TA ≤ 25°C

POWER RATING

DERATING FACTOR

ABOVE TA = 25°C

TA = 70°C

POWER RATING

TA = 85°C

POWER RATING

PT

1350 mW

10.8 mW/

°C

864 mW

702 mW

DISSIPATION RATING TABLE 2 – Case Temperature

PACKAGE

TC ≤ 25°C

POWER RATING

DERATING FACTOR

ABOVE TC = 25°C

TC = 70°C

POWER RATING

TC= 85°C

POWER RATING

PT

6579 mW

52.6 mW/

°C

4212 mW

3423 mW