TPS2205

DUAL-SLOT PC CARD POWER-INTERFACE SWITCH

FOR PARALLEL PCMCIA CONTROLLERS

SLVS128D OCTOBER 1995 – REVISED JUNE 1998

20

POST OFFICE BOX 655303

APPLICATION INFORMATION

overcurrent and thermal protection (continued)

Thermal limiting prevents destruction of the IC from overheating if the package power-dissipation ratings are

exceeded. Thermal limiting disables all power outputs (both A and B slots) until the device has cooled.

calculating junction temperature

20, 21, 22, and 23 using an initial temperature estimate about 50

°C above ambient. Then calculate the power

dissipation for each switch, using the formula:

P

D +

r

DS(on)

I2

Next, sum the power dissipation and calculate the junction temperature:

T

P

D

RqJA ) TA,RqJA + 108 C W

°

Compare the calculated junction temperature with the initial temperature estimate. If the temperatures are not

within a few degrees of each other, recalculate using the calculated temperature as the initial estimate.

logic input and outputs

The TPS2205 was designed to be compatible with most popular PCMCIA controllers and current PCMCIA and

JEIDA standards. However, some controllers require slightly counterintuitive connections to achieve desired

output states. The TPS2205 control logic inputs A_VCC3, A_VCC5, B_VCC3 and B_VCC5 are defined active

low (see Figure 31 and control-logic table). As such, they are directly compatible with the logic outputs of the

Cirrus Logic CL-PD6720 controller.

high-impedance state and reduces chip quiescent current to 1

µA to conserve battery power.

(see discussion above).