Texas Instruments newest dual-slot PC Card power interface switch - the TPS2202DFLE - features a new serial control topology that reduces the number of control lines. The new topology, dubbed the P2C (PCMCIA Peripheral Control) interface, gives high performance controller ICs more available pins.
The new release of the PC Card standard (rev 3.0) includes the CardBus specification, allowing bus interface speeds to increase from 20 MHz to 33 MHz. To accommodate the extra ground and VCC pins required for stability at higher speeds, controller ICs are being pushed into higher pin-count packages or they're sacrificing functionality to stay in lower pin-count packages for reduced board space and complexity. The TPS2202's P2C interface uses 3 lines (DATA, CLOCK, and LATCH) to serially program the switch instead of the 8 lines used for a parallel interface (4 for each slot). The five spare lines can be used for additional VCC, grounds, or for new controller functions.
Like the TPS2201* (out first switch, with a parallel control interface), the new serially-controlled TPS2202 features a fully-integrated set of switches to manage the 3-V, 5-V, and 12-V power requirements dictated by the PCMCIA standard. It includes current limiting and thermal protection to eliminate fuses. Current-limit reporting helps diagnostics isolate card faults. To save power and reduce external components, it uses its own internal charge pump to generate the switch gate-drive voltage. This allows the external 12-V supply to be shut down except when required during infrequent flash memory programming. Microampere-range supply currents and a shutdown mode add to power savings.
One 30-pin SSOP contains all the switches and control circuitry required for managing the power to two PC Cards - no external switches or components are required. The TPS2202IDF and TPS2201IDF meet all PCMCIA standards for PC Card power management.
Vol 11, Spring, 1995