This CompactFlash™ (CF) interface chip is designed to provide a single-chip solution for CF card interfaces. Separate V_CC rails for the system bus side and the CF connector bus side allow voltage-level shifting. This is helpful for interfacing between a core chipset, which may operate from 3.3 V down to 1.65 V, and CF cards, which operate from 3.3-V or 5-V supply voltages. All the input buffers feature the input-disable function, which allows conditional floating input signals. The input, output, and I/O buffers on the CF connector side have been defined to comply with CF+ and CompactFlash specification revisions 1.4 and 2.0.

This device has 16-bit data lines and 24-bit address/command lines. CD1\ and CD2\ have internal pullup resistors to pull them to a high logic state if there is no card in the CF slot. The presence of a CF card in the CF card slot generates a low logic signal at SCD\. A separate power-supply pin, V_{CC_SD}, controls the SCD\ output buffer. The SCD\ signal can be used to control a voltage regulator, which may power the CF slot and the CF side of this device. V_{CC_SD} is particularly helpful when the core processor operates at a low V_CC, but the regulator needs a higher control signal voltage.

The MASTER_EN\ signal controls all the buffers and transceivers except CD1\ and CD2\. If MASTER_EN\ is high, the SN74LV4320A is in a power-down mode. The BUF_EN\ signal, in conjunction with MASTER_EN\, controls the 11-bit address lines and 13-bit control/command lines.

The 16-bit data lines use two separate enable signals. ENL\, in conjunction with MASTER_EN\, controls the lower 8-bit data lines (D07-D00). ENH\, in conjunction with MASTER_EN\, controls the upper 8-bit data lines (D15-D08). A DIR(S\/CF) input controls the data direction between the system bus and the CF card. An additional DIR_OUT pin generates the DIR(S\/CF) signal using the SOE\ and SIORD\ signals. With either SOE\ or SIORD\ being low, the data direction is from the CF card side to the system side (DIR_OUT = L). DIR(S\/CF) and DIR_OUT are placed adjacent to each other, which is convenient for connecting DIR(S\/CF) and DIR_OUT, if DIR_OUT is used. This saves an additional signal from the system controller to control the data direction.

BVD1, BVD2, INPACK\, READY, WAIT\, and WP have 100-k internal pullup resistors, eliminating the need for external pullups. The resistors are within the tolerance of CF+ and CompactFlash specification revisions 1.4 and 2.0.

This device is fully specified for partial-power-down applications using I_off. The I_off circuitry disables the outputs, preventing damaging current backflow through the device when it is powered down.