The MAX780A provides the power switching and status signals necessary to control two Personal Computer Memory Card International Association (PCMCIA) Release 2.0 card slots. The MAX780A, used in conjunction with a PC Card Interface Digital Controller, forms a complete, minimum component count PCMCIA interface for palmtop and notebook computers.
The MAX780A incorporates two 0V/+5V/+12V/ high-impedance power outputs for flash VPP programming, level shifters for power MOSFET control of two separate +3.3V/+5V supplies, and two VPP power-ready status signals. The MAX780A may be directly connected to the control outputs from a PCMCIA digital controller, or may be configured to use internal edge-triggered registers for connection to the CPU data bus.
The MAX780B has all the features of the MAX780A but omits the reference and VPP valid indicators. The MAX780C has all the features of the MAX780A but omits the registers for the digital inputs. The MAX780D omits the reference, the VPP valid indicators, and the digital input registers.
All four versions (A, B, C, and D) of the MAX780 allow simple switching of PCMCIA card VPP to 0V, 5V, and 12V. On-chip power MOSFETs connect AVPP and BVPP to either GND, VCCIN, or VPPIN. The AVPP0 and AVPP1 control logic inputs determine the state of AVPP. Likewise, BVPP0 and BVPP1 control BVPP.
To prevent VPP overshoot due to parasitic inductance in the +12V supply, the VPPIN bypass capacitor (CIN) should be 10 times greater than the capacitance from AVPP (CA) or BVPP (CB) to GND. Hence, when CA and CB are 0.1μF, CIN should be 1.0μF.
The AGPI and BGPI status outputs signal when the VPP lines are valid. AGPI goes low when AVPP exceeds 11.05V; BGPI goes low when BVPP exceeds 11.05V. The status outputs and the reference are only active when SHDN is high.
Pulling SHDN low puts the MAX780 into a low supply - current mode and disables the reference and the AGPI and BGPI status outputs.
MAXIM MAX780ACAG+