PCMCIA. Application Note 8 MEMBER COMPANY. Pin Configuration. General Description. MIC2557 ( 1 2 MIC2558) Block Diagram

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1 Application Note Application Note Interfacing the MIC/ to PCMCIA Controllers by Bob Wolbert General Description The MIC and MIC provide "Programming and Peripheral" voltage (V PP ) switching for PCMCIA card sockets. They have simple logic compatible inputs and easily interface with industry standard PCMCIA controllers. This note gives circuit examples for several PCMCIA controllers. For controllers supporting dual (.V and.0v), two simple high current switch matrices are shown. Pin Configuration V PP IN GND MIC Hi-Z/Low PCMCIA MEMBER COMPANY V PP IN GND MIC 0 Hi-Z/Low Hi-Z/Low MIC ( MIC) Block Diagram V PP IN Hi-Z/Low Decoder, Driver & Bias Control High Impedance or Pull Down Select -

2 Application Note V Control V or V MIC0 Gate Control Input Source R 0k V Q Switched 0V /.V / V V or V.V MIC0 Q Gate Control.V Control Input Source Q Figure. PCMCIA Compatible Dual Switch Matrix. This circuit uses power MOSFETs driven by two MIC0 high side MOSFET drivers to select between.v and V. MOSFET "body diodes" are shown for information..v V MIC0 0kΩ Source A In A _EN VA Output Gate A In B _EN Source B VB Gate B 0 Figure. PCMCIA Compatible Dual Switch Matrix. This circuit uses power MOSFETs driven by a single MIC0 high side MOSFET drivers to select between.v and V. Switching Figures and show the MIC0 and MIC0 high side power MOSFET drivers configured as a select matrix. Both circuits operate identically; the MIC0 is a dual MIC0. For convenience, we will discuss the circuit operation referring to Figure. Initially, both MOSFET drivers are OFF and the MOSFET gates are clamped low, placing the output in the high impedance condition. A TTL High level on _EN enables Q, and V appears on OUT. Likewise, when _EN is High, Q and Q are ON and.v appears on the output. _EN and _EN are mutually exclusive: circuit damage might occur if both switches are commanded ON simultaneously. The inherent "body diode" of the power MOSFET, shown in Figure, creates circuit problems that are dealt with by adding another MOSFET, Q, connected in the reverse direction. Without Q, whenever the V supply is enabled, current would flow from OUT through the body diode of Q into the.v supply, thereby contaminating the low voltage supply. Q's reverse direction connects its body diode anode -

3 Application Note to anode with Q and eliminates reverse current. When _EN is High and the MIC0 enhances the MOSFET gates, both Q and Q are ON, and.v appears on OUT. The enhanced channel shorts out the body diodes, so no diode forward voltage drop is evident. The ON resistance of Q is slightly higher in its reverse direction than in normal Cirrus Logic CL-PD0 The Cirrus Logic CL-PD0 provides support for a single PCMCIA socket. Key features include full support for dual voltages (.V and.0v). The CL-PD0 assumes V PP is tied to V PP. The MIC, in a small -pin surface V operation, but with reasonably sized MOSFETs, the voltage drop is small. Although a Schottky diode would provide the required protection, its forward voltage drop is much too large and would prevent the.v switch from meeting its ±% accuracy requirement. mount package, provides V PP power control for this single socket. switching is accomplished using the circuit of (either) Figure or Figure. Note that no additional components are required, although filter capacitors are recommended for best performance. System V (.V or V) PCMCIA Socket VPP V PP V PP IN MIC MIC GND (pin ) CL-PD0 V PP _ (pin ) V PP _PGM (pin ) SLOT_ (pins, ) Figure. Cirrus Logic CL-PD0 Single card slot controller Slot (.V or V, Switchable) CL-PD0 & CL-PD0 Control Logic _EN _EN V PP_PGM V PP_V OUT () () High Z Clamped to Ground High Z High Z High Z High Z 0 0 High Z High Z Clamped to Ground High Z Clamped to Ground High Z 0 0 High Z Clamped to Ground 0 High Z High Z 0 High Z High Z High Z High Z -

4 Application Note V Slot (.V or V, Switchable) V PP V PP MIC MIC V 0 V PP V PP CL-PD0 A SLOT_ (pins, ) (pin ) System (.V or V) A V PP _ (pin ) A V PP _PGM (pin ) B V PP _ (pin 0) B V PP _PGM (pin 0) B SLOT_ (pins, ) Slot (.V or V, Switchable) Figure. Cirrus Logic CL-PD0 dual slot PCMCIA controller Cirrus Logic CL-PD0 As shown in Figure, the Cirrus Logic CL-PD0 provides support for two PCMCIA sockets. Key features include full support for dual voltages. The CL-PD0 assumes V PP is tied directly to V PP. The MIC, in a small -pin surface mount package, provides all necessary V PP power control for both sockets. switching is accomplished using the circuit of (either) Figure or Figure. No additional components are necessary, but filter capacitors are recommended for best performance. A complete dual slot PCMCIA power control subsystem using this controller appears as Figure. -

5 Application Note V Intel SL V PP MIC MIC 0 V V PP V PP MIC MIC 0 V V PP (pins 0,, etc.) V PP _ (pin ) V PP _ (pin ) V PP _ (pin ) V PP _ (pin ) V PP _ (pin ) V PP _ (pin ) V PP _ (pin 0) V PP _ (pin ) V PP X X 0 (reserved) Figure. Intel SL "PC Card Interface Controller (PCIC)" implementation Intel SL IN The Intel SL supports fully independent V PP and V PP for two PCMCIA slots. Two MIC allow the necessary voltage combinations for all four V PP pins. No additional components are necessary, although filter capacitors are recommended for best performance. The Intel SL does not support dual selection, so no other power control is required. ON/OFF is supported, and may be implemented by a simple switch consisting of a MIC0 and a single power MOSFET (per slot). Refer to Figure for details on this ON/OFF switch. ON OFF µf Control Input V Input MIC0 Source Gate IRLZ Switched OUT Figure. ON/OFF Switch for use with the Intel SL. -

6 Application Note V Databook TCIC-/N (pins,,, etc.) V PP V PP MIC MIC 0 VCPOL (pin ) SEL0 (pin ) V PP SEL0 (pin 0) SEL (pin ) V PP SEL (pin ) V PP V PP V Figure. Databook TCIC-/N family PCMCIA controller interfacing with the MIC. VPP SEL V SEL VPP OUT V 0 V PP 0 X X 0 (illegal) Databook TCIC-/N Control Logic Databook TCIC-/N Family The Databook TCIC-/N family of PCMCIA controllers has V PP and voltage enable signals a bit different than provided by the other controllers. A logic gate is necessary to complete the interface between the TCIC-/N and the MIC. The TCIC-/N has a pin, VCPOL, which controls the polarity of the output enable signals. When VCPOL is tied to, the control signals are active high, and with VCPOL low, the control outputs are active low. The configuration shown uses the active high option. -

7 Application Note Complete PCMCIA Power Control Circuitry Using MIC and Cirrus Logic CL-PD0 V.V V MIC0 Connect to EITHER.V or V. 0kΩ Source A In A VA Gate A In B Source B VB MIC VPP V PP OUT VPP V MIC V 0 VPP VPP V A SLOT_V (pins, ) CL-PD0 (pin ) A _(p.) A VPP_V (pin ) A _(p. ) A VPP_PGM (pin ) B _ B VPP_V (pin 0) B VPP_PGM (pin 0) B SLOT_V (pins, ) (p.0) B _ (p.0) 0kΩ MIC0 Source A Gate A Source B Gate B Gate B 0 In A VA In B VB 0 Figure. Complete dual slot PCMCIA power control system using MIC and Cirrus Logic CL-PD0 Figure shows a complete dual slot PCMCIA power control implementation for dual systems. CL-PD0 pin ("V") is connected to V if available, and to.v if the logic lines are powered from this voltage. This pin, and the MIC pin (pin ) set up reference levels for the logic input pins (and output pins on the CL-PD0). As of the time of this writing, the PCMCIA field is quite dynamic. Please contact for the latest information on PCMCIA controller compatibility and new devices designed for this application. -