1997

MIC2557

Micrel

Ordering Information

Part Number

Temperature Range

Package

MIC2557BM

C to +85

8-pin SOIC

MIC2557BM T&R

C to +85

8-SOIC Tape & Reel*

* 2,500 Parts per reel.

MIC2557

PCMCIA Card Socket V

Switching Matrix

Final Information

Features

Complete PCMCIA V

Switch Matrix in a Single IC

No External Components Required

Digital Selection of 0V, V

, V

, or High Imped

ance Output

No V

PP OUT

Overshoot or Switching Transients

Break-Before-Make Switching

Low Power Consumption

120mA V

(12V) Output Current

Optional Active Source Clamp for Zero Volt Condition

3.3V or 5V Supply Operation

8-Pin SOIC Package

General Description

The MIC2557 switches the four voltages required by PCMCIA
(Personal Computer Memory Card International Association)
card V

Pins. The MIC2557 provides selectable 0V, 3.3V,

5.0V, or 12.0V (

5%) from the system power supply to V

PP1

or V

PP2

. Output voltage is selected by two digital inputs.

Output current ranges up to 120mA. Four control states, V

, high impedance, and active logic low are available. An

auxiliary control input determines whether the high imped-
ance (open) state or low logic state is asserted.

In either quiescent mode or full operation, the device draws
very little current, typically less than 1

The MIC2557 is available in an 8-pin SOIC and an 8-pin
plastic DIP.

Applications

PCMCIA V

Pin Voltage Switch

Power Supply Management

Power Analog Switch

GND

EN1

EN0

MIC2557

+VCC

VDD
Hi-Z/Low

VPP OUT

VPP IN

+3.3V or +5V

VPP(n) OUT

0.1µF

EN0
EN1

1µF

+12V

+5V

Hi-Z/ Low Control

VDD

VCC

VPP IN

MIC2557

0.1µF

For a dual PCMCIA Card Socket V

Switching Matrix, see the MIC2558.

For a V

and V

Switching Matrix, see the MIC2560.

EN1

EN0 Hi-Z/Low V

PP OUT

0V, (Sink current)

Hi-Z (No Connect)

(3.3V or 5.0V)

Hi-Z (No Connect)

Simplified Block Diagram

VDD

VCC

VPP IN

EN0

EN1

Hi-Z/Low

Decoder,

Driver &

Bias Control

VPP OUT

High

Impedance or

Pull Down

Select

Typical Application

Pin Configuration

Micrel, Inc. · 1849 Fortune Drive · San Jose, CA 95131 · USA · tel + 1 (408) 944-0800 · fax + 1 (408) 944-0970 · http://www.micrel.com

1997

MIC2557

Micrel

Electrical Characteristics:

(Over operating temperature range with V

= V

= 5V, V

PP IN

= 12 V unless otherwise specified.)

Symbol

Parameter

Conditions

Min

Typ

Max

Units

INPUT

Logic 1 Input Voltage

= 3.3V or 5.0V

2.2

Logic 0 Input Voltage

= 3.3V or 5.0V

0.8

(Max)

Input Voltage Range

Input Current

0 V < V

< V

OUTPUT

Clamp Low Output Voltage

EN0 = EN1 = HiZ = 0, I

SINK

= 1.6mA

0.4

OUT

, Hi-Z

High Impedance Output

EN0 = EN1 = 0, HiZ = 1

Leakage Current

PP OUT

12V

Clamp Low Output Resistance

Resistance to Ground. I

SINK

= 2mA

130

250

EN0 = EN1 =0,HiZ=0

Switch Resistance,

PP OUT

= 10 mA (Sourcing)

2.5

PP OUT

= V

Switch Resistance,

PP OUT

= 100 mA (Sourcing)

0.5

PP OUT

= V

PP IN

SWITCHING TIME (See Figure 1)

Delay + Rise Time

PP OUT

= 0V to 5V (Notes 3, 5)

Delay + Rise Time

PP OUT

= 5V to 12V (Notes 3, 5)

Delay + Fall Time

PP OUT

= 12V to 5V (Notes 3, 5)

Delay + Fall Time

PP OUT

= 5V to 0V (Notes 3, 5)

100

Output Turn-On Delay

PP OUT

= Hi-Z to 5V (Notes 4, 5)

Output Turn-Off Delay

PP OUT

= 5V to Hi-Z (Notes 4, 5)

200

POWER SUPPLY

Supply Current

PP OUT

= 0

Supply Current

PP OUT

= 0 V

or V

. I

PPOUT

= 0.

PP OUT

= V

MIC2557

Micrel

MIC2557

1997

Hi-Z/Low

EN0

EN1

12V

VPP OUT

Figure 1. Timing Diagram

Electrical Characteristics, (continued)

Symbol

Parameter

Conditions

Min

Typ

Max

Units

POWER SUPPLY, continued

Operating Input Voltage

2.8

PP IN

Operating Input Voltage

8.0

14.5

NOTE 1:

Functional operation above the absolute maximum stress ratings is not implied.

NOTE 2:

Static-sensitive device. Store only in conductive containers. Handling personnel and equipment should be grounded to
prevent damage from static discharge.

NOTE 3:

With R

= 2.9k

and C

OUT

= 0.1

F on V

PP OUT

NOTE 4:

= 2.9k

. R

is connected to V

during t

, and is connected to ground during t

NOTE 5:

Rise and fall times are measured to 90% of the difference between initial and final values.

1997

MIC2557

Micrel

Applications Information

PCMCIA V

control is easily accomplished using the

MIC2557 voltage selector/switch IC. Two control bits deter-
mine output voltage and standby/operate mode condition.
Output voltages of 0V (defined as less than 0.4V), V

(3.3V

or 5V), V

, or a high impedance state, are available. When

either the high impedance or low voltage conditions are
selected, the device switches into "sleep" mode, and draws
only nanoamperes of leakage current.

The MIC2557 is a low-resistance power MOSFET switching
matrix that operates from the computer system main power
supply. Device power is obtained from V

, which may be

either 3.3V or 5V, and FET drive is obtained from V

PP IN

(usually +12V). Internal break-before-make switches deter-
mine the output voltage and device mode.

Supply Bypassing

For best results, bypass V

and V

PP IN

at their inputs with

F capacitors. V

PP OUT

should have a 0.01

F to 0.1

capacitor for noise reduction and electrostatic discharge
(ESD) damage prevention. Larger values of output capacitor
will create large current spikes during transitions, requiring
larger bypass capacitors on the V

and V

PP IN

pins.

Figure 2. MIC2557 Typical two slot PCMCIA applica-

tion with dual V

(5.0V or 3.3V).

Figure 3. MIC2557 Typical two slot PCMCIA applica-

tion with single 5.0V V

PCMCIA Implementation

The Personal Computer Memory Card International Asso-
ciation (PCMCIA) specification requires two V

supply pins

per PCMCIA slot. V

is primarily used for programming

Flash (EEPROM) memory cards. The two V

supply pins

may be programmed to different voltages. Fully implement-
ing PCMCIA specifications requires two MIC2557, and a
controller. Figure 2 shows this full configuration, supporting
both 5.0V and 3.3V V

operation. Figure 3 is a simplified

design with fixed V

= 5V. Palmtop computers, where size

and battery life are tantamount, can sometimes use a com-
promise implementation, with V

PP1

tied to V

PP2

(see Figure

4).

When a memory card is initially inserted, it should receive
V

, usually 5.0V

5%. The card sends a handshaking data

stream to the controller, which then determines whether or
not this card requires V

and if the card is designed for 5.0V

or 3.3V V

. If the card uses 3.3V V

, the controller

commands this change, which is reflected on the V

pins of

both the PCMCIA slot and the MIC2557.

During Flash memory programming, the PCMCIA controller
outputs a (1,0) to the MIC2557, which connects V

PP IN

System

Power

Supply

PCMCIA

Card Slot

Controller

MIC2557

PCMCIA

Card Slot

PCMCIA

Card Slot

MIC2557

12V

EN0

EN1

EN0

EN1

EN0

EN1

EN0

VPP1

VPP2

VCC

VPP1

VPP2

VCC

VCC Switch

VPP IN

VCC

VPP IN

VCC

VPP IN

VCC

VPP IN

VCC

System

Power

Supply

PCMCIA

Card Slot

Controller

VCC Select and

Switch

MIC2557

PCMCIA

Card Slot

PCMCIA

Card Slot

VCC Select and

Switch

MIC2557

3.3V

12V

EN0

EN1

EN0

EN1

EN0

EN1

EN0

VPP1

VPP2

VCC

VPP1

VPP2

VCC

VPP IN

VCC

VPP IN

VCC

VPP IN

VCC

VPP IN

VCC

MIC2557

Micrel

MIC2557

1997

Figure 4. MIC2557 Palmtop application. Note that the
V

PP1

and V

PP2

pins are combined. Although this does

not fully satisfy PCMCIA specifications, it simplifies the
circuitry and is acceptable in certain applications.

System

Power

Supply

MIC2557

PCMCIA

Card Slot

3.3V

3.3V to 12V

DCDC

Converter

EN0

EN1

VPP1

VPP2

PCMCIA

Card Slot

Controller

VCC

Switch

VPP IN VCC VDD

PP OUT

. The low ON resistance of the MIC2557 switch

requires only a small bypass capacitor on V

PP OUT

, with the

main filtering action performed by a large filter capacitor on
V

PP IN

. The V

PP OUT

transition from V

to 12.0V typically

takes 25

S. After programming is completed, the controller

outputs a (0,1) to the MIC2557, which then reduces V

PP OUT

to the V

level. Break-before-make switching action re-

duces switching transients and lowers maximum current
spikes through the switch from the output capacitor.

If no card is inserted, or the system is in sleep mode, the
controller outputs either a (0,0) or a (1,1) to the MIC2557.
Either input places the switch into its shutdown mode, where
only a small leakage current flows.

The HiZ/Low input controls the optional logic low output
clamp. With HiZ/Low in the high state and ENO = EN1 = 0,
V

PP OUT

enters a high impedance (open) state. With HiZ/

Low in the low state and EN0 = EN1 = 0, V

PP OUT

is clamped

to ground, providing a logic low signal. The clamp does not
require DC bias current for operation.

MOSFET drive and bias voltage is derived from V

PP IN

Internal device control logic is powered from V

, which

should be connected to the same supply voltage as the
PCMCIA controller (normally either 3.3V or 5V).

Output Current

MIC2557 output switches are capable of far more current
than usually needed in PCMCIA applications. PCMCIA V

output current is limited primarily by switch resistance voltage
drop (I x R) and the requirement that V

PP OUT

cannot drop

more than 5% below nominal. V

PP OUT

will survive output

short circuits to ground if V

PP IN

and V

are current limited

by the regulator that supplies these voltages.

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: MIC2557B

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: MIC2557B