MIC2558
Micrel
MIC2558
PCMCIA Dual Card Socket V
PP
Switching Matrix
General Description
The MIC2558 Dual V
PP
Matrix switches the four voltages
required by PCMCIA (Personal Computer Memory Card
International Association) card V
PP1
and V
PP2
Pins. The
MIC2558 provides selectable 0V, 3.3V, 5.0V, or 12.0V (±5%)
from the system power supply to V
PP1
and V
PP2
. Output
voltage is selected by two digital inputs per V
PP
pin. Output
current ranges up to 120mA. Four output states, V
PP
, V
CC
,
high impedance, and active logic low are available, and V
PP1
is independent of V
PP2
. An auxiliary control input determines
whether the high impedance (open) state or low logic state is
asserted.
In standby mode or full operation, the device draws very little
quiescent current, typically less than 1µA.
The MIC2558 is available in a 14-pin SOIC and a 14-pin
plastic DIP.
Features
•
•
•
•
•
•
•
•
•
•
Complete PCMCIA V
PP
Switch Matrix in a Single IC
Dual Matrix allows independent V
PP1
and V
PP2
Digital Selection of 0V, V
CC
, V
PP
, or High
Impedance Output
No V
PPOUT
Overshoot or Switching Transients
Break-Before-Make Switching
Ultra Low Power Consumption
120mA V
PP
(12V) Output Current
Optional Active Source Clamp for Zero Volt Condition
3.3V or 5V Supply Operation
14-Pin SOIC Package
Part Number
Temperature Range
–40°C to +85°C
–40°C to +85°C
Package
14-pin SOIC
14-SO Tape & Reel*
Ordering Information
MIC2558BM
MIC2558BM T&R
Applications
•
•
PCMCIA V
PP
Pin Voltage Switch
Power Supply Management
* 2,500 Parts per reel.
Typical Application
VPP IN
VCC
+12V +3.3V or +5V
VDD
+5V
Pin Configuration
VPP OUT1
NC
+VCC1
VPP IN
+VCC2
GND
VPP OUT2
14
2
13
VDD
Hi-Z/Low1
EN01
EN11
Hi-Z/Low2
EN02
EN12
0.1µF
VPP OUT 1
2
14
13
3
12
MIC2558
4
11
5
6
7
10
9
8
0.1µF
1µF
1µF
3
12
MIC2558
4
11
5
6
7
10
9
8
Hi-Z/ Low 1 Control
EN01
EN11
Hi-Z/ Low 2 Control
EN02
EN12
VPP OUT 2
0.1µF
EN1
0
0
0
1
1
EN0 Hi-Z/Low V
PP OUT
0
0
1
0
1
0
1
x
x
x
0V, (Sink current)
Hi-Z (No Connect)
V
V
CC
PP
(3.3V or 5.0V)
Hi-Z (No Connect)
2-10
1997
MIC2558
Micrel
Applications Information
PCMCIA V
PP1
and V
PP2
control is easily accomplished
using the MIC2558 voltage selector/switch IC. Two control
bits per V
PP OUT
pin determine output voltage and standby/
operate mode condition. Output voltages of 0V (defined as
less than 0.4V), V
CC
(3.3V or 5V), V
PP
, 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 MIC2558 is a dual low-resistance power MOSFET
switching matrix that operates from the computer system
main power supply. Device power is obtained from V
DD
,
which may be either 3.3V or 5V, and FET drive is obtained
from V
PP IN
(usually +12V). Internal break-before-make
switches determine the output voltage and device mode.
V
PP1
and V
PP2
are completely indepenent from each other.
Supply Bypassing
For best results, bypass V
CC
and V
PP IN
inputs with 1µF
capacitors. Both V
PP OUT
pins should have a 0.01µF to
0.1µF capacitor for noise reduction and electrostatic dis-
charge (ESD) damage prevention. Larger values of output
capacitor will create large current spikes during transitions,
requiring larger bypass capacitors on the V
CC
and V
PP IN
pins.
5V
System
Power 3.3V
Supply
12V
EN01
EN11
PCMCIA
Card Slot
A
MIC2558
VPP IN
VCC
5V
System
Power
Supply
12V
EN01
EN11
PCMCIA
Card Slot
A
MIC2558
VPP IN
VCC
VCC Switch
VCC
VPP1
EN02
EN12
VPP2
PCMCIA
Card Slot
Controller
VCC
EN01
EN11
VPP IN
VCC
VPP1
PCMCIA
Card Slot
B
MIC2558
VCC Select and
Switch
VCC
EN02
EN12
VPP2
VPP1
Figure 3. MIC2558 Typical two slot PCMCIA applica-
tion with single 5.0V V
CC
.
PCMCIA Implementation
The Personal Computer Memory Card International Asso-
ciation (PCMCIA) specification requires two V
PP
supply pins
per PCMCIA slot. V
PP
is primarily used for programming
Flash (EEPROM) memory cards. The two V
PP
supply pins
may be programmed to different voltages. Fully implement-
ing PCMCIA specifications requires a MIC2558 and a con-
troller. Figure 2 shows this full configuration, supporting both
5.0V and 3.3V V
CC
operation. Figure 3 is a simplified design
with fixed V
CC
= 5V.
When a memory card is initially inserted, it should receive
V
CC
— usually 5.0V
±5%.
The card sends a handshaking
data stream to the controller, which then determines whether
or not this card requires V
PP
and if the card is designed for
5.0V or 3.3V V
CC
. If the card uses 3.3V V
CC
, the controller
commands this change, which is reflected on the V
CC
pins of
both the PCMCIA slot and the MIC2558.
During Flash memory programming, the PCMCIA controller
outputs a (1,0) to one or both halves of the MIC2558, which
connects V
PP IN
to V
PP OUT1
and/or V
PP OUT2
. The low ON
resistance of the MIC2558 switch requires only a small
bypass capacitor on the V
PP OUT
pins, with the main filtering
2-14
1997
EN02
EN12
VPP2
PCMCIA
Card Slot
Controller
VCC Select and
Switch
VCC
EN01
EN11
VPP IN
VCC
VPP1
PCMCIA
Card Slot
B
MIC2558
EN02
EN12
VPP2
Figure 2. MIC2558 Typical two slot PCMCIA applica-
tion with dual V
CC
(5.0V or 3.3V).
Embedded System
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