MIC2568 Datasheet, PDF (8/10 Pages) Micrel Semiconductor – Dual-Slot PC Card/CardBus Power Controller

MIC2568
Applications Information
PC Card power control for two sockets is easily accomplished
using the Micrel MIC2568 PC Card/CardBus Slot Power
Controller IC.
Output Voltage Selection
Four control bits per socket determine V_CC and V_PP output
voltages and standby- or operate-mode conditions. Input
logic threshold voltages are compatible with common PC
Card logic controllers using either 3.3V or 5V supplies.
The V_CC outputs can be individually switched between 0V
(ground) or 3.3V and 5V at the maximum allowable PC Card
current. The V_PP outputs can be individually switched be-
tween 0V (ground), 3.3V or 5V (V_CC3 or V_CC5 voltages), or
high impedance. When V_CC = 0V (ground) is selected, the
MIC2568 goes into sleep mode and draws only nanoamperes
of leakage current.
Switching speeds are controlled to prevent damage to sensi-
tive loads and meet all PC Card Specification timing require-
ments. V_CC switches are turned on and off slowly. If com-
manded to switch directly from one V_CC to the other (without
first turning off and waiting 100ms), enhancement of the
second switch begins only after the first is off (break-before-
make protection).
Supply Input
The MIC2568 itself is powered from the V_CC3 IN pin (3.3V-
nominal supply input). Bias its internal MOSFETs is gener-
ated by a charge pump quadrupler. Refer to “5V-Only V_CC
Application” and Figure 4 for information on using the MIC2568
without a 3.3V supply.
Output Current and Protection
The MIC2568 meets or exceeds all PCMCIA current specifi-
cations. Its switches are capable of passing the maximum
current needed by any PC Card. For system and card
Micrel
protection, output currents are internally limited. For full
system protection, long-term output short circuits (millisec-
ond or longer) invoke overtemperature shutdown, protecting
the MIC2568, system power supplies, card socket pins, and
PC Card.
Bypass Capacitors
Both V_CC3 IN and V_CC5 IN pins should be bypassed with 1µF
low-ESR surface-mount ceramic capacitors mounted near
the MIC2568 chip.
Both V_CC OUT and V_PP OUT pins may use 0.01µF to 0.1µF
capacitors for noise reduction and to reduce the chance of
(electrostatic discharge) ESD damage.
PC Card Slot Implementation
The MIC2568 is designed for PC Card applications, including
the CardBus option, that do not require a 12V supply.
When a memory card is initially inserted, it must receive a V_CC
voltage (either 3.3V ±0.3V or 5.0V ±5%). The initial voltage is
determined by a combination of mechanical socket keys and
voltage-sense pins. Each card sends handshaking data to
the logic controller which determines whether that card
requires a V_PP voltage and whether the card is designed for
dual V_CC voltages. If the card is compatible with, and re-
quests, a different V_CC level, the controller disables V_CC,
waits at least 100ms, and then enables the new V_CC voltage.
If no card is inserted, or the system is in sleep mode, the logic
controller outputs a (V_CC3 EN, V_CC5 EN) = (0, 0) to the
MIC2568, which shuts down V_CC. This also places the switch
into its high-impedance output sleep mode.
Basic V_PP and V_CC Switch Application
Refer to Figure 3. A single system power supply feeds both
slot-A and slot-B supply inputs. Although the PC Card speci-
fication defines two V_PP outputs (V_PP 1 and V_PP 2) per card,
they are usually connected together.
MIC2568
Address and data lines
between logic controller and
PCMCIA cards not shown.
Dual-Slot
PC Card
Logic Controller
System Power Supply
3.3V
(OPTIONAL)
5V
A_{⁄BVCC3 IN} A_{⁄BVCC5 IN}
A EN1
A EN0
A V_CC5 EN
A V_CC3 EN
B EN1
B EN0
B V_CC5 EN
B V_CC3 EN
A V_PP OUT
A V_CC OUT
MIC2568-0
Power
Controller
GND
B V_PP OUT
B V_CC OUT
Slot A
V_PP1
V_PP2
V_CC
V_CC
Slot B
V_PP1
V_PP2
V_CC
V_CC
Motherboard
Figure 3. Basic V_PP and V_CC Switch
8
PC Card
A
PC Card
B
May 2003