MIC2563A_04 Datasheet, PDF (8/12 Pages) Micrel Semiconductor – Dual-Slot PCMCIA/CardBus Power Controller

MIC2563A
Applications Information
PC Card power control for two sockets is easily accomplished
using the MIC2563A PC Card/CardBus slot V_CC and V_PP
power controller IC. Four control bits per socket determine
V_CC OUT and V_PP OUT voltage and standby/operate mode
condition. V_CC outputs of 3.3V and 5V at the maximum
allowable PC Card current are supported. V_PP OUT output
voltages of V_CC (3.3V or 5V), V_PP, 0V, or a high impedance
state are available. When the V_CC clamped to ground condi-
tion is selected, the device switches into “sleep” mode and
draws only nanoamperes of leakage current. Full protection
from hot switching is provided which prevents feedback from
the V_CC OUT (from 5V to 3.3V, for example) by locking out the
low-voltage switch until the initial switch’s gate voltage drops
below the desired lower V_CC.
The MIC2563A operates from the computer system’s main
power supply. Device logic and internal MOSFET drive is
generated internally by charge pump voltage multipliers
powered from V_CC3 IN. Switching speeds are carefully con-
trolled to prevent damage to sensitive loads and meet all PC
Card Specification timing requirements.
Supply Bypassing
External capacitors are not required for operation. The
MIC2563A is a switch and has no stability problems. For best
results however, bypass V_CC3 IN, V_CC5 IN, and V_PP IN inputs
with 1µF capacitors to improve output ripple. As all internal
device logic and comparison functions are powered from the
V_CC3 IN line, the power supply quality of this line is the most
important, and a bypass capacitor may be necessary for
some layouts. Both V_CC OUT and V_PP OUT pins may use
0.01µF to 0.1µF capacitors for noise reduction and electro-
static discharge (ESD) damage prevention.
PC Card Slot Implementation
The MIC2563A is designed for full compatibility with the
PCMCIA PC Card Specification, (March 1995), including the
CardBus option.
When a memory card is initially inserted, it should receive
V_CC (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. 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 dual
V_CC. If the card is compatible with and desires a different V_CC
level, the controller commands this change by disabling V_CC,
waiting at least 100ms, and then re-enabling the other V_CC
voltage.
V_CC switches are turned ON and OFF slowly. If commanded
to immediately switch from one V_CC to the other (without
turning OFF and waiting 100ms first), enhancement of the
second switch begins after the first is OFF, realizing break-
before-make protection. V_PP switches are turned ON slowly
and OFF quickly, which also prevents cross conduction.
Micrel
If no card is inserted or the system is in sleep mode, the slot
logic controller outputs a (V_CC3 IN, V_CC5 IN) = (0,0) to the
MIC2563A, which shuts down V_CC. This also places the
switch into a high impedance output shutdown (sleep) mode,
where current consumption drops to nearly zero, with only
tiny CMOS leakage currents flowing.
Internal device control logic, MOSFET drive and bias voltage
is powered from V_CC3 IN. The high voltage bias is generated
by an internal charge pump quadrupler. Systems without
3.3V may connect V_CC3 IN to 5V. Input logic threshold
voltages are compatible with common PC Card logic control-
lers using either 3.3V or 5V supplies.
The PC Card specification defines two V_PP supply pins per
card slot. The two V_PP supply pins may be programmed to
different voltages. V_PP is primarily used for programming
Flash memory cards. Implementing two independent V_PP
voltages is easily accomplished with the MIC2563A and a
MIC2557 PCMCIA V_PP switching matrix. Figure 3 shows this
full configuration, supporting independent V_PP and both 5.0V
and 3.3V V_CC operation. However, few logic controllers
support multiple V_PP — most systems connect V_PP1 to V_PP2
and the MIC2557 is not required. This circuit is shown in
Figure 4.
During flash memory programming with standard (+12V)
flash memories, the PC Card slot logic controller outputs a
(0, 1) to the EN0, EN1 control pins of the MIC2563A, which
connects V_PP IN (nominally +12V) to V_PP OUT. The low ON
resistance of the MIC2563A switch allows using a small
bypass capacitor on the V_PP OUT pins, with the main filtering
action performed by a large filter capacitor on V_PP IN (usually
the main power supply filter capacitor is sufficient). Using a
small-value capacitor such as 0.1µF on the output causes
little or no timing delays. The V_PP OUT transition from V_CC to
12.0V typically takes 250µs. After programming is com-
pleted, the controller outputs a (EN1, EN0) = (0,1) to the
MIC2563A, which then reduces V_PP OUT to the V_CC level.
Break-before-make switching action and controlled rise times
reduces switching transients and lowers maximum current
spikes through the switch.
Figure 5 shows MIC2563A configuration for situations where
only a single +5V V_CC is available.
Output Current and Protection
MIC2563A output switches are capable of passing the maxi-
mum current needed by any PC Card. The MIC2563A meets
or exceeds all PCMCIA specifications. For system and card
protection, output currents are internally limited. For full
system protection, long term (millisecond or longer) output
short circuits invoke overtemperature shutdown, protecting
the MIC2563A, the system power supplies, the card socket
pins, and the PC Card.
M9999-110503
8
March 2004