MIC2558 Datasheet, PDF (6/6 Pages) Micrel Semiconductor – PCMCIA Dual Card Socket VPP Switching Matrix

MIC2558
Micrel
action performed by a large filter capacitor on V_{PP IN}. The
V_{PP OUT} transition from V_CC to 12.0V typically takes 25µS.
After programming is completed, the controller outputs a
(0,1) to the MIC2558, which then reduces V_{PP OUT} to the
V_CC level. Break-before-make switching action reduces
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 MIC2558.
Either input places the switch into shutdown mode, where
current consumption drops even further.
The HiZ/Low input controls the optional logic low output
clamp. With HiZ/Low in the high state and EN0 = 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 any DC bias current for operation.
MOSFET drive and bias voltage is derived from V_{PP IN}.
Internal device control logic is powered from V_DD, which
should be connected to the same supply voltage as the
PCMCIA controller (normally either 3.3V or 5V).
Output Current
MIC2558 output switches are capable of far more current
than usually needed in PCMCIA applications. PCMCIA V_PP
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} or V_CC are current limited by
the regulator that supplies these voltages.
VPP _IN
VDD
2
+12V
+5V
VPP _{OUT 1}
0.1µF
VPP _{OUT 2}
0.1µF
0.1µF
1µF
14
2
13
3
12
MIC2558
4
11
5
10
6
9
7
8
Hi-Z/ Low 1 Control
EN01
EN11
Hi-Z/ Low 2 Control
EN02
EN12
SHUTDOWN ₃
INPUT
SD
OFF
8
+V _IN
VOUT ¹
MIC2951
ON
TTL Logic Level
GND
4
FB
7
VIN = +5.3V to +15V
100pF
+
300kΩ ^3.3µF
1%
High (V > 1.5V) VCC = 5.0V
470 kΩ
Low (V < 0.5V) VCC = 3.3V
220kΩ
1%
180kΩ
1%
2N2222
VCC Switching and Control Block
Figure 3. Full PCMCIA Implementation of V_PP and V_CC switching using MIC2558 and MIC2951 voltage regulator.
1997
2-15