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MIC2557
Micrel
MIC2557
PCMCIA Card Socket VPP Switching Matrix
General Description
The MIC2557 switches the four voltages required by PCMCIA (Personal Computer Memory Card International Association) card VPP Pins. The MIC2557 provides selectable 0V, 3.3V, 5.0V, or 12.0V (5%) from the system power supply to VPP1 or VPP2. Output voltage is selected by two digital inputs. Output current ranges up to 120mA. Four control states, VPP, VCC, high impedance, and active logic low are available. An auxiliary control input determines whether the high impedance (open) state or low logic state is asserted. In either quiescent mode or full operation, the device draws very little current, typically less than 1A. The MIC2557 is available in an 8-pin SOIC and an 8-pin plastic DIP.
Features
* * * * * * * * * * Complete PCMCIA V Switch Matrix in a Single IC PP No External Components Required Digital Selection of 0V, VCC, VPP, or High Imped- ance Output No VPP OUT Overshoot or Switching Transients Break-Before-Make Switching Low Power Consumption 120mA V (12V) Output Current PP Optional Active Source Clamp for Zero Volt Condition 3.3V or 5V Supply Operation 8-Pin SOIC Package
Applications
* * * PCMCIA V
PP
Ordering Information
Part Number MIC2557BM MIC2557BM T&R Temperature Range -40C to +85C -40C to +85C Package 8-pin SOIC 8-SOIC Tape & Reel*
Pin Voltage Switch
Power Supply Management Power Analog Switch
* 2,500 Parts per reel.
Typical Application
VCC +3.3V or +5V VPP IN +12V VDD +5V
Pin Configuration
VPP IN VPP OUT +VCC
0.1F
8
8 2 7 MIC2557 3 6 4 5
VDD Hi-Z/Low EN0 EN1
GND
Hi-Z/ Low Control EN0 EN1
VPP(n) OUT 0.1F 1F 1F
2 7 MIC2557 3 6 4 5
Simplified Block Diagram
VDD VPP IN VCC
EN1
0 0 0 1 1
EN0 Hi-Z/Low VPP OUT
0 0 1 0 1 0 1 x x x 0V, (Sink current) Hi-Z (No Connect) VCC (3.3V or 5.0V) VPP Hi-Z (No Connect)
Hi-Z/Low EN0 EN1
Decoder, Driver & Bias Control High Impedance or Pull Down Select
VPP OUT
For a dual PCMCIA Card Socket VPP Switching Matrix, see the MIC2558. For a VPP and VCC Switching Matrix, see the MIC2560.
2-4 1997
MIC2557
Micrel
(Notes 1 and 2) 800 mW 4 mW/C -65C to +150C 125C -40C to +85C 260C 15V 7.5V 7.5V -0.3V to VDD 600mA 250mA
Absolute Maximum Ratings
Power Dissipation, TAMBIENT 25C SOIC Derating Factors (To Ambient) SOIC Storage Temperature Operating Temperature (Die) Operating Temperature (Ambient) Lead Temperature (5 sec) Supply Voltage, VPP IN VCC VDD Logic Input Voltages Output Current VPP OUT = 12V VPP OUT = VCC
2
Logic Block Diagram
VDD
8
1
VPP IN
EN1
5 VDD VDD VPP IN 3
VCC
EN0
6 VDD
VDD 2
VPP OUT
HiZ/ LOW 7
4
GND
1997
2-5
MIC2557
Micrel
(Over operating temperature range with VDD = VCC= 5V, VPP IN = 12 V unless otherwise specified.) Conditions Min Typ Max Units
Electrical Characteristics:
Symbol INPUT VIH VIL VIN (Max) IIN OUTPUT VOL IOUT, Hi-Z Logic 1 Input Voltage Logic 0 Input Voltage Input Voltage Range Input Current Parameter
VDD = 3.3V or 5.0V VDD = 3.3V or 5.0V
2.2 0.8 -5 VDD 1
V V V A
0 V < VIN < VDD
Clamp Low Output Voltage High Impedance Output Leakage Current Clamp Low Output Resistance Switch Resistance, VPP OUT = VCC Switch Resistance, VPP OUT = VPP IN
EN0 = EN1 = HiZ = 0, ISINK = 1.6mA EN0 = EN1 = 0, HiZ = 1 0 VPP OUT 12V Resistance to Ground. ISINK = 2mA EN0 = EN1 =0,HiZ=0 IPP OUT = -10 mA (Sourcing) 1
0.4 10
V A
ROC RO
130 2.5
250 5

RO
IPP OUT = -100 mA (Sourcing)
0.5
1
SWITCHING TIME (See Figure 1) t1 t2 t3 t4 t5 t6 Delay + Rise Time Delay + Rise Time Delay + Fall Time Delay + Fall Time Output Turn-On Delay Output Turn-Off Delay VPP OUT = 0V to 5V (Notes 3, 5) VPP OUT = 5V to 12V (Notes 3, 5) VPP OUT = 12V to 5V (Notes 3, 5) VPP OUT = 5V to 0V (Notes 3, 5) VPP OUT = Hi-Z to 5V (Notes 4, 5) VPP OUT = 5V to Hi-Z (Notes 4, 5) 15 12 25 45 10 75 50 50 75 100 50 200 s s s s s ns
POWER SUPPLY IDD ICC IPP VDD Supply Current VCC Supply Current IPP Supply Current IPP OUT = 0 VPP OUT = 0 V or VPP . IPPOUT = 0. VPP OUT = VCC - - - 1 1 10 A A A A
10
40
2-6
1997
MIC2557
Micrel
Electrical Characteristics, (continued)
Symbol Parameter Conditions Min Typ Max Units
POWER SUPPLY, continued VCC VDD VPP IN Operating Input Voltage Operating Input Voltage Operating Input Voltage 2.8 8.0 6 6 14.5 V V V
NOTE 1: NOTE 2: NOTE 3: NOTE 4: NOTE 5:
Functional operation above the absolute maximum stress ratings is not implied. Static-sensitive device. Store only in conductive containers. Handling personnel and equipment should be grounded to prevent damage from static discharge. With RL = 2.9k and C = 0.1F on V . RL = 2.9k. RL is connected to VCC during t5 , and is connected to ground during t6. Rise and fall times are measured to 90% of the difference between initial and final values.
OUT PP OUT
2
3V Hi-Z/Low 0 3V EN0 0 3V EN1 0 12V
VPP OUT
5V
0 t1 t2 t3 t4 t5 t6
Figure 1. Timing Diagram
1997
2-7
MIC2557
Micrel
Applications Information
PCMCIA VPP control is easily accomplished using the MIC2557 voltage selector/switch IC. Two control bits determine output voltage and standby/operate mode condition. Output voltages of 0V (defined as less than 0.4V), VCC (3.3V or 5V), VPP, 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 VDD, which may be either 3.3V or 5V, and FET drive is obtained from VPP IN (usually +12V). Internal break-before-make switches determine the output voltage and device mode. Supply Bypassing For best results, bypass VCC and VPP IN at their inputs with 1F capacitors. VPP OUT should have a 0.01F to 0.1F 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 VCC and VPP IN pins.
PCMCIA Card Slot Controller VCC 5V System Power Supply 12V EN0 EN1
VPP IN VCC
VCC Switch
VCC
VPP1 PCMCIA Card Slot A
MIC2557
EN0 EN1
VPP IN
VCC
VPP2
MIC2557
EN0 EN1
VPP IN
VCC
VPP1 PCMCIA Card Slot B
MIC2557
5V System Power 3.3V Supply 12V EN0 EN1
VPP IN VCC
VCC Select and Switch
VCC
EN0 EN1
VPP IN
VCC
VPP2
MIC2557
VPP1 PCMCIA Card Slot A
MIC2557
Figure 3. MIC2557 Typical two slot PCMCIA application with single 5.0V VCC. PCMCIA Implementation
EN0 EN1
VPP IN
VCC
VPP2
MIC2557
PCMCIA Card Slot Controller
VCC Select and Switch
VCC
EN0 EN1
VPP IN
VCC
VPP1 PCMCIA Card Slot B
MIC2557
The Personal Computer Memory Card International Association (PCMCIA) specification requires two VPP supply pins per PCMCIA slot. VPP is primarily used for programming Flash (EEPROM) memory cards. The two VPP supply pins may be programmed to different voltages. Fully implementing PCMCIA specifications requires two MIC2557, and a controller. Figure 2 shows this full configuration, supporting both 5.0V and 3.3V VCC operation. Figure 3 is a simplified design with fixed VCC = 5V. Palmtop computers, where size and battery life are tantamount, can sometimes use a compromise implementation, with VPP1 tied to VPP2 (see Figure 4). When a memory card is initially inserted, it should receive VCC, usually 5.0V 5%. The card sends a handshaking data stream to the controller, which then determines whether or not this card requires VPP and if the card is designed for 5.0V or 3.3V VCC. If the card uses 3.3V VCC, the controller commands this change, which is reflected on the VCC 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 VPP IN to 2-8 1997
EN0 EN1
VPP IN
VCC
VPP2
MIC2557
Figure 2. MIC2557 Typical two slot PCMCIA application with dual VCC (5.0V or 3.3V).
MIC2557
3.3V System Power Supply 3.3V to 12V DC-DC Converter VCC Switch
Micrel
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, VPP OUT enters a high impedance (open) state. With HiZ/ Low in the low state and EN0 = EN1 = 0, VPP 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 VPP IN. Internal device control logic is powered from VDD, which should be connected to the same supply voltage as the PCMCIA controller (normally either 3.3V or 5V).
EN0 EN1
VPP IN
VCC
VDD
VPP1
MIC2557
PCMCIA Card Slot
PCMCIA Card Slot Controller
VPP2
Figure 4. MIC2557 Palmtop application. Note that the VPP1 and VPP2 pins are combined. Although this does not fully satisfy PCMCIA specifications, it simplifies the circuitry and is acceptable in certain applications. VPP OUT. The low ON resistance of the MIC2557 switch requires only a small bypass capacitor on VPP OUT, with the main filtering action performed by a large filter capacitor on VPP IN. The VPP OUT transition from VCC to 12.0V typically takes 25S. After programming is completed, the controller outputs a (0,1) to the MIC2557, which then reduces VPP OUT to the VCC level. Break-before-make switching action reduces switching transients and lowers maximum current spikes through the switch from the output capacitor.
Output Current MIC2557 output switches are capable of far more current than usually needed in PCMCIA applications. PCMCIA VPP output current is limited primarily by switch resistance voltage drop (I x R) and the requirement that VPP OUT cannot drop more than 5% below nominal. VPP OUT will survive output short circuits to ground if VPP IN and VCC are current limited by the regulator that supplies these voltages.
2
1997
2-9

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