LTC1470_1

LTC1470/LTC1471 Single and Dual PCMCIA Protected 3.3V/5V VCC Switches FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Single 3.3V/5V Switch in 8-Pin SO Package Dual 3.3V/5V Switch in 16-Pin SO Package Built-In Current Limit and Thermal Shutdown Built-In Charge Pumps (No 12V Required) Extremely Low RDS(ON) MOSFET Switches Output Current Capability: 1A Inrush Current Limited (Drives 150µF Loads) Quiescent Current in Standby: 1µA No Parasitic Body Diodes Built-In XOR Function Eliminates “Glue” Logic Break-Before-Make Switching Controlled Rise and Fall Times Available in 8-Pin and 16-Pin SO Packages The LTC®1470 switches the VCC pins of a Personal Computer Memory Card International Association (PCMCIA) card slot between three operating states: OFF, 3.3V and 5V. Two low RDS(ON) N-channel power MOSFETs are driven by a built-in charge pump which generates a voltage higher than the supply voltage to fully enhance each switch when selected by the input control logic. The LTC1470 inputs are compatible with industry standard PCMCIA controllers. A built-in XOR ensures that both switches are never on at the same time. This function also makes the LTC1470 compatible with both active-low and active-high controllers (see Applications Information section). The switch rise times are controlled to eliminate power supply glitching. The LTC1470 features built-in SafeSlotTM current limit and thermal shutdown. The output is limited to 1A during short circuit to ground but 2A of peak operating current is allowed. The LTC1471 is a dual version of the LTC1470 and is available in a 16-pin SO package. , LTC and LT are registered trademarks of Linear Technology Corporation. SafeSlot is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. APPLICATIO S ■ ■ ■ ■ ■ ■ Set Top Box/Open Cable Notebook Computers Palmtop Computers Pen-Based Computers Handi-Terminals 3.3V/5V Power Supply Switch TYPICAL APPLICATIO 5V 0.1µF 5VIN 3VIN AOUT LTC1471 AEN1 PCMCIA CARD SLOT CONTROLLER AEN0 BEN1 Dual Slot PCMCIA 3.3V/5V VCC Switch 3.3V 0.1µF VCC (Hi-Z/3.3V/5V) VCC 10k VCC (Hi-Z/3.3V/5V) BOUT VCC 10k 1470/71 TA01 Linear Technology PCMCIA Product Family DEVICE LT ®1312 PCMCIA CARD SLOT DESCRIPTION Single PCMCIA VPP Driver/Regulator Dual PCMCIA VPP Driver/Regulator Single PCMCIA Switch Matrix Dual PCMCIA Switch Matrix Single Protected VCC 3.3V/5V Switch Matrix Dual Protected VCC 3.3V/5V Switch Matrix Protected VCC and VPP Switch Matrix LT1313 LTC1314 LTC1315 LTC1470 + 1µ F PCMCIA CARD SLOT LTC1471 LTC1472 BEN0 GND + 1µ F *Narrow Body U PACKAGE 8-Pin SO 16-Pin SO* 14-Pin SO 24-Pin SSOP 8-Pin SO 16-Pin SO* 16-Pin SO* 14701fa U U 1 LTC1470/LTC1471 ABSOLUTE MAXIMUM RATINGS 3.3V Supply Voltage (3VIN) (Note 2) ........................ 7V 5V Supply Voltage (5VIN) (Note 2) ............................ 7V Enable Input Voltage ..................... 5VIN to (GND – 0.3V) Output Voltage (OFF) (Note 2) ......... 7V to (GND – 0.3V) Output Short-Circuit Duration .......................... Indefinite PACKAGE/ORDER INFORMATION ORDER PART NUMBER TOP VIEW OUT 1 5VIN 2 EN1 3 EN0 4 8 7 6 5 OUT 3VIN 3VIN GND LTC1470CS8 LTC1470ES8 S8 PART MARKING 1470 1470E S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 100°C, θJA = 150°C/W Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS SYMBOL 3VIN 5VIN I3VIN PARAMETER 3.3V Supply Voltage Range 5V Supply Voltage Range 3.3V Supply Current The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. 3VIN = 3.3V, 5VIN = 5V (Note 3), unless otherwise noted. CONDITIONS MIN 2.70 4.75 Program to Hi-Z (Note 4) Program to 3.3V, No Load (Note 4) Program to 5V, No Load (Note 4) Program to Hi-Z (Note 4) Program to 3.3V (Note 4) Program to 5V (Note 4) Program to 3.3V, IOUT = 500mA Program to 5V, IOUT = 500mA Program to Hi-Z, 0V ≤ VOUT ≤ 5V (Note 4) Program to 3.3V, VOUT = 0V (Note 5) Program to 5V, VOUT = 0V (Note 5) ● ● ● ● ● ● ● ● ● I5VIN 5V Supply Current RON ILKG ILIM3V ILIM5V VENH VENL IEN 3.3V Switch ON Resistance 5V Switch ON Resistance Output Leakage Current OFF 3.3V Current Limit 5V Current Limit Enable Input High Voltage Enable Input Low Voltage Enable Input Current 0V ≤ VEN ≤ 5V 2 U U W WW U W (Note 1) Operating Temperature LTC1470C .............................................. 0°C to 70°C LTC1470E (Note 7) ............................. –40°C to 85°C Junction Temperature .......................................... 100°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................. 300°C TOP VIEW AOUT 1 A5VIN 2 AEN1 3 AEN0 4 GND 5 B3VIN 6 B3VIN 7 BOUT 8 16 AOUT 15 A3VIN 14 A3VIN 13 GND 12 BEN0 11 BEN1 10 B5VIN 9 BOUT ORDER PART NUMBER LTC1471CS S PACKAGE 16-LEAD PLASTIC SO TJMAX = 100°C, θJA = 100°C/W TYP MAX 3.60 5.25 UNITS V V µA µA µA µA µA µA Ω Ω µA A A V 0.01 40 0.01 0.01 100 140 0.12 0.14 1 1 2.0 10 80 10 10 160 200 0.16 0.18 ± 10 0.8 ±1 V µA 14701fa LTC1470/LTC1471 ELECTRICAL CHARACTERISTICS SYMBOL t0 to t3 t3 to t5 t0 to t5 PARAMETER Delay and Rise Time (Note 6) Delay and Rise Time (Note 6) Delay and Rise Time (Note 6) 3VIN = 3.3V, 5VIN = 5V (Note 3), TA = 25°C, unless otherwise noted. MIN 0.2 0.2 0.2 TYP 0.32 0.52 0.38 MAX 1.0 1.0 1.0 UNITS ms ms ms CONDITIONS Transition from 0V to 3.3V, ROUT = 100Ω, COUT = 1µF Transition from 3.3V to 5V, ROUT = 100Ω, COUT = 1µF Transition from 0V to 5V, ROUT = 100Ω, COUT = 1µF Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: For the LTC1470, the two output pins (1, 8) must be connected together and the two 3.3V supply input pins (6 , 7) must be connected together. For the LTC1471, the two AOUT pins (1, 16) must be connected together, the two BOUT pins (8, 9) must be connected together, the two A3VIN supply input pins (14, 15) must be connected together, the two B3VIN supply pins (6, 7) must be connected together and the two GND pins (5, 13) must be connected together. Note 3: Power for the input logic and charge pump circuitry is derived from the 5VIN supply pin(s) which must be continuously powered. Note 4: Measured current is per channel with the other channel programmed off for the LTC1471. Note 5: The output is protected with foldback current limit which reduces the short-circuit (0V) currents below peak permissible current levels at higher output voltages. Note 6: To 90% of final value. Note 7: The LTC1470 is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. TYPICAL PERFORMANCE CHARACTERISTICS 3VIN Supply Current (OFF) 5 4 3 2 1 0 –1 0 TA = 25°C PROGRAMMED TO OFF 3VIN SUPPLY CURRENT (µA) 3VIN SUPPLY CURRENT (µA) 80 60 40 20 0 5VIN SUPPLY CURRENT (µA) 3 1 2 3VIN SUPPLY VOLTAGE (V) 5VIN Supply Current (3.3V ON) 300 250 200 150 100 50 0 TA = 25°C PROGRAMMED TO 3.3V, NO LOAD 3.3V SWITCH RESISTANCE (Ω) 5VIN SUPPLY CURRENT (µA) 5VIN SUPPLY CURRENT (µA) 0 1 5 2 3 4 5VIN SUPPLY VOLTAGE (V) UW 4 1470/71 G04 (LTC1470 or 1/2 LTC1471) 5VIN Supply Current (OFF) 5 4 3 2 1 0 –1 TA = 25°C PROGRAMMED TO OFF 3VIN Supply Current (3.3V ON) 120 100 TA = 25°C PROGRAMMED TO 3.3V, NO LOAD 0 3 1 2 3VIN SUPPLY VOLTAGE (V) 4 1470/71 G05 0 1 5 2 3 4 5VIN SUPPLY VOLTAGE (V) 6 1470/71 G01 5VIN Supply Current (5V ON) 300 250 200 150 100 50 0 TA = 25°C PROGRAMMED TO 5V, NO LOAD 0.30 0.25 0.20 0.15 0.10 0.05 0 3.3V Switch Resistance PROGRAMMED TO 3.3V 6 0 1 5 2 3 4 5VIN SUPPLY VOLTAGE (V) 6 0 25 50 75 100 JUNCTION TEMPERATURE (°C) 125 1470/71 G07 1470/71 G03 1470/71 G02 14701fa 3 LTC1470/LTC1471 TYPICAL PERFORMANCE CHARACTERISTICS 5V Switch Resistance OUTPUT VOLTAGE (V) INRUSH CURRENT (A) 0.30 0.25 0.20 0.15 0.10 0.05 0 0 25 50 75 100 JUNCTION TEMPERATURE (°C) 125 1470/71 G06 PROGRAMMED TO 5V 2 1 0 TJ = 25°C OUTPUT VOLTAGE (V) INRUSH CURRENT (A) 5V SWITCH RESISTANCE (Ω) PIN FUNCTIONS LTC1470 OUT (Pins 1, 8): Output Pins. The outputs of the LTC1470 are switched between three operating states: OFF, 3.3V and 5V. These pins are protected against accidental short circuits to ground by SafeSlot current limit circuitry which protects the socket, the card, and the system power supplies against damage. A second level of protection is provided by thermal shutdown circuitry which protects both switches against over-temperature conditions. 5VIN (Pin 2): 5V Input Supply Pin. The 5VIN supply pin serves two purposes. The first purpose is as the power supply input for the 5V NMOS switch. The second purpose is to provide power for the input, gate drive, and protection circuitry for both the 3.3V and 5V VCC switches. This pin must therefore be continuously powered. EN1, EN0 (Pins 3, 4): Enable Inputs. The two VCC Enable inputs are designed to interface directly with industry standard PCMCIA controllers and are high impedance CMOS gates with ESD protection diodes to ground, and should not be forced above 5VIN or below ground. Both inputs have about 100mV of built-in hysteresis to ensure clean switching between operating modes. The LTC1470 is designed to operate without 12V power. The gates of the VCC NMOS switches are powered by charge pumps from the 5VIN supply pins (see Applications Information section for more detail). The Enable inputs should be turned off (both asserted high or both asserted low) at least 100µs before the 5VIN power is removed to ensure that both VCC NMOS switch gates are fully discharged and both switches are in the high impedance mode. GND (Pin 5): Ground Connection. 3VIN (Pins 6, 7): 3V Input Supply Pins. The 3VIN supply pins serve as the power supply input for the 3.3V switches. These pins do not provide any power to the internal control circuitry and therefore do not consume any power when unloaded or turned off. 4 UW (LTC1470 or 1/2 LTC1471) Inrush Current (5V Switch) 3 2 1 0 COUT = 150µF ROUT = 10Ω 6 4 2 0 – 0.2 0 0.2 0.4 0.6 0.8 TIME (ms) 1.0 1.2 1.4 1470/71 G08 Inrush Current (3.3V Switch) 3 COUT = 150µF ROUT = 6.6Ω CURRENT LIMITED TJ = 25°C COUT = 15µF ROUT = 6.6Ω 6 4 2 0 – 0.2 0 0.2 COUT = 150µF ROUT = 6.6Ω 0.4 0.6 0.8 TIME (ms) 1.0 1.2 1.4 COUT = 15µF ROUT = 10Ω 1470/71 G09 U U U 14701fa LTC1470/LTC1471 PIN FUNCTIONS LTC1471 AOUT, BOUT(Pins 1, 16, 8, 9): Output Pins. The outputs of the LTC1471 are switched between three operating states: OFF, 3.3V and 5V. These pins are protected against accidental short circuits to ground by SafeSlot current limit circuitry which protects the socket, the card, and the system power supplies against damage. A second level of protection is provided by thermal shutdown circuitry. 5VIN (Pins 2, 10): 5V Input Supply Pins. The 5VIN supply pins serve two purposes. The first purpose is as the power supply input for the 5V NMOS switches. The second purpose is to provide power for the input, gate drive, and protection circuitry. These pins must therefore be continuously powered. EN1, EN0 (Pins 3, 4, 11, 12): Enable Inputs. The enable inputs are designed to interface directly with industry standard PCMCIA controllers and are high impedance CMOS gates with ESD protection diodes to ground, and should not be forced above 5VIN or below ground. All four inputs have about 100mV of built-in hysteresis to ensure clean switching between operating modes. The LTC1471 is designed to operate without 12V power. The gates of the VCC NMOS switches are powered by charge pumps from the 5VIN supply pins (see Applications Information section for more detail). The enable inputs should be turned off at least 100µs before the 5VIN power is removed to ensure that all NMOS switch gates are fully discharged and are in the high impedance mode. GND (Pins 5, 13): Ground Connections. 3VIN (Pins 6, 7, 14, 15): 3V Input Supply Pins. The 3VIN supply pins serve as the power supply input for the 3.3V switches. These pins do not not provide any power to the internal control circuitry, and therefore, do not consume any power when unloaded or turned off. BLOCK DIAGRAM EN0 TTL-TO-CMOS CONVERTER EN1 TTL-TO-CMOS CONVERTER W U U U (LTC1470 or 1/2 LTC1471) 5VIN GATE CHARGE AND DISCHARGE CONTROL LOGIC 0.14Ω BREAK-BEFOREMAKE SWITCH AND CONTROL OSCILLATOR AND BIAS CHARGE PUMP CURRENT LIMIT AND THERMAL SHUTDOWN OUTPUT GATE CHARGE AND DISCHARGE CONTROL LOGIC 0.12Ω 3VIN LTC1470-BD01 14701fa 5 LTC1470/LTC1471 OPERATION The LTC1470 (or 1/2 of the LTC1471) consists of the following functional blocks: Input TTL/CMOS Converters The enable inputs are designed to accommodate a wide range of 3V and 5V logic families. The input threshold voltage is approximately 1.4V with approximately 100mV of hysteresis. The inputs enable the bias generator, the gate charge pumps and the protection circuity which are powered from the 5V supply. Therefore, when the inputs are turned off, the entire circuit is powered down and the 5V supply current drops below 1µA. XOR Input Circuitry By employing an XOR function, which locks out the 3.3V switch when the 5V switch is turned on and locks out the 5V switch when the 3.3V switch is turned on, there is no danger of both switches being on at the same time. This XOR function also makes it possible to work with either active -low or active-high PCMCIA VCC switch control logic (see Applications Information section for further details). Break-Before-Make Switch Control Built-in delays are provided to ensure that the 3.3V and 5V switches are non-overlapping. Further, the gate charge pump includes circuitry which ramps the NMOS switches on slowly (400µs typical rise time) but turns them off much more quickly (typically 10µs). Bias, Oscillator and Gate Charge Pump When either the 3.3V or 5V switch is enabled, a bias current generator and high frequency oscillator are turned on. The on-chip capacitive charge pump generates approximately 12V of gate drive for the internal low RDS(ON) NMOS VCC switches from the 5VIN power supply. Therefore, an external 12V supply is not required to switch the VCC output. The 5VIN supply current drops below 1µA when both switches are turned off. Gate Charge and Discharge Control All switches are designed to ramp on slowly (400µs typical rise time). Turn-off time is much quicker (typically 10µs). To ensure that both VCC NMOS switch gates are fully discharged, program the switch to the high impedance mode at least 100µs before turning off the 5V power supply. Switch Protection Both switches are protected against accidental short circuits with SafeSlot foldback current limit circuits which limit the output current to typically 1A when the output is shorted to ground. Both switches also have thermal shutdown which limits the power dissipation to safe levels. APPLICATIONS INFORMATION The LTC1470/LTC1471 are designed to interface directly with industry standard PCMCIA card controllers. Interfacing with the CL-PD6710 Figure 1 is a schematic diagram showing the LTC1470 interfaced with a standard PCMCIA slot controller. The LTC1470 accepts logic control directly from the CL-PD6710. The XOR input function allows the LTC1470 to interface directly to the active-low VCC control outputs of the CLPD6710 for 3.3V/5V voltage selection (see the following Switch Truth Table). Therefore, no “glue” logic is required to interface to this PCMCIA compatible card controller. 3.3V 0.1µF 3VIN 5V 0.1µF CL-PD6710 VCC _3 VCC _5 LTC1470 EN0 EN1 GND OUT OUT (OFF/3.3V/5V) 5VIN 3VIN 6 U W U U U + 1µF TANT TO CARD VCC PINS 10k 1470/71 F01 Figure 1. Direct Interface to CL-PD6710 PCMCIA Controller 14701fa LTC1470/LTC1471 APPLICATIONS INFORMATION Truth Table for CL-PD6710 Controller A_VCC _3 EN0 0 0 1 1 A_VCC _5 EN1 0 1 0 1 OUT Hi-Z 3.3V 5V Hi-Z Interfacing with “365” Type Controllers The LTC1470 also interfaces directly with “365” type controllers as shown in Figure 2. Note that the VCC Enable inputs are connected differently than to the CL-PD6710 controller because the “365” type controllers use activehigh logic control of the VCC switches (see the following Switch Truth Table). No “glue” logic is required to interface to this type of PCMCIA compatible controller. 3.3V 0.1µF 3VIN 5V 0.1µF “365” TYPE CONTROLLER A_VCC _EN0 A_VCC _EN1 LTC1470 EN0 EN1 GND OUT OUT (OFF/3.3V/5V) 5VIN 3VIN + 1µF TANT 10k 1470/71 F02 Figure 2. Direct Interface with “365” Type PCMCIA Controller Truth Table for “365” Type Controller A_VCC _EN0 EN0 0 0 1 1 A_VCC _EN1 EN1 0 1 0 1 OUT Hi-Z 3.3V 5V Hi-Z U W U U Supply Bypassing For best results bypass the supply input pins with 1µF capacitors as close as possible to the LTC1470. Sometimes much larger capacitors are already available at the outputs of the 3.3V and 5V power supply. In this case it is still good practice to use 0.1µF capacitors as close as possible to the device, especially if the power supply output capacitors are more than 2" away on the printed circuit board. Output Capacitors and Pull-Down Resistor The output pin is designed to ramp on slowly, typically 400µs rise time. Therefore, capacitors as large as 150µF can be driven without producing voltage spikes on the 3VIN or 5VIN supply pins (see graphs in Typical Performance Characteristics section). The output pin should have a 0.1µF to 1µF capacitor for noise reduction and smoothing. A 10k pull-down resistor is recommended at the output to ensure that the output capacitor is fully discharged when the output is switched OFF. This resistor also ensures that the output is discharged between the 3.3V and 5V transition. Supply Sequencing TO CARD VCC PINS Because the 5V supply is the source of power for both of the switch control circuits, it is best to sequence the power supplies such that the 5V supply is powered before, or simultaneous to, the application of 3.3V. It is interesting to note, however, that the switches are NMOS transistors which require charge pumps to generate gate voltages higher than the supply rails for full enhancement. Because the gate voltages start at 0V when the supplies are first activated, the switches always start in the off state and do not produce glitches at the outputs when powered. If the 5V supply must be turned off, it is important to program all switches to the Hi-Z or 0V state at least 100µs before the 5V power is removed to ensure that the NMOS switch gates are fully discharged to 0V. Whenever possible, however, it is best to leave the 5VIN pin(s) continuously powered. The LTC1470/LTC1471 quiescent current drops to