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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger General Description
The AAT4620 SmartSwitch is a current limited Pchannel MOSFET power switch designed for highside load-switching applications in PCMCIA GSM/GPRS/3G modem cards. Used in conjunction with a super capacitor, the AAT4620 will ensure that the power ratings of the PCMCIA host are not exceeded at any time. Featuring two independent, programmable current limits and a power loop, the AAT4620 can ensure that the super capacitor can be charged without exceeding PCMCIA specifications. The current limit is set by two external resistors allowing a 10% current limit accuracy over the normal operating temperature range. The switch can be controlled from either of the two enable inputs and in the off condition will block currents in both directions. The AAT4620 also incorporates a System READY function which can advise the system that the super capacitor is fully charged and ready for use. Adjustable hysteresis is provided with the addition of an external resistor. The quiescent supply current is typically a low 40A. In shutdown mode, the supply current decreases to less than 1A. The AAT4620 is available in a thermally enhanced, Pb-free, 12-pin TSOPJW package and is specified over the -40C to 85C temperature range.
Features
* *
SmartSwitchTM
* * *
* * * * * *
VIN Range: 3.0V to 5.5V Dual Independent Current Limits -- 100mA to 1200mA -- 10% Current Accuracy -- 20C Temperature Band Reverse Current Blocking Protection Power Loop Low Quiescent Current -- 40A Typical -- 1.0A Max with Switch Off 65m Typical RDS(ON) at 3V Only 1.4V Needed for Enable Control Pin System READY Output with Externally Programmable Hysteresis Under-Voltage Lockout Temperature Range: -40 to 85C 12-Pin TSOPJW Package
Applications
* * * * * CF Card Port Power Protection Express Card GSM/GPRS/3G Modems Hot Swap Supplies PCMCIA Card GSM/GPRS/3G Modems Personal Communication Devices
Typical Application
Reverse Blocking 100k OUT Over-Temp Protection UnderVoltage Lockout EN IL ENSUPERCAP EN OPERATION EN IU 1.2V Reference Current Limit Control ISETL To Load
VCC V CC
Power Loop
RDY
To C
ISETU GND SuperCap R HYS R SETU R SETL
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger Pin Descriptions
Pin #
1
Symbol
EN IU
Function
Enable input. Active low enable with internal pull up. Also switches in the higher current limit to allow the System to start functioning. Can be directly connected to System Ready for automatic enabling. When both EN IL and EN IU are enabled, ISETU will be selected. Enable input. Active low enable with internal pull up. Also switches in the lower current limit initiating the super capacitor to start charging. Device ground connection. Input pins to the P-channel MOSFET source. Connect 1F capacitor from VCC to GND. P-channel MOSFET drain connection. Connect to super capacitor from OUT to GND. Lower current-limit set input. A resistor from ISETL to ground sets the maximum lower current limit for the switch. Current limit can be set between 100mA and 1200mA. Upper current limit set input. A resistor from ISETU to ground sets the maximum upper current limit for the switch. Current limits can be set between 100mA and 1200mA. Connect to ground to disable current limit. System READY hysteresis. Connect a resistor to ground to set the System Ready comparator hysteresis. System ready pin. Open drain, active low, initiated when the capacitor is 98% charged.
2 3 4, 5, 6 7, 8 9 10
EN IL GND VCC OUT ISETL ISETU
11 12
RHYS RDY
Pin Configuration
TSOPJW-12 (Top View)
EN IU EN IL GND VCC VCC VCC
1 2 3 4 5 6
12 11 10 9 8 7
RDY RHYS ISETU ISETL OUT OUT
2
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger Absolute Maximum Ratings1
Symbol
VCC VEN VSET, VOUT IMAX
Description
VCC to GND EN to GND SET, OUT to GND Maximum Continuous Switch Current
Value
-0.3 to 6 -0.3 to VCC + 0.3 -0.3 to VCC + 0.3 2.5
Units
V V V A
Thermal Characteristics
Symbol
JA PD TJ
Description
Maximum Thermal Resistance Maximum Power Dissipation2 Operating Junction Temperature Range
2
Value
160 625 -40 to 150
Units
C/W mW C
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. 2. Mounted on an FR4 board. 4620.2007.04.1.1
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger Electrical Characteristics1
VCC = 3.0V to 5.5V, TA = -40C to 85C unless otherwise noted. Typical values are at TA = 25C. Symbol
VCC IQ IQU0 IQ(OFF) ISD(OFF) VUVLO RDS(ON) ILIMLACC ILIMUACC ILIM(MIN) VEN(L) VEN(H) IEN(SINK) TDEL(OFF) VRDY VRDYHYS VRDY(L) IRDY OTMP
Description
Operation Voltage Quiescent Current Quiescent Current U0 Off Supply Current Off Switch Current Under-Voltage Lockout On-Resistance Lower Current Limit Accuracy Upper Current Limit Accuracy Lower Minimum Current Limit EN Input Low Voltage EN Input High Voltage EN Input Leakage Turn-Off Delay Time System READY Trip Threshold System READY Hysteresis System READY Voltage Low RDY Leakage Current Shutdown Temperature
Conditions
EN IL or EN IU = VCC, IOUT = 0, RHYS = 200k EN IL = VCC, EN IU = GND, IOUT = 0, ISET = GND, RHYS = 200k EN IL = EN IU = VCC EN IL = EN IU = VCC, VSUPERCAP = 0 Rising edge, 1% hysteresis VCC =4.75V, RSETL = RSETU = 0k VCC =3.0V, RSETL = RSETU = 0k RSETL = 249k; TA 20C RSETL = 249k RSETU = 1.24M; TA 20C RSETU = 1.24M VCC =3.0V to 5.5V2 VCC = 3.0V to 5.5V2 VEN = 5.5V VCC = 5V VOUT rising, TA = 25C RHYS = 200k ISINK = 1mA VRDY < 5.5V, VOUT < 98% of VOUT
Min
3.0
Typ
Max
5.5
Units
V A A A A V m mA mA mA V V A s % of VOUT mV V A C
40 40 0.4 0.4 2.7 50 65 200 200 1000 1000 75
75 75 1.0 10 3.0 100 120 220 230 1100 1150 0.4
180 170 900 850
1.4 0.4 98 200 0.4 1.0 145 1.0 1.0
1. The AAT4620 is guaranteed to meet performance specification over the -40C to 85C operating temperature range and is assured by design, characterization and correlation with statistical process controls. 2. For VIN outside this range consult the Typical EN Threshold curve.
4
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger Typical Characteristics
Output Current vs. Output Voltage
(RSETU = 383k, 25C)
0.40
RSET vs. ILIM
(25C)
1.40
Output Current (A)
VIN = 3.3V
0.30
1.20 1.00
ILIM (A)
VIN = 3.3V
0.20
0.80 0.60 0.40 0.20
0.10
VIN = 5V
VIN = 5V
0.00 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3 3.3
0.00
0
200
400
600
800
1000
1200
1400
1600
Output Voltage (V)
RSET (k)
Reverse Off-Switch Current vs. Temperature
(ENUB = ENLB = VCC; VIN = 0V)
100 100
Off-Switch Current vs. Temperature
(ENUB = ENLB = VCC; VOUT = 0V)
IRSD(OFF) (A)
10
ISD(OFF) (A)
VOUT = 5V
10
VIN = 5V
1
1
0.1
VOUT = 3.3V
0.1
VIN = 3.3V
0.01 -40 -20 0 20 40 60 80 100 120
0.01 -40
-20
0
20
40
60
80
100
120
Temperature (C)
Temperature (C)
Off-Supply Current vs. Temperature
(ENUB = ENLB = VCC; VOUT = Open)
10
VIN = 5V
IQ(OFF) (A)
1
0.1
VIN = 3.3V
0.01 -40
-20
0
20
40
60
80
100
120
Temperature (C)
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger Typical Characteristics
RDS(ON) vs. Input Voltage
(RSET = 0k)
70 65 90 80
RDS(ON) vs. Temperature
(RSET = 0)
RDS(ON) (m)
RDS(ON) (m)
60 55 50 45 2.5
70 60 50 40 30 -40
VIN = 3V
VIN = 5V
-20 0 20 40 60 80 100
3
3.5
4
4.5
5
5.5
Input Voltage (V)
Temperature (C)
VRHYS vs. RRHYS
2.00 1.80 1.60 1.40 1.20 1.00 0.80 0.60 0.40 0.20 0.00 0 500 1000 1500
(VIN = 4V; VOUT = 3.85V; ENLB = 0V; RSET = 249k)
210
ILIM vs. Temperature
205
VRHYS (V)
ILIM (mA)
200
195
190 -50
-25
0
25
50
75
100
RRHYS (k)
Temperature (C)
(VIN = 4V; VOUT = 3.85V; ENUB = 0V; RSET = 1.24M)
1020
ILIM vs. Temperature
Quiescent Current IQU vs. Temperature
(ENUB = 0V; ENLB = VCC; or ENLB = 0V; ENUB = VCC;VOUT = Open)
55 50
VIN = 5V
ILIM (mA)
IQU (A)
1000
45 40 35 30
980
VIN = 3.3V
-20 0 20 40 60 80 100 120
960 -50
-25
0
25
50
75
100
25 -40
Temperature (C)
Temperature (C)
6
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger Typical Characteristics
VIL vs. Input Voltage
(ENUB = Open; Vary ENLB; 25C)
1.1 1.0 1.1 1.0
VIH vs. Input Voltage
(ENLB = Open; Vary ENUB; 25C)
VIH (V)
3.5 4.5 5.5 6.5 7.5
VIL (V)
0.9 0.8 0.7 0.6 2.5
0.9 0.8 0.7 0.6 2.50
3.50
4.50
5.50
6.50
7.50
Input Voltage (V)
Input Voltage (V)
VIL vs. Input Voltage
(ENLB = Open; Vary ENUB; 25C)
1.1 1.0 1.1 1.0
VIH vs. Input Voltage
(ENLB = Open; Vary ENUB; 25C)
VIH (V)
VIL (V)
0.9 0.8 0.7 0.6 2.5
0.9 0.8 0.7 0.6 2.50
3.5
4.5
5.5
6.5
7.5
3.50
4.50
5.50
6.50
7.50
Input Voltage (V)
Input Voltage (V)
Soft Short Circuit with 5 Series Impedance
(VIN = 5V)
Input Voltage (top) (V) Output Voltage (middle) (V)
6 4 2 0 0.4 0.2 0.0 -0.2
Hard Short Circuit
(VIN = 3.3V)
Input Voltage (top) (V) Output Voltage (middle) (V)
6 4 2 0 0.4 0.2 0.0 -0.2
Output Current (A)
Output Current (A)
Time (200ms/div)
Time (200ms/div)
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger Typical Characteristics
Short Circuit with 5 Series Impedance
(VIN = 3.3V)
Hard Short Circuit
(VIN = 5V)
Input Voltage (middle) (V) Output Voltage (bottom) (V)
0.8 0.6 0.4 0.2 0.0 4 2 0
Input Voltage (top) (V) Output Voltage (middle) (V)
1.0
6 4 2 0 0.4 0.2 0.0 -0.2
Output Current (A)
Output Current (A)
Time (200ms/div)
Time (200ms/div)
Charging Profile
(ILIMIT = 150mA; VIN = 5V; CO = 0.55F)
6 4 2 0 0.30 0.15 0.00 -0.15
Charging Profile
(ILIMIT = 150mA; VIN = 5V; CO = 0.55F)
Output Current (A)
Output Current (A)
Output Voltage (V)
Output Voltage (V)
2 0 0.15 0.10 0.05 0.00 -0.05
Time (5s/div)
Time (20ms/div)
Charging Profile
(ILIMIT = 1A; VIN = 5V; CO = 0.55F)
6 4 2 0 1.0 0.8 0.6 0.4 0.2 0.0 -0.2 6 4 2 0
Charging Profile
(VIN = 5V, VISETL = VISETU = 0V, CO = 0.55F)
Output Current (A)
Output Current (A)
Output Voltage (V)
Output Voltage (V)
1.5 1.0 0.5 0.0 -0.5
Time (2s/div)
Time (2s/div)
8
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger Functional Block Diagram
Reverse Blocking
VCC
OUT
Over-Temp Protection UnderVoltage Lockout
Power Loop
RDY
EN IL EN IU
1.2V Reference
Current Limit Control
ISETL ISETU
GND
RHYS
Functional Description
The AAT4620 is an integrated P-channel MOSFET load switch with an upper and lower adjustable current limits which can be enabled independently, over temperature protection, a power loop and a super capacitor charger. The current limit control is combined with an over temperature thermal limit and power loop circuit to provide a comprehensive system to protect the load switch and its supply from load conditions which exceed the supply specifications. The AAT4620 has been designed specifically to provide the interface between a PCMCIA
host and PCMCIA card where a super capacitor has been used to "average out" high pulse currents which would otherwise exceed the PCMCIA/ Express Card power specifications. e.g. GSM/ GPRS modem cards, where pulse currents during transmit signals can exceed the 1A maximum specification (1.3A in the case of Express Card). The current limit and over temperature circuits act independently. The device current limit is activated when the output load current exceeds an internal threshold level. There are two internal current limits which are enabled independently. The current limit threshold in each case is determined by exter-
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger
nal resistors connected between the two SET pins and ground. The minimum current limit threshold is specified by ILIM(MIN). If the load condition maintains the device in current limit and the chip temperature reaches a critical point, then an internal power loop will reduce the current to a safe level. Connecting ISETU to ground disables the current limit protection allowing a low impedance path to the host VCC. The load switch is turned off by applying a logic high level to both of the EN pins. When both EN IL and EN IU are selected ISETU will be selected. The EN function has logic level thresholds that allow the AAT4620 to be TTL compatible and may also be controlled by 2.5V to 5.0V CMOS circuits. The voltage level applied to the EN pins should not exceed the input supply level present on the VCC pin. The AAT4620 typically consumes 40A when operating, when off, the device draws less then 1A. In the off state, current is prevented from flowing between the input and output. Under-voltage lockout circuitry ensures that the VCC supply is high enough for correct operation of the IC. Also included is a System Ready function which will be activated when the capacitor voltage is charged and the load is permitted to take current. For automatic functionality, this pin can be directly connected to the EN IU pin. An external resistor is provided to add hysteresis to this function.
Application Information
ISETU and ISETL Current Limit Set
The AAT4620 current limit is set at two different levels. Resistors from ISETL and ISETU set the lower and upper current limit levels respectively. The ISETL and ISETU nodes operate within a window of 0.75V to 1.5V for resistor values ranging from 93.75 to 1.5M. Resistor values outside this range are not recommended. The ISETL and ISETU source current varies with the resistor value used according to Table 1. To determine the resulting current limit multiply the RSETU or RSETL node voltage times the gain in Table 1. Note that the voltage at the node varies from 0.75V to 1.5V and the current limit gain varies depending on the resistor value used.
VISET = RSET * IISET = 0.75V to 1.5V
If the set pin is open circuit or allowed to exceed 2V, all power devices are disabled and the input is disconnected from the output. Shorting the set pin to GND enables all power devices and shorts the VCC to the output pin with no current limit. To activate the upper current level (RSETU) pull EN IU low. To activate the lower current level (RSETL) pull EN IL low. If both EN IU and EN IL are pulled low the EN IU current limit level (RSETU) will be selected.
RSET Range
1.5Meg - 750k 750k - 375k 375k - 187.5k 187.5 - 93.75k
IISET (A)
1 2 4 8
ILIM/VISET (A/V)
0.8 0.4 0.2 0.1
Current Limit Range (A)
1.2-0.6 0.6-0.3 0.3-0.15 0.15-0.075
Current Limit
RSET*1A*0.8 RSET*2A*0.4 RSET*4A*0.2 RSET*8A*0.1
Table 1: RSET Table.
10
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger
ILOAD vs. RSETU and RSETL
1.2 1.0
ILOAD Limit (A)
0.8 0.6 0.4 0.2 0.0 0.10
die temperature exceeds 100C it decreases the load current by 1/32 of the current limit set point. If die temperature is less than 100C, it increases the load current in increments of 1/32 of the current limit set point until the set current limit point is reached or the die temperature exceeds 100C. The delay time between die temperature measurements varies depending on the load current limit set point. The delay ranges from 1ms for a 75mA current limit set point to 8ms for a 1.5A current limit set point. For the condition where there is no current limit set point (shorting RSETU or RSETL to ground) the soft start increments the current limit is 1/32 steps of 1.2A until the current reaches 1.2A, at which point the power MOSFET turns on fully. At this point, the current is limited by the RDS(ON) of the power MOSFET and other series resistance. The Power Loop and Over-Temperature Loop then takes control to limit the current until the output voltage has fully charged.
0.30
0.50
0.70
0.90
1.10
1.30
1.50
RSETU and RSETL (M)
Figure 1: Calculated Current Limit RSET Characteristic.
System Ready Hysteresis (RHYS) and System Ready (RDY)
In internal comparator senses the output voltage and delivers a ready signal to the external micro controller when the output voltage reaches 98% of the final value (VCC). The comparator hysteresis is programmed by a resistor from the RHYS pin to ground. The RHYS voltage determines the hysteresis voltage and is equal to the RHYS source current (1A) times the RHYS resistance.
VHYST = RHYS * 1A = 200k * 1A = 0.2V
Over-Temperature Protection
If the die temperature rate of rise is fast enough to exceed the power loop regulated temperature, over-temperature shutdown disables the device. The over-temperature threshold is 145C. After over-temperature shutdown, soft start is initiated once the die temperature drops to 130C.
Short Circuit Protection
The series pass power MOSFET turns off completely after the output has charged to within 18mV of the input voltage. This protects the device in the event of a short circuit applied to the output. Applying a short circuit or heavy load to the output initiates the digital soft start where the current ramps from zero to the final programmed value. The power loop will be activated once the digital soft start begins.
The system ready pin (RDY) is an open drain output that switches low when the output voltage reaches 98% of the input voltage. It requires an external pull up resistor tied to the input voltage with a typical value of 100k.
Power Loop
The AAT4620 power loop limits the load current in the event that the device power dissipation becomes excessive. The AAT4620 power loop regulates the die temperature to 100C, decreasing the load current in increments of 1/32 of the current limit set point when the die temperature reaches 100C. When the
Under-Voltage Shutdown
Under-voltage lockout enables the device at 2.7V typical with 100mV of hysteresis. The maximum UVLO level is 3.0V.
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger
Digitally Programmed Soft Start Current Limit
At turn on, the digital soft start increases the load current in discrete levels equal to 1/32 of the final programmed current limit set point from zero to the final programmed current limit level.
Reverse Current Blocking
An internal comparator disables the internal pass transistor when the input voltage is less than the output voltage blocking any reverse current from the output to the input.
Evaluation Board
The evaluation board schematic is shown in Figure 2. The PCB layout is shown in Figures 3 and 4.
J2
3 2 1
R1 4.7K
D1
ENIU
J1
3 2 1
1 2 3
ENIU ENIL GND VCC VCC VCC
RDY RHYS ISETU ISETL OUT OUT
12 11 10 9 8 7
RDY
ENIL
4 5
R3 1.00M
R2 200K
VCC GND J4
2 6 1
1 2
Out GND
AAT4620 C1 10F C2 10F
R4 120K
J3
Figure 2: AAT4620 Evaluation Board Schematic.
Figure 3: AAT4620 Evaluation Board PCB Top Side.
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger
Figure 4: AAT4620 Evaluation Board PCB Bottom Side.
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger Ordering Information
Package
TSOPJW-12
Marking1
UZXYY
Part Number (Tape and Reel)2
AAT4620ITP-T1
All AnalogicTech products are offered in Pb-free packaging. The term "Pb-free" means semiconductor products that are in compliance with current RoHS standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at http://www.analogictech.com/pbfree.
Package Information
TSOPJW-12
0.10 0.20 + 0.05 -
2.40 0.10
0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC
2.85 0.20
7 NOM 3.00 0.10
0.9625 0.0375 + 0.10 1.00 - 0.065
0.04 REF
0.15 0.05
0.055 0.045
4 4
0.010
0.45 0.15 2.75 0.25
All dimensions in millimeters.
1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD.
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AAT4620
PCMCIA Current Limit Interface and Capacitor Charger
(c) Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Except as provided in AnalogicTech's terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer's applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737-4600 Fax (408) 737-4611
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