AAT4621 - Skyworks Solutions, Inc.

DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
General Description
Features
The AAT4621 SmartSwitch family is a current limited
P-channel MOSFET power switch designed for high-side
load-switching applications in PC Card GSM/GPRS/3G
modem cards. Used in conjunction with a super capacitor, the AAT4621 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 AAT4621 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 AAT4621 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 40μA. In shutdown mode, the supply current decreases to less than
1μA. The AAT4621 has a current limit range from 75mA
to 1200mA; the AAT4621-1 has a current limit range
from 150mA to 2400mA.
• Operating Voltage Range: 3.0V to 5.5V
• Dual Independent Current Limits
▪ AAT4621: 75mA to 1200mA
▪ AAT4621-1: 150mA to 2400mA
▪ ±10% Current Accuracy
• Reverse Current Blocking Protection
• Power Loop
• Low Quiescent Current
▪ 40μA Typical
▪ 1.0μA Max with Switch Off
• 65m Typical RDS(ON) at 3V
• System READY Output with Externally Programmable
Hysteresis
• Only 1.4V Needed for Enable Control Pin
• Under-Voltage Lockout
• Over-Temperature Protection
• Temperature Range: -40 to 85°C
• 14-Pin TDFN33 Package
The AAT4621 is available in a thermally enhanced,
Pb-free 14-pin TDFN33 package and is specified over the
-40°C to 85°C temperature range.
Applications
•
•
•
•
•
Capacitor Charger
CF Card Port Power Protection
Express Card GSM/GPRS/3G Modems
PC Card GSM/GPRS Class 10/12 Modems
WiMAX Cards
Typical Application
100k
Reverse
Blocking
VCC
OUT
To Load
RDY
To μC
VCC
Over-Temp
Protection
Power
Loop
UnderVoltage
Lockout
EN IL
ENIL
ENIU
EN IU
1.2V
Reference
Current
Limit
Control
ISETL
ISETU
GND
SuperCap
R HYS
R SETU
R SETL
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201944A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 15, 2012
1
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Pin Descriptions
Pin #
Symbol
1
2
RDY
RHYS
3
ISETU
4
ISETL
5, 6, 7
8, 9, 10, 11
12
OUT
VCC
GND
13
EN IL
14
EN IU
EP
EP
Function
System ready pin. Open drain, active low, initiated when the capacitor is 98% charged.
System READY hysteresis. Connect a resistor to ground to set the System Ready comparator hysteresis.
Upper current limit set input. A resistor from ISETL to ground sets the maximum upper current limit for
the switch. The AAT4621 has a current limit range from 75mA to 1200mA; the AAT4621-1 has a current
limit range from 150mA to 2400mA. Connect to ground to disable current limit.
Lower current-limit set input. A resistor from ISETU to ground sets the maximum lower current limit for
the switch. The AAT4621 has a current limit range from 75mA to 1200mA; the AAT4621-1 has a current
limit range from 150mA to 2400mA. Connect to ground to disable current limit.
P-channel MOSFET drain connection. Connect to super capacitor from OUT to GND.
Input pins to the P-channel MOSFET source. Connect 1μF capacitor from VCC to GND.
Device ground connection.
Enable input. Active low enable with internal pull up. Also switches in the lower current limit initiating
the super capacitor to start charging.
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 B and EN IU B are enabled, ISETU will be selected.
The exposed thermal pad (EP) must be connected to the board ground plane and Pin 12. The ground
plane should include a large exposed copper pad under the package for thermal dissipation (see package outline).
Pin Configuration
TDFN33-14
(Top View)
RDY
RHYS
ISETU
ISETL
OUT
OUT
OUT
2
1
14
2
13
3
4
12
EP
11
5
10
6
9
7
8
ENIU
ENIL
GND
VCC
VCC
VCC
VCC
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201944A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 15, 2012
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Absolute Maximum Ratings1
Symbol
Description
VCC
VEN
VSET, VOUT
IMAX
TJ
TLEAD
TSTG
VCC to GND
ENIL, ENIU to GND
ISETL, ISETU, OUT to GND
Maximum Continuous Switch Current
Maximum Junction Operating Temperature Range
Maximum Soldering Temperature (at leads, 10 sec.)
Storage Temperature Range
Value
Units
-0.3 to 6.0
-0.3 to VCC + 0.3
-0.3 to VCC + 0.3
2.5
-40 to +150
300
-65 to 150
V
V
V
A
°C
°C
°C
Value
Units
50
2
°C/W
W
Thermal Characteristics
Symbol
JA
PD
Description
Maximum Thermal Resistance2
Maximum Power Dissipation2
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.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201944A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 15, 2012
3
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Electrical Characteristics1
VCC = 3.0V to 5.5V, TA = -40°C to 85°C unless otherwise noted. Typical values are at TA = 25°C.
Symbol
AAT4621
VCC
IQ
IQU0
Description
Operation Voltage
Quiescent Current
Quiescent Current U0
IQ(OFF)
ISD(OFF)
VUVLO
Off Supply Current
Off Switch Current
Under-Voltage Lockout
RDS(ON)
On-Resistance
ILIMACC
Lower Current Limit Accuracy
ILIMACC
Upper Current Limit Accuracy
ILIM(MIN)
VEN(L)
VEN(H)
IEN(SINK)
TDEL(OFF)
VRDY
VRDYHYS
VRDY(L)
IRDY
OTMP
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
Min
Typ
Max
Units
40
5.5
75
V
μA
40
75
μA
0.4
0.4
2.7
50
65
200
200
1000
1000
75
1.0
10
3.0
100
120
220
230
1100
1150
μA
μA
V
3.0
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 = 249KΩ; ΔTA ≤ 25°C
RSETL = 249KΩ
RSETU = 1.24MΩ; ΔTA ≤ 25°C
RSETU = 1.24MΩ
VCC = 3.0V to 5.5V2
VCC = 3.0V to 5.5V2
VEN = 5.5V
VCC = 5V
VOUT rising, TA = 25°C
RHYS = 200k
ISINK = 1mA
VRDY < 5.5V, VOUT < 98% of VOUT
180
170
900
850
0.4
1.4
0.4
98
200
1.0
1.0
0.4
1.0
145
m
mA
mA
mA
V
V
μA
μs
% of VOUT
mV
V
μA
°C
1. The AAT4621 is guaranteed to meet performance specification over the -40°C to 85°C operating temperature range and is assured by design, characterization and correlation
with statistical process controls.
2. For VCC outside this range consult the Typical EN Threshold curve.
4
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201944A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 15, 2012
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Electrical Characteristics1
VCC = 3.0V to 5.5V, TA = -40°C to 85°C unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Description
AAT4621-1
VCC
Operation Voltage
IQ
Quiescent Current
IQ(OFF)
Off Supply Current
ISD(OFF)
Off Switch Current
Under-Voltage Lockout
VUVLO
Hysteresis
RDS(ON)
On-Resistance
ILIMACC
Lower Current Limit Accuracy
ILIMACC
Upper Current Limit Accuracy
ILIM(MIN)
Minimum Current Limit
EN Input Low Voltage, VENLU
EN Input Low Voltage, VENLL
EN Input High Voltage, VENHU
EN Input High Voltage, VENHL
EN Input Leakage
Turn-Off Delay Time
System Ready Trip Threshold
System Ready Hysteresis
System Ready Voltage Low
RDY_ Leakage Current
VEN(L)
VEN(H)
IEN(SINK)
TDEL(OFF)
VRDY
VRDYHYS
VRDY(L)
IRDY
OTMP
Shutdown Temperature
Conditions
Min
Typ
Max
Units
5.5
75
1
10
3
V
μA
μA
μA
V
mV
3
ENIL or ENIU = 0V, IOUT = 0; RHYS = 200kΩ
ENIL = ENIU = High, VOUT = Open
ENIL = ENIU = High, VOUT = 0V
Rising Edge
VCC = 4.75V, RSETU = RSETL = 0K
VCC = 3.0V, RSETU = RSETL = 0K
RSETL = 249KΩ; ΔTA ≤ 25°C
RSETL = 249KΩ
RSETU = 1.24MΩ; ΔTA ≤ 20°C,
RSETU = 1.24MΩ ,
VCC = 3.0 to 5.5V
VCC = 3.0 to 5.5V
VCC = 3.0 to 5.5V
VCC = 3.0 to 5.5V
VEN = 5.5V
VCC = 5.0V
VOUT Rising, TA = 25°C (VIN = 3.3V)
RHYS = 200KΩ
ISINK = 1mA
VRDY < 5.5V, VOUT < 98% Of VOUT
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
360
340
1800
1700
40
0.4
0.4
2.7
120
50
65
400
400
2000
2000
150
100
120
440
460
2200
2300
0.4
0.4
1.4
1.4
0.4
98
200
1
1
0.4
1
150
15
mΩ
mA
mA
mA
V
V
V
V
μA
μs
% of VOUT
mV
V
μA
°C
1. The AAT4621 is guaranteed to meet performance specification over the -40°C to 85°C operating temperature range and is assured by design, characterization and correlation
with statistical process controls.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201944A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 15, 2012
5
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Typical Characteristics
AAT4621 Output Current vs. Output Voltage
(RSETU = 383kΩ, 25°C)
AAT4621-1 Output Current vs. Output Voltage
(RSETU = 374KΩ; TA = 25°C)
0.7
VCC = 3.3V
Output Current (A)
Output Current (A)
0.40
0.30
0.20
VCC = 5V
0.10
0.6
0.5
0.3
0.2
0.1
0
0.00
0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
3
1.5
3.3
1.8
2.1
2.4
Output Voltage (V)
3.3
3.6
3.9
4.2
4.5
4.8
5.1
(25°C)
1.40
3
1.20
2.5
2
VCC = 3.3V
ILIM (A)
ILIM (A)
3.0
AAT4621-1 ILIM vs. RSET
(25°C)
1.00
2.7
Output Voltage (V)
AAT4621 ILIM vs. RSET
0.80
0.60
VCC = 3.3V
1.5
1
VCC = 5V
0.40
VCC = 5V
0.5
0.20
0
0.00
0
200
400
600
800
1000
1200
1400
1600
0
200
400
600
800
1000
1200
1400
1600
RSET (kΩ)
RSET (kΩ)
Reverse Off-Switch Current vs. Temperature
Off-Switch Current vs. Temperature
(ENIU = ENIL = High; VCC = 0V)
(ENIU = ENIL = High; VOUT = 0V)
100
100
10
10
VOUT = 5V
ISD(OFF) (μA)
IRSD(OFF) (μA)
VCC = 5V
VCC = 3.3V
0.4
1
0.1
VOUT = 3.3V
VCC = 5V
1
0.1
VCC = 3.3V
0.01
-40
-20
0
20
40
60
Temperature (°C)
6
80
100
120
0.01
-40
-20
0
20
40
60
80
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201944A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 15, 2012
100
120
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Typical Characteristics
Off-Supply Current vs. Temperature
RDS(ON) vs. Input Voltage
(ENIU = ENIL = VCC; VOUT = Open)
(RSET = 0kΩ
Ω)
10
70
65
RDS(ON) (mΩ)
IQ(OFF) (μA)
VCC = 5V
1
0.1
VCC = 3.3V
0.01
-40
-20
0
20
40
60
80
100
60
55
50
45
2.5
120
3
3.5
4
4.5
Temperature (°C)
Input Voltage (V)
RDS(ON) vs. Temperature
VRHYS vs. RRHYS
(RSET = 0Ω)
5
5.5
2.00
90
1.80
1.60
VCC = 3V
1.40
70
VRHYS (V)
RDS(ON) (mΩ)
80
60
50
1.20
1.00
0.80
0.60
0.40
VCC = 5V
40
30
-40
0.20
0.00
-20
0
20
40
60
80
0
100
500
Temperature (°C)
1000
1500
RRHYS (kΩ)
AAT4621 ILIM vs. Temperature
AAT4621 ILIM vs. Temperature
(VCC = 4V; VOUT = 3.85V; ENIL = 0V; RSETL = 249kΩ)
(VCC = 4V; VOUT = 3.85V; ENIU = 0V; RSETU = 1.3MΩ)
205
1020
1010
1000
ILIM (mA)
ILIM (mA)
200
195
990
980
970
190
960
185
-50
-25
0
25
50
Temperature (°C)
75
100
950
-50
-25
0
25
50
75
100
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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7
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Typical Characteristics
AAT4621-1 ILIM vs. Temperature
AAT4621-1 ILIM vs. Temperature
(VCC = 5V; VOUT = 4.5V; ENIL = 0V; RSETL = 249kΩ)
(VCC = 5V; VOUT = 4.5V; ENIU = 0V; RSETU = 1.24MΩ)
2100
420
2080
2060
ILIM (mA)
ILIM (mA)
415
410
405
2040
2020
2000
1980
400
1960
1940
395
-50
-25
0
25
50
75
100
-50
-25
Temperature (°C)
75
(ENIU = Open; Vary ENIL; T = 25°C)
VEN(H)
1.0
VIH and VIL (V)
VCC = 5V
45
40
35
0.9
0.8
VEN(L)
0.7
30
VCC = 3.3V
-20
0
20
40
60
80
100
120
Temperature (°C)
0.6
2.5
3.5
4.5
5.5
6.5
Input Voltage (V)
VEN(H) and VEN(L) vs. Input Voltage
(ENIL = Open; Vary ENIU; T = 25°C)
VEN(H) and VEN(L) (V)
1.1
VEN(H)
1.0
0.9
0.8
VEN(L)
0.7
0.6
2.5
3.5
4.5
5.5
6.5
7.5
Input Voltage (V)
8
100
1.1
55
IQ (μA)
50
VEN(H) and VEN(L) vs. Input Voltage
(ENIU = 0V; ENIL = VCC; or ENIL = 0V;
ENIU = VCC; VOUT = Open)
25
-40
25
Temperature (°C)
Quiescent Current IQ vs. Temperature
50
0
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201944A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 15, 2012
7.5
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Typical Characteristics
Hard Short Circuit
Hard Short Circuit
2
VOUT
0
1.5
1.0
IOUT
0.5
0.0
6
VCC
4
2
VOUT
0
1.5
1.0
IOUT
0.0
Time (20ms/div)
Time (20ms/div)
Soft Short Circuit with 5Ω Series Impedance
Soft Short Circuit with 5Ω Series Impedance
(VCC = 5V)
6
5
5
0.6
IOUT
0.4
0.2
0.0
Time (2ms/div)
Charging Profile
0.8
I OUT
0.6
0.4
0.2
0.0
Charging Profile
(ILIMIT = 1A; VCC = 4.5V; CO = 0.55F)
6
6
VOUT
0
0.15
0.10
I OUT
0.05
0.00
Time (5s/div)
2
Thermal Foldback
VOUT
1.0
0.8
0
0.6
0.4
IOUT
0.2
0.0
Output Current (A)
2
Output Voltage (V)
4
Output Current (A)
Output Voltage (V)
1.0
4
Time (2ms/div)
(ILIMIT = 150mA; VCC = 4.5V; CO = 0.55F)
4
VCC and VOUT
Output Current (A)
VCC and VOUT
3
Input Voltage (V)
Output Voltage (V)
6
Output Current (A)
Input Voltage (V)
Output Voltage (V)
(VCC = 3.3V)
4
0.5
Output Current (bottom) (A)
VCC
4
Input Voltage (top) (V)
Output Voltage (middle) (V)
(VCC = 5V)
Output Current (bottom) (A)
Input Voltage (top) (V)
Output Voltage (middle) (V)
(VCC = 3.3V)
Time (1s/div)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201944A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 15, 2012
9
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Typical Characteristics
2.0
1.5
1.0
I OUT
0.5
0.0
-0.5
Input Voltage (top) (V)
Output Voltage (middle) (V)
VOUT = 3.80V
VCC = 3.83V
VOUT = 3.76V
2.0
1.5
1.0
I OUT
0.5
0.0
-0.5
Time (1ms/div)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201944A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 15, 2012
Output Current (bottom) (A)
VCC = 3.83V
Time (1ms/div)
10
GSM900 GPRS Class 12 Transmit
2-Slot Ch975, 33dBm
Output Current (bottom) (A)
Input Voltage (top) (V)
Output Voltage (middle) (V)
GSM900 GPRS Class 12 Transmit
1-Slot Ch975, 33dBm
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Functional Block Diagram
Reverse
Blocking
OUT
VCC
Over-Temp
Protection
Power
Loop
UnderVoltage
Lockout
RDY
EN IL
EN IU
1.2V
Reference
Current Limit
Control
GND
Functional Description
The AAT4621 SmartSwitch family 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 AAT4621
has been designed specifically to provide the interface
between a PCMCIA host and PC 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 external resistors connected between
the two SET pins and ground. The minimum current limit
ISETL
ISETU
RHYS
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 AAT4621 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 AAT4621 typically consumes 40μA when
operating, when off, the device draws less then 1μA. 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.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201944A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 15, 2012
11
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Application Information
ISETU and ISETL Current Limit Set
The AAT4621/AAT621-1 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.
The AAT4621 has a current limit range from 75mA to
1200mA; the AAT4621-1 has a current limit range from
150mA to 2400mA.
ILIM/VISET (A/V)
Current Limit (mA)
3000
2500
2000
AAT4621-1
1500
1000
500
AAT4621
0
100
300
500
700
900
1100
1500
1300
RSETU and RSETL (Ω)
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 (1μA) times the RHYS resistance.
VHYST = RHYS · 1µA
= 200kΩ · 1µA
= 0.2V
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.
Current Limit Range (A)
Current Limit (A)
RSET Range
(Ω)
IISET (μA)
AAT4621
AAT4621_1
AAT4621
AAT4621_1
AAT4621
AAT4621_1
1.5Meg -750K
750K -375K
375K -187.5K
187.5K-93.75K
1
2
4
8
0.8
0.4
0.2
0.1
1.6
0.8
0.4
0.2
1.2-0.6
0.6-0.3
0.3-0.15
0.15-0.075
2.4 - 1.2
1.2 - 0.6
0.6 -0.3
0.3 - 0.15
RSET*1*0.8
RSET*2*0.4
RSET*4*0.2
RSET*8*0.1
RSET*1*1.6
RSET*2*0.8
RSET*4*0.4
RSET*8*0.2
Table 1: RSET Table.
12
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Power Loop
Over-Temperature Protection
The AAT4621 power loop limits the load current in the
event that the device power dissipation becomes excessive. The AAT4621 power loop regulates the die temperature to 110°C (or 130°C for the AAT4621-1), decreasing
the load current in increments of 1/32 of the current limit
set point when the die temperature reaches 110°C (or
130°C for the AAT4621-1). When the die temperature
exceeds 110°C (or 130°C for the AAT4621-1) it decreases the load current by 1/32 of the current limit set point.
If die temperature is less than 110°C (or 130°C for the
AAT4621-1), 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
110°C (or 130°C for the AAT4621-1).
If the die temperature rate of rise is fast enough to
exceed the power loop regulated temperature, overtemperature shutdown disables the device. The overtemperature threshold is 145°C (or 150°C for the
AAT4621-1). After over-temperature shutdown, soft
start is initiated once the die temperature drops to
130°C (or 135°C for the AAT4621-1).
The delay time between die temperature measurements
varies depending on the load current limit set point. The
delay ranges from 0.5ms for a 75mA (or 150mA for the
AAT4621-1) current limit set point to 4ms for a 1.2A (or
2.4A for the AAT4621-1) 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 (or 2.4A for
the AAT4621-1) until the current reaches 1.2A (or 2.4A
for the AAT4621-1), 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.
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 where a short
circuit is applied to the output. After applying a short
circuit or heavy load to the output, which causes the
output to sink below the 18mV threshold plus some hysteresis, the current will immediately attempt to slew
from zero to the final programmed value. The device will
continue to output the current limit as long as the output
is VIN - 18mV or until the die temperature reaches
110°C. If temperature fold-back occurs, then the power
loop will become active.
Under-Voltage Shutdown
Under-voltage lockout enables the device at 2.7V typical
with 120mV of hysteresis. The maximum UVLO level is
3.0V.
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.
Once the AAT4621 has fully charged the supercap, the
soft start circuit is disabled. The soft start function will
only reactivate under the following conditions:
1.
2.
3.
4.
The power source or enable is cycled off and back on
The thermal shutdown is activated
Switching from ENIU to ENIL or vice versa
Following an over-current event.
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 AAT4621/AAT4621-1 evaluation board schematic is
shown in Figure 2. The AAT4621/AAT4621-1 PCB layout
is shown in Figures 3 and 4.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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13
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Layout Guidance
2.
When laying out the PC board, the following layout
guideline should be followed to ensure proper operation
of the AAT4621/AAT4621-1:
3.
1.
The exposed pad EP must be reliably soldered to
GND. The exposed thermal pad should be connected
to the board ground plane and Pin 12. The ground
plane should include a large exposed copper pad
under the package with VIAs to all board layers for
thermal dissipation.
J1
VCC
VCC
EN IU
EN IU
R1
1.5K
The power traces, including GND traces and the VCC
trace should be kept short, direct and wide to allow
large current flow. Use several via pads when routing between layers.
The input capacitors (C1) should be connected as
close as possible to VCC (Pins 8, 9, 10, 11) and GND
(Pin 12) to get good power filtering.
The output capacitor (C2) should be connected as
close as possible to OUT (Pins 5, 6, 7) and GND (Pin
12) to get good power filtering as the device will
recharge the Supercap when the output voltage level
sensed on the OUT pin is reduced by approximately
18-20mV below its input voltage (VCC) level.
4.
D1
P1
RDY
LED RED
RDY
U1
J2
VCC
14
EN IL
EN IL
13
12
VCC
P2
VCC
P4
GND
11
TB1
C1
10µF
10
9
IN
8
EN IU
RDY
EN IL
RHYS
GND
ISETU
VCC
ISETL
VCC
OUT
VCC
OUT
VCC
OUT
AAT4621/AAT4621-1
1
2
RHYS
3
ISETU
4
ISETL
R2
200K
R3
1M
5
6
R4
120K
P3
OUT
7
C2
10µF
+
OUT
R5
47.5K
+
SC1
0.55F
R6
47.5K
TB 2
OUT
P5
GND
Figure 2: AAT4621/AAT4621-1 Evaluation Board Schematic.
Figure 3: AAT4621/AAT4621-1 Evaluation Board PCB Top Side.
14
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201944A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 15, 2012
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Figure 4: AAT4621/AAT4621-1 Evaluation Board PCB Bottom Side.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201944A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 15, 2012
15
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TDFN33-14
TDFN33-14
YWXYY
K5XYY
AAT4621IWO-T1
AAT4621IWO-1-T1
Skyworks Green™ products are compliant with
all applicable legislation and are halogen-free.
For additional information, refer to Skyworks
Definition of Green™, document number
SQ04-0074.
Package Information3
TDFN33-14
Detail "A"
3.000 ± 0.050
2.500 ± 0.050
Index Area
3.000 ± 0.050
1.650 ± 0.050
Top View
Bottom View
+ 0.100
- 0.000
Pin 1 Indicator
(Optional)
0.180 ± 0.050
Side View
0.400 BSC
0.000
0.203 REF
0.750 ± 0.050
0.425 ± 0.050
Detail "A"
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing
process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection.
16
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201944A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 15, 2012
DATA SHEET
AAT4621
PC Card Current Limit Interface and Capacitor Charger
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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17