201960A.pdf

DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
General Description
Features
The AAT4685 OVPSwitch™ is a member of Skyworks'
Application Specific Power MOSFET™ (ASPM™) product
family. It is an N-channel MOSFET power switch with
precise over-voltage protection control, designed to protect low-voltage systems against high-voltage faults up
to +28V. It also integrates over-current protection
(OCP), battery over-voltage protection (BOVP) and overtemperature protection (OTP).
• VIN Range: 3.0V – 28V
• OVP Threshold Setting Range: 4V – 7V
▪ Fixed: 5.85V and 6.8V
▪ Adjustable
• Fast OVP Response:
1μs (max) Response to Over-Voltage Transient
• OVP Recovery Delay Time: 8ms
• Over-Current Protection
• Adjustable 0.3 – 1.8A
• Battery OVP 4.35V
• Thermal Shutdown Protection
• Low Quiescent Current
▪ 600μA Typical
▪ 100μA Typical Standby Current
• Under-Voltage Lockout
• 120mΩ Typical RDS(ON) at 5.0V
• Active Low Enable with Internal 200kΩ Pull-Down
Resistor
• Input Supply Power Good Indicator, Open Drain
• OVP/OCP/BOVP/OT Fault Indicator, Open Drain
• Temperature Range: -40°C to 85°C
• 3x3mm TDFN-12 Package
When the input voltage exceeds the programmed overvoltage threshold, the N-channel MOSFET switch will be
turned off to prevent damage to the output load circuits.
An external resistor divider is adopted to program the
adjustable version over-voltage trip point. Over-current
protection protects the case of output short circuits by
disconnecting the load from the input supply.
A battery voltage monitor is integrated and disconnect
the IN and OUT when the battery voltage exceed its rated
voltage. The AAT4685 also monitors its own die temperature and OVP switch off if it becomes too hot.
The AAT4685 includes an under-voltage lockout (UVLO)
protection circuit, which puts the device into sleep mode
at low input voltages only consuming 100μA current. It
also includes two indicators: input supply power good
indicator (POK) which is always active whether EN is low
or high, and a fault flag indicator (FLT) which goes to
active low when a fault condition (OV, OC, BOV and OT)
occurs at EN = low.
Applications
•Cell Phones
•Digital Still Cameras
•MP3
•Personal Data Assistants (PDAs)
The AAT4685 is offered in a Pb-free, 3x3mm 12-pin
TDFN package with a pin-out optimized for safety and is
specified for operation over the -40°C to +85°C ambient
temperature range.
Typical Application
VIN 3.0V – 28V
IN
OVP
C1
1μF
ROVP2
ROCP
VOUT
OUT
AAT4685
ROVP1
OCP
IC
EN GND
Fault Flag
FLT
POK
BAT
BOVP
C2
1μF
VIO
VIO
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201960A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 16, 2012
1
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Pin Descriptions
Pin #
Symbol
1
2
3
OCP
IC
EN
4
POK
5,6
7,8
9
OUT
IN
GND
10
FLT
11
BOVP
12
OVP (N/C)
Function
Over-current protection threshold input. Connect resistor to ground to set OCP limit.
Internally connected. Connect this pin to ground.
Active low enable with internal 200kΩ resistor pull down to GND
Input supply power-good status pin, open-drain. The POK function is always active whether EN is low or
high. Connect a 1kΩ to 100kΩ pull-up resistor to the logic I/O voltage of the host system.
Output. Connect a 0.1μF~47uF capacitor from OUT to GND.
Power input pin. Connect 1μF capacitor from IN to GND.
Ground connection.
Open-drain output. Active low when input over-voltage, input over-current, battery over-voltage, or over
temperature and EN = low. The FLT pin goes to high impedance state when EN = high. Connect a 1kΩ to
100kΩ pull-up resistor to the logic I/O voltage of the host system.
Battery voltage sense input. Connect to battery positive terminal through a 100kΩ resistor to limit the
current in case of a short circuit condition.
Over-voltage protection threshold input (Adjustable only). Fixed version not connected.
Pin Configuration
TDFN33-12
(Top View)
OCP
IC
EN
POK
OUT
OUT
2
1
12
2
11
3
10
4
9
5
8
6
7
OVP (N/C)
BOVP
FLT
GND
IN
IN
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201960A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 16, 2012
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Absolute Maximum Ratings1
Symbol
VIN
VN
VP
IMAX
TJ
TS
TLEAD
Description
IN to GND
BOVP, OVP , OCP, OUT , IC to GND
FLT, EN, POK to GND
Maximum Continuous Switch Current
Operating Junction Temperature Range
Storage Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
Units
-0.3 to 28
-0.3 to VP +0.3
-0.3 to 7.5
1.9
-40 to 150
-65 to 150
300
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, 3
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 a FR4 board.
3. Derate 25mW/°C above 25°C.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201960A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 16, 2012
3
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Electrical Characteristics1
VIN = 5V, VBOVP = 4.2V, V/EN = 0V , ROCP = 30k , TA = -40°C to 85°C unless otherwise noted. Typical values are at TA
= 25°C.
Symbol
VIN
IQ
Description
Conditions
Input Voltage Range
Operation Quiescent Current
IOUT = 0, ROCP = 30kΩ
Standby Current (Only UVLO and OVP
ISTDBY
circuit is “Enable”, other function blocks
EN = 5V, VOUT = 0
are all “Disable”)
VUVLO
Under-Voltage Lockout Threshold
Rising edge
VUVLO_HYS
Under-Voltage Lockout Hysteresis
Deglitch Time, Input Power Detected
Time measured from VIN 0V to 5V;
TDGL
Status
1μs rise time to Output Turn ON
Input OVP – Adjustable (AAT4685-1) ( Measured at OVP pin )
VOVP_TH
Over-Voltage Lockout Threshold
Rising Edge
Over-Voltage Lockout Threshold
VOVP_HYS
Hysteresis
Over-Voltage Lockout Threshold
VOVP_RANGE
Adjustable Range
TRESP_OV
Over-Voltage Response Time
VOVP rise to 1.13V from 1.07V in 1ns
Recovery Time From Input Over-Voltage
TOVP_REC
VOVP fall to 1.07V from 1.13V in 1ns
Release
Input OVP – Fixed (AAT4685-2 and AAT4685-3) ( Measured at IN pin )
Overvoltage Protection AAT4685-2
Rising Edge
VOVPT
Trip Voltage
AAT4685-3
Over-Voltage Protection Trip Point
VOVP_HYS
Hysteresis
TRESP_OV
Over-Voltage Response Time
VIN rise to 7.5V from 5V
Recovery Time From Input Over-Voltage
VIN fall to 5V from 7.5V
TOVP_REC
Release
Input OCP
IOCP
Over-Current Range (Programmable)
Rising Edge. ROCP = 30k
IOCP/IOCP Over-Current Trip Tolerance
Blanking Time, Input Over-Current
TOCP_BL
Detected
Recovery Time From Input Over-Current
TOCP_REC
Condition
Battery OVP ( Measured at BOVP pin )
Battery Over-Voltage Protection Trip
Rising Edge
VBOVPT
Voltage
Battery Over-Voltage Protection Trip
VBOVP_HYS
Point Hysteresis
IBOVP
Battery OVP Pin Input Current
TBOVP_BL
Battery OVP Pin Blanking Time
Min
Typ
Max
Units
600
28
800
V
μA
100
150
μA
2.7
0.1
2.9
V
V
3
2.5
8
0.97
1.0
ms
1.03
20
4
mV
7
V
1.0
μs
8
6.60
5.71
6.80
5.85
ms
7.0
6.0
60
8
4.2
1.0
V
V
mV
1.0
0.3
0.9
V
μs
ms
1.8
1.1
A
A
180
μs
64
ms
4.35
4.5
275
V
mV
100
180
nA
μs
1. The AAT4685 is guaranteed to meet performance specification over the -40 to 85°C operating temperature range and are assured by design, characterization and correlation
with statistical process controls.
4
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201960A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 16, 2012
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Electrical Characteristics1
VIN = 5V, VBOVP = 4.2V, V/EN = 0V , ROCP = 30k , TA = -40°C to 85°C unless otherwise noted. Typical values are at TA
= 25°C.
Symbol
Description
OVP Switch
On-Resistance
RDS(ON)
ID(OFF)
Switch Off-Leakage
Logic Control and Protection
VEN(L)
EN Input Low Voltage
VEN(H)
EN Input High Voltage
IEN(H)
EN Input Current
VFLT
FLT Output Low Voltage
IFLT
FLT Output Leakage
VPOK
POK Output Low Voltage
IPOK
POK Output Leakage
TON
OVP Switch Turn On Delay Time
TSHDN
Chip Thermal Shutdown Temperature
Conditions
Min
ROCP = 16.5k, IOUT = 1200mA
EN = 5V
Typ
Max
Units
120
200
1
m
μA
0.4
V
V
μA
V
μA
V
μA
ms
1.2
VEN = 5.0V, Internal Pulldown = 200k
IFLT = 4mA
VIN = 0V, FLT = 5.5V
IPOK = 4mA
VIN = 0V, POK = 5.5V
EN from 0V to 5V; ROUT = 10; COUT= 1μF
Threshold
Hysteresis
25
0.4
1
0.4
1
8
140
15
ºC
1. The AAT4685 is guaranteed to meet performance specification over the -40 to 85°C operating temperature range and are assured by design, characterization and correlation
with statistical process controls.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201960A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 16, 2012
5
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Typical Characteristics
Operation Quiescent Current vs. Temperature
Standby Current vs. Temperature
110
620
105
ISB (μA)
IQ (μA)
610
600
590
100
95
90
580
-40
-15
10
35
60
85
-40
85
-15
Temperature (°C)
Operation Quiescent and Standby Current
vs. Supply Voltage
UVLO Threshold (V)
Current (μA)
60
85
2.80
IQ
ISB
600
500
400
300
200
100
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
UVLO_Hi
UVLO_Lo
2.75
2.70
2.65
2.60
2.55
-40
7.5
-15
Supply Voltage (V)
10
35
60
85
Temperature (°C)
AAT4685-1 Input OVP Threshold
vs. Temperature
Battery Over-Voltage Protection Trip Voltage
vs. Temperature
(VIN = 5.0V)
1.01
OVP_Rising
OVP_Falling
4.50
Battery OVP_Thresh_hi
Battery OVP_Thresh_low
4.45
1.00
4.40
VBOVPT (V)
OVP Threshold (V)
35
Under-Voltage Lockout Threshold
vs. Temperature
700
0
3.0
10
Temperature (°C)
0.99
4.35
4.30
4.25
4.20
4.15
0.98
4.10
4.05
0.97
-40
-15
10
35
Temperature (°C)
6
60
85
4.00
-40
-15
10
35
60
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201960A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 16, 2012
85
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Typical Characteristics
EN VIH and VIL vs. Supply Voltage
EN Pin vs. Temperature
(VIN = 5.0V)
0.90
0.90
VIH
VIL
0.85
0.80
VEN (V)
0.80
VEN (V)
VIH
VIL
0.85
0.75
0.75
0.70
0.70
0.65
0.65
0.60
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
0.60
-40
7.0
-15
10
35
60
85
Temperature (°C)
Supply Voltage (V)
Over-Current Limit vs. ROCP
NMOS On-Resistance vs. Temperature
2.25
155
2.00
1.75
RDS(ON) (mΩ)
140
IOCP (A)
1.50
1.25
1.00
0.75
125
110
0.50
0.25
0.00
10
100
95
-40
-15
10
ROCP (kΩ)
35
60
85
Temperature (°C)
Normal Power-On Startup
Over-Current Protection
(ROUT = 6.3Ω)
(IOUT switches from 0.8A to 1.5A, ILIM = 1A)
VIN
(5V/div)
VOUT
(2V/div)
VIN
(2V/div)
5V
IOUT
(500mA/div)
VOUT
(2V/div)
FLT
(5V/div)
IOUT
(500mA/div)
Time (2ms/div)
Time (50μs/div)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201960A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 16, 2012
7
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Typical Characteristics
Over-Voltage Protection Response
for Input Step
Recovery from Over-Voltage Protection
(VIN = 7V to 5V)
(VIN = 5V to 12V)
VIN
(2V/div)
VIN
(2V/div)
VOUT
(2V/div)
IOUT
(500mA/div)
VOUT
(2V/div)
FLT
(5V/div)
FLT
(5V/div)
Time (20μs/div)
Time (2ms/div)
Battery Over-Voltage Protection
Recovery from Battery Over-Voltage Protection
(VBOVP steps from 3.8V to 4.5V)
(VBOVP = 4.5V to 3.8V)
VBOVP
(1V/div)
VOUT
(2V/div)
VBOVP
(1V/div)
IOUT
(500mA/div)
VOUT
(2V/div)
IOUT
(500mA/div)
FLT
(5V/div)
FLT
(5V/div)
Time (100μs/div)
Time (500μs/div)
Battery Over-Voltage Protection
Power-up into Short Circuit
on the OUT Pin
(VBOVP Cycles Between 4V and 4.5V)
VBOVP
(2V/div)
VIN
(5V/div)
VOUT
(2V/div)
IOUT
(500mA/div)
VOUT
(5V/div)
FLT
(5V/div)
FLT
(5V/div)
Time (20ms/div)
8
Time (200ms/div)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201960A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 16, 2012
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Functional Block Diagram
OVP
Switch
OUT
IN
UVLO
OVP
POK
OCP
CP
Driver
VREF
POK
Detect
INT
_VP
INT
Regulator
FLT
INT
_VP
POR
Bias VREF
and BG
INT
_VP
BOVP
OCP
Control
and Timer
INT
_VP
VREF
EN
OTP
option
Functional Description
The AAT4685 provides up to 28V over-voltage and overcurrent protection when powering low-voltage systems
such as cell phones, MP3, and PDAs or when charging
Lithium Ion batteries from a badly regulated supply. The
AAT4685 is inserted between the power supply or charger source and the load to be protected. The AAT4685 IC
consists of a low resistance OVP switch, under-voltage
lockout protection, over-voltage monitor and protection,
over-current protection, battery over-voltage protection,
fast shut-down circuitry and a fault output flag.
In normal operation the OVP switch acts as a slew-rate
controlled load switch, connecting and disconnecting the
power supply from IN to OUT. A low resistance N channel MOSFET is used as to minimize the voltage drop
between the voltage source and the load and to reduce
the power dissipation.
When the voltage on the input exceeds the programmed
over-voltage trip point, the device immediately turns off
GND
the internal OVP switch disconnecting the load from the
abnormal voltage, preventing damage to any downstream components. In the case of an over current condition, it limits the system current at the threshold value,
and if the over current persists, the OVP switch is turned
off after a blanking period. If the battery voltage rises to
an unsafe level (BOVP threshold), the IC disconnects
OUT from the charging input power IN until the battery
voltage returns to an acceptable value. BOVP or OCP
blanking time ignores short time transients of over-battery voltage and overload current. Additionally, AAT4685
also monitors its own die temperature and turns the OVP
switch off if it becomes too hot.
The AAT4685 has a fault flag (FLT) pin to indicate the
fault conditions of input power over-voltage, load current
over-current, battery over-voltage, and over-temperature by pulling the flag signal down to alert the system.
If an input over-voltage condition or over-voltage battery
condition exists at the time of the device enable, then
the OVP switch will remain OFF and FLT is always low.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201960A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 16, 2012
9
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Under-Voltage Lockout (UVLO)
The AAT4685 has a fixed 2.7V under-voltage lockout
level (UVLO) trip level for IN rising. When the input voltage is less than 2.7V - VUVLO_HYS, the OVP switch is turned
off. 100mV of hysteresis is included to ensure circuit
stability.
Over-Voltage Protection (OVP)
The AAT4685 adjustable version has a 1.0V ± 3% overvoltage trip threshold on the OVP pin. With a resistor
divider on OVP pin from IN to GND, the over-voltage
protection point of IN can be adjusted between 4V and
7V. If the over-voltage trip level is triggered, the OVP
switch will start to be turned off in 1μs. The FLT pin is
driven low. When the input voltage pin returns below
VOVPT – VOVP_HYS (but is still above VUVLO), the OVP switch
is turned on again after a TOVP_REC recovery time to ensure
that the input supply has stabilized.
Fixed OVP products are also available where the resistive
divider is internally integrated. Pin 12 is designed to be
not connected.
Over-Current Protection (OCP)
The AAT4685 integrates adjustable over-current protection. Once the load current exceeds the pre-set limit of
IOCP current (ILOAD>IOCP), the load current is limited after
the OCP blanking time (typical 180μs). During the OCP
blanking time, the OVP switch stays ON. Once the load
current drops below IOCP, current restriction will be
removed. If the over-current state continues after the
blanking period, the OVP switch turns off and FLT is
pulled down. In order to prevent the input voltage from
spiking up due to the inductance of the input cable, the
OVP switch is turned off slowly, resulting in a "soft-stop."
The OVP switch will turn back on again after TOCP_REC
(typical 64ms) and the current is monitored all over
again. Each time an OCP fault occurs, an internal counter
is incremented. If 15 OCP faults occur in one charge
cycle, the OVP switch is turned off permanently. The
counter is cleared either by removing and re-applying
input power, or by disabling and re-enabling the device
via the EN pin.
10
The OCP threshold is set by an external resistor (ROCP)
connected between OCP and ground. IOCP is approximated by the following formula:
IOCP =
30
(current in A, resistance in kΩ)
ROCP
Battery Over-Voltage Protection (BOVP)
The AAT4685 monitors the positive battery terminal and
turns the OVP switch off when the battery voltage
exceeds the BOVP threshold (typical 4.35V). The monitor
has blanking time TBOVP_BL (typical 180μs) to prevent any
transient voltage from false triggering the BOVP. A resistor is required between the BOVP pin and the battery, to
limit the current in case of a short circuit condition. If the
battery voltage exceeds the BOVP trip threshold VBOVPT,
the OVP switch is turned off, and the FLT pin is driven
low. In order to prevent the input voltage from spiking
up due to the inductance of the input cable, the OVP
switch is turned off slowly , resulting in a "soft-stop." The
OVP switch is turned back on once the battery voltage
drops to VBOVPT – VBOVP_HYS. Each time a battery overvoltage fault occurs, an internal counter is incremented.
If 15 such faults occur in one charge cycle, the OVP
switch is turned off permanently. The counter is cleared
either by removing and re-applying input power, or by
disabling and re-enabling the device via the EN pin.
Over-Temperature Protection
(OT Protection)
If the junction temperature of the device exceeds TSHDN,
the OVP switch is turned off, and the FLT pin is driven
low. The OVP switch is turned back on when the junction
temperature falls below TSHDN - 15°C.
Fault Indicator (FLT)
The FLT output is an active-low open-drain fault (OV/OC/
BOVP/OT) reporting output. A pull-up resistor should be
connected from FLT to the logic I/O voltage of the host
system. When EN is low, FLT is asserted by pulling down
in the case of an over-voltage, over-current, or battery
over-voltage or over-temperature fault occuring; FLT is
de-asserted into high impedance state with the fault
removed. When EN is high, FLT is in high impedance
status.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201960A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 16, 2012
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Enable Control (EN)
Device Start-Up Operation
EN is an active low enable with internal 200kΩ resistor
pulled down to GND. EN is driven low, connected to
ground, or left floating for normal device operation. Set
EN low to turn the OVP switch on after turn on delay
time. Set EN high to turn the OVP switch off. In the case
of an over-voltage or UVLO condition toggling EN will not
override the fault condition and the OVP switch will
remain off. The OCP counter and the BOVP counter are
both reset when the device is re-enabled by the EN pin.
On initial power-up, if VUVLO < IN < VOVP, VBAT < VBOVP, and
EN is low, the OVP switch starts to turn on after TON delay
time (typical 8ms) to be stabilized for input. This turn on
uses Soft Start to control the inrush current to minimize
ringing at the input. Because of the deglitch time at
power on, if the input voltage rises rapidly past the OVP
threshold, the device does not switch on at all; instead
it goes into protection mode and indicate a fault on the
FLT pin. After successful start-up, if ILOAD > IOCP limit the
device turns off and the fault flag is asserted.
IC Input
Internally connected to GND through a 100kΩ resistor.
Connect this pin to ground.
The Soft Start function is defined as follows: "current
limit is stepped digitally from low level to its final current
limit level for soft starting."
Power–OK Indicator (POK)
The AAT4685 contains an open-drain POK output that
goes low when a valid input source is detected at the IN
pin. The valid input range is between VUVLO (typical 2.7V)
and VOVP voltage (fixed 5.85V / fixed 6.8V / adjustable
OVP threshold set by external resistors). After a valid
input has been established, charging is sustained. The
POK function is always active whether the EN pin is at
low or high state.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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11
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
System Flowchart
Power ON
Any State :
If V(IN) < UVLO go to “Power ON”
If EN = H go to “Standby”
N
EN = L
All functions OFF
Y
Reset :
Timers reset
Counters reset
FLT = HiZ
UVLO : ON
N
V(IN) > UVLO
BOVP, TSD : ON
Y
OVP : ON
N
FLT=HiZ
Y
Standby
Wait t DGL
(8ms)
OCP : ON
Turn On OVP
switch,
FLT = HiZ
FLT state
VIN > OVP
Y
Turn Off OVP
swtch,
FLT = L
V(IN) < OVP
N
Y
Wait tOVP_REC
(8ms)
N
FLT state
VBAT > BOVP
Y
Blanking Time
180μs
N
Y
Turn Off OVP
switch,
FLT = L,
Incr BOVP counter
count <15 ?
N
Y
VBAT < BOVP
N
EN = H
Y
N
Y
Goto
Standby
N
FLT state
I > IOCP
Y
Limit
Current
Blanking Time
180μs
Turn Off OVP
switch,
FLT = L,
Incr OCP counter
Y
Y
Wait t OCP_REC
(64ms)
Y
Goto
Standby
N
N
N
count <15 ?
EN = H
N
FLT state
TJ > TSHDN
N
12
Y
Turn Off OVP
swtch,
FLT = HiZ
TJ < TSHDN -15
Y
N
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Application Information
Table 2 summarizes 1% standard metal film resistors for
several over-current settings.
Over-Voltage Protection Resistors
The over-voltage protection threshold is programmed
with two resistors, R1 and R2. To limit the current going
through the external resistor string while maintaining
good noise immunity, use smaller resistor values, such as
10kΩ for R2. Using a larger value will further reduce the
system current, but will also increase the impedance of
the OVP node, making it more sensitive to external noise
and interference. A suggested value for R2 is 100kΩ. R1
can be calculated using the following equation:
R1 =
VOVP
- 1 · R2 = (VOVP - 1) · 100
VOVP_TH
Table 1 summarizes 1% standard metal film resistors for
several over-voltage settings.
R2 (kΩ)
R1 (kΩ)
VOVP Setting (V)
100
100
100
100
100
100
100
300
348
402
442
499
549
604
4.0
4.5
5.0
5.5
6.0
6.5
7.0
Table 1: 1% Standard Resistor Values
for OVP Setting.
Over-Current Protection Resistor
The over-current threshold is programmed by an external resistor (ROCP) connected from the OCP pin to GND.
ROCP can be calculated by the following equation.
ROCP =
30
· 1000
IOCP
R3 (kΩ)
IOCP Setting (A)
100.0
86.6
75.0
66.5
60.4
54.9
49.9
43.0
37.4
33.2
30.1
24.9
21.5
18.7
16.5
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.70
0.80
0.90
1.00
1.20
1.40
1.60
1.80
Table 2: 1% Standard Resistor Values
for OCP Setting.
Input Capacitor
A 1μF or larger capacitor is typically recommended for
CIN. CIN should be located as close to the device IN pin as
practically possible. Ceramic, tantalum, or aluminum
electrolytic capacitors may be selected for CIN. There is
no specific capacitor equivalent series resistance (ESR)
requirement for CIN. However, for higher current operation, ceramic capacitors are recommended for CIN due to
their inherent capability over tantalum capacitors to
withstand input current surges from low impedance
sources such as batteries in portable devices.
Capacitors are typically manufactured in different voltage ratings. If the maximum possible surge voltage is
known, select capacitors with a voltage rating at least 5V
higher than the maximum possible surge voltage. 50V
rated capacitors are generally good for most OVP applications to prevent any surge voltage.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201960A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 16, 2012
13
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Output Capacitor
PCB Layout Recommendations
In order to insure stability while current limit is active, a
small output capacitance of approximately 1μF is required
at the output. Likewise, with the output capacitor, there
is no specific capacitor ESR requirement. If desired, COUT
may be increased to accommodate any load transient
condition.
For proper thermal management and to take advantage
of the low RDS (ON) of the AAT4685, certain circuit board
layout rules should be followed:
1.
VIN and VOUT should be routed using wider than normal traces.
2. GND should be connected to a ground plane. The
ground plane area connected to the ground pins
should be made as large as possible. Exposed pad
should be connected to ground plane to get best
power dissipation.
3. For best performance, CIN and COUT should be placed
close to the IN and OUT pins.
Evaluation Board Schematic
+5V
Red LED
7
VIN
R1
604k
1
2
+5V
Disable
8
C1 R2
1μF 100k
IN
OUT
6
OUT
5
11
12
OVP
BOVP
1
OCP
POK
EN
FLT
10
IC
GND
9
3
R3
30k
U1
AAT4685
IN
R5
1.74k
2
Green LED
R6
1.74k
VOUT
BATT
R4
100k
4
C2
1μF
Figure 1: AAT4685 Evaluation Board Schematic.
14
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
201960A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 16, 2012
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Evaluation Board Layout
Figure 2: AAT4685 Evaluation Board
Top Side Layout.
Figure 3: AAT4685 Evaluation Board
Bottom Side Layout.
Evaluation Board Bill of Materials
Designator
Part Number
Description
Manufacturer
U1
C1, C2
R1
R3
R2, R4
R5, R6
LED1
LED2
AAT4685IWP-1-T1
GRM21BR71H105K
RC0603FR-07604KL
RC0603FR-0730K1L
RC0603FR-07100KL
RC0603FR-071K74RL
0805KRCT
0805KGCT
IC Over-Voltage Protection Switch with OCP
Cap Ceramic 1μF 0805 X7R 50V 10%
Res 604kΩ 1/10W 1% 0603 SMD
Res 30.1KΩ 1/10W 1% 0603 SMD
Res 100KΩ 1/10W 1% 0603 SMD
Res 1.74kΩ 1/10W 1% 0603 SMD
LED Red 0805
LED Green 0805
Skyworks
Murata
Yageo
HB
Table 3: AAT4685 Evaluation Board Bill of Materials (BOM).
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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15
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Ordering Information
Package
OVP Trip Voltage
Marking1
Part Number (Tape and Reel)2
TDFN33-12
TDFN33-12
TDFN33-12
Adjustable
6.80V
5.85V
8LXYY
AAT4685IWP-1-T1
AAT4685IWP-2-T1
AAT4685IWP-3-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.
Packaging Information
TDFN33-12
Index Area
0.40 ± 0.05
Detail "A"
C0.3
0.45 ± 0.05
2.40 ± 0.05
3.00 ± 0.05
0.1 REF
3.00 ± 0.05
1.70 ± 0.05
Top View
Bottom View
0.23 ± 0.05
Pin 1 Indicator
(optional)
0.05 ± 0.05
0.23 ± 0.05
0.75 ± 0.05
Detail "A"
Side View
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 • [email protected] • www.skyworksinc.com
201960A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 16, 2012
DATA SHEET
AAT4685
Over-Voltage Protection Switch with OCP and BOVP
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
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service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no
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THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR
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Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for
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17