MAX4981ETA+ [MAXIM]
Surge Protection Circuit, BICMOS, PDSO8, 2 X 3 MM, LEAD FREE, TDFN-8;
| 型号： | MAX4981ETA+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Surge Protection Circuit, BICMOS, PDSO8, 2 X 3 MM, LEAD FREE, TDFN-8 信息通信管理 光电二极管 |
| 文件： | 总10页 (文件大小：160K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-4137; Rev 0; 5/08
Overvoltage Protector with
Active Current Limit
7–MAX4981
General Description
Features
♦ Input Voltage Protection Up to +28V
♦ Integrated nFET Switch, 85mΩ (typ)
The MAX4978–MAX4981 overvoltage-protection devices
protect low-voltage systems against voltage faults up to
+28V and feature a low 85mΩ R
FET, an active cur-
ON
♦ Preset Overvoltage Protection Trip Level
5.7V (typ) (MAX4978/MAX4980/MAX4981)
6.8V (typ) (MAX4979)
♦ Low-Current Undervoltage Lockout Mode
♦ Overcurrent Protection
rent limiter, and lithium-ion battery overcharge protec-
tion (MAX4980/MAX4981). These devices are used to
protect the charger input port on a portable device.
The overvoltage protector feature protects against volt-
ages up to 28V with two different trip thresholds: 5.7V
(MAX4978/MAX4980/MAX4981) and 6.8V (MAX4979).
There is an undervoltage protector with two different trip
thresholds: 4.4V (MAX4978) and 2.63V (MAX4979/
MAX4980/MAX4981).
♦ Internal 160ms (typ) Startup Delay
♦ Thermal-Shutdown Protection
♦ Battery Overcharge Protection
(MAX4980/MAX4981)
♦ Startup Debounce Time Indicator
The overcurrent limiter and battery voltage monitor fea-
tures provide a second layer of protection for a lithium-
ion battery charger. The overcurrent limiter is available
in two different thresholds: 0.9A (MAX4978/MAX4979/
MAX4980) and 1.95A (MAX4981). Once current reach-
es the threshold, it is held for a 20ms blanking time. If
the current is still at the limit after the blanking time, the
FET is turned off, and the device restarts the cycle after
160ms. The battery voltage monitor measures the volt-
age of a lithium-ion battery and disables the FET if the
battery voltage reaches 4.4V (MAX4980/MAX4981).
(MAX4978/MAX4979)
♦ Small, 8-Pin (2mm x 3mm) TDFN Package
Pin Configuration
TOP VIEW
OUT I.C.
I.C. GND
8
7
6
5
The MAX4978–MAX4981 are available in a small 8-pin
TDFN (2mm x 3mm) package and are specified over
the extended -40°C to +85°C temperature range.
MAX4978
MAX4979
MAX4980
MAX4981
Applications
*EP
Cell Phones
PDAs and Palmtop
Devices
MP3 Players
1
2
3
4
Digital Still Cameras
SDT(BAT)
IN
I.C.
EN
TDFN-EP
(BAT) IS FOR MAX4980/MAX4981 ONLY.
*EP = EXPOSED PAD. CONNECT EP TO GND.
Typical Application Circuit appears at end of data sheet.
Ordering Information/Selector Guide
CURRENT
LIMIT (mA)
BATTERY
MONITOR
UVLO
(V)
OVLO
(V)
TOP
MARK
PKG
CODE
PART
PIN-PACKAGE
8 TDFN-EP*
8 TDFN-EP*
8 TDFN-EP*
8 TDFN-EP*
MAX4978ETA+
MAX4979ETA+**
MAX4980ETA+
MAX4981ETA+
900
900
No
No
4.4
5.7
6.8
5.7
5.7
AAK
AAL
AAM
AAN
T823-1
T823-1
T823-1
T823-1
2.63
2.63
2.63
900
Yes
Yes
1950
Note: All devices specified over the -40°C to +85°C operating temperature range.
+Denotes a lead-free package.
*EP = Exposed pad.
**Future product—contact factory for availability.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Overvoltage Protector with
Active Current Limit
ABSOLUTE MAXIMUM RATINGS
(Voltages referenced to GND.)
Junction-to-Case Thermal Resistance (θ ) (Note 1)
JC
IN, SDT ................................................................. -0.3V to +30V
OUT ........................................................................... -0.3V to IN
EN, BAT .................................................................. -0.3V to +6V
SDT Continuous Current ................................................. 50mA
8-Pin 2mm x 3mm TDFN ......................................... 10.8°C/W
Junction-to-Ambient Thermal Resistance (θ ) (Note 1)
JA
8-Pin 2mm x 3mm TDFN ............................................ 60°C/W
Operating Temperature Range ......................... -40°C to +85°C
Junction Temperature .................................................... +150°C
Storage Temperature Range ........................... -65°C to +150°C
Lead Temperature (soldering, 10s) ................................+300°C
Continuous Power Dissipation (T = +70°C)
A
8-Pin 2mm x 3mm TDFN (derate 16.7mW/°C
above +70°C) ........................................................... 1333mW
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a 4-layer
board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
7–MAX4981
(V = 5.0V, V = 0V, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 2)
IN
EN
A
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
28
UNITS
V
Input Voltage Range
Input Supply Current
UVLO Supply Current
Shutdown Supply Current
V
2.3
IN
IN
I
I
< I
130
35
190
60
µA
OUT
LIM_MIN
I
V
V
= 2.3V
µA
UVLO
SHDN
IN
I
= 5V
15
23
µA
EN
V
V
V
V
falling
rising
falling
rising
4.2
4.3
IN
IN
IN
IN
MAX4978
4.4
4.5
IN Undervoltage Lockout
V
V
%
V
UVLO
2.5
MAX4979/MAX4980/
MAX4981
2.56
2.63
1
2.70
IN Undervoltage Lockout
Hysteresis
V
V
V
V
falling
rising
falling
rising
5.5
5.6
IN
IN
IN
IN
MAX4978/MAX4980/
MAX4981
5.7
5.8
6.95
4.5
IN Overvoltage Lockout
V
OVLO
6.5
MAX4979
6.65
6.80
1
IN Overvoltage Lockout Hysteresis
BAT Overvoltage Trip Level
BAT Overvoltage Hysteresis
BAT Input Leakage Current
Switch On-Resistance
%
V
V
MAX4980/MAX4981, V
MAX4980/MAX4981
MAX4980/MAX4981, V
rising
4.3
4.4
1
BOTL
BAT
BAT
%
I
= 4.2V
1
µA
mΩ
LKGB
R
I
= 100mA
OUT
85
160
ON
T =+25°C
850
800
900
950
A
MAX4978, MAX4979,
MAX4980
T = 0°C to +85°C
A
1000
1000
2050
2150
Overcurrent Protection Threshold
Thermal Shutdown
I
T = -40°C to +0°C
A
780
mA
°C
LIM
T =+25°C
A
1850
1750
1950
1950
160
MAX4981
T = -40°C to +85°C
A
T
T rising
A
SHDN
2
_______________________________________________________________________________________
Overvoltage Protector with
Active Current Limit
7–MAX4981
ELECTRICAL CHARACTERISTICS (continued)
(V = 5.0V, V = 0V, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 2)
IN
EN
A
A
PARAMETER
SYMBOL
CONDITIONS
MIN
1.5
-1
TYP
MAX
UNITS
Thermal-Shutdown Hysteresis
EN Input High Voltage
10
°C
V
V
IH
EN Input Low Voltage
V
0.6
+1
1
V
IL
EN Input Leakage Current
SDT Output Low Voltage
I
I
V
= 5.5V or 0V
EN
µA
V
LKGE
V
MAX4978/MAX4979, I
= 20mA
SINK
OL
MAX4978/MAX4979, V
deasserted
= 28V, SDT
SDT
SDT Leakage Current
DYNAMIC (Note 3)
IN Debounce Time
1
µA
LKGS
V
< V < V
to charge-pump
OVLO
UVLO
IN
t
t
120
160
1.5
5
200
ms
ms
µs
DEB
enable, Figure 1
Time from V
= 10% of V to V = 90%
OUT
OUT
IN
Switch Turn-On Time
Switch Turn-Off Time
t
ON
of V , R = 10Ω, C = 10µF
IN
L
L
V
< V
or V > V
to internal
OVLO
IN
UVLO
IN
15
25
OFF
switch off, R = 1kΩ
L
Current-Limit Blanking Time
Current-Limit Reaction Time
Overcurrent Autoretry Time
t
Short circuit applied, Figure 1
Short circuit applied
Figure 1
15
20
5
ms
µs
BLANK
t
REAC
t
120
160
200
ms
RETRY
Note 2: All devices are 100% production tested at T = +25°C. Specifications over -40°C to +85°C are guaranteed by design.
A
Note 3: All timing is measured using 10% and 90% levels, unless otherwise noted.
_______________________________________________________________________________________
3
Overvoltage Protector with
Active Current Limit
Timing Diagram
t
t
t
BLANK
BLANK
BLANK
t
t
RETRY
t
t
DEB
RETRY
DEB
OVLO
UVLO
IN
OUT
CURRENT LIMIT
LOAD CURRENT
7–MAX4981
SDT
Figure 1. Timing Diagram
4
_______________________________________________________________________________________
Overvoltage Protector with
Active Current Limit
7–MAX4981
Typical Operating Characteristics
(V = 5.0V, EN = GND, T = +25°C, unless otherwise noted.)
IN
A
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
NORMALIZED UVLO THRESHOLD
vs. TEMPERATURE
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
1.3
1.2
1.1
1.0
0.9
0.8
0.7
1.010
1.005
1.000
0.995
0.990
160
140
120
100
80
MAX4980/MAX4981
MAX4978
60
40
20
0
-40
-15
10
35
60
85
-40
-15
10
35
60
85
2
7
12
17
(V)
22
27
TEMPERATURE (°C)
TEMPERATURE (°C)
V
IN
NORMALIZED OVLO THRESHOLD
vs. TEMPERATURE
NORMALIZED CURRENT LIMIT
vs. TEMPERATURE
BATTERY OVERVOLTAGE THRESHOLD
vs. TEMPERATURE
1.010
1.005
1.000
0.995
0.990
1.10
1.05
1.00
0.95
0.90
4.50
4.45
4.40
4.35
4.30
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
NORMALIZED STARTUP DELAY/AUTORETRY/
BLANKING TIME vs. TEMPERATURE
OVERVOLTAGE FAULT RESPONSE
POWER-UP RESPONSE
MAX4978-81 toc09
MAX4978-81 toc08
1.008
R = 1kΩ
L
1.006
1.004
1.002
1.000
0.998
0.996
0.994
0.992
V
IN
V
IN
5V/div
5V/div
5V/div
2V/div
2V/div
V
V
V
OUT
OUT
SDT
4μs/div
40ms/div
-40
-15
10
35
60
85
TEMPERATURE (°C)
_______________________________________________________________________________________
5
Overvoltage Protector with
Active Current Limit
Typical Operating Characteristics (continued)
(V = 5.0V, EN = GND, T = +25°C, unless otherwise noted.)
IN
A
UNDERVOLTAGE FAULT RESPONSE
SHORT-CIRCUIT RESPONSE
MAX4978-81toc12
BATTERY OVERVOLTAGE FAULT RESPONSE
MAX4978-81 toc10
MAX4978-81 toc11
R = 1kΩ
L
V
IN
2V/div
2V/div
V
BAT
V
OUT
V
IN
5V/div
2V/div
2V/div
V
SDT
V
5V/div
1A/div
OUT
V
OUT
I
OUT
4μs/div
100ms/div
2μs/div
7–MAX4981
Pin Description
PIN
NAME
FUNCTION
MAX4978/ MAX4980/
MAX4979
MAX4981
Supply Voltage Input. IN powers the charge pump required to turn on the internal FET.
When the correct adapter is plugged in, a 160ms debounce timer prevents a false turn-on of
the internal FET. Bypass IN to GND with a 1µF ceramic capacitor as close to the device as
possible to enable 15kV (HBM) ESD protection.
1
1
IN
Startup Debounce Time Indicator. SDT is an active-low open-drain output that asserts low
during the debounce/autoretry time.
2
—
2
SDT
Battery Monitor Input. Connect BAT to Li-ion battery terminal. Bypass BAT to GND with a 1µF
ceramic capacitor as close to the device as possible to enable 15kV (HBM) ESD protection.
—
BAT
3, 6, 7
3, 6, 7
I.C.
Internally Connected. Connect I.C. to GND.
4
5
8
4
5
8
EN
Active-Low Enable Input. Drive EN low for normal operation. Drive EN high to disable the device.
GND Ground
OUT Output Voltage. Output of internal FET.
Exposed Pad. Internally connected to GND. Connect EP to a large ground plane to maximize
thermal performance. Do not use EP as the sole GND connection.
—
—
EP
6
_______________________________________________________________________________________
Overvoltage Protector with
Active Current Limit
7–MAX4981
MAX4978/MAX4979 Functional Diagram
IN
OUT
nFET
CHARGE
PUMP
BANDGAP
REFERENCE
OVLO
UVLO
+
-
CONTROL
LOGIC
EN
+
-
MAX4978
MAX4979
SDT
GND
MAX4980/MAX4981 Functional Diagram
OUT
IN
nFET
CHARGE
PUMP
BANDGAP
REFERENCE
OVLO
UVLO
+
-
+
-
CONTROL
LOGIC
EN
-
+
BAT
MAX4980
MAX4981
GND
_______________________________________________________________________________________
7
Overvoltage Protector with
Active Current Limit
Battery Overcharge Protector
(MAX4980/MAX4981)
Detailed Description
The MAX4978–MAX4981 family of devices is a combi-
The MAX4980/MAX4981 feature a battery overcharge
protection input (BAT) that triggers a voltage fault, turn-
nation of an overvoltage protector, overcurrent limiter,
and lithium-ion battery overcharge protector (MAX4980/
MAX4981). These devices feature a low 85mΩ (typ)
ing off the FET, when V
exceeds 4.4V.
BAT
R
ON
FET and are used to protect the charger input port
Startup Debounce Time Indicator (SDT)
(MAX4978/MAX4979)
on a portable device. If the input voltage exceeds the
overvoltage threshold (OVLO) or falls below the under-
voltage threshold (UVLO), the FET is turned off to pre-
vent damage to the protected components. The internal
charge pump’s 160ms debounce time prevents false
turn-on of the internal FET during startup. SDT is an
active-low open-drain output that asserts low during the
debounce time after a valid voltage is applied to the
input (MAX4978/MAX4979).
SDT is an open-drain output that asserts low during the
startup debounce time and during the autoretry time.
SDT returns to high impedance once the charge pump
turns on. This feature is useful for discharging the AC
adapter capacitance during the startup debounce time
(Figures 1, 2).
Thermal Shutdown Protection
The MAX4978–MAX4981 have a thermal-shutdown fea-
ture to protect the devices from overheating. The
device immediately turns off when the junction temper-
ature exceeds +160°C (typ). These devices exit thermal
shutdown after the junction temperature cools by 10°C
(typ).
The MAX4978–MAX4981 feature an overcurrent limiter
as a second layer of protection for a lithium-ion battery
charger that limits current to a 900mA (MAX4978/
MAX4979/MAX4980) or 1950mA (MAX4981) threshold
for a 20ms blanking time. At the end of the blanking time,
if current is still at the threshold, the FET is turned off and
the device restarts the cycle after 160ms. The battery
voltage monitor measures the voltage of a lithium-ion
battery and disables the FET if the battery voltage
exceeds 4.4V (MAX4980/MAX4981).
7–MAX4981
EN Input
EN is an active-low enable input. Drive EN low for nor-
mal operation. Drive EN high to disable the device.
Applications Information
Autoretry
When the current-limit threshold is reached, the t
BLANK
IN Bypass Capacitor
For most applications, bypass IN to GND with a 1µF
ceramic capacitor as close to the device as possible to
enable 15kV (HBM) ESD protection on IN. If the power
source has significant inductance due to long lead
length, take care to prevent overshoots due to the LC
tank circuit and provide protection if necessary to pre-
vent exceeding the 30V absolute maximum rating on IN.
timer begins counting. The timer resets if the overcur-
rent condition disappears before t has elapsed.
BLANK
A retry time delay, t
BLANK
At the end of t
, is started immediately after
RETRY
t
has elapsed and during that time, the FET is off.
, the FET is turned on again. If the
RETRY
fault still exists, the cycle is repeated. If the fault has
been removed, the FET stays on.
Undervoltage Lockout (UVLO)
The MAX4978 has a 4.4V UVLO threshold, while the
MAX4979/MAX4980/MAX4981 have a 2.63V UVLO
threshold. When an undervoltage lockout condition
occurs with high load current, the voltage at the input to
the UVLO comparator may recover due to internal para-
sitic resistance causing the device to restart.
BAT Bypass Capacitor
For most applications, bypass BAT to GND with a 1µF
ceramic capacitor as close to the device as possible to
enable 15kV (HBM) ESD protection on BAT. If high
ESD protection is not necessary, no capacitor is
required on BAT.
ESD Test Conditions
ESD performance depends on a number of conditions.
The MAX4978–MAX4981 are specified for 15kV
(HBM) typical ESD resistance on IN and BAT when IN
and BAT are bypassed to ground with a 1µF low ESR
ceramic capacitor. Contact Maxim for a reliability report
that documents test setup, methodology, and results.
Overvoltage Lockout (OVLO)
The MAX4979 has a 6.8V OVLO threshold, while the
MAX4978/MAX4980/MAX4981 have a 5.7V OVLO
threshold.
8
_______________________________________________________________________________________
Overvoltage Protector with
Active Current Limit
7–MAX4981
LONG WIRE
RESISTANCE
CHARGER
IN
OUT
AC-DC
PHONE
CONVERTER
LOADS
nFET
~0.5Ω
1μF
5V AC
ADAPTER
CHARGE
C0NTROL
PUMP
BANDGAP
REFERENCE
OVLO
UVLO
+
1kΩ
-
EN
CONTROL
LOGIC
+
-
MAX4978/
MAX4979
SDT
GND
Figure 2. Typical Application Circuit with SDT
R
C
R
D
1MΩ
1.5kΩ
I 100%
90%
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
I
P
r
DISCHARGE
RESISTANCE
CHARGE CURRENT-
LIMIT RESISTOR
AMPERES
HIGH-
VOLTAGE
DC
DEVICE
UNDER
TEST
36.8%
C
s
100pF
STORAGE
CAPACITOR
10%
0
SOURCE
TIME
0
t
RL
t
DL
CURRENT WAVEFORM
Figure 3. Human Body ESD Test Model
Figure 4. Human Body Current Waveform
Human Body Model
Figure 3 shows the Human Body Model, and Figure 4
shows the current waveform it generates when dis-
charged into a low impedance. This model consists of a
100pF capacitor charged to the ESD voltage of interest
that is then discharged into the device through a 1.5kΩ
resistor.
Chip Information
PROCESS: BiCMOS
_______________________________________________________________________________________
9
Overvoltage Protector with
Active Current Limit
Typical Application Circuit
CHARGER
IN
OUT
5V AC
PHONE
ADAPTER
LOADS
nFET
1µF
CHARGE
PUMP
C0NTROL
BANDGAP
REFERENCE
OVLO
UVLO
+
-
+
-
EN
CONTROL
LOGIC
7–MAX4981
-
BAT
+
MAX4980
MAX4981
GND
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
8 TDFN-EP
T823-1
21-0174
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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