19-3885; Rev 0; 12/05
KIT
ATION
EVALU
BLE
AVAILA
Low-Cost Battery Charger
General Description
Features
♦
♦
♦
♦
Small Inductor (3.5µH)
Programmable Charge Current > 4.5A
Automatic Power-Source Selection
Analog Inputs Control Charge Current and
Charge Voltage
♦
Monitor Outputs for
AC Adapter Current
Battery-Discharge Current
AC Adapter Presence
♦
Independent 3.3V 20mA Linear Regulator
♦
Up to 17.6V (max) Battery Voltage
♦
+8V to +28V Input Voltage Range
♦
Reverse Adapter Protection
♦
System Short-Circuit Protection
♦
Cycle-by-Cycle Current Limit
MAX8730
The MAX8730 highly integrated, multichemistry, battery-
charger control IC simplifies construction of accurate
and efficient chargers. The MAX8730 operates at high
switching frequency to minimize external component
size and cost. The MAX8730 uses analog inputs to con-
trol charge current and voltage, and can be pro-
grammed by a microcontroller or hardwired.
The MAX8730 reduces charge current to give priority to
the system load, effectively limiting the adapter current
and reducing the adapter current requirements.
The MAX8730 provides a digital output that indicates
the presence of an AC adapter, and an analog output
that monitors the current drawn from the AC adapter.
Based on the presence and absence of the AC
adapter, the MAX8730 automatically selects the appro-
priate source for supplying power to the system by con-
trolling two external switches. Under system control, the
MAX8730 allows the battery to undergo a relearning
cycle in which the battery is completely discharged
through the system load and then recharged.
An analog output indicates adapter current or battery-
discharge current. The MAX8730 provides a low-quies-
cent-current linear regulator, which may be used when
the adapter is absent, or disabled for reduced current
consumption
The MAX8730 is available in a small, 5mm x 5mm, 28-
pin, thin (0.8mm) QFN package. An evaluation kit is
available to reduce design time. The MAX8730 is
available in a lead-free package.
Ordering Information
PART
MAX8730ETI+
TEMP
RANGE
-40°C to +85°C
PIN-
PACKAGE
28 Thin QFN
(5mm x 5mm)
PKG
CODE
T2855-5
+Denotes
lead-free package.
Typical Operating Circuit
ADAPTER
INPUT
SYSTEM
LOAD
Applications
Notebook Computers
Tablet PCs
Portable Equipment with Rechargeable Batteries
CSSP
PDS
SRC
CSSN
DHIV
PDL
DHI
ASNS
MAX8730
CSIP
CSIN
BATT
SWREF
REF
BATTERY
LDO
REF
ACIN
ACOK
VCTL
CLS
MODE
ICTL
REFON
INPON
HOST
RELTH
LDO
CCS
CCV
GND
Pin Configuration appears at end of data sheet.
IINP
CCI
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Low-Cost Battery Charger
MAX8730
ABSOLUTE MAXIMUM RATINGS
CSSP, SRC,
A C O K,
ASNS, DHIV, BATT,
CSIP to GND.......................................................-0.3V to +30V
CSIP to CSIN or CSSP to CSSN ............................-0.3V to +0.3V
DHIV to SRC .................................................-6V to (SRC + 0.3V)
DHI to DHIV ...............................................-0.3V to (SRC + 0.3V)
PDL, PDS to GND ........................................-0.3V to (SRC + 0.3)
CCI, CCS, CCV, IINP, SWREF, REF,
MODE, ACIN to GND.............................-0.3V to (LDO + 0.3V)
RELTH, VCTL, ICTL, REFON, CLS, LDO,
INPON to GND .....................................................-0.3V to +6V
LDO Short-Circuit Current...................................................50mA
Continuous Power Dissipation (T
A
= +70°C)
28-Pin TQFN (derate 20.8mW/°C above +70°C) .......1667mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature
............................................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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
(Circuit of Figure 1. V
SRC
= V
ASNS
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
VCTL
= V
ICTL
= 1.8V, MODE = float,
ACIN = 0, CLS = REF, REFON = LDO, INPON = LDO, RELTH = 2V.
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at
T
A
= +25°C.)
PARAMETER
CHARGE-VOLTAGE REGULATION
VCTL Range
V
VCTL
= 3.6V
or 0V
Not including resistor
tolerances
Including 1% resistor
tolerances
0
-1.0
-1.05
-0.5
4.4
0
0
4
16
µA
3.6
+1.0
+1.05
+0.5
V
%
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Battery-Regulation Voltage
Accuracy
V
VCTL
= VLDO (3 or 4 cells)
V
VCTL
Default Threshold
VCTL Input Bias Current
CHARGE-CURRENT REGULATION
ICTL Range
Full-Charge-Current Accuracy
(CSIP to CSIN)
Trickle-Charge-Current Accuracy
Charge-Current Gain Error
Charge-Current Offset Error
BATT/CSIP/CSIN Input Voltage
Range
Charging enabled
CSIP/CSIN Input Current
Charging disabled, SRC = BATT,
ASNS = GND or V
ICTL
= 0V
V
ICTL
= 3.6V
VI
CTL
= 2.0V
V
ICTL
= 120mV
Based on V
ICTL
= 3.6V and V
ICTL
= 0.12V
Based on V
ICTL
= 3.6V and V
ICTL
= 0.12V
V
VCTL
rising
V
VCTL
= 3V
SRC = BATT, ASNS = GND INPON =
REFON = 0, V
VCTL
= 5V
0
128.25
-5
71.25
-5
2.5
-1.9
-2
0
300
8
4.5
75
135
3.6
141.75
+5
78.75
+5
7.5
+1.9
+2
19
600
16
V
mV
%
mV
%
mV
%
mV
V
µA
2
_______________________________________________________________________________________
Low-Cost Battery Charger
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1. V
SRC
= V
ASNS
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
VCTL
= V
ICTL
= 1.8V, MODE = float,
ACIN = 0, CLS = REF, REFON = LDO, INPON = LDO, RELTH = 2V.
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at
T
A
= +25°C.)
PARAMETER
ICTL Power-Down Mode
Threshold
ICTL Input Bias Current
CSSP-to-CSSN Full-Scale
Current-Sense Voltage
V
CLS
= REF (trim point)
Input Current-Limit Accuracy
V
CLS
= REF x 0.7
V
CLS
= REF x 0.5
CSSP/CSSN Input Voltage Range
CSSP/CSSN Input Current
CLS Input Range
CLS Input Bias Current
IINP Transconductance
V
CLS
= 2.0V
V
CSSP
- V
CSSN
= 56mV
V
CSSP
- V
CSSN
= 100mV, V
IINP
= 0 to 4.5V
IINP Accuracy
V
CSSP
- V
CSSN
= 75mV
V
CSSP
- V
CSSN
= 56mV
V
CSSP
- V
CSSN
= 20mV
IINP Gain Error
IINP Offset Error
IINP Fault threshold
SUPPLY AND LINEAR REGULATOR
SRC Input Voltage Range
SRC Undervoltage Lockout
Threshold
SRC falling
SRC rising
8.0
7
7.4
7.5
8
28
V
V
Based on V
ICTL
= REF x 0.5 and V
ICTL
= REF
Based on V
ICTL
= REF x 0.5 and V
ICTL
= REF
IINP rising
V
CSSP
= V
CSSN
= V
SRC
> 8.0V
V
SRC
= 0V
1.1
-1
2.66
-5
-8
-5
-12.5
-7
-2
4.1
4.2
2.8
SYMBOL
ICTL falling
ICTL rising
V
ICTL
= 3V
SRC = BATT, ASNS = GND, V
ICTL
= 5V
CONDITIONS
MIN
50
70
-1
-1
72.75
72.75
-4
50
-5.6
36
-6.6
8.0
400
0.1
38
53
75.75
75.75
TYP
65
90
MAX
80
110
+1
+1
78.75
78.75
+4
56
+5.6
40.5
+6.6
28
800
1
REF
+1
2.94
+5
+8
+5
+12.5
+7
+2
4.3
%
mV
V
%
UNITS
mV
µA
mV
mV
%
mV
%
mV
%
V
µA
V
µA
µA/mV
MAX8730
_______________________________________________________________________________________
3
Low-Cost Battery Charger
MAX8730
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1. V
SRC
= V
ASNS
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
VCTL
= V
ICTL
= 1.8V, MODE = float,
ACIN = 0, CLS = REF, REFON = LDO, INPON = LDO, RELTH = 2V.
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at
T
A
= +25°C.)
PARAMETER
SYMBOL
Normal mode
V
INPON
=V
REFON
= low
SRC Quiescent Current
(INPON/REFON = Don’t Care)
V
SRC
= V
BATT
=
12V, ASNS =
GND (Note 2)
V
INPON
= low,
V
REFON
= high
V
INPON
= high,
V
REFON
= low
V
INPON
= V
REFON
= high
BATT Input Current
V
BATT
= 16.8V, V
SRC
= 19V, ICTL = 0
V
BATT
= 2V to 19V, V
SRC
> V
BATT
+ 0.3V
I
CSIP
+ I
CSIN
+ I
BATT
, ASNS = GND
Battery-Leakage Current
I
CSIP
+ I
CSIN
+ I
BATT
+
I
CSSP
+ I
CSSN
+ I
SRC
,
ASNS = REFON = GND
8.0V < V
SRC
< 28V, no load
0 < ILDO < 10mA
V
SRC
= 8.0V
V
REFON
= 5.4V
INPON = GND
5.2
CONDITIONS
MIN
TYP
4
10
300
300
350
8
300
2
300
2
5.35
20
4
MAX
6
20
600
µA
600
600
16
600
5
600
5
5.5
50
V
mV
V
µA
µA
UNITS
mA
LDO Output Voltage
LDO Load Regulation
LDO Undervoltage Lockout
Threshold
REFERENCES
REF Output Voltage
REF Undervoltage Lockout
Threshold
SWREF Output Voltage
SWREF Load Regulation
TRIP POINTS
ACIN Threshold
ACIN Threshold Hysteresis
ACIN Input Bias Current
SWITCHING REGULATOR
DHI Off-Time
DHI Off-Time K Factor
Sense Voltage for Minimum
Discontinuous Mode Ripple
Current
Cycle-by-Cycle Current-Limit
Sense Voltage
Charge Disable Threshold
DHIV Output Voltage
DHIV Sink Current
Ref
4.18
REF falling
8.0V < VSRC < 28V, no load
0.1mA < I
SWREF
< 20mA
ACIN rising
V
ACIN
= 2.048V
V
BATT
= 16.0V
V
BATT
= 16.0V
V
CSIP
- V
CSIN
2.037
-1
300
4.8
3.234
4.20
3.1
3.3
20
2.1
60
4.22
3.9
3.366
50
2.163
+1
V
V
V
mV
V
mV
µA
ns
V x µs
mV
350
5.6
7
400
6.4
160
V
SRC
- V
BATT
, SRC falling
With respect to SRC
40
-4.3
10
200
60
-4.8
240
80
-5.5
mV
mV
V
mA
4
_______________________________________________________________________________________
Low-Cost Battery Charger
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1. V
SRC
= V
ASNS
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
VCTL
= V
ICTL
= 1.8V, MODE = float,
ACIN = 0, CLS = REF, REFON = LDO, INPON = LDO, RELTH = 2V.
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at
T
A
= +25°C.)
PARAMETER
DHI Resistance Low
DHI Resistance High
ERROR AMPLIFIERS
GMV Loop Transconductance
GMI Loop Transconductance
GMS Loop Transconductance
CCI/CCS/CCV Clamp Voltage
LOGIC LEVELS
MODE, REFON Input Low Voltage
MODE Input Middle Voltage
MODE, REFON Input High Voltage
MODE, REFON, INPON Input
Bias Current
INPON Threshold
ADAPTER DETECTION
ACOK Voltage Range
ACOK Sink Current
ACOK Leakage Current
BATTERY DETECTION
BATT Overvoltage Threshold
BATT Overvoltage Hysteresis
RELTH Operating Voltage Range
RELTH Input Bias Current
BATT Minimum Voltage Trip
Threshold
PDS, PDL SWITCH CONTROL
Adapter-Absence Detect
Threshold
Adapter-Detect Threshold
PDS Output Low Voltage
PDS/PDL Output High Voltage
PDS/PDL Turn-Off Current
V
ASNS
- V
BATT
, V
ASNS
falling
V
ASNS
- V
BATT
Result with respect to SRC, I
PDS
= 0
Result with respect to SRC, I
PD_
= 0
V
PDS
= V
SRC
- 2V, V
SRC
= 16V
6
-300
-140
-8
-280
-100
-10
-0.2
12
-240
-60
-12
-0.5
mV
mV
V
V
mA
V
RELTH
= 0.9V to 2.6V
V
BATT
falling
V
RELTH
= 0.9V
V
RELTH
= 2.6V
0.9
-50
4.42
12.77
4.5
13.0
V
VCTL
= V
LDO
, BATT
rising; result with respect
to battery-set voltage
V
MODE
= V
LDO
V
MODE
= FLOAT
+140
mV
+100
100
2.6
+50
4.58
13.23
mV
V
nA
V
V
ACOK
= 0.4V, ACIN = 1.5V
V
ACOK
= 28V, ACIN = 2.5V
0
1
1
28
V
mA
µA
MODE = 0 or 3.6V
V
INPON
rising
V
INPON
falling
1.9
3.4
-2
2.2
0.8
+2
2.65
0.5
3.3
V
V
V
µA
V
V
VCTL = 3.6V, V
BATT
= 16.8V, MODE = LDO
VCTL = 3.6V, V
BATT
= 12.6V, MODE = FLOAT
ICTL = 3.6V, V
CSSP
- V
CSIN
= 75mV
V
CLS
= 2.048V, V
CSSP
- V
CSSN
= 75mV
1.1V < V
CCV
< 3.0V,
1.1V < V
CCI
< 3.0V,
1.1V < V
CCS
< 3.0V
0.0625
0.0833
0.5
0.5
150
0.125
0.167
1
1
300
0.250
0.333
2
2
600
mA/V
mA/V
mA/V
mV
SYMBOL
I
DHI
= -10mA
I
DHI
= 10mA
CONDITIONS
MIN
TYP
2
1
MAX
4
2
UNITS
Ω
Ω
MAX8730
_______________________________________________________________________________________
5
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
