Maxim MAX1648 Chemistry-independent battery charger Datasheet

19-1158; Rev 0; 12/96
Chemistry-Independent
Battery Chargers
The MAX1647/MAX1648 provide the power control necessary to charge batteries of any chemistry. In the MAX1647,
all charging functions are controlled via the Intel System
Management Bus (SMBus™) interface. The SMBus 2-wire
serial interface sets the charge voltage and current, and
provides thermal status information. The MAX1647 functions as a level 2 charger, compliant with the Duracell/Intel
Smart Battery Charger Specification. The MAX1648 omits
the SMBus serial interface, and instead sets the charge
voltage and current proportional to the voltage applied to
external control pins.
In addition to the feature set required for a level 2 charger,
the MAX1647 generates interrupts to signal the host when
power is applied to the charger or a battery is installed or
removed. Additional status bits allow the host to check
whether the charger has enough input voltage, and
whether the voltage on or current into the battery is being
regulated. This allows the host to determine when lithiumion batteries have completed charge without interrogating
the battery.
The MAX1647 is available in a 20-pin SSOP with a 2mm
profile height. The MAX1648 is available in a 16-pin SO
package.
________________________Applications
Notebook Computers
Personal Digital Assistants
____________________________Features
♦ Charges Any Battery Chemistry:
Li-Ion, NiCd, NiMH, Lead Acid, etc.
♦ Intel SMBus 2-Wire Serial Interface (MAX1647)
♦ Intel/Duracell Level 2 Smart Battery Compliant
(MAX1647)
♦ 4A, 2A, or 1A Maximum Battery-Charge Current
♦ 11-Bit Control of Charge Current
♦ Up to 18V Battery Voltage
♦ 10-Bit Control of Voltage
♦ ±0.75% Voltage Accuracy with External ±0.1%
Reference
♦ Up to 28V Input Voltage
♦ Battery Thermistor Fail-Safe Protection
______________Ordering Information
TEMP. RANGE
PIN-PACKAGE
MAX1647EAP
-40°C to +85°C
20 SSOP
MAX1648ESE
-40°C to +85°C
16 Narrow SO
PART
Charger Base Stations
Phones
__________________________________________________________Pin Configurations
TOP VIEW
IOUT
1
20 BST
DCIN 2
19 LX
16 BST
DCIN 1
15 LX
VL 3
18 DHI
VL 2
CCV 4
17 DLO
CCV 3
16 PGND
CCI 4
15 DACV
CS 5
12 PGND
14 SDA
BATT 6
11 SETV
10 SETI
CCI
5
MAX1647
SEL 6
CS
7
BATT
8
13 SCL
REF 7
REF
9
12 THM
AGND 8
AGND 10
11 INT
14 DHI
MAX1648
13 DLO
9
THM
SO
SSOP
SMBus is a trademark of Intel Corp.
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
MAX1647/MAX1648
_______________General Description
MAX1647/MAX1648
Chemistry-Independent
Battery Chargers
ABSOLUTE MAXIMUM RATINGS
DCIN to AGND..........................................................-0.3V to 30V
DCIN to IOUT...........................................................-0.3V to 7.5V
BST to AGND ............................................................-0.3V to 36V
BST, DHI to LX ............................................................-0.3V to 6V
LX to AGND ..............................................................-0.3V to 30V
THM, CCI, CCV, DACV, REF,
DLO to AGND ................................................-0.3V to (VL + 0.3V)
VL, SEL, INT, SDA, SCL to AGND (MAX1647) ...........-0.3V to 6V
SETV, SETI to AGND (MAX1648)................................-0.3V to 6V
BATT, CS+ to AGND.................................................-0.3V to 20V
PGND to AGND .....................................................-0.3V to +0.3V
SDA, INT Current ................................................................50mA
VL Current ...........................................................................50mA
Continuous Power Dissipation (TA = +70°C)
16-Pin SO (derate 8.7mW/°C above +70°C).................696mW
20-Pin SSOP (derate 8mW/°C above +70°C) ...............640mW
Operating Temperature Range
MAX1647EAP, MAX1648ESE ...........................-40°C to +85°C
Storage Temperature.........................................-60°C to +150°C
Lead Temperature (soldering, 10sec) .............................+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
(VDCIN = 18V, VREF = 4.096V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
SUPPLY AND REFERENCE
DCIN Input Voltage Range
7.5
DCIN Quiescent Current
7.5V < VDCIN < 28V, logic inputs = VL
VL Output Voltage
7.5V < VDCIN < 28V, no load
VL Load Regulation
ILOAD = 10mA
VL AC_PRESENT Trip Point
MAX1647
3.20
REF Output Voltage
0µA < ISOURCE < 500µA
3.74
5.15
28
V
4
6
mA
5.4
5.65
V
100
mV
4
5.15
V
3.9
4.07
V
700
µA
300
kHz
REF Overdrive Input Current
SWITCHING REGULATOR
Oscillator Frequency
200
250
DHI Maximum Duty Cycle
89
93
%
DHI On-Resistance
High or low
4
7
Ω
DLO On-Resistance
High or low
6
14
Ω
VL < 3.2V, VBATT = 12V
1
5
VL < 5.15V, VBATT = 12V
350
500
BATT Input Current (Note 1)
CS Input Current (Note 1)
VL < 3.2V, VCS = 12V
1
5
VL < 5.15V, VCS = 12V
170
400
BATT, CS Input Voltage Range
0
CS to BATT Single-Count
Current-Sense Voltage
MAX1647, SEL = open,
ChargingCurrent( ) = 0x0020
CS to BATT Full-Scale
Current-Sense Voltage
MAX1647, SEL = open,
ChargingCurrent( ) = 0x07F0;
MAX1648, VSETI = 1.024V
Voltage Accuracy
MAX1647, ChargingVoltage( ) = 0x1060,
ChargingVoltage( ) = 0x3130; MAX1648,
VSETV = 3.15V, VSETV = 1.05V
2
19
2.94
170
185
-0.65
_______________________________________________________________________________________
µA
µA
V
mV
200
mV
0.65
%
Chemistry-Independent
Battery Chargers
MAX1647/MAX1648
ELECTRICAL CHARACTERISTICS (continued)
(VDCIN = 18V, VREF = 4.096V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
ERROR AMPLIFIERS
GMV Amplifier Transconductance
1.4
mA/V
GMI Amplifier Transconductance
0.2
mA/V
GMV Amplifier Maximum
Output Current
±80
µA
GMI Amplifier Maximum
Output Current
±200
µA
CCI Clamp Voltage with
Respect to CCV
1.1V < VCCV < 3.5V
25
80
200
mV
CCV Clamp Voltage with
Respect to CCI
1.1V < VCCI < 3.5V
25
80
200
mV
TRIP POINTS AND LINEAR CURRENT SOURCES
BATT POWER_FAIL Trip Point
MAX1647
86.5
89
91.5
% of
VDCIN
THM THERMISTOR_OR
Over-Range Trip Point
MAX1647
89.5
91
92.5
% of
VREF
THM THERMISTOR_COLD
Trip Point
74
75.5
77
% of
VREF
THM THERMISTOR_HOT
Trip Point
22
23.5
25
% of
VREF
3
4.5
6
% of
VREF
25
31
35
mA
10
µA
-1.0
V
THM THERMISTOR_UR
Under-Range Trip Point
MAX1647
IOUT Output Current
MAX1647,
VDCIN = 7.5V,
VIOUT = 0V
IOUT Operating Voltage Range
With respect to DCIN voltage
ChargingCurrent( ) = 0x001F
ChargingCurrent( ) = 0x0000
-7.5
CURRENT- AND VOLTAGE-SETTING DACs (MAX1647)
CDAC Current-Setting DAC Resolution
Guaranteed monotonic
6
bits
VDAC Voltage-Setting DAC Resolution
Guaranteed monotonic
10
bits
SETV, SETI (MAX1648)
SETV Input Bias Current
SETI Input Bias Current
1
µA
5
µA
SETV Input Voltage Range
0
4.2
V
SETI Input Voltage Range
0
1.024
V
0.8
V
LOGIC LEVELS (MAX1647)
SDA, SCL Input Low Voltage
SDA, SCL Input High Voltage
2.8
SDA, SCL Input Bias Current
SDA Output Low Sink Current
-1
VSDA = 0.6V
V
1
6
µA
mA
Note 1: When DCIN is less than 4V, VL is less than 3.2V, causing the battery current to be typically 2µA (CS plus BATT input
current).
_______________________________________________________________________________________
3
MAX1647/MAX1648
Chemistry-Independent
Battery Chargers
ELECTRICAL CHARACTERISTICS
(VDCIN = 18V, VREF = 4.096V, TA = -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted. Limits over this
temperature range are guaranteed by design.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
SUPPLY AND REFERENCE
DCIN Quiescent Current
7.5V < VDCIN < 28V, logic inputs = VL
4
6
mA
VL Output Voltage
7.5V < VDCIN < 28V, no load
5.15
5.4
5.65
V
REF Output Voltage
0µA < ISOURCE < 500µA
3.74
3.9
4.07
V
200
250
310
kHz
SWITCHING REGULATOR
Oscillator Frequency
DHI Maximum Duty Cycle
89
%
DHI On-Resistance
High or low
4
7
Ω
DLO On-Resistance
High or low
6
14
Ω
BATT Input Current
VL < 3.2V, VBATT = 12V
5
µA
CS Input Current
VL < 3.2V, VCS = 12V
5
µA
CS to BATT Full-Scale
Current-Sense Voltage
MAX1647, SEL = open,
ChargingCurrent( ) = 0x07F0;
MAX1648, VSETI = 1.024V
200
mV
Voltage Accuracy
MAX1647, ChargingVoltage( ) = 0x1060,
ChargingVoltage( ) = 0x3130; MAX1648,
VSETV = 3.15V, VSETV = 1.05V
0.65
%
160
185
-0.65
ERROR AMPLIFIERS
GMV Amplifier Transconductance
1.4
mA/V
GMI Amplifier Transconductance
0.2
mA/V
GMV Amplifier Maximum
Output Current
±130
µA
GMI Amplifier Maximum
Output Current
±320
µA
TRIP POINTS AND LINEAR CURRENT SOURCES
THM THERMISTOR_OR
Over-Range Trip Point
89.5
91
92.5
% of
VREF
THM THERMISTOR_COLD
Trip Point
74
75.5
77
% of
VREF
THM THERMISTOR_HOT
Trip Point
22
23.5
25
% of
VREF
3
4.5
6
% of
VREF
SETV Input Bias Current
1
µA
SETI Input Bias Current
5
µA
0.8
V
1
µA
THM THERMISTOR_UR
Under-Range Trip Point
MAX1647
MAX1647
SETV, SETI (MAX1648)
LOGIC LEVELS (MAX1647)
SDA, SCL Input Low Voltage
SDA, SCL Input High Voltage
2.8
SDA, SCL Input Bias Current
-1
SDA Output Low Sink Current
4
VSDA = 0.6V
6
_______________________________________________________________________________________
V
mA
Chemistry-Independent
Battery Chargers
MAX1647/MAX1648
TIMING CHARACTERISTICS—MAX1647
(TA = 0°C to +85°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SCL Serial-Clock High Period
tHIGH
4
µs
SCL Serial-Clock Low Period
tLOW
4.7
µs
Start-Condition Setup Time
tSU:STA
4.7
µs
Start-Condition Hold Time
tHD:STA
4
µs
SDA Valid to SCL Rising-Edge
Setup Time, Slave Clocking in Data
tSU:DAT
250
ns
SCL Falling Edge to SDA Transition
tHD:DAT
0
ns
SCL Falling Edge to SDA Valid,
Master Clocking in Data
tDV
1
µs
MAX
UNITS
TIMING CHARACTERISTICS—MAX1647
(TA = -40°C to +85°C, unless otherwise noted. Limits over this temperature range are guaranteed by design.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
SCL Serial-Clock High Period
tHIGH
4
µs
SCL Serial-Clock Low Period
tLOW
4.7
µs
Start-Condition Setup Time
tSU:STA
4.7
µs
Start-Condition Hold Time
tHD:STA
4
µs
SDA Valid to SCL Rising-Edge
Setup Time, Slave Clocking in Data
tSU:DAT
250
ns
SCL Falling Edge to SDA Transition
tHD:DAT
0
ns
SCL Falling Edge to SDA Valid,
Master Clocking in Data
tDV
1
µs
_______________________________________________________________________________________
5
__________________________________________Typical Operating Characteristics
(Circuit of Figure 3, TA = +25°C, unless otherwise noted.)
MAX1647
BATT LOAD TRANSIENT
MAX1647
BATT LOAD TRANSIENT
MAX1647/48-02
MAX1647/48-01
1.1A TO 0.9A TO 1.1A
CCI
CCI
VCCV
2.3V VCCI
100mV/div
CCV
CCV
VCCI
2.4V VCCV
200mV/div
CCI
CCV
12V
CCV
CCV
CCI
CCI
VBATT
1V/div
12V
VBATT
5V/div
0.9A TO 1.9A TO 0.9A
2ms/div
1ms/div
ChargingVoltage( ) = 0x2EE0 = 12000mV
ChargingCurrent( ) = 0x03E8 = 1000mA
ACDCIN = 18.0V, SEL = OPEN, C1 = 68µF,
C2 = 0.1µF, C3 = 47nF, R1 = 0.1Ω
R2 = 10kΩ, L1 = 22µH, VREF = 4.096V
ChargingVoltage( ) = 0x2EE0 = 12000mV
ChargingCurrent( ) = 0xFFFF = MAX VALUE
ACDCIN = 18.0V, SEL = OPEN, R1 = 0.1Ω
R2 = 10kΩ, C1 = 68µF, C2 = 0.1µF, C3 = 47nF
L1 = 22µH, VREF = 4.096V
VL VOLTAGE vs. LOAD CURRENT
INTERNAL REFERENCE VOLTAGE
5.0
MAX1647/48-04
3.86
MAX1647/48-03
5.5
3.84
3.82
VL (V)
VREF (V)
4.5
4.0
3.80
3.78
3.76
3.74
3.5
CIRCUIT OF FIGURE 3
VDCIN = 6.6V
3.72
0
3.70
10
20
30
50
40
0
0.5
LOAD CURRENT (mA)
MAX1647
OUTPUT V-I CHARACTERISTIC
25
20
POWER INTO
CIRCUIT
15
10
POWER TO BATT
5
0
6
MAX1647/48-06
BATT NO-LOAD
OUTPUT VOLTAGE = 16.384V
0.01
OUTPUT VOLTAGE ERROR
0.1
1
10
VDCIN = 28V, VREF = 4.096V
ChargingVoltage( ) = 0xFFFF
ChargingCurrent( ) = 0xFFFF
100
0
500
1000
1500
2000
CURRENT INTO BATT (mA)
2500
2.0
1.5
0.8
OUTPUT VOLTAGE ERROR (%)
30
0.001
DROP IN BATT OUTPUT VOLTAGE (%)
VDCIN = 28V
VBATT = 12.6V
ChargingCurrent( ) = 0xFFFF
ChargingVoltage( ) = 0xFFFF
35
MAX1647/48-05
INPUT AND OUTPUT POWER
40
1.0
LOAD CURRENT (mA)
MAX1647/48-07
0
POWER (W)
MAX1647/MAX1648
Chemistry-Independent
Battery Chargers
0.6
3mA LOAD
0.4
0.2
0
300mA LOAD
-0.2
-0.4
0
500
1000
1500
LOAD CURRENT (mA)
2000
2500
4500
8500
12,500
16,500
PROGRAMMED VOLTAGE CODE IN DECIMAL
_______________________________________________________________________________________
Chemistry-Independent
Battery Chargers
PIN
NAME
FUNCTION
MAX1647
MAX1648
1
—
IOUT
Linear Current-Source Output
2
1
DCIN
Input Voltage for Powering Charger
3
2
VL
4
3
CCV
Voltage-Regulation-Loop Compensation Point
5
4
CCI
Current-Regulation-Loop Compensation Point
6
—
SEL
Current-Range Selector. Tying SEL to VL sets a 4A full-scale current. Leaving SEL open
sets a 2A full-scale current. Tying SEL to AGND sets a 1A full-scale current.
7
5
CS
Current-Sense Positive Input
8
6
BATT
9
7
REF
10
8
AGND
—
10
SETI
Current-Regulation-Loop Set Point
11
—
INT
Open-Drain Interrupt Output
—
11
SETV
Voltage-Regulation-Loop Set Point
12
9
THM
Thermistor Sense Voltage Input
13
—
SCL
Serial Clock
14
—
SDA
Serial Data
15
—
DACV
Voltage DAC Output
16
12
PGND
Power Ground
17
13
DLO
Low-Side Power MOSFET Driver Output
18
14
DHI
High-Side Power MOSFET Driver Output
19
15
LX
Power Connection for the High-Side Power MOSFET Driver
20
16
BST
Power Connection for the High-Side Power MOSFET Driver
Chip Power Supply. 5.4V linear regulator output from DCIN.
Battery Voltage Input and Current-Sense Negative Input
3.9V Reference Voltage Output or External Reference Input
Analog Ground
_______________________________________________________________________________________
7
MAX1647/MAX1648
______________________________________________________________Pin Description
MAX1647/MAX1648
Chemistry-Independent
Battery Chargers
START
CONDITION
MOST SIGNIFICANT
ADDRESS BIT (A6)
CLOCKED INTO SLAVE
A5 CLOCKED
INTO SLAVE
A3 CLOCKED
INTO SLAVE
A4 CLOCKED
INTO SLAVE
SCL
tHIGH
tLOW
tHD:STA
SDA
tSU:STA
tSU:DAT
tSU:DAT
tHD:DAT
tHD:DAT
Figure 1. SMBus Serial Interface Timing—Address
ACKNOWLEDGE
BIT CLOCKED
INTO MASTER
RW BIT
CLOCKED
INTO SLAVE
MOST SIGNIFICANT BIT
OF DATA CLOCKED
INTO MASTER
SCL
SLAVE PULLING
SDA LOW
SDA
tDV
tDV
Figure 2. SMBus Serial Interface Timing—Acknowledge
8
_______________________________________________________________________________________
Chemistry-Independent
Battery Chargers
GND
6
MAX1647/MAX1648
4
VIN 2
MAX874
VOUT
10
D5
AGND
IOUT
1
Q1
C9
C4
DCIN
9
SEL
REF
VL
2
6
N.C.
R6
R7
D6
3
R3
R4
12
THM
R5
C5
(NOTE 2)
MAX1647
D4*
C6
D2
BST
5
CCI
DHI
20
DC SOURCE
M1
18
C3
C7
LX
DLO
4
7.5V–28V
19
D1 L1
M2
17
CCV
PGND
R2
16
D3
(NOTE 1)
C1
C2
CS
7
R1A
R1B
SDA
INT
13
14
11
= HIGH-CURRENT TRACES (8A MAX)
NOTE 1: C6, M2, D1, AND C1 GROUNDS MUST CONNECT TO
THE SAME RECTANGULAR PAD ON THE LAYOUT.
NOTE 2: C5 MUST BE PLACED WITHIN 0.5cm OF THE MAX1647,
WITH TRACES NO LONGER THAN 1cm CONNECTING
VL AND PGND.
*OPTIONAL (SEE NEGATIVE INPUT VOLTAGE PROTECTION SECTION).
GND
SCL
8
KINT-
C8
BATT
SMBDATA
DACV
SMBCLOCK
15
-
T
D
C
+
SMART BATTERY
STANDARD CONNECTOR
HOST & LOAD
Figure 3. MAX1647 Typical Application Circuit
_______________________________________________________________________________________
9
MAX1647/MAX1648
Chemistry-Independent
Battery Chargers
Table 1a. Component Selection for Figure 3 Circuit (Also Use for Figure 4)
DESIGNATION
QTY
UNITS
C1
47
µF
20V, ESR at 250kHz ≤ 0.4Ω
C2, C4, C7, C9
C3
C5
C6
C8
0.1
47
1
22
22
µF
nF
µF
µF
nF
10V, ceramic or low ESR
35V
10V
3A IDC, 30V Schottky diode,
PD > 0.8W, 1N5821 equivalent
D1, D3, D4
SOURCE/TYPE
Sprague, 595D476X0020D7T, D case
AVX, TPSE476M020R0150, E case
NIEC, NSQ03A04, FLAT-PAK (SMC)
NIEC, 30VQ04F, TO-252AA (SMD)
Motorola, MBRS340T3, SMC
Motorola, MBRD340T4, DPAK
Diodes Inc., SK33, SMC
IR, 30BQ040, SMC
50mA IDC, 40V fast-recovery diode,
1N4150 equivalent
D2, D5
D6
4.3V zener diode,
1N4731 or equivalent
L1
±20%, 3A ISAT
Note: size in L x W x H
Sumida, RCH-110/220M, 10mm x 10mm x 10mm
Coiltronics, UP2-220, 0.541" x 0.345" x 0.231"
Coilcraft, DO3340P-223, 0.510" x 0.370" x 0.450"
Coilcraft, DO5022P-223, 0.730" x 0.600" x 0.280"
RDS, ON ≤ 0.1Ω, VDSS ≥ 30V,
PD > 0.5W, logic level, N-channel
power MOSFET
Motorola, MMSF5N03HD, SO-8
Motorola, MMDF3N03HD, SO-8
Motorola, MTD20N03HDL, DPAK
IR, IRF7201, SO-8
IR, IRF7303, SO-8
IR, IRF7603, Micro8
Siliconix, Si9410DY, SO-8
Siliconix, Si9936DY, SO-8
Siliconix, Si6954DQ, TSSOP-8
M2
RDS, ON ≤ 10Ω, VDSS ≥ 30V,
logic level, N-channel power
MOSFET, 2N7002 equivalent
Motorola, 2N7002LT1, SOT23
Motorola, MMBF170LT1, SOT23
Diodes Inc., 2N7002, SOT23
Diodes Inc., BS870, SOT23
Zetex, ZVN3306F, SOT23
Central Semiconductor, 2N7002, SOT23
Q1
VCE, MAX ≤ -30V, 50mA IC, CONT,
2N3906 equivalent
22
µH
M1
10
NOTES
R1A
100
mΩ
±1%, 1W
R1B
1
Ω
±5%, 1/8W
R2, R4
10
kΩ
±5%, 1/16W
R3
10
kΩ
±1%, 1/16W
R5, R7
10
Ω
±5%, 1/16W
R6
10
kΩ
±5%, 1/8W
IRC, CHP1100R100F13, 2512
IRC, LR251201R100F, 2512
Dale, WSL-2512/0.1Ω/±1%, 2512
______________________________________________________________________________________
Chemistry-Independent
Battery Chargers
MANUFACTURER
Output Characteristics
PHONE
FAX
AVX
(803) 946-0690
(803) 626-3123
Central Semiconductor
(516) 435-1110
(516) 435-1824
Coilcraft
(847) 639-6400
(847) 639-1469
Coiltronics
(561) 241-7876
(561) 241-9339
Dale
(605) 668-4131
(605) 665-1627
IR
(310) 322-3331
(310) 322-3332
IRC
(512) 992-7900
(512) 992-3377
NIEC
(805) 867-2555
(805) 867-2698
Siliconix
(408) 988-8000
(408) 970-3950
Sprague
(603) 224-1961
(603) 224-1430
Sumida
(847) 956-0666
(847) 956-0702
Zetex
(516) 543-7100
(516) 864-7630
The MAX1647/MAX1648 contain both a voltageregulation loop and a current-regulation loop. Both
loops operate independently of each other. The voltage-regulation loop monitors BATT to ensure that its
voltage never exceeds the voltage set point (V0). The
current-regulation loop monitors current delivered to
BATT to ensure that it never exceeds the current-limit
set point (I0). The current-regulation loop is in control
as long as BATT voltage is below V0. When BATT voltage reaches V0, the current loop no longer regulates,
and the voltage-regulation loop takes over. Figure 5
shows the V-I characteristic at the BATT pin.
C4
C5
REF
R3
VL
R4
THM
R5
MAX1648
D2
CCI
C3
DCIN
D4
C6
M1
DHI
DC SOURCE
BST
7.5V–28V
L1
C7
CCV
LX
D1
R2
DLO
C2
D3
M2
PGND
R8
CS
R1
SETI
R9
BATT
R10
C1
SETV
AGND
BATTERY
R11
T
Figure 4. MAX1648 Typical Operating Circuit
______________________________________________________________________________________
11
MAX1647/MAX1648
_______________Detailed Description
Table 1b. Component Suppliers
MAX1647/MAX1648
Chemistry-Independent
Battery Chargers
Whether the MAX1647 is controlling the voltage or current at any time depends on the battery’s state. If the
battery has been discharged, the MAX1647’s output
reaches the current-regulation limit before the voltage
limit, causing the system to regulate current. As the battery charges, the voltage rises until the voltage limit is
reached, and the charger switches to regulating voltage.
The transition from current to voltage regulation is done
by the charger, and need not be controlled by the host.
BATT
VOLTAGE
V0
V0 = VOLTAGE SET POINT
I0 = CURRENT-LIMIT SET POINT
Voltage Control
I0
AVERAGE CURRENT
THROUGH THE RESISTOR
BETWEEN CS AND BATT
Figure 5. Output V-I Characteristic
Setting V0 and I0 (MAX1647)
Set the MAX1647’s voltage and current-limit set points
via the Intel System Management Bus (SMBus™) 2-wire
serial interface. The MAX1647’s logic interprets the
serial-data stream from the SMBus interface to set internal digital-to-analog converters (DACs) appropriately.
See the MAX1647 Logic section for more information.
Setting V0 and I0 (MAX1648)
Set the MAX1648’s voltage- and current-limit set points
(V0 and I0, respectively) using external resistive dividers.
Figure 6b is the MAX1648 block diagram. V0 equals four
times the voltage on the SETV pin. I0 equals the voltage
on SETI divided by 5.5, divided by R1 (Figure 4).
_____________________Analog Section
The MAX1647/MAX1648 analog section consists of a
current-mode PWM controller and two transconductance error amplifiers: one for regulating current and
the other for regulating voltage. The MAX1647 uses
DACs to set the current and voltage level, which are
controlled via the SMBus interface. The MAX1648 eliminates the DACs and controls the error amplifiers directly from SETI (for current) and SETV (for voltage). Since
separate amplifiers are used for voltage and current
control, both control loops can be compensated separately for optimum stability and response in each state.
The following discussion relates to the MAX1647; however, MAX1648 operation can easily be inferred from
the MAX1647.
12
The internal GMV amplifier controls the MAX1647’s output voltage. The voltage at the amplifier’s noninverting
input amplifier is set by a 10-bit DAC, which is controlled
by a ChargingVoltage( ) command on the SMBus (see
the MAX1647 Logic section for more information). The
battery voltage is fed to the GMV amplifier through a 4:1
resistive voltage divider. With an external 4.096V reference, the set voltage ranges between 0 and 16.38V with
16mV resolution.
This poses a challenge for charging four lithium-ion
cells in series: because the lithium-ion battery’s typical
per-cell voltage is 4.2V maximum, 16.8V is required. A
larger reference voltage can be used to circumvent
this. Under this condition, the maximum battery voltage
no longer matches the programmed voltage. The solution is to use a 4.2V reference and host software.
Contact Maxim’s applications department for more
information.
The GMV amplifier’s output is connected to the CCV
pin, which compensates the voltage-regulation loop.
Typically, a series-resistor/capacitor combination can
be used to form a pole-zero couplet. The pole introduced rolls off the gain starting at low frequencies. The
zero of the couplet provides sufficient AC gain at midfrequencies. The output capacitor then rolls off the midfrequency gain to below 1, to guarantee stability before
encountering the zero introduced by the output capacitor’s equivalent series resistance (ESR). The GMV
amplifier’s output is internally clamped to between onefourth and three-fourths of the voltage at REF.
Current Control
The internal GMI amplifier and an internal current
source control the battery current while the charger is
regulating current. Since the regulator current’s accuracy is not adequate to ensure full 11-bit accuracy, an
internal linear current source is used in conjunction with
the PWM regulator to set the battery current. The current-control DAC’s five least significant bits set the
______________________________________________________________________________________
Chemistry-Independent
Battery Chargers
10k
10k
10k
DCIN
10k
16mA
THERMISTOR_OR
8mA
4mA
2mA
1mA
5
IOUT
THERM_SHUT
THERMAL
SHUTDOWN
THERMISTOR_COLD
SEL
LOGIC
BLOCK
THM
SCL
THERMISTOR_HOT
SDA
DCIN
INT
VL
THERMISTOR_UR
30k
100k
3k
AC_PRESENT
5.4V LINEAR
REGULATOR
500Ω
INTERNAL 3.9V
REFERENCE
REF
AGND
AGND
CCV
CCV_LOW
3R
REF
CS
CURRENT-SENSE
LEVEL SHIFT AND
GAIN OF 5.5
BATT
R
AGND
REF
FROM LOGIC
BLOCK
6
3/8 REF = ZERO CURRENT
6-BIT DAC
CCI
R
BST
NOTE: APPROX. REF/4 + VTHRESH
TO 3/4 REF + VTHRESH
LEVEL
SHIFT
GMI
DRIVER
DHI
NOTE: REF/4 TO 3/4 REF
R
R
SUMMING
COMPARATOR
BLOCK
R
FROM LOGIC BLOCK
BATT
AGND
TO LOGIC BLOCK
TO LOGIC BLOCK
R
MIN
VOLTAGE_INREG
CURRENT_INREG CLAMP
AGND
R
R
R
VL
CLAMP
TO REF
(MAX)
GMV
LX
DRIVER
FROM LOGIC
BLOCK
DLO
PGND
CCV
REF
AGND
FROM LOGIC BLOCK
10
10-BIT DAC
AGND
TO LOGIC BLOCK
DACV
POWER_FAIL
DCIN/4.5
Figure 6a. MAX1647 Block Diagram
______________________________________________________________________________________
13
MAX1647/MAX1648
REF
MAX1647/MAX1648
Chemistry-Independent
Battery Chargers
REF
10k
10k
THERMISTOR_COLD
THM
THERMISTOR_HOT
30k
3k
AGND
DCIN
VL
AC_PRESENT
CS
BATT
5.4V LINEAR
REGULATOR
CURRENT-SENSE
LEVEL SHIFT AND
GAIN OF 5.5
ON
INTERNAL 3.9V
REFERENCE
REF
AGND
BST
LEVEL
SHIFT
CCI
DRIVER
DHI
GMI
LX
SETI
REF / 2 =
ZERO CURRENT
BATT
CLAMP
MIN
SUMMING
COMPARATOR
BLOCK
ON
VL
R
DRIVER
GMV
R
R
R
CCV
AC_PRESENT AND
NOT (THERMISTOR_HOT
OR THERMISTOR_COLD)
AGND
SETV
Figure 6b. MAX1648 Block Diagram
14
______________________________________________________________________________________
PGND
DLO
Chemistry-Independent
Battery Chargers
PWM Controller
The battery voltage or current is controlled by the current-mode, pulse-width-modulated (PWM), DC-DC converter controller. This controller drives two external
N-channel MOSFETs, which switch the voltage from the
input source. This switched voltage feeds an inductor,
which filters the switched rectangular wave. The controller sets the pulse width of the switched voltage so that
it supplies the desired voltage or current to the battery.
The heart of the PWM controller is the multi-input comparator. This comparator sums three input signals to
determine the pulse width of the switched signal, setting the battery voltage or current. The three signals are
the current-sense amplifier’s output, the GMV or GMI
error amplifier’s output, and a slope-compensation signal, which ensures that the controller’s internal currentcontrol loop is stable.
The PWM comparator compares the current-sense
amplifier’s output to the higher output voltage of either
the GMV or the GMI amplifier (the error voltage). This
current-mode feedback corrects the duty ratio of the
switched voltage, regulating the peak battery current
and keeping it proportional to the error voltage. Since
the average battery current is nearly the same as the
peak current, the controller acts as a transconductance
amplifier, reducing the effect of the inductor on the output filter LC formed by the output inductor and the battery’s parasitic capacitance. This makes stabilizing the
circuit easy, since the output filter changes from a complex second-order RLC to a first-order RC. To preserve
the inner current-control loop’s stability, slope compensation is also fed into the comparator. This damps out
perturbations in the pulse width at duty ratios greater
than 50%.
At heavy loads, the PWM controller switches at a fixed
frequency and modulates the duty cycle to control the
battery voltage or current. At light loads, the DC current
through the inductor is not sufficient to prevent the current from going negative through the synchronous rectifier (Figure 3, M2). The controller monitors the current
through the sense resistor RSEN; when it drops to zero,
the synchronous rectifier turns off to prevent negative
current flow.
MOSFET Drivers
The MAX1647 drives external N-channel MOSFETs to
regulate battery voltage or current. Since the high-side
N-channel MOSFET’s gate must be driven to a voltage
higher than the input source voltage, a charge pump is
used to generate such a voltage. The capacitor C7
(Figure 3) charges to approximately 5V through D2
when the synchronous rectifier turns on. Since one side
of C7 is connected to the LX pin (the source of M1), the
high-side driver (DHI) can drive the gate up to the voltage at BST, which is greater than the input voltage,
when the high-side MOSFET turns on.
The synchronous rectifier behaves like a diode, but with
a smaller voltage drop to improve efficiency. A small
dead time is added between the time that the high-side
MOSFET turns off and the synchronous rectifier turns
on, and vice versa. This prevents crowbar currents (currents that flow through both MOSFETS during the brief
time that one is turning on and the other is turning off).
Connect a Schottky rectifier from ground to LX (across
the source and drain of M2) to prevent the synchronous
rectifier’s body diode from conducting. The body diode
typically has slower switching-recovery times, so allowing it to conduct would degrade efficiency.
______________________________________________________________________________________
15
MAX1647/MAX1648
internal current sources’ state, and the six most significant bits control the switching regulator’s current. The
internal current source supplies 1mA resolution to the
battery to comply with the smart-battery specification.
When the current is set to a number greater than 32,
the internal current source remains at 31mA. This guarantees that battery-current setting is monotonic regardless of current-sense resistor choice and current-sense
amplifier offset.
The GMI amplifier’s noninverting input is driven by a 4:1
resistive voltage divider, which is driven by the 6-bit
DAC. If an external 4.096V reference is used, this input
is approximately 1.0V at full scale, and the resolution is
16mV. The current-sense amplifier drives the inverting
input to the GMI amplifier. It measures the voltage
across the current-sense resistor (RSEN ) (which is
between the CS and BATT pins), amplifies it by approximately 5.45, and level shifts it to ground. The full-scale
current is approximately 0.2V / RSEN, and the resolution
is 3.2mV / RSEN.
The current-regulation-loop is compensated by adding
a capacitor to the CCI pin. This capacitor sets the current-feedback loop’s dominant pole. The GMI amplifier’s
output is clamped to between approximately one-fourth
and three-fourths of the REF voltage. While the current is
in regulation, the CCV voltage is clamped to within
80mV of the CCI voltage. This prevents the battery voltage from overshooting when the DAC voltage setting is
updated. The converse is true when the voltage is in
regulation and the current is not at the current DAC setting. Since the linear range of CCI or CCV is about 1.5V
to 3.5V or about 2V, the 80mV clamp results in a relatively negligible overshoot when the loop switches from
voltage to current regulation or vice versa.
The synchronous rectifier may not be completely
replaced by a diode because the BST capacitor
charges while the synchronous rectifier is turned on.
Without the synchronous rectifier, the BST capacitor
may not fully charge, leaving the high-side MOSFET
with insufficient gate drive to turn on. However, the synchronous rectifier may be replaced with a small MOSFET, such as a 2N7002, to guarantee that the BST
capacitor is allowed to charge. In this case, most of the
current at high currents is carried by the diode and not
by the synchronous rectifier.
BOLD LINE INDICATES THAT
THE MAX1647 PULLS SDA LOW
ACK
D8
ChargingMode( ) = 0 x 12
ChargingVoltage( ) = 0 x 15
ChargingCurrent( ) = 0 x 14
AlarmWarning( ) = 0 x 16
ChargerStatus( ) = 0 x 13
D9
D10
D11
D12
D13
D14
Internal Regulator and Reference
D15
D2
THERMISTOR_HOT
D3
THERMISTOR_UR
D4
ALARM_INHIBITED
D5
POWER_FAIL
D6
BATTERY_PRESENT
D7
AC_PRESENT
CMD2
CMD3
CMD4
CMD5
CMD6
CMD7
ACK
MAX1647 Logic
The MAX1647 uses serial data to control its operation. The
serial interface complies with the SMBus specification (see
System Management Bus Specification , from Intel
Architecture Labs; http://www.intel.com/IAL/powermgm.html; Intel Architecture Labs: 800-253-3696).
Charger functionality complies with the Intel/Duracell
Smart Charger Specification for a level 2 charger.
The MAX1647 uses the SMBus Read-Word and WriteWord protocols to communicate with the battery it is
charging, as well as with any host system that monitors
the battery to charger communications. The MAX1647
never initiates communication on the bus; it only
receives commands and responds to queries for status
information. Figure 7 shows examples of the SMBus
Write-Word and Read-Word protocols.
1
0
0
1
0
0
0
SDA
START
ACK
1
CHARGE_INHIBITED
1
MASTER_MODE
0
VOLTAGE_NOTREG
0
CURRENT_NOTREG
1
LEVEL_2
0
LEVEL_3
0
CURRENT_OR
0
VOLTAGE_OR
ACK
ACK
W
R
1
1
0
0
0
0
1
1
0
0
0
0
0
0
START
REPEATED
START
SDA
CMD1
ACK
SCL
WRITE WORD: ChargingMode( ), ChargingVoltage( ), ChargingCurrent( ), AlarmWarning( )
ACK
CMD0
Figure 7. Write-Word and Read-Word Examples
______________________________________________________________________________________
READ WORD: ChargersStatus( )
THERMISTOR_COLD
SDA
THERMISTOR_OR
D1
SCL
D0
W
16
ACK
ACK
SCL
The MAX1647 uses an internal low-dropout linear regulator to create a 5.4V power supply (VL), which powers its
internal circuitry. VL can supply up to 20mA. A portion of
this current powers the internal circuitry, but the remaining current can power the external circuitry. The current
used to drive the MOSFETs comes from this supply,
which must be considered when calculating how much
power can be drawn. To estimate the current required to
drive the MOSFETs, multiply the total gate charge of
each MOSFET by the switching frequency (typically
250kHz). The internal circuitry requires as much as 6mA
from the VL supply. To ensure VL stability, bypass the VL
pin with a 1µF or greater capacitor.
The MAX1647 has an internal ±2% accurate 3.9V reference voltage. An external reference can be used to
increase the charger’s accuracy. Use a 4.096V reference,
such as the MAX874, for compliance with the Intel/
Duracell smart-battery specification. Voltage-setting
accuracy is ±0.65%, so the total voltage accuracy is the
accuracy added to the reference accuracy. For 1% total
voltage accuracy, use a reference with ±0.35% or greater
accuracy. If the internal reference is used, bypass it with
a 0.1µF or greater capacitor.
TIME
MAX1647/MAX1648
Chemistry-Independent
Battery Chargers
Chemistry-Independent
Battery Chargers
ChargingVoltage( )
The ChargingVoltage( ) command uses Write-Word
protocol. The command code for ChargingVoltage( ) is
0x15; thus, the CMD7–CMD0 bits in Write-Word protocol should be 0b00010101. The 16-bit binary number
formed by D15–D0 represents the voltage set point
(V0) in millivolts; however, since the MAX1647 has only
16mV resolution in setting V0, the D0, D1, D2, and D3
bits are ignored. For D15 = D14 = 0:
ChargerMode( )
The ChargerMode( ) command uses Write-Word protocol. The command code for ChargerMode( ) is 0x12;
thus the CMD7–CMD0 bits in Write-Word protocol
should be 0b00010010. Table 2 describes the functions
of the 16 different data bits (D0–D15). Bit 0 refers to the
D0 bit in the Write-Word protocol (Figure 7).
Whenever the BATTERY_PRESENT status bit is clear,
the HOT_STOP bit is set, regardless of any previous
ChargerMode( ) command. To charge a battery that
has a thermistor impedance in the HOT range (i.e.,
THERMISTOR_HOT = 1 and THERMISTOR_UR = 0),
the host must use the ChargerMode( ) command to
clear HOT_STOP after the battery is inserted. The
HOT_STOP bit returns to its default power-up condition
(‘1’) whenever the battery is removed.
VOLTAGE_OR = 0 and V0 in Volts = 4 x REF x
(
)
VDAC
210
In equation 1, VDAC is the decimal equivalent of the
binary number represented by bits D13, D12, D11,
D10, D9, D8, D7, D6, D5, and D4 programmed with the
ChargingVoltage( ) command. For example, if D4–D13
are all set, VDAC is the decimal equivalent of
0b1111111111 (1023). If either D15 or D14, or both
D15 and D14, are set, all the bits in the voltage DAC
(Figure 6a) are set, regardless of D13–D0, and the
status register’s VOLTAGE_OR bit is set. For D15 = 1
and/or D14 = 1:
(
)
VOLTAGE_OR = 1 and V0 in Volts = 4 x REF x
210 - 1
210
Table 2. ChargerMode( ) Bit Functions
BIT
POSITION*
POR
VALUE**
INHIBIT_CHARGE
0
0
0 = Allow normal operation; clear the CHG_INHIBITED status bit.
1 = Turn the charger off; set the CHG_INHIBITED status bit.
ENABLE_POLLING
1
—
Not implemented. Write 0 into this bit.
POR_RESET
2
—
0 = No change in any non-ChargerMode( ) settings.
1 = Change the voltage and current settings to 0xFFFF and 0x00C0
respectively; clear the THERMISTOR_HOT and ALARM_INHIBITED bits.
RESET_TO_ZERO
3
—
Not implemented. Write 0 into this bit.
4, 7, 8, 9,
11–15
—
Not implemented. Write 1 into this bit.
BATTERY_PRESENT_MASK
5
0
0 = Interrupt on either edge of the BATTERY_PRESENT status bit.
1 = Do not interrupt because of a BATTERY_PRESENT bit change.
POWER_FAIL_MASK
6
1
0 = Interrupt on either edge of the POWER_FAIL status bit.
1 = Do not interrupt because of a POWER_FAIL bit change.
HOT_STOP
10
1
0 = The THERMISTOR_HOT status bit does not turn the charger off.
1 = THERMISTOR_HOT turns the charger off.
BIT NAME
N/A
*Bit position in the D15–D0 data.
N/A = Not available.
FUNCTION
**Power-on reset value.
______________________________________________________________________________________
17
MAX1647/MAX1648
Each communication with the MAX1647 begins with a
start condition that is defined as a falling edge on SDA
with SCL high. The device address follows the start
condition. The MAX1647 device address is 0b0001001
(0b indicates a binary number), which may also be
denoted as 0x12 (0x indicates a hexadecimal number)
for Write-Word commands, or 0x13 in hexadecimal for
Read-Word commands (note that the address is only
seven bits, and the hexadecimal representation uses
R/W as its least significant bit).
Figure 8 shows the mapping between V0 (the voltageregulation-loop set point) and the ChargingVoltage( )
data.
The power-on reset value for the ChargingVoltage( )
register is 0xFFF0; thus, the first time a MAX1647 is
powered on, the BATT voltage regulates to 16.368V
with VREF = 4.096V. Any time the BATTERY_PRESENT
status bit is clear, the ChargingVoltage( ) register
returns to its power-on reset state.
ChargingCurrent( )
The ChargingCurrent( ) command uses Write-Word
protocol. The command code for ChargingCurrent( ) is
0x14; thus, the CMD7–CMD0 bits in Write-Word protocol should be 0b00010100. The 16-bit binary number
formed by D15–D0 represents the current-limit set point
(I0) in milliamps. Tying SEL to AGND selects a 1.023A
maximum setting for I0. Leaving SEL open selects a
2.047A maximum setting for I0. Tying SEL to VL selects
a 4.095A maximum setting for I0.
16.368
VREF = 4.096V
12.592
VOLTAGE SET POINT (V0)
MAX1647/MAX1648
Chemistry-Independent
Battery Chargers
8.400
4.192
0
0b000000000000xxxx
0x000x
0b000100000110xxxx
0x106x
0b001000001101xxxx
0x20Dx
0b001100010011xxxx
0x313x
0b001111111111xxxx
0x3FFx
0b111111111111xxxx
0xFFFx
ChargingVoltage( ) D15–D0 DATA
Figure 8. ChargingVoltage( ) Data to Voltage Mapping
18
______________________________________________________________________________________
Chemistry-Independent
Battery Chargers
IOUT sources from 1mA to 31mA. Table 3 shows the
relationship between the value programmed with the
ChargingCurrent( ) command and IOUT source current.
The CCV_LOW comparator checks to see if the output
voltage is too high by comparing CCV to REF / 4. If
CCV_LOW = 1 (when CCV < REF / 4), IOUT shuts off,
preventing the output voltage from exceeding the voltage
set point specified by the ChargingVoltage( ) register.
VOLTAGE_NOTREG = 1 whenever the internal clamp
pulls down on CCV. (The internal clamp pulls down on
CCV to keep its voltage close to CCI’s voltage.)
Table 3. Relationship Between IOUT Source Current and ChargingCurrent( ) Value
CHARGE_
INHIBITED
(NOTE 1)
ALARM_
INHIBITED
ChargingVoltage( )
ChargingCurrent( )
CCV_LOW
VOLTAGE_
NOTREG
IOUT
OUTPUT
CURRENT
0
0
0
0x0010–0xFFFF
0x0001–0x001F
0
x
1mA–31mA
0
0
0
0x0010–0xFFFF
0x0001–0x001F
1
0
0mA
0
0
0
0x0010–0xFFFF
0x0001–0x001F
1
1
1mA–31mA
0
0
0
0x0010–0xFFFF
0x0020–0xFFFF
0
x
31mA
0
0
0
0x0010–0xFFFF
0x0020–0xFFFF
1
0
0mA
0
0
0
0x0010–0xFFFF
0x0020–0xFFFF
1
1
31mA
0
0
0
x
0x0000
x
x
0mA
0
0
0
0x0000–0x000F
x
x
x
0mA
0
x
1
x
x
x
x
0mA
0
1
x
x
x
x
x
0mA
1
x
x
x
x
x
x
0mA
Note 1: Logical AND of THERMISTOR_HOT, HOT_STOP, NOT(THERMISTOR_UR).
185
AVERAGE CS - BATT VOLTAGE
IN CURRENT REGULATION (mV)
SEL = OPEN OR SEL = VL
94
2.94
0b000001
0b100000
0b111111
CURRENT DAC CODE, DA5–DA0 BITS
Figure 9. Average Voltage Between CS and BATT vs. Current DAC Code
______________________________________________________________________________________
19
MAX1647/MAX1648
Two sources of current in the MAX1647 charge the battery: a binary-weighted linear current source sources
from IOUT, and a switching regulator controls the current
flowing through the current-sense resistor (R1). IOUT
provides a small maintenance charge current to compensate for battery self-discharge, while the switching
regulator provides large currents for fast charging.
MAX1647/MAX1648
Chemistry-Independent
Battery Chargers
Table 4. Relationship Between Current DAC Code and the ChargingCurrent( ) Value
CHARGE_
INHIBITED
(NOTE 1)
ALARM_
INHIBITED
ChargingVoltage( )
SEL
ChargingCurrent( )
CURRENT
DAC
CODE
0
0
0
0x0010–0xFFFF
0V
0x0001–0x001F
0
0
0
0x0010–0xFFFF
0V
0x0020–0x003F
0
0
0
0x0010–0xFFFF
0V
0
0
0
0x0010–0xFFFF
0V
0
0
0
0x0010–0xFFFF
0
0
0
0
0
0
0
SW REG
ON?
(NOTE 2)
0
No
0
2
Yes
0
0x0040–0x03DF
4–60
Yes
0
0x03E0–0x03FF
62
Yes
0
0V
0x0400–0xFFFF
62
Yes
1
0x0010–0xFFFF
open
0x0001–0x001F
0
No
0
0
0x0010–0xFFFF
open
0x0020–0x003F
1
Yes
0
0
0
0x0010–0xFFFF
open
0x0040–0x07DF
2–62
Yes
0
0
0
0x0010–0xFFFF
open
0x07E0–0x07FF
63
Yes
0
0
0
0
0x0010–0xFFFF
open
0x0800–0xFFFF
63
Yes
1
0
0
0
0x0010–0xFFFF
VL
0x0001–0x001F
0
No
0
0
0
0
0x0010–0xFFFF
VL
0x0020–0x003F
1
Yes
0
0
0
0
0x0010–0xFFFF
VL
0x0040–0x007F
1
Yes
0
0
0
0
0x0010–0xFFFF
VL
0x0080–0x0F9F
2–62
Yes
0
0
0
0
0x0010–0xFFFF
VL
0x0FA0–0x0FBF
63
Yes
0
0
0
0
0x0010–0xFFFF
VL
0x0FC0–0x0FFF
63
Yes
0
0
0
0
0x0010–0xFFFF
VL
0x0001–0xFFFF
63
Yes
1
0
0
0
x
x
0x0000
0
No
0
0
0
0
0x0010–0xFFFF
x
x
N/C
No
N/C
0
x
1
x
x
x
N/C
No
N/C
0
1
x
x
x
x
N/C
No
N/C
1
x
x
x
x
x
N/C
No
N/C
Note 1: Logical AND of THERMISTOR_HOT, HOT_STOP, NOT(THERMISTOR_UR).
Note 2: Value of CURRENT_OR bit in the ChargerStatus( ) register.
N/C = No change
Table 5. Effect of SEL Pin-Strapping on the ChargingCurrent( ) Data Bits
SEL
R1
(mΩ)
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
AGND
181
0
0
0
0
0
0
DA5
DA4
DA3
DA2
DA1
I4
I3
I2
I1
I0
Open
90
0
0
0
0
0
DA5
DA4
DA3
DA2
DA1
DA0
I4
I3
I2
I1
I0
VL
45
0
0
0
0
DA5
DA4
DA3
DA2
DA1
DA0
*
I4
I3
I2
I1
I0
*When SEL = VL, D5 = 1 forces DA0 to be 1 regardless of the D6 bit value.
With the switching regulator on, the current through R1
(Figure 3) is regulated by sensing the average voltage
between CS and BATT. A 6-bit current DAC controls
the current-limit set point. DA5–DA0 denote the bits in
the current DAC code. Figure 9 shows the relationship
between the current DAC code and the average voltage between CS and BATT.
20
When the switching regulator is off, DHI is forced to
LX and DLO is forced to ground. This prevents current
from flowing through inductor L1. Table 4 shows the
relationship between the ChargingCurrent( ) register
value and the switching regulator current DAC code.
______________________________________________________________________________________
Chemistry-Independent
Battery Chargers
AlarmWarning( )
The AlarmWarning( ) command uses Write-Word protocol.
The command code for AlarmWarning( ) is 0x16; thus the
CMD7–CMD0 in Write-Word protocol should be
0b00010110. The AlarmWarning( ) command sets the
ALARM_INHIBITED status bit in the MAX1647 if D15, D14,
or D12 of the Write-Word protocol data equals 1. Table 6
summarizes the AlarmWarning( ) command’s function.
The ALARM_INHIBITED status bit remains set until
BATTERY_PRESENT = 0 (battery removed) or a
ChargerMode() command is written with the POR_RESET
bit set. As long as ALARM_INHIBITED = 1, the MAX1647
switching regulator and IOUT current source remain off.
ChargerStatus( )
The ChargerStatus( ) command uses Read-Word protocol. The command code for ChargerStatus( ) is 0x13;
thus, the CMD7–CMD0 bits in Write-Word protocol
should be 0b00010011. The ChargerStatus( ) command returns information about thermistor impedance
and the MAX1647’s internal state. The Read-Word
protocol returns D15–D0 (Figure 7). Table 7 describes
the meaning of the individual bits. The latched bits,
THERMISTOR_HOT and ALARM_INHIBITED, are
cleared whenever BATTERY_PRESENT = 0 or
ChargerMode( ) is written with POR_RESET = 1.
Interrupts and the Alert-Response
Address
An interrupt is triggered (INT goes low) whenever power
is applied to DCIN, the BATTERY_PRESENT bit changes,
or the POWER_FAIL bit changes. BATTERY_PRESENT
and POWER_FAIL have interrupt masks that can be set
or cleared via the ChargerMode( ) command. INT stays
low until the interrupt is cleared. There are two methods
for clearing the interrupt: issuing a ChargerStatus( ) command, and using the Receive Byte protocol with a 0x19
Alert-Response address. The MAX1647 responds to the
Alert-Response address with the 0x89 byte.
__________Applications Information
Using the MAX1647
with Duracell Smart Batteries
The following pseudo-code describes an interrupt routine that is triggered by the MAX1647 INT output going
low. This interrupt routine keeps the host informed of
any changes in battery-charger status, such as DCIN
power detection, or battery removal and insertion.
DOMAX1647:
{ This is the beginning of the routine that handles
MAX1647 interrupts. }
{ Check the status of the MAX1647. }
TEMPWORD = ReadWord( SMBADDR = 0b00010011
= 0x13, COMMAND = 0x13 )
{ Check for the normal power-up case without a battery
installed. THERMISTOR_OR = 1, BATTERY_PRESENT =
0. Use 0b1011111011111111 = 0xBEFF as the mask. }
IF (TEMPWORD OR 0xBEFF) = 0xBFFF THEN GOTO
NOBATT:
{ Check to see if the battery is installed. BATTERY_
PRESENT = 1. Use 0b1011111111111111 = 0xBFFF as
the mask. }
Table 6. Effect of the AlarmWarning( ) Command
AlarmWarning( ) WRITE-WORD PROTOCOL DATA
D15 D14 D13 D12 D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
RESULT
1
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
Set ALARM_INHIBITED
x
1
x
x
x
x
x
x
x
x
x
x
x
x
x
x
Set ALARM_INHIBITED
x
x
x
1
x
x
x
x
x
x
x
x
x
x
x
x
Set ALARM_INHIBITED
______________________________________________________________________________________
21
MAX1647/MAX1648
With SEL = AGND, R1 should be as close as possible to
0.185 / 1.023 = 181mΩ to ensure that the actual output
current matches the data value programmed with the
ChargingCurrent( ) command. With SEL = open, R1
should be as close as possible to 90mΩ. With SEL = VL,
R1 should be as close as possible to 45mΩ. Table 5 summarizes how SEL affects the R1 value and the meaning of
data bits D15–D0 in the ChargingCurrent( ) command.
DA5–DA0 denote the current DAC code bits, and I4–I0
denote the IOUT linear-current source binary weighting
bits. Note that whenever any current DAC bits are set, the
linear-current source is set to full scale (31mA).
The power-on reset value for the ChargingCurrent( )
register is 0x000C. Irrespective of the SEL pin setting,
the MAX1647 powers on with I0 set to 12mA (i.e.,
DA5–DA0, I1, and I0 all equal to zero, and only I3 and
I2 set). Anytime the BATTERY_PRESENT status bit is
clear (battery removed), the ChargingCurrent( ) register
returns to its power-on reset state. This ensures that
upon insertion of a battery, the initial charging current is
12mA.
MAX1647/MAX1648
Chemistry-Independent
Battery Chargers
IF (TEMPWORD OR 0xBEFF) = 0xFFFF THEN GOTO
HAVEBATT:
GOTO ENDINT:
HAVEBATT:
{ A battery is installed. Turn the battery’s broadcast
mode off to monitor the charging process. Using the
BatteryMode( ) command, make sure the CHARGER_
MODE bit is set. }
WriteWord(SMBADDR = 0b00010110 = 0x16,
COMMAND = 0X03, DATA = 0x4000)
GOTO ENDINT:
NOBATT:
{ Notify the system that AC power is present, but no battery is present. }
GOTO ENDINT:
ENDINT:
{ This is the end of the interrupt routine. }
The following pseudo-code describes a polling routine
that queries the battery for its desired charge voltage and
charge current, checks to make sure that the requested
charge current and charge voltage are valid, and
instructs the MAX1647 to comply with the request.
DOPOLLING:
{ This is the beginning of the polling routine. }
{ Ask the battery what voltage it wants using the battery’s ChargingVoltage( ) command. }
TEMPVOLTAGE = ReadWord( SMBADDR =
0b00010111 = 0x17, COMMAND = 0x15 )
{ Ask the battery what current it wants using the battery’s ChargingCurrent( ) command. }
TEMPCURRENT = ReadWord( SMBADDR =
0b00010111 = 0x17, COMMAND = 0x14 )
{ Now the routine can check that the TEMPVOLTAGE
and TEMPCURRENT values make sense and that the
battery is not malfunctioning. }
{ With valid TEMPVOLTAGE and TEMPCURRENT values, instruct the MAX1647 to comply with the request. }
WriteWord( SMBADDR = 0b00010010 = 0x12 ,
COMMAND = 0x15, DATA = TEMPVOLTAGE )
WriteWord( SMBADDR = 0b00010010 = 0x12 ,
COMMAND = 0x14, DATA = TEMPCURRENT )
ENDPOL:
{ This is the end of the polling routine. }
22
Negative Input Voltage Protection
In most portable equipment, the DC power to charge
batteries enters via a two-conductor cylindrical power
jack. It is easy for the end user to add an adapter to
switch the DC power’s polarity. Polarized capacitor C6
would be destroyed if a negative voltage were applied.
Diode D4 in Figure 3 prevents this from happening.
If reverse-polarity protection for the DC input power is
not necessary, diode D4 can be omitted. This eliminates
the power lost due to the voltage drop on diode D4.
Selecting External Components for the
MAX1647 4A Application
The MAX1647 can be configured to charge at a maximum current of 4A (instead of 2A, as shown in Figure 3)
by changing the external power components and tying
SEL to REF. The following paragraphs discuss the selection requirements for each component in Figure 3 that
must be changed to accommodate the 4A application.
Diode D4 in Figure 3 has to support both the charge
current and the current required to operate the host
load (i.e., what the batteries normally power when not
charging). This means that the continuous current flowing through D4 exceeds 4A. One possible choice for
D4 is the Motorola MBRD835L 8A Schottky barrier
diode in a DPAK surface-mount package. Care must
be taken in thermal management of the circuit board
when using the 4A application circuit, by mounting D4
on a three-square-inch piece of copper.
Motorola’s MBRD835L can also be used for D3. The
Siliconix Si4410DY is a good choice for M1 and M2 in the
4A application. Changing M2 from a 2N7002 (Table 1) to
a Si4410DY increases the power dissipated by the
MAX1647’s 20-pin SSOP.
High-current inductors are difficult to find in surface-mount
packages. Low-cost solutions use toroidal powdered-iron
cores with exposed windings of heavy-gauge wire. The
Coiltronics CTX20-5-52 20µH 5A inductor provides a highefficiency solution.
R1A must also dissipate more power in the 4A application circuit than in the circuit of Figure 3. R1A’s value
decreases to 50mΩ in the 4A application. IRC’s
LR2512-01-R050-F meets this requirement with a 1W
maximum power-dissipation rating.
______________________________________________________________________________________
Chemistry-Independent
Battery Chargers
MAX1647/MAX1648
Table 7. ChargerStatus( ) Bit Descriptions
NAME
BIT
POSITION
LATCHED?
CHARGE_INHIBITED
0
Yes
0 = Ready to charge a smart battery
1 = Charger is off; IOUT current = 0mA; DLO = PGND; DHI = LX
MASTER_MODE
1
N/A
Always returns ‘0’
VOLTAGE_NOTREG
2
No
0 = BATT voltage is limited at the voltage set point (BATT = V0).
1 = BATT voltage is less than the voltage set point (BATT < V0).
CURRENT_NOTREG
3
No
0 = Current through R1 is at its limit (IBATT = I0).
1 = Current through R1 is less than its limit (IBATT < I0).
LEVEL_2
4
N/A
Always returns 1
LEVEL_3
5
N/A
Always returns 0
CURRENT_OR
6
No
0 = ChargingCurrent( ) value is valid for MAX1647.
1 = ChargingCurrent( ) value exceeds what MAX1647 can actually deliver.
VOLTAGE_OR
7
No
0 = ChargingVoltage( ) value is valid for MAX1647.
1 = ChargingVoltage( ) value exceeds what MAX1647 can actually deliver.
THERMISTOR_OR
8
No
0 = THM voltage < 91% of REF voltage
1 = THM voltage > 91% of REF voltage
THERMISTOR_COLD
9
No
0 = THM voltage < 75% of REF voltage
1 = THM voltage > 75% of REF voltage
DESCRIPTION
THERMISTOR_HOT
10
Yes
This bit reports the state of an internal SR flip-flop (denoted THERMISTOR_HOT
flip-flop). The THERMISTOR_HOT flip-flop is set whenever THM is below 23%
of REF. It is cleared whenever BATTERY_PRESENT = 0 or ChargerMode( ) is
written with POR_RESET = 1.
THERMISTOR_UR
11
No
0 = THM voltage > 5% of REF voltage
1 = THM voltage < 5% of REF voltage
ALARM_INHIBITED
12
Yes
This bit reports the state of an internal SR flip-flop (denoted ALARM_INHIBITED
flip-flop). The ALARM_INHIBITED flip-flop is set whenever the AlarmWarning( )
command is written with D15, D14, or D12 set. The ALARM_INHIBITED flip-flop
is cleared whenever BATTERY_PRESENT = 0 or ChargerMode( ) is written with
POR_RESET = 1.
POWER_FAIL
13
No
0 = BATT voltage < 89% of DCIN voltage
1 = BATT voltage > 89% of DCIN voltage
BATTERY_PRESENT
14
No
0 = No battery is present (THERMISTOR_OR = 1).
1 = A battery is present (THERMISTOR_OR = 0).
AC_PRESENT
15
No
0 = VL voltage < 4V
1 = VL voltage > 4V
*Bit position in the D15-D0 data
N/A = Not applicable
___________________Chip Information
TRANSISTOR COUNT: 3612
SUBSTRATE CONNECTED TO AGND
______________________________________________________________________________________
23
MAX1647/MAX1648
Chemistry-Independent
Battery Chargers
DIM
A
A1
B
C
D
E
e
H
L
α
α
E
H
C
L
INCHES
MILLIMETERS
MIN
MAX
MIN
MAX
0.068
0.078
1.73
1.99
0.002
0.008
0.05
0.21
0.010
0.015
0.25
0.38
0.004
0.008
0.09
0.20
SEE VARIATIONS
0.205
0.209
5.20
5.38
0.0256 BSC
0.65 BSC
0.301
0.311
7.65
7.90
0.025
0.037
0.63
0.95
0˚
8˚
0˚
8˚
DIM PINS
e
SSOP
SHRINK
SMALL-OUTLINE
PACKAGE
A
B
A1
D
D
D
D
D
14
16
20
24
28
INCHES
MILLIMETERS
MAX
MIN MAX MIN
6.33
0.239 0.249 6.07
6.33
0.239 0.249 6.07
7.33
0.278 0.289 7.07
8.33
0.317 0.328 8.07
0.397 0.407 10.07 10.33
21-0056A
D
DIM
D
0°-8°
A
0.101mm
0.004in.
e
B
A1
E
C
L
Narrow SO
SMALL-OUTLINE
PACKAGE
(0.150 in.)
H
A
A1
B
C
E
e
H
L
INCHES
MAX
MIN
0.069
0.053
0.010
0.004
0.019
0.014
0.010
0.007
0.157
0.150
0.050
0.244
0.228
0.050
0.016
DIM PINS
D
D
D
8
14
16
MILLIMETERS
MIN
MAX
1.35
1.75
0.10
0.25
0.35
0.49
0.19
0.25
3.80
4.00
1.27
5.80
6.20
0.40
1.27
INCHES
MILLIMETERS
MIN MAX
MIN
MAX
0.189 0.197 4.80
5.00
0.337 0.344 8.55
8.75
0.386 0.394 9.80 10.00
21-0041A
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.
24 __________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
© 1996 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.