MAXIM MAX1909, MAX8725 User Manual
General Description
The MAX1909/MAX8725 highly integrated control ICs
simplify construction of accurate and efficient multichemistry battery chargers. The MAX1909/MAX8725
use analog inputs to control charge current and voltage, and can be programmed by a host microcontroller
(µC) or hardwired. High efficiency is achieved through
use of buck topology with synchronous rectification.
The maximum current drawn from the AC adapter is programmable to avoid overloading the AC adapter when
supplying the load and the battery charger simultaneously. The MAX1909/MAX8725 provide 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 or absence of the
AC adapter, the MAX1909/MAX8725 automatically select
the appropriate source for supplying power to the system by controlling two external p-channel MOSFETs.
Under system control, the MAX1909/MAX8725 allow the
battery to undergo a relearning or conditioning cycle in
which the battery is completely discharged through the
system load and then recharged.
The MAX1909 includes a conditioning charge feature
while the MAX8725 does not. The MAX1909/MAX8725
are available in space-saving 28-pin, 5mm 5mm thin
QFN packages and operate over the extended -40°C to
+85°C temperature range. The MAX1909/MAX8725 are
now available in lead-free packages.
Applications
Notebook and Subnotebook Computers
Hand-Held Data Terminals
Features
o ±0.5% Accurate Charge Voltage (0°C to +85°C)
o ±3% Accurate Input Current Limiting
o ±5% Accurate Charge Current
o Programmable Charge Current >4A
o Automatic System Power-Source Selection
o Analog Inputs Control Charge Current and
Charge Voltage
o Monitor Outputs for
Current Drawn from AC Input Source
AC Adapter Presence
o Up to 17.65V (max) Battery Voltage
o Maximum 28V Input Voltage
o Greater than 95% Efficiency
o Charge Any Battery Chemistry: Li+, NiCd, NiMH,
Lead Acid, etc.
MAX1909/MAX8725
Multichemistry Battery Chargers with Automatic
System Power Selector
________________________________________________________________
Maxim Integrated Products
1
Ordering Information
19-2805; Rev 2; 9/04
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.
EVALUATION KIT AVAILABLE
PART TEMP RANGE PIN-PACKAGE
MAX1909ETI -40°C to +85°C 28 Thin QFN
MAX1909ETI+ -40°C to +85°C 28 Thin QFN
MAX8725ETI -40°C to +85°C 28 Thin QFN
MAX8725ETI+ -40°C to +85°C 28 Thin QFN
28 27 26 25 24 23 22
8 9 10 11 12 13 14
15
16
17
18
19
20
21
7
6
5
4
3
2
1
MAX1909
MAX8725
THIN QFN
TOP VIEW
LDO
DCIN
ACIN
REF
GND/PKPRES
ACOK
MODE
PDL
PDS
CSSP
CSSN
SRC
DHI
DHIV
DLOV
DLO
PGND
CSIP
CSIN
BATT
GND
CCS
CCV
CCI
VCTL
ICTL
CLS
IINP
Pin Configuration
CSSP CSSN
LDO
DHI
DLOV
DLO
PGND
CSIP
CSIN
BATT
GND
DCIN
VCTL
ICTL
MODE
ACIN
ACOK
CLS
CCV
CCI
CCS
REF
LDO
AC ADAPTER: INPUT
P3
0.01Ω
10μH
N1
P1
0.015Ω
TO
EXTERNAL LOAD
LDO
PDS
PDL
SRC
LDO
REF
IINP
IINP
DHIV
SRC
P2
MAX1909
MAX8725
PKPRES
MAX8725 ONLY
Minimum Operating Circuit
+
Denotes lead-free package.
MAX1909/MAX8725
Multichemistry Battery Chargers with Automatic
System Power Selector
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
VCTL
= V
ICTL
= 1.8V, MODE = float, ACIN = 0, CLS =
REF, GND = PGND = 0, PKPRES = GND, LDO = DLOV, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°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.
DCIN, CSSP, CSSN, SRC, ACOK to GND..............-0.3V to +30V
DHIV ........................................................…SRC + 0.3, SRC - 6V
DHI, PDL, PDS to GND ...............................-0.3V to (V
SRC
+ 0.3)
BATT, CSIP, CSIN to GND .....................................-0.3V to +20V
CSIP to CSIN or CSSP to CSSN or PGND to GND ...-0.3V to +0.3V
CCI, CCS, CCV, DLO, IINP, REF,
ACIN to GND ........................................-0.3V to (V
LDO
+ 0.3V)
DLOV, VCTL, ICTL, MODE, CLS, LDO,
PKPRES to GND ...................................................-0.3V to +6V
DLOV to LDO.........................................................-0.3V to +0.3V
DLO to PGND ..........................................-0.3V to (DLOV + 0.3V)
LDO Short-Circuit Current...................................................50mA
Continuous Power Dissipation (T
A
= +70°C)
28-Pin TQFN (derate 20.8mW/°C above +70°C) .......1666mW
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
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
CHARGE VOLTAGE REGULATION
VCTL Range 0 3.6 V
V
VCTL
= 3.6V (3 or 4 cells);
not including VCTL resistor tolerances
V
VCTL
= 3.6V/20 (3 or 4 cells); not including
VCTL resistor tolerances
V
VCTL
= 3.6V (3 or 4 cells); including VCTL
resistor tolerances of 1%
Battery Regulation Voltage
Accuracy
V
VCTL
= V
LDO
(3 or 4 cells, default
threshold of 4.2V/cell)
%
V
VCTL
Default Threshold V
VCTL
rising 4.1 4.3 V
V
VCTL
= 3V 0 2.5
VCTL Input Bias Current
V
DCIN
= 0, V
VCTL
= 5V 0 12
µA
CHARGE-CURRENT REGULATION
MAX1909 0 3.6
ICTL Range
MAX8725 0 3.2
V
CSIP-to-CSIN Full-Scale Current-
Sense Voltage
mV
MAX1909: V
ICTL
= 3.6V (not including ICTL
resistor tolerances)
MAX8725: V
ICTL
= 3.2V (not including ICTL
resistor tolerances)
-5 +5
MAX1909: V
ICTL
= 3.6V x 0.5, MAX8725:
V
ICTL
= 3.2V x 0.5 (not including ICTL
resistor tolerances)
-5 +5
MAX1909: V
ICTL
= 0.9V (not including ICTL
resistor tolerances)
Charge-Current Accuracy
MAX8725: V
ICTL
= 0.18V (not including
ICTL resistor tolerances)
-30
%
-0.8
-0.8
-1.0
-0.5
69.37 75.00 80.63
-7.5
-7.5
+0.8
+0.8
+1.0
+0.5
+7.5
+7.5
+30
MAX1909/MAX8725
Multichemistry Battery Chargers with Automatic
System Power Selector
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
VCTL
= V
ICTL
= 1.8V, MODE = float, ACIN = 0, CLS =
REF, GND = PGND = 0, PKPRES = GND, LDO = DLOV, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1909: V
ICTL
= 3.6V x 0.5, MAX8725:
V
ICTL
= 3.2V x 0.5 (including ICTL resistor
tolerances of 1%)
Charge-Current Accuracy
V
ICTL
= V
LDO (default threshold of 45mV)
-5 +5
%
V
ICTL
Default Threshold V
ICTL
rising 4.1 4.2 4.3 V
BATT/CSIP/CSIN Input Voltage
Range
0 19 V
Charging enabled
650
CSIP/CSIN Input Current
0.1 1
µA
MAX1909
ICTL Power-Down Mode
Threshold Voltage
MAX8725
V
MAX1909
ICTL Power-Up Mode Threshold
Voltage
MAX8725
V
V
ICTL
= 3V -1 +1
ICTL Input Bias Current
V
DCIN
= 0V, V
ICTL
= 5V
-1 +1
µA
INPUT CURRENT REGULATION
CSSP-to-CSSN Full-Scale
Current-Sense Voltage
mV
V
CLS
= REF -3 +3
V
CLS
= REF x 0.75 -3 +3
Input Current-Limit
Accuracy
V
CLS
= REF x 0.5 -4 +4
%
8.0 28 V
V
CSSP
= V
CSSN
= V
DCIN
> 8.0V
730
CSSP/CSSN Input Current
V
DCIN
= 0 0.1 1
µA
CLS Input Range 1.6
V
CLS Input Bias Current V
CLS
= 2.0V -1 +1 µA
IINP Transconductance V
CSSP
- V
CSSN
= 56mV 2.7 3.0 3.3
mA/V
V
CSSP
- V
CSSN
= 75mV, terminated with
10kΩ
V
CSSP
- V
CSSN
= 56mV, terminated with
10kΩ
-5 +5IINP Accuracy
V
CSSP
- V
CSSN
= 20mV, terminated with
10kΩ
-10
%
IINP Output Current V
CSSP
- V
CSSN
= 150mV, V
IINP
= 0V
µA
IINP Output Voltage V
CSSP
- V
CSSN
= 150mV, V
IINP
= float
3.5 V
C S S P /C S S N Inp ut V ol tag e Rang e
Charging disabled; V
DCIN
= 0 or V
ICTL
= 0
-7.0
+7.0
350
0.75
0.06
0.85
0.11
72.75 75.00 77.25
450
REF
-7.5
+7.5
+10
350
MAX1909/MAX8725
Multichemistry Battery Chargers with Automatic
System Power Selector
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
VCTL
= V
ICTL
= 1.8V, MODE = float, ACIN = 0, CLS =
REF, GND = PGND = 0, PKPRES = GND, LDO = DLOV, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SUPPLY AND LINEAR REGULATOR
DCIN Input Voltage Range V
DCIN
8.0 28 V
DCIN falling 7 7.4
DCIN Undervoltage-Lockout Trip
Point
DCIN rising 7.5
V
DCIN Quiescent Current I
DCIN
8.0V < V
DCIN
< 28V 2.7 6 mA
V
BATT
= 19V, V
DCIN
= 0V, or ICTL = 0V 0.1 1
V
BATT
= 16.8V, V
DCIN
= 19V, ICTL = 0V 0.1 1
BATT Input Current I
BATT
V
BATT
= 2V to 19V, V
DCIN
> V
BATT
+ 0.3V
500
µA
LDO Output Voltage 8.0V < V
DCIN
< 28V, no load
5.4
V
LDO Load Regulation 0 < I
LDO
< 10mA 80 115 mV
LDO Undervoltage-Lockout Trip
Point
V
DCIN
= 8.0V
4
V
REFERENCE
REF Output Voltage Ref 0 < I
REF
< 500µA
V
REF Undervoltage-Lockout Trip
Point
REF falling 3.1 3.9 V
TRIP POINTS
BATT POWER_FAIL Threshold V
DCIN
- V
BATT
, V
DCIN
falling 50
150 mV
BATT POWER_FAIL Threshold
Hysteresis
300 mV
ACIN Threshold ACIN rising
V
ACIN Threshold Hysteresis 10 20 30 mV
ACIN Input Bias Current V
ACIN
= 2.048V -1 +1 µA
SWITCHING REGULATOR
DHI Off-Time V
B AT T
= 16.0V , V
D C I N
= 19V , V
M OD E
= 3.6V
440 ns
DHI Minimum Off-Time V
B AT T
= 16.0V , V
D C I N
= 17V , V
M OD E
= 3.6V
350 ns
DLOV Supply Current I
DLOV
DLO low 5 10 µA
Sense Voltage for Minimum
Discontinuous Mode Ripple
Current
7.5 mV
Cycle-by-Cycle Current-Limit
Sense Voltage
97 mV
Sense Voltage for Battery
Undervoltage Charge Current
MAX1909 only, BATT = 3.0V per cell 3 4.5 6 mV
MAX1909 only, MODE = float (3 cell),
V
BATT
rising
Battery Undervoltage Threshold
MAX1909 only, MODE = LDO (4 cell),
V
BATT
rising
V
DHIV Output Voltage With respect to SRC
V
7.85
200
5.25
3.20
4.2023 4.2235 4.2447
100
100 200
2.007 2.048 2.089
360 400
260 300
9.18
12.235
-4.5 -5.0 -5.5
5.55
5.15
9.42
12.565
MAX1909/MAX8725
Multichemistry Battery Chargers with Automatic
System Power Selector
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
VCTL
= V
ICTL
= 1.8V, MODE = float, ACIN = 0, CLS =
REF, GND = PGND = 0, PKPRES = GND, LDO = DLOV, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DHIV Sink Current 10 mA
DHI On-Resistance Low DHI = V
DHIV
, I
DHI
= -10mA 2 5 Ω
DHI On-Resistance High DHI = V
CSSN
, I
DHI
= 10mA 2 4 Ω
DLO On-Resistance High V
DLOV
= 4.5V, I
DLO
= +100mA 3 7 Ω
DLO On-Resistance Low V
DLOV
= 4.5V, I
DLO
= -100mA 1 3 Ω
ERROR AMPLIFIERS
V C TL = 3.6, V
BATT
= 16.8V , M OD E = LD O
GMV Loop Transconductance
V C TL = 3.6, V
BATT
= 12.6V , M OD E = FLOAT
mA/V
GMI Loop Transconductance
MAX1909: ICTL = 3.6V, MAX8725: V
ICTL
=
3.2V, V
CSSP
- V
CSIN
= 75mV
0.5 1 2
mA/V
GMS Loop Transconductance V
CLS
= 2.048V, V
CSSP
- V
CSSN
= 75mV 0.5 1 2
mA/V
CCI/CCS/CCV Clamp Voltage
0.25V < V
CCS
< 2.0V
600 mV
LOGIC LEVELS
MODE Input Low Voltage 0.8 V
MODE Input Middle Voltage 1.6 1.8 2.0 V
MODE Input High Voltage 2.8 V
MODE Input Bias Current MODE = 0V or 3.6V -2 +2 µA
ACOK AND PKPRES
ACOK Input Voltage Range 0 28 V
ACOK Sink Current V
ACOK
= 0.4V, ACIN = 1.5V 1 mA
ACOK Leakage Current V
ACOK
= 28V, ACIN = 2.5V 1 µA
PKPRES Input Voltage
Range
0
V
PKPRES Input Bias Current -1 +1 µA
PKPRES Battery Removal Detect
Threshold
MAX8725, PKPRES rising 55
% of
LDO
PKPRES Hysteresis MAX8725 1 %
PDS, PDL SWITCH CONTROL
PDS Switch Turn-Off Threshold V
DCIN
- V
BATT
, V
DCIN
falling 50
150 mV
V
DCIN
- V
BATT
300 mV
PDS Output Low Voltage, PDS
Below SRC
I
PDS
= 0A 8 10 12 V
PDS Turn-On Current PDS = SRC 6 12 mA
PDS Turn-Off Current V
PDS
= V
SRC
- 2V, V
DCIN
= 16V 10 50 mA
PDL Switch Turn-On Threshold V
DCIN
- V
BATT
, V
DCIN
falling 50
150 mV
V
DCIN
- V
BATT
300 mV
0.0625 0.125 0.2500
0.0833 0.167 0.3330
0.25V < V
< 2.0V, 0.25V < V
CCV
< 2.0V,
CCI
150 300
PDS Switch Threshold Hysteresis
100 200
100
PDL Switch Threshold Hysteresis
100 200
100
LDO
MAX1909/MAX8725
Multichemistry Battery Chargers with Automatic
System Power Selector
6 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
VCTL
= V
ICTL
= 1.8V, MODE = float, ACIN = 0, CLS =
REF, GND = PGND = 0, PKPRES = GND, LDO = DLOV, T
A
= -40°C to +85°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
CHARGE VOLTAGE REGULATION
VCTL Range 0 3.6 V
V
VCTL
= 3.6V (3 or 4 cells); not including
VCTL resistor tolerances
V
VCTL
= 3.6V/20 (3 or 4 cells); not including
VCTL resistor tolerances
V
VCTL
= 3.6V (3 or 4 cells); including VCTL
resistor tolerances of 1%
Battery Regulation Voltage
Accuracy
V
VCTL
= V
LDO
(3 or 4 cells, default
threshold of 4.2V/cell)
%
V
VCTL
Default Threshold V
VCTL
rising 4.1 4.3 V
V
VCTL
= 3V 0 2.5
VCTL Input Bias Current
V
DCIN
= 0V, V
VCTL
= 5V
0 12
µA
CHARGE-CURRENT REGULATION
MAX1909 0 3.6
ICTL Range
MAX8725 0 3.2
V
CSIP-to-CSIN Full-Scale Current-
Sense Voltage
mV
MAX1909: V
ICTL
= 3.6V (not including ICTL
resistor tolerances)
MAX8725: V
ICTL
= 3.2V (not including ICTL
resistor tolerances)
-5 +5
MAX1909: V
ICTL
= 3.6V x 0.5, MAX8725:
V
ICTL
= 3.2V x 0.5 (not including ICTL
resistor tolerances)
-5 +5
MAX1909: V
ICTL
= 0.9V (not including ICTL
resistor tolerances)
Charge-Current Accuracy
MAX8725: V
ICTL
= 0.18V (not including
ICTL resistor tolerances)
-30
%
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
VCTL
= V
ICTL
= 1.8V, MODE = float, ACIN = 0, CLS =
REF, GND = PGND = 0, PKPRES = GND, LDO = DLOV, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
PDL Turn-On Resistance PDL = GND 50
150 kΩ
PDL Turn-Off Current V
SRC
- V
PDL
= 1.5V 6 12 mA
SRC = 19V, DCIN = 0V 1
SRC Input Bias Current
SRC = 19, V
BATT
= 16V
µA
Delay Time Between PDL and
PDS Transitions
2.5 5 7.5 µs
100
450 1000
-0.8
-0.8
-1.0
-0.8
69.37
-7.5
-7.5
+0.8
+0.8
+1.0
+0.8
80.63
+7.5
+7.5
+30
MAX1909/MAX8725
Multichemistry Battery Chargers with Automatic
System Power Selector
_______________________________________________________________________________________ 7
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
VCTL
= V
ICTL
= 1.8V, MODE = float, ACIN = 0, CLS =
REF, GND = PGND = 0, PKPRES = GND, LDO = DLOV, T
A
= -40°C to +85°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1909: V
ICTL
= 3.6V x 0.5, MAX8725:
V
ICTL
= 3.2V x 0.5 (including ICTL resistor
tolerances of 1%)
Charge-Current Accuracy
V
ICTL
= V
LDO (default threshold of 45mV)
-5 +5
%
V
ICTL
Default Threshold V
ICTL
rising 4.3 V
BATT/CSIP/CSIN Input Voltage
Range
0 19 V
CSIP/CSIN Input Current Charging enabled 650 µA
MAX1909
ICTL Power-Down Mode
Threshold Voltage
MAX8725
V
MAX1909
ICTL Power-Up Mode Threshold
Voltage
MAX8725
V
INPUT CURRENT REGULATION
CSSP-to-CSSN Full-Scale
Current-Sense Voltage
mV
V
CLS
= REF -3 +3
V
CLS
= REF x 0.75 -3 +3Input Current-Limit Accuracy
V
CLS
= REF x 0.5 -4 +4
%
8.0 28 V
CSSP/CSSN Input Current V
CSSP
= V
CSSN
= V
DCIN
> 8.0V 730 µA
CLS Input Range 1.6
V
IINP Transconductance V
CSSP
- V
CSSN
= 56mV 2.7 3.3
mA/V
V
CSSP
- V
CSSN
= 75mV, terminated with
10kΩ
V
CSSP
- V
CSSN
= 56mV, terminated with
10kΩ
-5 +5IINP Accuracy
V
CSSP
- V
CSSN
= 20mV, terminated with
10kΩ
-10
%
IINP Output Current V
CSSP
- V
CSSN
= 150mV, V
IINP
= 0V
µA
IINP Output Voltage V
CSSP
- V
CSSN
= 150mV, V
IINP
= float
3.5 V
SUPPLY AND LINEAR REGULATOR
DCIN Input Voltage Range V
DCIN
8.0 28 V
DCIN falling 7
D C IN U nd er vol tag e- Lockout Tr i p
P oi nt
DCIN rising
V
DCIN Quiescent Current I
DCIN
8.0V < V
DCIN
< 28V 6 mA
BATT Input Current I
BATT
V
BATT
= 2V to 19V, V
DCIN
> V
BATT
+ 0.3V 500 µA
LDO Output Voltage 8.0V < V
DCIN
< 28V, no load
V
LDO Load Regulation 0 < I
LDO
< 10mA 115 mV
-7.0
CSSP/CSSN Input Voltage Range
0.85
0.11
72.75
-7.5
350
5.25
+7.0
0.75
0.06
77.25
REF
+7.5
+10
7.85
5.55
MAX1909/MAX8725
Multichemistry Battery Chargers with Automatic
System Power Selector
8 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
VCTL
= V
ICTL
= 1.8V, MODE = float, ACIN = 0, CLS =
REF, GND = PGND = 0, PKPRES = GND, LDO = DLOV, T
A
= -40°C to +85°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
LDO Undervoltage-Lockout Trip
Point
V
DCIN
= 8.0V
V
REFERENCE
REF Output Voltage Ref 0 < I
REF
< 500µA
V
REF Undervoltage-Lockout Trip
Point
REF falling 3.9 V
TRIP POINTS
BATT POWER_FAIL Threshold V
DCIN
- V
BATT
, V
DCIN
falling 50 150 mV
BATT POWER_FAIL Threshold
Hysteresis
300 mV
ACIN Threshold ACIN rising
V
ACIN Threshold Hysteresis 10 30 mV
SWITCHING REGULATOR
DHI Off-Time
440 ns
DHI Minimum Off-Time
350 ns
DLOV Supply Current I
DLOV
DLO low 10 µA
Sense Voltage for Battery
Undervoltage Charge Current
MAX1909 only, BATT = 3.0V per cell 3 6 mV
MAX1909 only, MODE = float (3 cell),
V
BATT
rising
Battery Undervoltage Threshold
MAX1909 only, MODE = LDO (4 cell),
V
BATT
rising
V
DHIV Output Voltage With respect to SRC
V
DHIV Sink Current 10 mA
DHI On-Resistance Low DHI = V
DHIV
, I
DHI
= -10mA 5 Ω
DHI On-Resistance High DHI = V
CSSN
, I
DHI
= 10mA 4 Ω
DLO On-Resistance High V
DLOV
= 4.5V, I
DLO
= +100mA 7 Ω
DLO On-Resistance Low V
DLOV
= 4.5V, I
DLO
= -100mA 3 Ω
ERROR AMPLIFIERS
V C TL = 3.6, V
BATT
= 16.8V , M OD E = LD O
GMV Loop Transconductance
V C TL = 3.6, V
BATT
= 12.6V , M OD E = FLOAT
mA/V
GMI Loop Transconductance
MAX1909: ICTL = 3.6V, MAX8725: V
ICTL
=
3.2V, V
CSSP
- V
CSIN
= 75mV
0.5 2.0
mA/V
GMS Loop Transconductance V
CLS
= 2.048V, V
CSSP
- V
CSSN
= 75mV 0.5 2.0
mA/V
CCI/CCS/CCV Clamp Voltage
0.25V < V
CCV
< 2.0V, 0.25V < V
CCI
< 2.0V,
0.25V < V
CCS
< 2.0V
600 mV
LOGIC LEVELS
MODE Input Low Voltage 0.8 V
MODE Input Middle Voltage 1.6 2.0 V
3.20
4.1960
V
V
100
2.007
= 16.0V, V
BATT
= 16.0V, V
BATT
DCIN
DCIN
= 19V, V
= 17V, V
= 3.6V 360
MODE
= 3.6V 260
MODE
9.18
12.235
-4.5
0.0625
0.0833
150
5.15
4.2520
2.089
9.42
12.565
-5.5
0.2500
0.3330
MAX1909/MAX8725
Multichemistry Battery Chargers with Automatic
System Power Selector
_______________________________________________________________________________________ 9
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
DCIN
= V
CSSP
= V
CSSN
= 18V, V
BATT
= V
CSIP
= V
CSIN
= 12V, V
VCTL
= V
ICTL
= 1.8V, MODE = float, ACIN = 0, CLS =
REF, GND = PGND = 0, PKPRES = GND, LDO = DLOV, T
A
= -40°C to +85°C, unless otherwise noted.)
PARAMETER
CONDITIONS
UNITS
MODE Input High Voltage 2.8 V
ACOK AND PKPRES
ACOK Input Voltage Range 0 28 V
ACOK Sink Current V
ACOK
= 0.4V, ACIN = 1.5V 1 mA
PKPRES Input Voltage Range 0
V
PKPRES Battery Removal Detect
Threshold
MAX8725, PKPRES rising 55
% of
LDO
PDS, PDL SWITCH CONTROL
PDS Switch Turn-Off Threshold V
DCIN
- V
BATT
, V
DCIN
falling 50 150 mV
P D S S w i tch Thr eshol d H yste r esi s V
DCIN
- V
BATT
300 mV
PDS Output Low Voltage, PDS
Below SRC
I
PDS
= 0A 8 12 V
PDS Turn-On Current PDS = SRC 6 mA
PDS Turn-Off Current V
PDS
= V
SRC
- 2V, V
DCIN
= 16V 10 mA
PDL Switch Turn-On Threshold V
DCIN
- V
BATT
, V
DCIN
falling 50 150 mV
P D L S w i tch Thr eshol d H yster esi s V
DCIN
- V
BATT
300 mV
PDL Turn-On Resistance PDL = GND 50 150 kΩ
PDL Turn-Off Current V
SRC
- V
PDL
= 1.5V 6 mA
SRC Input Bias Current SRC = 19, V
BATT
= 16V
µA
Note 1: Guaranteed by design. Not production tested.
BATTERY INSERTION
AND REMOVAL RESPONSE
MAX1909/MAX8725 toc01
500μs/div
1V
0V
2V
3V
16V
17V
0A
0A
I
IN
I
BATT
V
BATT
V
CCI
, V
CCV
5A/div
5A/div
V
CCI
V
CCV
V
CCV
V
CCV
V
CCI
V
CCI
SYSTEM LOAD-TRANSIENT RESPONSE
MAX1909/MAX8725 toc02
100μs/div
1V
0V
2V
3V
5A
5A
0A
5A
0A
0A
I
BATT
I
IN
I
SYSTEMLOAD
V
CCS
V
CCI
CCS
CCI
Typical Operating Characteristics
(Circuit of Figure 2, V
DCIN
= 20V, charge current = 3A, 4 Li+ series cells, TA= +25°C, unless otherwise noted.)
SYMBOL
MIN TYP MAX
100
100
LDO
1000