max8725e_1909e.pdf

19-2805; Rev 2; 9/04

Multichemistry Battery Chargers with Automatic

System Power Selector

General Description

The MAX1909/MAX8725 highly integrated control ICs

simplify construction of accurate and efficient multi-

chemistry battery chargers. The MAX1909/MAX8725

use analog inputs to control charge current and volt-

age, 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 pro-

grammable to avoid overloading the AC adapter when

supplying the load and the battery charger simultane-

ously. 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 sys-

tem 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

±0.5% Accurate Charge Voltage (0 ° C to +85 ° C)

±3% Accurate Input Current Limiting

±5% Accurate Charge Current

Programmable Charge Current >4A

Automatic System Power-Source Selection

Analog Inputs Control Charge Current and

Charge Voltage

Monitor Outputs for

Current Drawn from AC Input Source

AC Adapter Presence

Up to 17.65V (max) Battery Voltage

Maximum 28V Input Voltage

Greater than 95% Efficiency

Charge Any Battery Chemistry: Li+, NiCd, NiMH,

Lead Acid, etc.

Ordering Information

PART

TEMP RANGE

PIN-PACKAGE

MAX1909 ETI

-40

C to +85

28 Thin QFN

MAX1909ETI+

-40 ° C to +85 ° C

28 Thin QFN

MAX8725 ETI

-40

C to +85

28 Thin QFN

MAX8725ETI+

-40

C to +85

28 Thin QFN

+ Denotes lead-free package.

Minimum Operating Circuit

E XTE R NA L LOAD

0.01 Ω

A C ADA P TER: INPUT

SRC

CSSP

CSSN

PDS

DHIV

SRC

PDL

Pin Configuration

DCIN

MAX1909

MAX8725

LDO

VCTL

ICTL

MODE

TOP VIEW

LDO

DLOV

ACIN

LDO

IINP

DLOV

DCIN

REF

DHI

CLS

LDO

DLO

ACOK

ACIN

REF

PGND

CSIP

LDO

DLO

10 µ H

MAX1909

MAX8725

GND/PKPRES

CSIN

PGND

PKPRES

MAX8725 ONLY

ACOK

BATT

CSIP

MODE

GND

0.015 Ω

CCV

CCI

CCS

CSIN

BATT

GND

REF

THIN QFN

Functional Diagrams appear at end of data sheet.

________________________________________________________________ Maxim Integrated Products

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.

Multichemistry Battery Chargers with Automatic

System Power Selector

ABSOLUTE MAXIMUM RATINGS

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

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 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 T A = +25°C.)

MIN

TYP

MAX

UNITS

PARAMETER

SYMBOL

CONDITIONS

CHARGE VOLTAGE REGULATION

VCTL Range

3.6

V VCTL = 3.6V (3 or 4 cells);

not including VCTL resistor tolerances

-0.8

+0.8

V VCTL = 3.6V/20 (3 or 4 cells); not including

VCTL resistor tolerances

-0.8

+0.8

Battery Regulation Voltage

Accuracy

V VCTL = 3.6V (3 or 4 cells); including VCTL

resistor tolerances of 1%

-1.0

+1.0

V VCTL = V LDO (3 or 4 cells, default

threshold of 4.2V/cell)

-0.5

+0.5

V VCTL Default Threshold

V VCTL rising

4.1

4.3

V VCTL = 3V

2.5

µA

VCTL Input Bias Current

V DCIN = 0, V VCTL = 5V

CHARGE-CURRENT REGULATION

MAX1909

3.6

ICTL Range

MAX8725

3.2

CSIP-to-CSIN Full-Scale Current-

Sense Voltage

69.37

75.00

80.63

MAX1909: V ICTL = 3.6V (not including ICTL

resistor tolerances)

-7.5

+7.5

MAX8725: V ICTL = 3.2V (not including ICTL

resistor tolerances)

-5

MAX1909: V ICTL = 3.6V x 0.5, MAX8725:

V ICTL = 3.2V x 0.5 (not including ICTL

resistor tolerances)

-5

Charge-Current Accuracy

MAX1909: V ICTL = 0.9V (not including ICTL

resistor tolerances)

-7.5

+7.5

MAX8725: V ICTL = 0.18V (not including

ICTL resistor tolerances)

-30

+30

_______________________________________________________________________________________

Multichemistry Battery Chargers with Automatic

System Power Selector

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 T A = +25°C.)

PARAMETER

MIN

TYP

MAX

UNITS

SYMBOL

CONDITIONS

MAX1909: V ICTL = 3.6V x 0.5, MAX8725:

V ICTL = 3.2V x 0.5 (including ICTL resistor

tolerances of 1%)

-7.0

+7.0

Charge-Current Accuracy

V ICTL = V LDO (default threshold of 45mV)

-5

V ICTL Default Threshold

V ICTL rising

4.1

4.2

4.3

BATT/CSIP/CSIN Input Voltage

Range

Charging enabled

350

650

CSIP/CSIN Input Current

µA

Charging disabled; V DCIN = 0 or V ICTL = 0

0.1

MAX1909

0.75

ICTL Power-Down Mode

Threshold Voltage

MAX8725

0.06

MAX1909

0.85

ICTL Power-Up Mode Threshold

Voltage

MAX8725

0.11

V ICTL = 3V

-1

µA

ICTL Input Bias Current

V DCIN = 0V, V ICTL = 5V

-1

INPUT CURRENT REGULATION

CSSP-to-CSSN Full-Scale

Current-Sense Voltage

72.75

75.00

77.25

V CLS = REF

-3

Input Current-Limit

Accuracy

V CLS = REF x 0.75

-3

V CLS = REF x 0.5

-4

CSSP/CSSN Input Voltage Range

8.0

V CSSP = V CSSN = V DCIN > 8.0V

450

730

µA

CSSP/CSSN Input Current

V DCIN = 0

0.1

CLS Input Range

1.6

REF

CLS Input Bias Current

V CLS = 2.0V

-1

µA

IINP Transconductance

V CSSP - V CSSN = 56mV

2.7

3.0

3.3

mA/V

V CSSP - V CSSN = 75mV, terminated with

10k Ω

-7.5

+7.5

V CSSP - V CSSN = 56mV, terminated with

10k Ω

-5

IINP Accuracy

V CSSP - V CSSN = 20mV, terminated with

10k Ω

-10

+10

IINP Output Current

V CSSP - V CSSN = 150mV, V IINP = 0V

350

µA

IINP Output Voltage

V CSSP - V CSSN = 150mV, V IINP = float

3.5

_______________________________________________________________________________________

Multichemistry Battery Chargers with Automatic

System Power Selector

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 T A = +25°C.)

PARAMETER

MIN

TYP

MAX

UNITS

SYMBOL

CONDITIONS

SUPPLY AND LINEAR REGULATOR

DCIN Input Voltage Range

V DCIN

8.0

DCIN falling

7.4

DCIN Undervoltage-Lockout Trip

Point

DCIN rising

7.5

7.85

DCIN Quiescent Current

I DCIN

8.0V < V DCIN < 28V

2.7

V BATT = 19V, V DCIN = 0V, or ICTL = 0V

0.1

BATT Input Current

I BATT

V BATT = 16.8V, V DCIN = 19V, ICTL = 0V

0.1

µA

V BATT = 2V to 19V, V DCIN > V BATT + 0.3V

200

500

LDO Output Voltage

8.0V < V DCIN < 28V, no load

5.25

5.4

5.55

LDO Load Regulation

0 < I LDO < 10mA

115

LDO Undervoltage-Lockout Trip

Point

V DCIN = 8.0V

3.20

5.15

REFERENCE

REF Output Voltage

Ref

0 < I REF < 500µA

4.2023

4.2235

4.2447

REF Undervoltage-Lockout Trip

Point

REF falling

3.1

3.9

TRIP POINTS

BATT POWER_FAIL Threshold

V DCIN - V BATT , V DCIN falling

100

150

BATT POWER_FAIL Threshold

Hysteresis

100

200

300

ACIN Threshold

ACIN rising

2.007

2.048

2.089

ACIN Threshold Hysteresis

ACIN Input Bias Current

V ACIN = 2.048V

-1

µA

SWITCHING REGULATOR

V BATT = 16.0V, V DCIN = 19V, V MODE = 3.6V

360

400

440

DHI Off-Time

V BATT = 16.0V, V DCIN = 17V, V MODE = 3.6V

260

300

350

DHI Minimum Off-Time

DLOV Supply Current

I DLOV

DLO low

µA

Sense Voltage for Minimum

Discontinuous Mode Ripple

Current

7.5

Cycle-by-Cycle Current-Limit

Sense Voltage

Sense Voltage for Battery

Undervoltage Charge Current

MAX1909 only, BATT = 3.0V per cell

4.5

MAX1909 only, MODE = float (3 cell),

V BATT rising

9.18

9.42

Battery Undervoltage Threshold

MAX1909 only, MODE = LDO (4 cell),

V BATT rising

12.235

12.565

DHIV Output Voltage

With respect to SRC

-4.5

-5.0

-5.5

_______________________________________________________________________________________

Multichemistry Battery Chargers with Automatic

System Power Selector

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 T A = +25°C.)

PARAMETER

MIN

TYP

MAX

UNITS

SYMBOL

CONDITIONS

DHIV Sink Current

DHI On-Resistance Low

DHI = V DHIV , I DHI = -10mA

Ω

DHI On-Resistance High

DHI = V CSSN , I DHI = 10mA

Ω

DLO On-Resistance High

V DLOV = 4.5V, I DLO = +100mA

Ω

DLO On-Resistance Low

V DLOV = 4.5V, I DLO = -100mA

Ω

ERROR AMPLIFIERS

VCTL = 3.6, V BATT = 16.8V, MODE = LDO

0.0625

0.125

0.2500

GMV Loop Transconductance

mA/V

VCTL = 3.6, V BATT = 12.6V, MODE = FLOAT

0.0833

0.167

0.3330

MAX1909: ICTL = 3.6V, MAX8725: V ICTL =

3.2V, V CSSP - V CSIN = 75mV

GMI Loop Transconductance

0.5

mA/V

GMS Loop Transconductance

V CLS = 2.048V, V CSSP - V CSSN = 75mV

0.5

mA/V

0.25V < V CCV < 2.0V, 0.25V < V CCI < 2.0V,

0.25V < V CCS < 2.0V

CCI/CCS/CCV Clamp Voltage

150

300

600

LOGIC LEVELS

MODE Input Low Voltage

0.8

MODE Input Middle Voltage

1.6

1.8

2.0

MODE Input High Voltage

2.8

MODE Input Bias Current

MODE = 0V or 3.6V

-2

µA

ACOK AND PKPRES

ACOK Input Voltage Range

ACOK Sink Current

V ACOK = 0.4V, ACIN = 1.5V

ACOK Leakage Current

V ACOK = 28V, ACIN = 2.5V

µA

PKPRES Input Voltage

Range

LDO

PKPRES Input Bias Current

-1

µA

PKPRES Battery Removal Detect

Threshold

% of

LDO

MAX8725, PKPRES rising

PKPRES Hysteresis

MAX8725

PDS, PDL SWITCH CONTROL

PDS Switch Turn-Off Threshold

V DCIN - V BATT , V DCIN falling

100

150

PDS Switch Threshold Hysteresis

V DCIN - V BATT

100

200

300

PDS Output Low Voltage, PDS

Below SRC

I PDS = 0A

PDS Turn-On Current

PDS = SRC

PDS Turn-Off Current

V PDS = V SRC - 2V, V DCIN = 16V

PDL Switch Turn-On Threshold

V DCIN - V BATT , V DCIN falling

100

150

PDL Switch Threshold Hysteresis

V DCIN - V BATT

100

200

300

_______________________________________________________________________________________

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