Rainbow Electronics MAX1873 User Manual

General Description

The low-cost MAX1873R/S/T provides all functions needed to simply and efficiently charge 2-, 3-, or 4series lithium-ion cells at up to 4A or more. It provides a regulated charging current and voltage with less than ±0.75% total voltage error at the battery terminals. An external P-channel MOSFET operates in a step-down DC-DC configuration to efficiently charge batteries in low-cost designs.

The MAX1873R/S/T regulates the battery voltage and charging current using two control loops that work together to transition smoothly between voltage and current regulation. An additional control loop limits current drawn from the input source so that AC adapter size and cost can be minimized. An analog voltage output proportional to charging current is also supplied so that an ADC or microcontroller can monitor charging current.

The MAX1873 may also be used as an efficient currentlimited source to charge NiCd or NiMH batteries in multichemistry charger designs. The MAX1873R/S/T is available in a space-saving 16-pin QSOP package. Use the evaluation kit (MAX1873EVKIT) to help reduce design time.

Applications

Notebook Computers

Portable Internet Tablets

2-, 3-, or 4-cell Li+ Battery Pack Chargers

6-, 9-, or 10-cell Ni Battery Pack Chargers

Hand-Held Instruments

Portable Desktop Assistants (PDAs)

Desktop Cradle Chargers

Features

♦ Low-Cost and Simple Circuit

♦ Charges 2-, 3-, or 4-Series Lithium-Ion Cells

♦ AC Adapter Input-Current-Limit Loop

♦ Also Charges Ni-Based Batteries

♦ Analog Output Monitors Charge Current

♦ ±0.75% Battery-Regulation Voltage

♦ 5µA Shutdown Battery Current

♦ Input Voltage Up to 28V

♦ 200mV Dropout Voltage/100% Duty Cycle

♦ Adjustable Charging Current

♦ 300kHz PWM Oscillator Reduces Noise

♦ Space-Saving 16-Pin QSOP

♦ MAX1873 Evaluation Kit Available to Speed

Designs

MAX1873

Simple Current-Limited Switch-Mode

Li+ Charger Controller

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-2099; Rev 0; 7/01

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.

EVALU

ATIO

IT A

ILA

BLE

Selector Guide

Typical Operating Circuit

Pin Configuration appears at end of data sheet.

PART TEMP. RANGE PIN-PACKAGE

MAX1873REEE -40°C to +85°C 16 QSOP

MAX1873SEEE -40°C to +85°C 16 QSOP

MAX1873TEEE -40°C to +85°C 16 QSOP

VIN 9V TO

28V

(9V MIN

FOR 2-

CELLS)

VH VL CSSP

SYSTEM LOAD

MAX1873

PART SERIES CELLS TO CHARGE

MAX1873REEE

MAX1873SEEE

MAX1873TEEE 4-Cell Li+ 10-cell Ni Battery Packs

2-Cell Li+ or 5- or 6-cell Ni Battery

3-Cell Li+ or 7- or 9-cell Ni Battery

4V OUT PER

200mV ON R

DCIN

IOUT

ICHG/EN

REF

VADJ

GND

CSSN

EXT

CSB

BATT

CCI

CCS

CCV

2- TO 4-CELL

Li+

MAX1873

Simple Current-Limited Switch-Mode Li+ Charger Controller

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, V

DCIN

= V

CSSP

= V

CSSN

= 18V, V

ICHG/EN

= V

REF

, V

VADJ

= V

REF

/2. MAX1873R: V

BATT

= V

CSB

= 8.4V;

MAX1873S: V

BATT

= V

CSB

= 12.6V; MAX1873T: V

BATT

= V

CSB

= 16.8V; TA= 0°C to +85°C. Typical values are at TA= +25°C, unless

otherwise noted.)

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.

CSSP, CSSN, DCIN to GND ...................................-0.3V to +30V

VL, ICHG/EN to GND................................................-0.3V to +6V

VH, EXT to DCIN.......................................................-6V to +0.3V

VH, EXT to GND ......................................(V

DCIN

+ 0.3V) to -0.3V

EXT to VH .................................................................+6V to -0.3V

DCIN to VL..............................................................+30V to -0.3V

VADJ, REF, CCI, CCV, CCS,

IOUT to GND.............................................-0.3V to (VL + 0.3V)

BATT, CSB to GND.................................................-0.3V to +20V

CSSP to CSSN.......................................................-0.3V to +0.6V

CSB to BATT..........................................................-0.3V to +0.6V

VL Source Current ............................................................+50mA

VH Sink Current ................................................................+40mA

Continuous Power Dissipation (T

= +70°C)

16-Pin QSOP (derate 8.3mW/°C above +70°C..........+667mW

Operating Temperature Range

MAX1873_EEE................................................-40°C to +85°C

Junction Temperature..................................................... +150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) ................................ +300°C

INPUT SUPPLY AND REFERENCE

DCIN Input Voltage Range 628V

D C IN Qui escent S up p l y C ur r ent

DCIN to BATT Undervoltage Threshold CSSP = DCIN, input falling 0.05 0.175 V

DCIN to BATT Undervoltage Threshold CSSP = DCIN, input rising 0.22 0.38 V

VL Output Voltage 6.0V < V

VL Output Load Regulation IVL = 0 to 3mA 15 50 mV

REF Output Voltage I

REF Line Regulation 6.0V < V

REF Load Regulation I

SWITCHING REGULATOR

PWM Oscillator Frequency 270 300 330 kHz EXT Driver Source On-Resistance 47Ω EXT Driver Sink On-Resistance 2.5 4.5 Ω

VH Output Voltage DCIN - VH, 6V < V

CSSN/CSSP Input Current V

CSSN/CSSP Off-State Leakage V

BATT, CSB Input Current

BATT, CSB Input Current DCIN ≤ BATT (input power removed) 1.5 5 µA

PARAMETER CONDITIONS MIN TYP MAX UNITS

6.0V < V DCIN ≤ BATT 0.1 10 µA

= 21µA (200kΩ load) 4.179 4.20 4.221 V

REF

= 0 to 1mA 6 13 mV

REF

CSSN/VCSSP

DCIN

ICHG/EN = 0 (charger disabled) 0.2 1

ICHG/EN = REF (charger enabled) 250 500

< 28V 4 7 mA

DCIN

< 28V 5.15 5.40 5.65 V

DCIN

< 28V

DCIN

= 28V, V

= V

SSN/VCSSP

<28V, IVH = 0 to 20mA 4.75 5.75 V

DCIN

= 28V 70 200 µA

DCIN

= 18V, V

BATT

= V

= 18V 1.5 5 µA

CSB

26mV

22 65 ppm/V

µA

MAX1873

Simple Current-Limited Switch-Mode

Li+ Charger Controller

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, V

DCIN

= V

CSSP

= V

CSSN

= 18V, V

ICHG/EN

= V

REF

, V

VADJ

= V

REF

/2. MAX1873R: V

BATT

= V

CSB

= 8.4V;

MAX1873S: V

BATT

= V

CSB

= 12.6V; MAX1873T: V

BATT

= V

CSB

= 16.8V; TA= 0°C to +85°C. Typical values are at TA= +25°C, unless

otherwise noted.)

PARAMETER CONDITIONS MIN TYP MAX UNITS

Battery Regulation Voltage

BATT Undervoltage Threshold

CURRENT SENSE

CSB to BATT Battery Current-Sense Voltage

CSB to BATT Current-Sense Voltage when V

< 2.5V per Cell

BATT

CSSP to CSSN Current-Sense Voltage 6V < V

CONTROL INPUTS/OUTPUTS

ICHG/EN Input Threshold Includes 50mV of hysteresis 500 600 700 mV

ICHG/EN Input Voltage Range For Charge Current Adjustment

VADJ Input Current V

ICHG/EN Input Current V

VADJ Input Voltage Range 0V

IOUT Voltage

2-cell version MAX1873R 10.45 11 11.55

3-cell version MAX1873S 15.675 16.5 17.325BATT Overvoltage Cutoff Threshold

4-cell version MAX1873T (Note 1) 17.575 18.5 19.425

= 0 7.898 7.958 8.018

MAX1873R (2 Li+ cells)

MAX1873S (3 Li+ cells)

MAX1873T (4 Li+ cells)

VADJ

= V

/2 8.337 8.4 8.463

REF

= V

(Note 1) 8.775 8.842 8.909

REF

= 0 11.847 11.937 12.027

= V

/2 12.505 12.6 12.695

REF

= V

(Note 1) 13.163 13.263 13.363

REF

= 0 15.796 15.916 16.036

= V

/2 16.674 16.8 16.926

REF

= V

(Note 1) 17.551 17.684 17.817

REF

VADJ

MAX1873R 4.8 5.0 5.2

For I charge

CHG

ICHG/EN

/20 trickle

MAX1873S 7.2 7.5 7.8

MAX1873T 9.6 10 10.4

= V

REF

= V

/4 40 50 60

REF

190 200 210

51015mV

< 28V 90 100 110 mV

CSSP

700 V

= V

VADJ

ICHG/EN

Full scale

25% scale

Trickle charge V

No charge current

/2 -100 100 nA

REF

= V

REF

- V

CSB

0 < I

OUT

- V

CSB

0 < I

OUT

- V

CSB

- V

CSB

= sinking 20µA

IOUT

= 200mV,

BATT

< 500µA

= 50mV,

BATT

< 500µA

= 10mV 75 200 325

BATT

= 0,

BATT

-100 100 nA

3.6 4.0 4.4

0.9 1.0 1.1

40 70 90

REF

MAX1873

Simple Current-Limited Switch-Mode Li+ Charger Controller

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, V

DCIN

= V

CSSP

= V

CSSN

= 18V, V

ICHG/EN

= V

REF

, V

VADJ

= V

REF

/2. MAX1873R: V

BATT

= V

CSB

= 8.4V;

MAX1873S: V

BATT

= V

CSB

= 12.6V; MAX1873T: V

BATT

= V

CSB

= 16.8V; TA= -40°C to +85°C. Typical values are at TA= +25°C,

unless otherwise noted.)

PARAMETER CONDITIONS MIN MAX UNITS

INPUT SUPPLY AND REFERENCE

DCIN Input Voltage Range 628V

D C IN Qui escent S up p l y C ur r ent

DCIN to BATT Undervoltage Threshold CSSP = DCIN, input falling 0.05 0.2 V

DCIN to BATT Undervoltage Threshold CSSP = DCIN, input rising 0.22 0.38 V

VL Output Voltage 6.0V < V

VL Output Load Regulation IVL = 0 to 3mA 50 mV

REF Output Voltage I

REF Line Regulation 6.0V < V

REF Load Regulation I

SWITCHING REGULATOR

PWM Oscillator Frequency 270 330 kHz

EXT Driver Source On-Resistance 7 Ω

EXT Driver Sink On-Resistance 4.5 Ω

VH Output Voltage DCIN - VH, 6V < V

CSSN/CSSP Input Current V

CSSN/CSSP Off-State Leakage V

BATT, CSB Input Current

BATT, CSB Input Current DCIN ≤ BATT (input power removed) 5 µA

BATT Overvoltage Cutoff Threshold

Battery Regulation Voltage

6.0V < V

< 28V 7 mA

DCIN

DCIN ≤ BATT 10 µA

< 28V 5.15 5.65 V

DCIN

= 21µA (200kΩ load) 4.179 4.221 V

REF

< 28V

DCIN

= 0 to 1mA 13 mV

REF

<28V, IVH = 0 to 20mA 4.75 5.75 V

DCIN

CSSN/VCSSP

= V

DCIN

SSN/VCSSP

= 28V, V

= 28V 200 µA

DCIN

= 18V V

BATT

= V

= 18V 5 µA

CSB

6mV

65 ppm/V

ICHG/EN = 0 (charger disabled) 1

ICHG/EN = REF (charger enabled) 500

2-cell version MAX1873R 10.45 11.55

3-cell version MAX1873S 15.675 17.325

4-cell version MAX1873T (Note 1) 17.575 19.425

= 0 7.898 8.018

MAX1873R (2 Li+ cells)

MAX1873S (3 Li+ cells)

MAX1873T (4 Li+ cells)

VADJ

= V

/2 8.337 8.463

REF

= V

(Note 1) 8.775 8.909

REF

= 0 11.847 12.027

= V

/2 12.505 12.695

REF

= V

(Note 1) 13.163 13.363

REF

= 0 15.796 16.036

= V

/2 16.674 16.926

REF

= V

(Note 1) 17.551 17.817

REF

VADJ

µA

MAX1873

Simple Current-Limited Switch-Mode

Li+ Charger Controller

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, V

DCIN

= V

CSSP

= V

CSSN

= 18V, V

ICHG/EN

= V

REF

, V

VADJ

= V

REF

/2. MAX1873R: V

BATT

= V

CSB

= 8.4V;

MAX1873S: V

BATT

= V

CSB

= 12.6V; MAX1873T: V

BATT

= V

CSB

= 16.8V; TA= -40°C to +85°C. Typical values are at TA= +25°C,

unless otherwise noted.)

Note 1: While it may appear possible to set the Battery Regulation Voltage higher than the Battery Overvoltage Cutoff Threshold, this

cannot happen because both parameters are derived from the same reference and track each other.

Note 2: Specifications to -40°C are guaranteed by design, not production tested.

PARAMETER CONDITIONS MIN MAX UNITS

BATT Undervoltage Threshold

CURRENT SENSE

CSB to BATT Battery Current-Sense Voltage

CSB to BATT Current-Sense Voltage when V

< 2.5V per Cell

BATT

CSSP to CSSN Current-Sense Voltage 6V < V

CONTROL INPUTS/OUTPUTS

ICHG/EN Input Threshold Includes 50mV of hysteresis 500 700 mV

ICHG/EN Input Voltage Range for Charge Current Adjustment

VADJ Input Current V

ICHG/EN Input Current V

VADJ Input Voltage Range 0V

IOUT Voltage

For I

CHG

/20 trickle

charge

ICHG/EN

CSSP

= V

VADJ

ICHG/EN

= V

< 28V 90 110 mV

REF

= V

Full scale

25% scale

Trickle charge V

No charge current

MAX1873R 4.8 5.2

MAX1873S 7.2 7.8

MAX1873T 9.6 10.4

REF

/4 40 60 mV

REF

190 210 mV

515mV

700 V

REF

/2 -100 100 nA

REF

- V

CSB

0 < I

OUT

- V

CSB

0 < I

OUT

- V

CSB

- V

CSB

= sinking 20µA

IOUT

= 200mV,

BATT

< 500µA

= 50mV,

BATT

< 500µA

= 10mV 75 325

BATT

= 0,

BATT

-100 100 nA

REF

3.6 4.4

0.9 1.1

40 90

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