Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - battery management Charge management Multi-Chemistry QSOP 16 Surface-mount

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800

_______________General Description

The MAX846A is a cost-saving multichemistry battery-

charger system that comes in a space-saving 16-pin

QSOP. This integrated system allows different battery

chemistries (Li-Ion, NiMH or NiCd cells) to be charged

using one circuit.

In its simplest application, the MAX846A is a stand-

alone, current-limited float voltage source that charges

Li-Ion cells. It can also be paired up with a low-cost

microcontroller (µC) to build a universal charger capa-

ble of charging Li-Ion, NiMH, and NiCd cells.

An internal 0.5%-accurate reference allows safe charg-

ing of Li-Ion cells that require tight voltage accuracy.

The voltage- and current-regulation loops used to con-

trol a low-cost external PNP transistor (or P-channel

MOSFET) are independent of each other, allowing more

flexibility in the charging algorithms.

The MAX846A has a built-in 1%, 3.3V, 20mA linear regu-

lator capable of powering the µC and providing a refer-

ence for the µC’s analog-to-digital converters. An

on-board reset notifies the controller upon any unex-

pected loss of power. The µC can be inexpensive, since

its only functions are to monitor the voltage and current

and to change the charging algorithms.

________________________Applications

Li-Ion Battery Packs

Desktop Cradle Chargers

Li-Ion/NiMH/NiCd Multichemistry Battery

Chargers

Cellular Phones

Notebook Computers

Hand-Held Instruments

____________________________Features

♦ Multichemistry Charger System (Li-Ion, NiMH, NiCd)

♦ Independent Voltage and Current Loops

♦ ±0.5% Internal Reference for Li-Ion Cells

♦ Lowers Cost:

—Stands Alone or Uses Low-Cost µC

—Built-In 1% Linear Regulator Powers µC

—Linear Regulator Provides Reference to µC ADCs

—Built-In µC Reset

—Controls Low-Cost External PNP Transistor or

P-Channel MOSFET

♦ Space-Saving 16-Pin QSOP

♦ Charging-Current-Monitor Output

♦ <1µA Battery Drain when Off

MAX846A

Cost-Saving Multichemistry

Battery-Charger System

________________________________________________________________

Maxim Integrated Products

__________________Pin Configuration

MAX846A

Li-ION

BATTERY

ISET

CELL2

GND

PGND

DCIN

CS+

CS-

DRV

3.5V

TO

20V

CCV

CCI

PWROK

BATT

DRV

PGND

CS-

CS+

BATT

ON

CELL2

PWROK

DCIN

VL

CCI

GND

CCV

VSET

ISET

OFFV

TOP VIEW

MAX846A

QSOP

__________Typical Operating Circuit

19-1121; Rev 0; 9/96

PART

MAX846AC/D

MAX846AEEE -40°C to +85°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

Dice*

16 QSOP

*Dice are tested at T

= +25°C only. Contact factory for details.

______________Ordering Information

EVALUATION KIT

AVAILABLE

Summary of content (12 pages)

PAGE 1
9-1121; Rev 0; 9/96 KIT ATION EVALU E L B A AVAIL Cost-Saving Multichemistry Battery-Charger System The MAX846A is a cost-saving multichemistry batterycharger system that comes in a space-saving 16-pin QSOP. This integrated system allows different battery chemistries (Li-Ion, NiMH or NiCd cells) to be charged using one circuit. In its simplest application, the MAX846A is a standalone, current-limited float voltage source that charges Li-Ion cells.
PAGE 2
MAX846A Cost-Saving Multichemistry Battery-Charger System ABSOLUTE MAXIMUM RATINGS DCIN, DRV, CS+, CS-, BATT to GND........................-0.3V, +21V PGND to GND.....................................................................±0.3V VL to GND......................................................................-0.3V, 7V IPWROK ................................................................................10mA PWROK, ISET, CCI, CCV, OFFV, VSET, CELL2, ON to GND .........................................
PAGE 3
Cost-Saving Multichemistry Battery-Charger System MAX846A ELECTRICAL CHARACTERISTICS (continued) (VDCIN = 10V, ON = VL, IVL = IVSET = 0mA, VCS- = VCS+ = 10V, VBATT = 4.5V, VOFFV = VCELL2 = 0V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS MIN TYP MAX UNITS VOLTAGE LOOP Voltage-Loop Set Point VVSET = 1.650V, VCELL2 = 0V, IDRV = 1mA, VDRV = 10V -0.25% 4.2 +0.25% VVSET = 1.650V, VCELL2 = VL, IDRV = 1mA, MAX846A VDRV = 10V -0.25% 8.4 +0.
PAGE 4
MAX846A Cost-Saving Multichemistry Battery-Charger System ELECTRICAL CHARACTERISTICS (Note 1) (VDCIN = 10V, ON = VL, IVL = IVSET = 0mA, VCS- = VCS+ = 10V, VBATT = 4.5V, VOFFV = VCELL2 = 0V, TA = -40°C to +85°C, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS 5 mA 3.259 3.341 V 2.9 3.1 V 2.5 3.0 V VL REGULATOR DCIN Supply Current VDCIN = 20V, IDRV = IVL = 0mA Output Voltage 0mA < IVL < 20mA, 3.
PAGE 5
Cost-Saving Multichemistry Battery-Charger System BATTERY INPUT CURRENT vs. BATTERY VOLTAGE CURRENT-SENSE AMPLIFIER TRANSCONDUCTANCE vs. ISET VOLTAGE 80 CELL2 = VL 70 ∆V = 100mV 1.015 ∆V = 165mV 1.010 1.005 1.000 ∆V = 200mV 0.995 CELL2 = GND 60 82kΩ 50 128kΩ ON 40 30 20 OFF 10 ∆V = 250mV 0 0.990 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.
PAGE 6
MAX846A Cost-Saving Multichemistry Battery-Charger System ______________________________________________________________Pin Description PIN NAME FUNCTION 1 DCIN 2 VL 3.3V, 20mA, 1% Linear-Regulator Output. VL powers the system µC and other components. Bypass to GND with a 4.7µF tantalum or ceramic capacitor. 3 CCI Current-Regulation-Loop Compensation Pin. Connect a compensation capacitor (typically 10nF) from CCI to VL. 4 GND Ground 5 CCV Voltage-Regulation-Loop Compensation Pin.
PAGE 7
Cost-Saving Multichemistry Battery-Charger System Stability The Typical Operating Characteristics show the loop gains for the current loop and voltage loop. The dominant pole for each loop is set by the compensation capacitor connected to each capacitive compensation pin (CCI, CCV). The DC loop gains are about 50dB for the current loop and about 33dB for the voltage loop, for a battery impedance of 250mΩ. The CCI output impedance (50kΩ) and the CCI capacitor determine the current-loop dominant pole.
PAGE 8
MAX846A Cost-Saving Multichemistry Battery-Charger System DC INPUT (OR P-CHANNEL) 3.5V TO 20V 0.01µF RDRV 660Ω DCIN 3.3V TO µC VL 3.3V, 1% LDO 4.7µF DRV CS+ PGND GND OR DAC RCS 165mΩ IBATT 1k BST N CSA CS- ISET 10k VL TO ADC 2V CL VL 5nF CCI 1.65V CA VL 5nF CCV BATT Li OR Ni VA VA 4.7µF 2 Li 1 Li OFF CELL2 N OFFV ON OPEN OR DAC RVSET VSET 400k, 1% (±5% ADJ) 20k, 2% 1.65V, 0.5% REF N VL REFOK GND CS- > 2V DRV ENABLE PWROK MAX846A VL > 3V ON ON OFF Figure 1.
PAGE 9
Cost-Saving Multichemistry Battery-Charger System BATT DCIN 3.7V TO 20V RCS MAX846A (0.165V ) I EXTERNAL PASS TRANSISTOR CAN BE EITHER PNP OR PMOS FET. 10nF 4.7µF RDRV 660Ω CS+ CS- DRV VL BATT RVSET ADJUST (UP) VSET DCIN (DOWN) VL MAX846A 100k 10k PWROK ISET RISET ON 0.01µF CCI VL CCV (2 CELLS) 0.01µF CELL2 OFFV (1 CELL) 4.7µF GND PGND Figure 2. Stand-Alone Li-Ion Charger RVSET = 20kΩ   4.2 VX − VF   1.65    VF − 4.
PAGE 10
MAX846A Cost-Saving Multichemistry Battery-Charger System P DCIN 3.7V TO 20V Li OR Ni CS+ CS- DRV BATT DCIN ADC (MEASURE V(BATT)) CCI CCV MAX846A ON CELL2 I/O (LOW = TURN OFF CHARGE) I/O (HIGH = 2 Li CELLS) OFFV I/O (HIGH = DISABLE FLOAT V) VSET PWM/DAC (CONTROL FLOAT V) ISET PWM/DAC (CONTROL CHARGE I) ADC (MEASURE IBATT) GND VL VDD MICROCONTROLLER PGND PWROK RST Figure 3. Desktop Multichemistry Charger Concept Component selection is similar to that of stand-alone operation.
PAGE 11
Cost-Saving Multichemistry Battery-Charger System MAX846A 20k 400k VSET 1.65V 0 TO VL 20k VSET 1.65V DAC 2% 0 2% 1% MAX846A MAX846A 100% µC PWM OUTPUT 400k 1% n WITH VOLTAGE OUTPUT DAC WITH PWM FROM MICROCONTROLLER Figure 4. VSET Adjustment Methods MAX846A MAX846A 20k ISET 0 ISET DAC 20k 10k 10k 100% µC PWM OUTPUT 20k n WITH VOLTAGE OUTPUT DAC WITH PWM FROM MICROCONTROLLER Figure 5.
PAGE 12
MAX846A Cost-Saving Multichemistry Battery-Charger System ___________________Chip Topography VL DCIN DRV PGND CS- CCI CS+ GND 0.105" (2.67mm) BATT CCV VSET ON ISET OFFV PWROK CELL2 0.085" (2.165mm) SUBSTRATE CONNECTED TO GND TRANSISTOR COUNT: 349 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.