Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - battery management Charge management Multi-Chemistry TQFN 28 (5x5) Surface-mount

AVAILABLE

EVALUATION KIT AVAILABLE

Functional Diagrams

Pin Configurations appear at end of data sheet.

Functional Diagrams continued at end of data sheet.

UCSP is a trademark of Maxim Integrated Products, Inc.

For pricing, delivery, and

ordering information, please contact Maxim Direct

at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

General Description

The MAX1908/MAX8724/MAX8765/MAX8765A highly

integrated, multichemistry battery-charger control ICs

simplify the construction of accurate and efficient charg-

ers. These devices use analog inputs to control charge

current and voltage, and can be programmed by the host

or hardwired. The MAX1908/MAX8724/MAX8765/

MAX8765A achieve high efficiency using a buck topology

with synchronous rectification.

The MAX1908/MAX8724/MAX8765/MAX8765A feature

input current limiting. This feature reduces battery

charge current when the input current limit is reached

to avoid overloading the AC adapter when supplying

the load and the battery charger simultaneously. The

MAX1908/MAX8724/MAX8765/MAX8765A provide out-

puts to monitor current drawn from the AC adapter (DC

input source), battery-charging current, and the pres-

ence of an AC adapter. The MAX1908’s conditioning

charge feature provides 300mA to safely charge deeply

discharged lithium-ion (Li+) battery packs.

The MAX1908 includes a conditioning charge feature

while the MAX8724/MAX8765/MAX8765A do not.

The MAX1908/MAX8724/MAX8765/MAX8765A charge two

to four series Li+ cells, providing more than 5A, and are

available in a space-saving, 28-pin, thin QFN package (5mm

× 5mm). An evaluation kit is available to speed designs.

Applications

Notebook and Subnotebook Computers

Personal Digital Assistants

Handheld Terminals

Features

o ±0.5% Output Voltage Accuracy Using Internal

Reference (±0.4% for MAX8765A, 2-/3-Cell Only)

o ±4% Accurate Input Current Limiting

o ±5% Accurate Charge Current

o Analog Inputs Control Charge Current and

Charge Voltage

o Outputs for Monitoring

Current Drawn from AC Adapter

Charging Current

AC Adapter Presence

o Up to 17.6V Battery-Voltage Set Point

o Maximum 28V Input Voltage

o > 95% Efficiency

o Shutdown Control Input

o Charge Any Battery Chemistry

Li+, NiCd, NiMH, Lead Acid, etc.

Low-Cost Multichemistry Battery Chargers

IINP

CSSP

CSSN

DHI

BST

DLOV

SHDN

ICHG

ACIN

ACOK

REFIN

ICTL

GND

15161718192021

VCTL

BATT

CELLS

CSIN

CSIP

PGND

DLO

7654321

CCV

CCI

CCS

REF

CLS

LDO

DCIN

MAX1908

MAX8724

MAX8765

MAX8765A

THIN QFN

TOP VIEW

Pin Configuration

Ordering Information

MAX1908

MAX8724

MAX8765

MAX8765A

AC ADAPTER

INPUT

TO EXTERNAL

LOAD

LDO

FROM HOST µP

10µH

0.015Ω

BATT+

DCIN

REFIN

VCTL

ICTL

ACIN

ACOK

SHDN

ICHG

IINP

CCV

CCI

CCS

CELLS

LDO

BST

DLOV

DHI

DLO

PGND

CSIP

CSIN

BATT

REF CLS

GND

CSSP CSSN

0.01Ω

Minimum Operating Circuit

PART TEMP RANGE PIN-PACKAGE

MAX1908ETI+ -40°C to +85°C 28 Thin QFN-EP*

MAX8724ETI+ -40°C to +85°C 28 Thin QFN-EP*

MAX8765ETI+ -40°C to +85°C 28 Thin QFN-EP*

MAX8765AETI+ -40°C to +85°C 28 Thin QFN-EP*

Denotes a lead(Pb)-free/RoHS-compliant package.

EP = Exposed pad.

19-2764; Rev 5; 11/09

MAX1908/MAX8724/

MAX8765/MAX8765A

Summary of content (30 pages)

PAGE 1
EVALUATION KIT AVAILABLE MAX1908/MAX8724/ MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers LE AVAILAB General Description The MAX1908/MAX8724/MAX8765/MAX8765A highly integrated, multichemistry battery-charger control ICs simplify the construction of accurate and efficient chargers. These devices use analog inputs to control charge current and voltage, and can be programmed by the host or hardwired.
PAGE 2
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers ABSOLUTE MAXIMUM RATINGS DCIN, CSSP, CSSN, ACOK to GND.......................-0.3V to +30V BST to GND ............................................................-0.3V to +36V BST to LX..................................................................-0.3V to +6V DHI to LX ...................................................-0.3V to (VBST + 0.3V) LX to GND .................................................................
PAGE 3
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x VREFIN, CELLS = open, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, CLDO = 1µF, LDO = DLOV, CREF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX 400 650 6.0 6.
PAGE 4
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x VREFIN, CELLS = open, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, CLDO = 1µF, LDO = DLOV, CREF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.
PAGE 5
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x VREFIN, CELLS = open, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, CLDO = 1µF, LDO = DLOV, CREF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.
PAGE 6
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x VREFIN, CELLS = open, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, CLDO = 1µF, LDO = DLOV, CREF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 0.0625 0.
PAGE 7
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x VREFIN, CELLS = open, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, CLDO = 1µF, LDO = DLOV, CREF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = -40°C to +85°C, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS CHARGE-VOLTAGE REGULATION VVCTL = VREFIN -0.
PAGE 8
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x VREFIN, CELLS = open, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, CLDO = 1µF, LDO = DLOV, CREF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = -40°C to +85°C, unless otherwise noted.) (Note 2) PARAMETER SYMBOL ICHG Accuracy CONDITIONS MIN TYP MAX VCSIP - VCSIN = 75mV -7.
PAGE 9
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x VREFIN, CELLS = open, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, CLDO = 1µF, LDO = DLOV, CREF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = -40°C to +85°C, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 28 V 8.
PAGE 10
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers ELECTRICAL CHARACTERISTICS (continued) (VDCIN = VCSSP = VCSSN = 18V, VBATT = VCSIP = VCSIN = 12V, VREFIN = 3V, VVCTL = VICTL = 0.75 x VREFIN, CELLS = open, CLS = REF, VBST - VLX = 4.5V, ACIN = GND = PGND = 0, CLDO = 1µF, LDO = DLOV, CREF = 1µF; CCI, CCS, and CCV are compensated per Figure 1a; TA = -40°C to +85°C, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 0.0625 0.
PAGE 11
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers Typical Operating Characteristics (continued) (Circuit of Figure 1, VDCIN = 20V, TA = +25°C, unless otherwise noted.) LDO LINE REGULATION LDO LOAD REGULATION MAX1908 toc04 VDCIN 10V/div -0.1 -0.2 INDUCTOR CURRENT 500mA/div -0.3 -0.4 -0.5 0.03 0.01 0 -0.02 -0.7 -0.8 -0.03 VLDO = 5.4V -0.9 -0.04 -0.05 -1.0 0 1 2 3 4 5 6 7 8 9 8 10 VIN (V) 0.06 VREF ERROR (%) VREF ERROR (%) -0.03 0.08 -0.04 -0.05 -0.06 0.
PAGE 12
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers Typical Operating Characteristics (continued) (Circuit of Figure 1, VDCIN = 20V, TA = +25°C, unless otherwise noted.) ICHG ERROR vs. CHARGE CURRENT CURRENT-SETTING ERROR vs. ICTL 4 MAX1908 toc14 5.0 MAX1908 toc13 4.5 4.0 VREFIN = 3.3V VREFIN = 3.3V 3.5 3 ICHG (%) CURRENT-SETTING ERROR (%) 5 2 1 3.0 VBATT = 16V VBATT = 12V VBATT = 8V 2.5 2.0 1.5 1.0 0 0.5 0 -1 0 0.5 1.0 1.5 0 2.0 0.5 1.0 IINP ERROR vs.
PAGE 13
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers Pin Description PIN NAME FUNCTION 1 DCIN Charging Voltage Input. Bypass DCIN with a 1µF capacitor to PGND. 2 LDO Device Power Supply. Output of the 5.4V linear regulator supplied from DCIN. Bypass with a 1µF capacitor to GND. 3 CLS Source Current-Limit Input. Voltage input for setting the current limit of the input source. 4 REF 4.096V Voltage Reference. Bypass REF with a 1µF capacitor to GND.
PAGE 14
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers Detailed Description The MAX1908/MAX8724/MAX8765/MAX8765A include all the functions necessary to charge Li+ batteries. A high-efficiency synchronous-rectified step-down DC-DC converter controls charging voltage and current. The device also includes input-source current limiting and analog inputs for setting the charge current and charge voltage. Control charge current and voltage using the ICTL and VCTL inputs, respectively.
PAGE 15
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers Typical Application Circuits AC ADAPTER INPUT 8.5V TO 28V RS1 0.01Ω D1 0.1µF D2 R6 59kΩ 1% R7 19.6kΩ 1% TO EXTERNAL LOAD CSSP CSSN CELLS DCIN C5 1µF C1 2 × 10µF 0.1µF OPEN (3 CELLS SELECT) LDO LDO C13 1µF VCTL R13 33Ω D3 BST DAC OUTPUT ICTL DLOV 12.6V OUTPUT VOLTAGE VCC C15 0.
PAGE 16
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers Typical Application Circuits (continued) AC ADAPTER INPUT 8.5V TO 28V RS1 0.01Ω P1 TO EXTERNAL LOAD R11 15kΩ C1 2 × 10µF 0.01µF 0.01µF R12 12kΩ LDO R6 59kΩ 1% CSSP ACOK DCIN D2 R7 19.6kΩ 1% CSSN CELLS C5 1µF R14 10.5kΩ 1% LDO VCTL LDO C13 1µF R13 33Ω D3 REFIN BST R15 8.25kΩ 1% DLOV 16.8V OUTPUT VOLTAGE 2.5A CHARGE LIMIT R16 8.25kΩ 1% FROM HOST µP (SHUTDOWN) REFIN (4 CELLS SELECT) N C15 0.
PAGE 17
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers Functional Diagram DCIN SHDN 23.5% REFIN LDO RDY GND MAX1908 MAX8724 MAX8765 MAX8765A GND LOGIC BLOCK 5.4V LINEAR REGULATOR 4.096V REFERENCE REF MAX1908/MAX8724 ONLY 1/55 REFIN ICTL SRDY ACIN ACOK DCIN N REF/2 CCS x CLS CSSP 75mV REF CSIP GM ICHG CSI LEVEL SHIFTER CSIN IINP GMS LEVEL SHIFTER CSSN GM BST x ICTL GMI 75mV REFIN LEVEL SHIFTER DRIVER DHI CCI MAX1908 ONLY 3.
PAGE 18
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers Setting the Charging-Current Limit The ICTL input sets the maximum charging current. The current is set by current-sense resistor RS2, connected between CSIP and CSIN. The full-scale differential voltage between CSIP and CSIN is 75mV; thus, for a 0.015Ω sense resistor, the maximum charging current is 5A. Battery-charging current is programmed with ICTL using the equation: ICHG = VICTL 0.
PAGE 19
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers VREF/2. Since ACOK can withstand 30V (max), ACOK can drive a p-channel MOSFET directly at the charger input, providing a lower dropout voltage than a Schottky diode (Figure 2). In the MAX1908/MAX8724 the ACOK comparator is enabled after REFIN is ready. In the MAX8765/MAX8765A, the ACOK comparator is independent of REFIN. Current Measurement Use ICHG to monitor the battery-charging current being sensed across CSIP and CSIN.
PAGE 20
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers DC-DC Functional Diagram 5ms S RESET CSSP MAX1908 MAX8724 MAX8765 MAX8765A BST IMAX R 1.8V Q R CSS X20 AC ADAPTER RS1 D3 BST Q CCMP N1a DHI DHI LDO CSSN CBST LX CHG S IMIN Q 0.15V DLO N1b DLO L1 tOFF GENERATOR CSIP ZCMP 0.1V CSI X20 LVC RS2 CSIN GMS BATT COUT BATTERY GMI GMV SETV CONTROL SETI CLS CELLS CCS CCI CELL SELECT LOGIC CCV Figure 4.
PAGE 21
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers In normal operation, the controller starts a new cycle by turning on the high-side n-channel MOSFET and turning off the low-side n-channel MOSFET. When the charge current is greater than the control point (LVC), CCMP goes high and the off-time is started. The off-time turns off the high-side n-channel MOSFET and turns on the low-side n-channel MOSFET.
PAGE 22
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers where RL varies with load according to RL = VBATT/ICHG.
PAGE 23
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers The 22µF ceramic capacitor has a typical ESR of 0.003Ω, which sets the output zero at 2.412MHz. The output pole is set at: fP _ OUT = 1 = 1.08kHz 2πRL × COUT where: RL = ∆VBATT = Battery ESR ∆ICHG Set the compensation zero (fZ_CV) so it is equivalent to the output pole (fP_OUT = 1.
PAGE 24
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers CSIP To calculate the CCI loop compensation pole, CCI: GMI = 1µA/mV GMOUT = 3.33A/V CSIN GMOUT ROGMI = 10MΩ f = 400kHz Choose crossover frequency fCO_CI to be 1/5th the MAX1908/MAX8724/MAX8765/MAX8765A switching frequency: RS2 CSI CCI ROGMI CCI Solving for CCI, CCI = 2nF. To be conservative, set C CI = 10nF, which sets the crossover frequency at: ICTL Figure 7.
PAGE 25
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers the charge-current amplifier transconductance = 1µA/mV. GM IN is the DC-DC converter transconductance = 3.3A/V.
PAGE 26
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers Choose crossover frequency fCO_CS to be 1/5th the MAX1908/MAX8724/MAX8765/MAX8765A switching frequency: fCO _ CS = GMS = 80kHz 2πCCS Solving for CCS, CCS = 2nF. To be conservative, set CCS = 10nF, which sets the crossover frequency at: fCO _ CS = GMS = 16kHz 2π10nF The compensation pole, fP_CS is set at: fP _ CS = 1 2πROGMS × CCS = 0.
PAGE 27
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers where dV is the maximum voltage sag of 0.5V while delivering energy to the inductor during the high-side MOSFET on-time, and dt is the period at highest operating frequency (400kHz): I 2.5µs C1 > C1 × 2 0.5V Both tantalum and ceramic capacitors are suitable in most applications. For equivalent size and voltage rating, tantalum capacitors have higher capacitance, but also higher ESR than ceramic capacitors.
PAGE 28
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers 2) Place the IC and signal components. Keep the main switching node (LX node) away from sensitive analog components (current-sense traces and REF capacitor). Important: The IC must be no further than 10mm from the current-sense resistors. Keep the gate-drive traces (DHI, DLO, and BST) shorter than 20mm, and route them away from the current-sense lines and REF. Place ceramic bypass capacitors close to the IC.
PAGE 29
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers Package Information Chip Information TRANSISTOR COUNT: 3772 PROCESS: BiCMOS Maxim Integrated For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
PAGE 30
MAX1908/MAX8724/MAX8765/MAX8765A Low-Cost Multichemistry Battery Chargers Revision History REVISION NUMBER REVISION DATE DESCRIPTION 0 2/03 Initial release 5 11/09 Added the MAX8765A to the data sheet. PAGES CHANGED — 1–30 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.