Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - battery management Charge management Li-Ion, NiCd, NiMH QFN 32 (5x5) Surface-mount

General Description

The MAX1870A step-up/step-down multichemistry bat-

tery charger charges with battery voltages above and

below the adapter voltage. This highly integrated

charger requires a minimum number of external compo-

nents. The MAX1870A uses a proprietary step-up/step-

down control scheme that provides efficient charging.

Analog inputs control charge current and voltage, and

can be programmed by the host or hardwired.

The MAX1870A accurately charges two to four lithium-

ion (Li+) series cells at greater than 4A. A programma-

ble input current limit is included, which avoids

overloading the AC adapter when supplying the load

and the battery charger simultaneously. This reduces

the maximum adapter current, which reduces cost. The

MAX1870A provides analog outputs to monitor the cur-

rent drawn from the AC adapter and charge current. A

digital output indicates the presence of an AC adapter.

When the adapter is removed, the MAX1870A con-

sumes less than 1µA from the battery.

The MAX1870A is available in a 32-pin thin QFN (5mm

x 5mm) package and is specified over the -40°C to

+85°C extended temperature range. The MAX1870A

evaluation kit (MAX1870AEVKIT) is available to help

reduce design time.

Applications

Notebook and Subnotebook Computers

Handheld Terminals

Features

♦ Step-Up/Step-Down Control Scheme

♦ ±0.5% Charge-Voltage Accuracy

♦ ±9% Charge-Current Accuracy

♦ ±8% Input Current-Limit Accuracy

♦ Programmable Maximum Battery Charge Current

♦ Analog Inputs Control Charge Current, Charge

Voltage, and Input Current Limit

♦ Analog Output Indicates Adapter Current

♦ Input Voltage from 8V to 28V

♦ Battery Voltage from 0 to 17.6V

♦ Charges Li+ or NiCd/NiMH Batteries

♦ Tiny 32-Pin Thin QFN (5mm x 5mm) Package

MAX1870A

Step-Up/Step-Down

Li+ Battery Charger

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

MAX1870A

REFIN

DCIN

CSSP

CSSN

DHI

DBST

CSIP

CSIN

BATT

SHDN

ASNS

VCTL

IINP

PGND

SYSTEM

LOAD

GND

ICTL

CLS

CELLS

FROM WALL ADAPTER

CSSS

VHN

VHP

BLKP

REF

LDO

DLOV

Typical Operating Circuit

19-3243; Rev 1; 9/05

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

Pin Configuration appears at end of data sheet.

PART TEMP RANGE PIN-PACKAGE

MAX1870AETJ

-40°C to +85°C 32 Thin QFN

MAX1870AETJ+

-40°C to +85°C 32 Thin QFN

+Denotes lead-free package.

Summary of content (32 pages)

PAGE 1
9-3243; Rev 1; 9/05 KIT ATION EVALU E L B AVAILA Step-Up/Step-Down Li+ Battery Charger The MAX1870A step-up/step-down multichemistry battery charger charges with battery voltages above and below the adapter voltage. This highly integrated charger requires a minimum number of external components. The MAX1870A uses a proprietary step-up/stepdown control scheme that provides efficient charging. Analog inputs control charge current and voltage, and can be programmed by the host or hardwired.
PAGE 2
MAX1870A Step-Up/Step-Down Li+ Battery Charger ABSOLUTE MAXIMUM RATINGS DCIN, CSSP, CSSS, CSSN, VHP, VHN, DHI to GND ......................................-0.3V to +30V VHP, DHI to VHN .....................................................-0.3V to +6V BATT, CSIP, CSIN, BLKP to GND ..........................-0.3V to +20V CSIP to CSIN, CSSP to CSSN, CSSP to CSSS, PGND to GND ..........................-0.3V to +0.3V CCI, CCS, CCV, REF, IINP to GND ..........-0.3V to (VLDO + 0.3V) DBST to GND...................
PAGE 3
Step-Up/Step-Down Li+ Battery Charger (Circuit of Figure 2, VDCIN = VCSSP = VCSSN = VCSSS = VVHP = 18V, VBATT = VCSIP = VCSIN = VBLKP = 12V, VREFIN = 3.0V, VICTL = 0.75 x VREFIN, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, VDLOV = 5.4V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CSIN Input Current TYP MAX DCIN = 0 CONDITIONS MIN 0.1 2 ICTL = 0 0.1 2 ICTL = REFIN ICTL Power-Down-Mode Threshold Voltage ICTL Input Bias Current REFIN / 100 0.
PAGE 4
MAX1870A Step-Up/Step-Down Li+ Battery Charger ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 2, VDCIN = VCSSP = VCSSN = VCSSS = VVHP = 18V, VBATT = VCSIP = VCSIN = VBLKP = 12V, VREFIN = 3.0V, VICTL = 0.75 x VREFIN, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, VDLOV = 5.4V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS MIN TYP MAX UNITS 4.076 4.096 4.116 V 5 10 mV 3.1 3.9 V 3.
PAGE 5
Step-Up/Step-Down Li+ Battery Charger (Circuit of Figure 2, VDCIN = VCSSP = VCSSN = VCSSS = VVHP = 18V, VBATT = VCSIP = VCSIN = VBLKP = 12V, VREFIN = 3.0V, VICTL = 0.75 x VREFIN, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, VDLOV = 5.4V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER GMS Amplifier Loop Transconductance CCV Output Current CONDITIONS MIN TYP MAX VCLS = REF, VCSSP - VCSSN = 102mV, VCSSP = VCSSS 1.2 1.7 2.
PAGE 6
MAX1870A Step-Up/Step-Down Li+ Battery Charger ELECTRICAL CHARACTERISTICS (Circuit of Figure 2, VDCIN = VCSSP = VCSSN = VCSSS = VVHP = 18V, VBATT = VCSIP = VCSIN = VBLKP = 12V, VREFIN = 3.0V, VICTL = 0.75 x VREFIN, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, VDLOV = 5.4V, TA = -40°C to +85°C.) (Note 1) PARAMETER CONDITIONS MIN TYP MAX UNITS V CHARGE-VOLTAGE REGULATION VCTL Range Battery Regulation Voltage Accuracy VCTL Default Threshold 0 3.6 VVCTL = VLDO (2 cells) -0.8 +0.
PAGE 7
Step-Up/Step-Down Li+ Battery Charger (Circuit of Figure 2, VDCIN = VCSSP = VCSSN = VCSSS = VVHP = 18V, VBATT = VCSIP = VCSIN = VBLKP = 12V, VREFIN = 3.0V, VICTL = 0.75 x VREFIN, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, VDLOV = 5.4V, TA = -40°C to +85°C.) (Note 1) PARAMETER CONDITIONS MIN TYP MAX UNITS 28 V SUPPLY AND LINEAR REGULATOR DCIN Input Voltage Range DCIN Undervoltage Lockout DCIN Quiescent Current 8 DCIN falling 4 DCIN rising 7.85 8.
PAGE 8
MAX1870A Step-Up/Step-Down Li+ Battery Charger ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 2, VDCIN = VCSSP = VCSSN = VCSSS = VVHP = 18V, VBATT = VCSIP = VCSIN = VBLKP = 12V, VREFIN = 3.0V, VICTL = 0.75 x VREFIN, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, VDLOV = 5.4V, TA = -40°C to +85°C.) (Note 1) PARAMETER CONDITIONS MIN TYP MAX UNITS ERROR AMPLIFIERS GMV Amplifier Loop Transconductance VCTL = REFIN, VBATT = 16.8V 0.05 0.
PAGE 9
Step-Up/Step-Down Li+ Battery Charger BATTERY INSERTION AND REMOVAL BATTERY REMOVAL BATTERY INSERTION 20V RCV = 10kΩ, COUT = 22μF MAX1870Atoc02 MAX1870Atoc01 BATTERY-REMOVAL RESPONSE 18V VBATT 16V ICHARGE 5A/div 0 CCV 21V 20V RCV = 10kΩ, COUT = 44μF 19V VBATT 18V RCV = 20kΩ, COUT = 44μF CCI CCI 4V CCI AND CCV 2V CCV 17V 16V 0 2.00ms/div 10.
PAGE 10
Typical Operating Characteristics (continued) (Circuit of Figure 1, VDCIN = 16V, CELLS = REFIN, VCLS =VREF, VICTL = VREFIN = 3.3V, TA = +25°C, unless otherwise noted.) 90 EFFICIENCY (%) VIN = 16V 80 75 70 VBATT = 12.6V 85 VBATT = 8.4V 80 75 70 0.2 0.1 -0.2 -0.3 -0.4 -0.5 8 10 12 14 18 16 0 0.5 1.0 1.5 2.0 VBATT = 16.8V -0.1 60 6 VBATT = 8.4V 0 60 4 MAX1870A toc09 0.3 65 0 2.5 0.5 1.0 1.5 2.
PAGE 11
Step-Up/Step-Down Li+ Battery Charger REFERENCE ERROR vs. TEMPERATURE 0.40 REFERENCE ERROR (%) 4.08 4.07 4.06 0.35 5.36 VIN = 28V 5.34 0.30 0.25 0.20 0.15 4.05 0.10 4.04 0.05 4.03 500 1000 1500 2500 2000 5.32 VIN = 16V 5.30 5.28 VIN = 9V 5.26 5.24 0 -40 -20 LOAD CURRENT (μA) 0 20 40 60 0 100 80 10 20 TEMPERATURE (°C) 30 40 50 LOAD (mA) OUTPUT VOLTAGE RIPPLE vs. BATTERY VOLTAGE LDO vs. TEMPERATURE 160 RMS OUTPUT RIPPLE (mV) 0.6 MAX1870Atoc20 180 MAX1870A toc19 0.8 0.
PAGE 12
Typical Operating Characteristics (continued) (Circuit of Figure 1, VDCIN = 16V, CELLS = REFIN, VCLS =VREF, VICTL = VREFIN = 3.3V, TA = +25°C, unless otherwise noted.) STEP-UP SWITCHING WAVEFORM STEP-UP/STEP-DOWN LIGHT LOAD VIN = 12V VBATT = 16V 20V 10V D4 CATHODE 0V MAX1870Atoc24 MAX1870Atoc23 MAX1870A Step-Up/Step-Down Li+ Battery Charger VIN = 16V VBATT = 16V 10V D3 ANODE 0V 4A INDUCTOR CURRENT 2A 10V D4 CATHODE 0V 10V D3 ANODE 0V CHARGE CURRENT = 300mA VBATT (AC-COUPLED) 50mV/div 2.
PAGE 13
Step-Up/Step-Down Li+ Battery Charger PIN NAME FUNCTION 12 ICTL Charge-Current Control Input. Drive ICTL from VREFIN / 32 to VREFIN to adjust the charge current. See the Setting the Charge Current section. Drive ICTL to GND to disable charging. 13 CELLS 14 IINP 15 SHDN Shutdown Comparator Input. Pull SHDN low to stop charging. Optionally connect a thermistor to stop charging when the battery temperature is too hot.
PAGE 14
MAX1870A Step-Up/Step-Down Li+ Battery Charger OPTIONAL REVERSEADAPTER PROTECTION D2 + AC ADAPTER C8 22μF D1 - CSSS 32 C7 1μF 28 30 VHP DCIN VHN C5 1μF CSSP 26 RS1a 30mΩ 31 SYSTEM LOAD RS1b 30mΩ 2.2μF 2 C1 1μF REF CSSN R3 DHI 3 MAX1870A 5 6 7 C2 0.01μF C3 0.01μF M1 27 C4 0.01μF P L1 10μH CLS R4 R5 10kΩ 29 D4 CCV DBST D3 M2 22 N CCI CCS CSIP 18 2.
PAGE 15
Step-Up/Step-Down Li+ Battery Charger MAX1870A OPTIONAL REVERSEADAPTER PROTECTION OPTIONAL D2 + AC ADAPTER C8 22μF D1 32 C7 1μF 28 30 CSSS VHP DCIN VHN C5 1μF CSSP 26 RS1a 30mΩ 31 SYSTEM LOAD 13 2 C1 1μF R3 SHORT 3 RS1b 30mΩ 2.2μF CELLS REF CSSN CLS DHI 29 M1 27 P L1 10μH R4 OPEN D4 9 15 R9 OPEN R1 SHORT 11 12 LDO MAX1870A REFIN SHDN DBST M2 22 D3 N VCTL CSIP ICTL 18 2.
PAGE 16
MAX1870A Step-Up/Step-Down Li+ Battery Charger Detailed Description The MAX1870A includes all of the functions necessary to charge Li+, NiMH, and NiCd batteries. A high-efficiency H-bridge topology DC-DC converter controls charge voltage and current. A proprietary control scheme offers improved efficiency and smaller inductor size compared to conventional H-bridge controllers and operates from input voltages above and below the battery voltage.
PAGE 17
Step-Up/Step-Down Li+ Battery Charger MAX1870A IINP ASNS INPUT-CURRENT BLOCK CSSN CSS A = 18V/V Gm IMAX1 CURRENTSENSE AMPLIFIERS 3.6V (6.7A FOR 30mΩ) 0.81mV (1.5A FOR 30mΩ) CSSP A = 18V/V CSSS GMS CLS MAX1870A CCS LVC CCI 0.15V x 50mV REFIN ICTL CSIP GMI A = 18V/V CSI CSIN VHP LVC 22.5mV (42mA ON 30mΩ) IZX IMIN HIGHSIDE DRIVER IMAX1 STEP-UP/DOWN CURRENT-MODE STATE MACHINE CHARGE-CURRENT BLOCK (6.7A FOR 30mΩ) 3.
PAGE 18
MAX1870A Step-Up/Step-Down Li+ Battery Charger The input source current is the sum of the MAX1870A quiescent current, the charger input current, and the system load current. The MAX1870A’s 6mA maximum quiescent current is minimal compared to the charge and load currents.
PAGE 19
Step-Up/Step-Down Li+ Battery Charger up with a dI/dt of (VIN - VBATT) / L. M1 remains on until a step-down on-time timer expires. This on-time is calculated based on the input and output voltage to maintain pseudo-fixed-frequency 400kHz operation. At the end of state B, another step-down off-time (state A) is initiated and the cycle repeats. The off-time is valley regulated according to the error signal.
PAGE 20
MAX1870A Step-Up/Step-Down Li+ Battery Charger up operation. During this mode, the MAX1870A regulates the step-up on-time. Initially DBST switches M2 on (state C) and the inductor current ramps up with a dI/dt of VIN / L. After the inductor current crosses the target current (set by the error integrators), DBST switches M2 off (state B) and the inductor current ramps down with a dI/dt of (VBATT - VIN) / L. M2 remains off until a stepup off-time timer expires.
PAGE 21
Step-Up/Step-Down Li+ Battery Charger MAX1870A dl VIN - VOUT = L dt dl VOUT = L dt STATE B STATE A VALLEY REGULATED OFF-TIME PRECALCULATED STEP-DOWN ON-TIME VIN > 1.4 x VBATT DUTY = VIN / VOUT Figure 6. MAX1870A Step-Down Inductor Current Waveform dl VIN - VOUT = L dt STATE B STATE C VIN > 0.9 x VBATT PEAK REGULATED ON-TIME dl VOUT = L dt PRECALCULATED OFF-TIME DUTY = 1 - VIN / VOUT Figure 7.
PAGE 22
MAX1870A Step-Up/Step-Down Li+ Battery Charger • • CCMP: CCMP compares the current-mode control point, LVC, to the inductor current. In step-down mode, the off-time (state A) is terminated when the inductor current falls below the current threshold set by LVC. In step-up mode, the on-time (state C) is terminated when the inductor current rises above the current threshold set by LVC. IMAX: The IMAX comparators provide a cycle-bycycle inductor current limit.
PAGE 23
Step-Up/Step-Down Li+ Battery Charger Compensation Each of the three regulation loops (the battery voltage, the charge current, and the input current limit) are compensated separately using the CCV, CCI, and CCS pins, respectively. Compensate the voltage regulation loop with a 10kΩ resistor in series with a 0.01µF capacitor from CCV to GND. Compensate the charge current loop and source current loop with 0.01µF capacitors from CCI to GND and from CCS to GND, respectively.
PAGE 24
MAX1870A Step-Up/Step-Down Li+ Battery Charger LTF = GMPWM x RL = 0.2Ω RCV GMV sCOUT fOSC = 400kHz RCV = Setting the LTF = 1 to solve for the unity-gain frequency yields: ⎛ ⎞ RCV fCO _ CV = GMPWM x GMV ⎜ ⎟ ⎝ 2π x COUT ⎠ For stability, choose a crossover frequency lower than 1/10th of the switching frequency. The crossover frequency must also be below the RHP zero, calculated at maximum charge current, minimum input voltage, and maximum battery voltage.
PAGE 25
Step-Up/Step-Down Li+ Battery Charger LTF = GMPWM x ACS _ x RS _ x GM _ ROGM _ 1 + sROGM _ x CC _ which describes a single-pole system. Since GMPWM = 1 ACS _ x RS _ For stability, choose a crossover frequency lower than 1/10th of the switching frequency and lower than half of the RHP zero.
PAGE 26
LDO provides a 5.4V supply derived from DCIN and delivers over 10mA. The n-channel MOSFET driver DBST is powered by DLOV and can source 2.5A and sink 5A. Since LDO provides power to the internal analog circuitry, use an RC filter from LDO to DLOV as shown in Figure 1 to minimize noise at LDO. LDO also supplies the 4.096V reference (REF) and most of the internal control circuitry. Bypass LDO with a 1µF or greater capacitor to GND.
PAGE 27
Step-Up/Step-Down Li+ Battery Charger Inductor Selection Select the inductor to minimize power dissipation in the MOSFETs, inductor, and sense resistors. To optimize resistive losses and RMS inductor current, set the LIR (inductor current ripple) to 0.3. Because the maximum resistive power loss occurs at the step-up boundary of hybrid mode, select LIR for operating in this mode.
PAGE 28
MAX1870A Step-Up/Step-Down Li+ Battery Charger Table 5.
PAGE 29
Step-Up/Step-Down Li+ Battery Charger Bypass DCIN with a 1µF to ground (Figure 1). Optional diodes D1 and D2 protect the MAX1870A when the DC power-source input is reversed. A signal diode for D1 is adequate because DCIN only powers the LDO and the internal reference. Good PC board layout is required to achieve specified noise, efficiency, and stable performance.
PAGE 30
MAX1870A Step-Up/Step-Down Li+ Battery Charger BATT C9 PGND RS2 L1 D3 D4 P M1 M2 C8 N IN RS1b RS1a LOAD Figure 14. Recommended Layout for the MAX1870A Pin Configuration I.C. PGND DBST I.C. I.C.
PAGE 31
Step-Up/Step-Down Li+ Battery Charger QFN THIN.EPS D2 D b C L 0.10 M C A B D2/2 D/2 k L MARKING XXXXX E/2 E2/2 C L (NE-1) X e E DETAIL A PIN # 1 I.D. e/2 E2 PIN # 1 I.D. 0.35x45° e (ND-1) X e DETAIL B e L1 L C L C L L L e e 0.10 C A C 0.08 C A1 A3 PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.
PAGE 32
MAX1870A Step-Up/Step-Down Li+ Battery Charger Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) COMMON DIMENSIONS PKG. 16L 5x5 20L 5x5 EXPOSED PAD VARIATIONS 28L 5x5 32L 5x5 40L 5x5 SYMBOL MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. A A1 A3 b D E e k L L1 N ND NE JEDEC 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 0.