MAX1870AETJ+ ,Step-Up/Step-Down Li+ Battery ChargerElectrical Characteristics(Circuit of Figure 2, V = V = V = V = V = 18V, V = V = V = V = 12V, V = 3 ..
MAX1870AETJ+ ,Step-Up/Step-Down Li+ Battery ChargerFeaturesThe MAX1870A step-up/step-down multichemistry• Highly Flexible Input Voltage Range Works wi ..
MAX1873REEE ,Simple Current-Limited Switch-Mode Li Charger ControllerELECTRICAL CHARACTERISTICS(Circuit of Figure 1, V = V = V = 18V, V = V , V = V /2. MAX1873R: V = V ..
MAX1873REEE+ ,Simple Current-Limited Switch-Mode Li+ Charger ControllerFeaturesThe low-cost MAX1873R/S/T provides all functions♦ Low-Cost and Simple Circuitneeded to simp ..
MAX1873REEE+T ,Simple Current-Limited Switch-Mode Li+ Charger ControllerELECTRICAL CHARACTERISTICS(Circuit of Figure 1, V = V = V = 18V, V = V , V = V /2. MAX1873R: V = V ..
MAX1873SEEE ,Simple Current-Limited Switch-Mode Li Charger ControllerMAX187319-2099; Rev 0; 7/01Simple Current-Limited Switch-Mode Li+ Charger Controller
MAX480ESA ,High-precision, low-voltage, micropower op amp.Applications MAX480CPA 0°C to +70°C 8 Plastic DIPMAX480CSA 0°C to +70°C 8 SOPrecision Micropower Am ..
MAX480ESA+ ,High Precision, Low-Voltage, Micropower Op AmpApplications MAX480CPA 0°C to +70°C 8 Plastic DIPMAX480CSA 0°C to +70°C 8 SOPrecision Micropower Am ..
MAX4810CTN+ ,Dual, Unipolar/Bipolar, High-Voltage Digital PulsersApplications GC2C 47 24 INP2DC2Ultrasound Medical Flaw DetectionV 23 EN248EE2ImagingPiezoelectric D ..
MAX481CPA ,Low-Power, Slew-Rate-Limited RS-485/RS-422 TransceiversApplicationsIndustrial-Control Local Area Networks Ordering Information appears at end of data shee ..
MAX481CPA ,Low-Power, Slew-Rate-Limited RS-485/RS-422 TransceiversApplicationsguarantees a logic-high output if the input is open circuit.MAX3030E–MAX3033E: ±15kV E ..
MAX481CPA ,Low-Power, Slew-Rate-Limited RS-485/RS-422 TransceiversApplicationsMAX3483E/MAX3485E/MAX3486E/MAX3488E/Low-Power RS-485 TransceiversMAX3490E/MAX3491E: +3. ..
MAX1870AETJ+
Step-Up/Step-Down Li+ Battery Charger
MAX1870AStep-Up/Step-Down
Li+ Battery ChargerEVALUATION KIT AVAILABLE
General DescriptionThe 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 com-
ponents. 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 program-
mable 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
consumes 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 avaiable
to help reduce design time.
ApplicationsNotebook and Subnotebook Computers
Handheld Terminals
Benefits and FeaturesHighly Flexible Input Voltage Range Works with
Affordable AC AdaptersStep-Up/Step-Down Control SchemeInput Voltage from 8V to 28VAnalog Output Indicates Adapter Current
Accurately Charge Li+ or NiCd/NiMH BatteriesBattery Voltage from 0 to 17.6V±0.5% Charge-Voltage Accuracy±9% Charge-Current Accuracy±8% Input Current-Limit Accuracy
Tune Design to Increase Safety and EfficiencyProgrammable Maximum Battery Charge CurrentAnalog Inputs Control Charge Current, Charge
Voltage, and Input Current Limit
32-Pin Thin QFN (5mm x 5mm) Package Saves
Space While Supporting Step-Up and Step-Down
Operation
Ordering InformationMAX1870A
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
PARTTEMP RANGEPIN-PACKAGEMAX1870AETJ-40°C to +85°C32 Thin QFN
MAX1870AETJ+-40°C to +85°C32 Thin QFN
+Denotes a lead(Pb)-free/RoHS-compliant package.
MAX1870AStep-Up/Step-Down
Li+ Battery Charger
Absolute Maximum RatingsStresses 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.
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..........................................-0.3V to (VDLOV+ 0.3V)
DLOV, VCTL, ICTL, REFIN, CELLS,
CLS, LDO, ASNS, SHDNto GND.........................-0.3V to +6V
LDO Current........................................................................50mA
Continuous Power Dissipation (TA= +70°C)
32-Pin Thin QFN 5mm x 5mm
(derate 21mW/°C above +70°C)......................................1.7W
Operating Temperature Range
MAX1870AETJ.................................................-40°C to +85°C
Storage Temperature Range.............................-60°C to +150°C
Lead Temperature (soldering, 10s)................................+300°C
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
= 0°C to +85°C, unless otherwise noted. Typicalvalues are at TA= +25°C.)
PARAMETERCONDITIONS MIN TYP MAX UNITSCHARGE-VOLTAGE REGULATION VCTL Range 0 3.6 VVVCTL = VLDO (2 cells) -0.5 +0.5VVCTL = VLDO (3 cells) -0.5 +0.5VVCTL = VLDO (4 cells) -0.5 +0.5VVCTL = VREFIN (2 cells) -0.8 +0.8VVCTL = VREFIN (3 cells) -0.8 +0.8VVCTL = VREFIN (4 cells) -0.8 +0.8VVCTL = VREFIN / 20 (2 cells) -1.2 +1.2VVCTL = VREFIN / 20 (3 cells) -1.2 +1.2Battery Regulation Voltage
AccuracyVVCTL = VREFIN / 20 (4 cells) -1.2 +1.2%VCTL Default Threshold VCTL rising 4.0 4.1 4.2 V0 < VVCTL < VREFIN -1 +1DCIN = 0, VREFIN = VVCTL = 3.6V -1 +1 VCTL Input Bias CurrentVCTL = DCIN = 0, VREFIN = 3.6V -1 +1µA
CHARGE-CURRENT REGULATION ICTL Range 0 3.6 VVICTL = VREFIN 67 73 79VICTL = VREFIN x 0.8 54 59 64 Quick-Charge-Current AccuracyVICTL = VREFIN x 0.583 39 43 47mVTrickle-Charge-Current Accuracy VICTL = VREFIN x 0.0625 3.0 4.5 6.0 mVBATT/CSIP/CSIN Input Voltage
Range 0 19 VDCIN = 0 0.1 2ICTL = 0 0.1 2 CSIP Input CurrentICTL = REFIN 350 600µA
MAX1870AStep-Up/Step-Down
Li+ Battery Charger
PARAMETERCONDITIONS MIN TYP MAX UNITSDCIN = 0 0.1 2ICTL = 0 0.1 2 CSIN Input CurrentICTL = REFIN 0.1 2µAICTL Power-Down-Mode
Threshold Voltage REFIN /
100 REFIN / REFIN / V0 < VICTL < VREFIN -1 +1 ICTL Input Bias Current ICTL = DCIN = 0, VREFIN = 3.6V -1 +1 µA
INPUT-CURRENT REGULATION CLS = REF 97 105 113 Charger-Input Current-Limit
Accuracy (VCSSP - VCSSN) CSSS = CSSP CLS = REF x 0.845 81 88 95 mVCLS = REF 97 105 113 System-Input Current-Limit
Accuracy (VCSSP - VCSSS) CSSN = CSSP CLS = REF x 0.845 81 88 95 mVCSSP/CSSS/CSSN Input Voltage
Range 8 28 VVCSSP = VCSSN = VCSSS = VDCIN = 6V -1 +1 CSSP Input Current VCSSP = VCSSN = VCSSS = VDCIN = 8V, 28V 700 1200 µAVCSSP = VCSSN = VCSSS = VDCIN = 6V -1 +1 CSSS/CSSN Input Current VCSSP = VCSSN = VCSSS = VDCIN = 8V, 28V -1 +1 µACLS Input Range VREF / 2 VREF VCLS Input Bias Current CLS = REF -1 +1 µAIINP Transconductance VCSSP - VCSSS = 102mV, CSSN = CSSP 2.5 2.8 3.1 µA/mVVCSSP - VCSSN = 200mV, VIINP = 0V 350 IINP Output Current VCSSP - VCSSS = 200mV, VIINP = 0V 350 µAVCSSP - VCSSN = 200mV, IINP float 3.5 IINP Output Voltage VCSSP - VCSSS = 200mV, IINP float 3.5 V
SUPPLY AND LINEAR REGULATOR DCIN Input Voltage Range 8 28 VDCIN falling 4 6.2 DCIN Undervoltage Lockout DCIN rising 6.3 7.85 VDCIN Quiescent Current 8.0V < VDCIN < 28V 3.5 6 mABATT Input Voltage Range 0 19 VDCIN = 0 0.1 1 BATT Input Bias Current VBATT = 2V to 19V 300 500 µALDO Output Voltage No load 5.3 5.4 5.5 VLDO Load Regulation 0 < ILDO < 10mA 70 150 mVLDO Undervoltage Lockout VDCIN = 8V, LDO rising 4.00 5.0 5.25 V
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. Typicalvalues are at TA= +25°C.)
MAX1870AStep-Up/Step-Down
Li+ Battery Charger
PARAMETERCONDITIONS MIN TYP MAX UNITSREFERENCE REF Output Voltage IREF = 0µA 4.076 4.096 4.116 VREF Load Regulation 0 < IREF < 500µA 5 10 mVREF Undervoltage-Lockout Trip
Point VREF falling 3.1 3.9 VREFIN Input Range 2.5 3.6 VREFIN UVLO Rising 1.9 2.2 VREFIN UVLO Hysteresis 50 mVVDCIN = 18V 50 100 REFIN Input Bias Current DCIN = 0, VREFIN = 3.6V -1 +1 µA
SWITCHING REGULATOR C ycl e- b y- C ycl e S tep - U p M axi m um ur r ent- Li m i t S ense V ol tag e VDCIN = 12V, VBATT = 16.8V 135 150 165 mVC ycl e- b y- C ycl e S tep - D ow naxi m um C ur r ent- Li m i t S enseol tag e VDCIN = 19V, VBATT = 16.8V 135 150 165 mVStep-Down On-Time VDCIN = 18V, VBATT = 16.8V 2.2 2.4 2.6 µsMinimum Step-Down Off-Time VDCIN = 18V, VBATT = 16.8V 0.15 0.4 0.50 µsStep-Up Off-Time VDCIN = 12V, VBATT = 16.8V 1.6 1.8 2.0 µsMinimum Step-Up On-Time VDCIN = 12V, VBATT = 16.8V 0.15 0.3 0.40 µs
MOSFET DRIVERS VHP - VHN Output Voltage 8V < VVHP < 28V, no load 4.5 5 5.5 VVHN Load Regulation 0 < IVHN < 10mA 70 150 mVDHI On-Resistance High ISOURCE = 10mA 2 5 ΩDHI On-Resistance Low ISINK = 10mA 1 3 ΩDCIN = 0 0.1 1 µA VHP Input Bias Current VDCIN = 18V 1.3 2 mAICTL = 0 0.1 2 BLKP Input Bias Current VICTL = VREFIN = 3.3V 100 400 µADLOV Supply Current DBST low 5 10 µADBST On-Resistance High ISOURCE = 10mA 2 5 ΩDBST On-Resistance Low ISINK = 10mA 1 3 Ω
ERROR AMPLIFIERS GMV Amplifier Loop
Transconductance V C TL = RE FIN , V BAT T = 16.8V 0.05 0.1 0.20 µA/mVGMI Amplifier Loop
Transconductance ICTL = REFIN, VCSIP - VCSIN = 72mV 1.8 2.4 3.0 µA/mV
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. Typicalvalues are at TA= +25°C.)
MAX1870AStep-Up/Step-Down
Li+ Battery Charger
PARAMETERCONDITIONS MIN TYP MAX UNITSVCLS = REF, VCSSP - VCSSN = 102mV, VCSSP = VCSSS 1.2 1.7 2.2 GMS Amplifier Loop
Transconductance VCLS = REF, VCSSP - VCSSS = 102mV, VCSSP = VCSSN 1.2 1.7 2.2 µA/mVVCTL = REFIN, VBATT = 15.8V 50 CCV Output Current VCTL = REFIN, VBATT = 17.8V -50 µAICTL = REFIN, VCSIP - VCSIN = 0mV 150 CCI Output Current ICTL = REFIN, VCSIP - VCSIN = 150mV -150 µACLS = REF, VCSSP = VCSSN, VCSSP = VCSSS 100 CCS Output Current CLS = REF, VCSSP - VCSSN = 200mV,
VCSSP - VCSSS = 200mV -100 µACCI/CCS/CCV Clamp Voltage 1.1V < VCCV < 3.5V, 1.1V < VCCS < 3.5V,
1.1V < VCCI < 3.5V 100 300 500 mV
LOGIC LEVELS ASNS Output-Voltage Low VIINP = GND, ISINK = 1mA 0.4 VASNS Output-Voltage High VIINP = 4V, ISOURCE = 1mA LDO -
0.5 VVIINP rising 1.1 1.15 1.2 V ASNS Current Detect Hysteresis 50 mVVSHDN = 0 to VREFIN -1 +1 SHDN Input Bias Current DCIN = 0, VREFIN = 5V, VSHDN = 0 to VREFIN -1 +1 µASHDN Threshold SHDN falling, VREFIN = 2.8V to 3.6V 22 23.5 25 % of
REFINSHDN Hysteresis 1 % of
REFINCELLS Input Low Voltage 0.75 VCELLS Float Voltage 40 50 60 % of
REFINCELLS Input High Voltage RE FIN -
0.75V VCELLS Input Bias Current CELLS = 0 to REFIN -2 +2 µA
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. Typicalvalues are at TA= +25°C.)
MAX1870AStep-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)
PARAMETERCONDITIONS MIN TYP MAX UNITSCHARGE-VOLTAGE REGULATION VCTL Range 0 3.6 VVVCTL = VLDO (2 cells) -0.8 +0.8VVCTL = VLDO (3 cells) -0.8 +0.8VVCTL = VLDO (4 cells) -0.8 +0.8VVCTL = VREFIN (2 cells) -1.2 +1.2VVCTL = VREFIN (3 cells) -1.2 +1.2VVCTL = VREFIN (4 cells) -1.2 +1.2VVCTL = VREFIN / 20 (2 cells) -1.4 +1.4VVCTL = VREFIN / 20 (3 cells) -1.4 +1.4Battery Regulation Voltage
AccuracyVVCTL = VREFIN / 20 (4 cells) -1.4 +1.4%VCTL Default Threshold VCTL rising 4.0 4.2 V
CHARGE-CURRENT REGULATION ICTL Range 0 3.6 VVICTL = VREFIN 66 80VICTL = VREFIN x 0.8 53 65 Quick-Charge-Current AccuracyVICTL = VREFIN x 0.583 38 48mVBATT/CSIP/CSIN Input Voltage
Range 0 19 VCSIP Input Current ICTL = REFIN 600 µAICTL Power-Down-Mode
Threshold Voltage REFIN /
100 REFIN / V
INPUT-CURRENT REGULATION CLS = REF 95 115 Charger-Input Current-Limit
Accuracy (VCSSP - VCSSN) CSSS = CSSP CLS = REF x 0.845 79 97 mVCLS = REF 95 115 System-Input Current-Limit
Accuracy (VCSSP - VCSSS) CSSN = CSSP CLS = REF x 0.845 79 97 mVCSSP/CSSS/CSSN Input Voltage
Range 8 28 VCSSP Input Current VCSSP = VCSSN = VCSSS = VDCIN = 8V, 28V 1200 µACLS Input Range VREF / 2 VREF VIINP Transconductance VCSSP - VCSSS = 102mV, CSSN = CSSP 2.5 3.1 µA/mVVCSSP - VCSSN = 200mV, VIINP = 0V 350 IINP Output Current VCSSP - VCSSS = 200mV, VIINP = 0V 350 µAVCSSP - VCSSN = 200mV, IINP float 3.5 IINP Output Voltage VCSSP - VCSSS = 200mV, IINP float 3.5 V
MAX1870AStep-Up/Step-Down
Li+ Battery Charger
PARAMETERCONDITIONS MIN TYP MAX UNITSSUPPLY AND LINEAR REGULATOR DCIN Input Voltage Range 8 28 VDCIN falling 4 DCIN Undervoltage Lockout DCIN rising 7.85 VDCIN Quiescent Current 8.0V < VDCIN < 28V 6 mABATT Input Voltage Range 0 19 VBATT Input Bias Current VBATT = 2V to 19V 500 µALDO Output Voltage No load 5.3 5.5 VLDO Undervoltage Lockout VDCIN = 8V, LDO rising 4.00 5.25 V
REFERENCE REF Output Voltage IREF = 0µA 4.060 4.132 VREF Load Regulation 0 < IREF < 500µA 10 mVREF Undervoltage-Lockout Trip
Point VREF falling 3.9 VREFIN Input Range 2.5 3.6 VREFIN UVLO Rising 2.2 VREFIN Input Bias Current VDCIN = 18V 100 µA
SWITCHING REGULATOR C ycl e- b y- C ycl e S tep - U p M axi m um ur r ent- Li m i t S ense V ol tag e VDCIN = 12V, VBATT = 16.8V 130 170 mVC ycl e- b y- C ycl e S tep - D ow naxi m um C ur r ent- Li m i t S enseol tag e VDCIN = 19V, VBATT = 16.8V 130 170 mVStep-Down On-Time VDCIN = 18V, VBATT = 16.8V 2.2 2.6 µsMinimum Step-Down Off-Time VDCIN = 18V, VBATT = 16.8V 0.15 0.50 µsStep-Up Off-Time VDCIN = 12V, VBATT = 16.8V 1.6 2.0 µsMinimum Step-Up On-Time VDCIN = 12V, VBATT = 16.8V 0.15 0.40 µs
MOSFET DRIVERS VHP - VHN Output Voltage 8V < VVHP < 28V, no load 4.5 5.5 VVHN Load Regulation 0 < IVHN < 10mA 150 mVDHI On-Resistance High ISOURCE = 10mA 5 ΩDHI On-Resistance Low ISINK = 10mA 3 ΩVHP Input Bias Current VDCIN = 18V 2 mABLKP Input Bias Current VICTL = VREFIN = 3.3V 400 µADLOV Supply Current DBST low 10 µADBST On-Resistance High ISOURCE = 10mA 5 ΩDBST On-Resistance Low ISINK = 10mA 3 Ω
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)
MAX1870AStep-Up/Step-Down
Li+ Battery Charger
PARAMETERCONDITIONS MIN TYP MAX UNITSERROR AMPLIFIERS GMV Amplifier Loop
Transconductance V C TL = RE FIN , V BAT T = 16.8V 0.05 0.20 µA/mVGMI Amplifier Loop
Transconductance ICTL = REFIN, VCSIP - VCSIN = 72mV 1.8 3.0 µA/mVVCLS = REF, VCSSP - VCSSN = 102mV, VCSSP = VCSSS 1.2 2.2 GMS Amplifier Loop
Transconductance VCLS = REF, VCSSP - VCSSS = 102mV, VCSSP = VCSSN 1.2 2.2 µA/mVVCTL = REFIN, VBATT = 15.8V 50 CCV Output Current VCTL = REFIN, VBATT = 17.8V -50 µAICTL = REFIN, VCSIP - VCSIN = 0mV 150 CCI Output Current ICTL = REFIN, VCSIP - VCSIN = 150mV -150 µACLS = REF, VCSSP = VCSSN, VCSSP = VCSSS 100 CCS Output Current CLS = REF, VCSSP - VCSSN = 200mV,
VCSSP - VCSSS = 200mV -100 µACCI/CCS/CCV Clamp Voltage 1.1V < VCCV < 3.5V, 1.1V < VCCS < 3.5V,
1.1V < VCCI < 3.5V 100 500 mVLOGIC LEVELS ASNS Output-Voltage Low VIINP = GND, ISINK = 1mA 0.4 VASNS Output-Voltage High VIINP = 4V, ISOURCE = 1mA LDO -
0.5 VASNS Current Detect VIINP rising 1.1 1.15 1.2 VSHDN Threshold SHDN falling, VREFIN = 2.8V to 3.6V 22 25 % of
REFINCELLS Input Low Voltage 0.75 VCELLS Float Voltage 40 60 % of
REFINCELLS Input High Voltage RE FIN -
0.75V V
Note 1:Specifications to -40°C are guaranteed by design, not production tested.
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)
MAX1870AStep-Up/Step-Down
Li+ Battery Charger
BATTERY INSERTION AND REMOVAL
MAX1870Atoc01
VBATT
18V
16V
ICHARGE
5A/div
CCI AND CCVCCI
CCV
20V
2.00ms/div
BATTERY REMOVAL
BATTERY
INSERTION
CCV CCI
BATTERY-REMOVAL RESPONSE
MAX1870Atoc02
VBATT
21V
18V
20V
19V
16V
17V
10.0μs/div
RCV = 10kΩ, COUT = 22μF
RCV = 10kΩ, COUT = 44μF
RCV = 20kΩ, COUT = 44μF
SYSTEM LOAD-TRANSIENT RESPONSE
MAX1870Atoc034A
INDUCTOR CURRENT
SYSTEM LOAD
INPUT CURRENT
BATTERY CURRENT
200μs
STEP-DOWN MODE
SYSTEM LOAD-TRANSIENT RESPONSE
MAX1870Atoc044A
INDUCTOR CURRENT
SYSTEM LOAD
INPUT CURRENT
BATTERY CURRENT
100μs
HYBRID MODE
CHARGE-CURRENT STEP RESPONSE
MAX1870Atoc05
INDUCTOR CURRENT
BATTERY CURRENT
CCI
VICTL
400μs
STEP-DOWN
MODE
CHARGE-CURRENT STEP RESPONSE
MAX1870Atoc062A
INDUCTOR CURRENT
BATTERY CURRENT
CCI
VICTL
400μs
HYBRID MODE
Typical Operating Characteristics
(Circuit of Figure 1, VDCIN= 16V, CELLS = REFIN, VCLS =VREF, VICTL = VREFIN = 3.3V, TA= +25°C, unless otherwise noted.)
MAX1870AStep-Up/Step-Down
Li+ Battery Charger
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VDCIN= 16V, CELLS = REFIN, VCLS =VREF, VICTL = VREFIN = 3.3V, TA= +25°C, unless otherwise noted.)
EFFICIENCY vs. BATTERY VOLTAGE
MAX1870A toc07
BATTERY VOLTAGE (V)
EFFICIENCY (%)481614610
VIN = 12V
VIN = 16V
EFFICIENCY vs. CHARGE CURRENT
MAX1870A toc08
CHARGE CURRENT (A)
EFFICIENCY (%)
VBATT = 16.8V
VBATT = 8.4V
VBATT = 12.6V
BATTERY VOLTAGE ERROR IN CV MODE
MAX1870A toc09
CHARGE CURRENT (A)
BATTERY VOLTAGE ERROR (%)
VBATT = 16.8V
VBATT = 12.6V
VBATT = 8.4V
BATTERY VOLTAGE ERROR vs. VCTL
MAX1870Atoc10
VCTL (V)
BATTERY VOLTAGE ERROR (%)
CHARGE-CURRENT ERROR vs. ICTLMAX1870Atoc11
VICTL (V)
CHARGE-CURRENT ERROR (mA)
CHARGE-CURRENT ERROR
vs. BATTERY VOLTAGE
MAX1870Atoc12
VBATT (V)
CHARGE-CURRENT ERROR (%)105
ICHG = 0.15A
ICHG = 2.4A
ICHG = 1.9A
ICHG = 1.4A
IINP ERROR vs. SYSTEM LOADMAX1870Atoc13
SYSTEM LOAD (A)
IINP ERROR (mV)
INPUT CURRENT-LIMIT ERROR
vs. SYSTEM CURRENT
MAX1870A toc14
SYSTEM CURRENT (A)
INPUT CURRENT-LIMIT ERROR (%)
VBATT = 16V
VBATT = 14V
VBATT = 10VVBATT = 8V
VBATT = 6V
VBATT = 12V
INPUT CURRENT-LIMIT ERROR
vs. CLSMAX1870A toc15
VCLS (V)
INPUT CURRENT-LIMIT ERROR (mA)
-3005.00
MAX1870AStep-Up/Step-Down
Li+ Battery Charger
Typical Operating Characteristics (continued)(Circuit of Figure 1, VDCIN= 16V, CELLS = REFIN, VCLS =VREF, VICTL = VREFIN = 3.3V, TA= +25°C, unless otherwise noted.)
REF LOAD REGULATIONMAX1870A toc16
LOAD CURRENT (μA)
REF
(V)
REFERENCE ERROR vs. TEMPERATURE
MAX1870Atoc17
TEMPERATURE (°C)
REFERENCE ERROR (%)6020400-20
LDO LOAD REGULATION
MAX1870A toc18
LOAD (mA)
LDO
(V)301020
VIN = 28V
VIN = 16V
VIN = 9V
LDO vs. TEMPERATUREMAX1870A toc19
TEMPERATURE (°C)
LDO VOLTAGE ERROR (%)40-2006020
OUTPUT VOLTAGE RIPPLE
vs. BATTERY VOLTAGE
MAX1870Atoc20
VBATT (V)
RMS OUTPUT RIPPLE (mV)105
STEP-UP/STEP-DOWN
SWITCHING WAVEFORM
MAX1870Atoc21
10V
CATHODE
D3 ANODE
INDUCTOR CURRENT
VBATT
(AC-COUPLED)
200mV/div
10V
20V
2.00μs
VIN = 16V
VBATT = 16V
STEP-DOWN
SWITCHING WAVEFORMMAX1870Atoc22
10V
CATHODE
D3 ANODE
INDUCTOR CURRENT
VBATT
(AC-COUPLED)
10mV/div
10V
20V
2.00μs
VIN = 16V
VBATT = 12V
MAX1870AStep-Up/Step-Down
Li+ Battery Charger
PINNAMEFUNCTION1LDODevice Power Supply. Output of the 5.4V linear regulator supplied from DCIN. Bypass LDO to GND with
a 1µF or greater ceramic capacitor.REF4.096V Voltage Reference. Bypass REF to GND with a 1µF or greater ceramic capacitor.CLSSource Current-Limit Input. Voltage input for setting the current limit of the input source. See the Setting
the Input Current Limit section.
4, 8GNDAnalog GroundCCVVoltage Regulation Loop Compensation Point. Connect a 10kΩ resistor in series with a 0.01µF capacitor
to GND.CCICharge-Current Regulation Loop Compensation Point. Connect a 0.01µF capacitor to GND.CCSInput-Current Regulation Loop Compensation Point. Connect a 0.01µF capacitor to GND.REFINReference Input. ICTL and VCTL are ratiometric with respect to REFIN for increased accuracy.ASNSAdapter Sense Output. Logic output is high when input current is greater than 1.5A (using 30mΩ sense
resistors and a 10kΩ resistor from IINP to GND).VCTLCharge-Voltage Control Input. Drive VCTL from 0 to VREFIN to adjust the charge voltage from 4V to 4.4V
per cell. See the Setting the Charge Voltage section.
STEP-UP
SWITCHING WAVEFORMMAX1870Atoc23
10V
CATHODE
D3 ANODE
INDUCTOR CURRENT
VBATT
(AC-COUPLED)
50mV/div
10V
20V
2.00μs
VIN = 12V
VBATT = 16V
STEP-UP/STEP-DOWN
LIGHT LOADMAX1870Atoc24
10V
CATHODE
D3 ANODE
INDUCTOR CURRENT
VBATT(AC-COUPLED)
50mV/div
10V
20V
2.00μs
VIN = 16V
VBATT = 16V
CHARGE CURRENT = 300mA
Typical Operating Characteristics (continued)(Circuit of Figure 1, VDCIN= 16V, CELLS = REFIN, VCLS =VREF, VICTL = VREFIN = 3.3V, TA= +25°C, unless otherwise noted.)
Pin Description
MAX1870AStep-Up/Step-Down
Li+ Battery Charger
Pin Description (continued)
PINNAMEFUNCTIONICTLCharge-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.CELLSCell-Count Selection Input. Connect CELLS to GND for two Li+ cells. Float CELLS for three Li+ cells, or
connect CELLS to REFIN for four Li+ cells.IINP
Input-Current Monitor Output. IINP is a replica of the input current sensed by the MAX1870. It represents
the sum of the current consumed by the charger and the current consumed by the system. IINP has a
transconductance of 2.8µA/mV.SHDNShutdown Comparator Input. Pull SHDN low to stop charging. Optionally connect a thermistor to stop
charging when the battery temperature is too hot.BATTBattery-Voltage Feedback InputCSINCharge Current-Sense Negative InputCSIPCharge Current-Sense Positive Input. Connect a current-sense resistor from CSIP to CSIN. Connect a
2.2µF capacitor from CSIP to GND.BLKPPower Connection for Current-Sense Amplifier. Connect BLKP to BATT.
20, 21I.C.Internally Connected. Do not connect this pin.DBSTStep-Up Power MOSFET (NMOS) Gate-Driver OutputPGNDPower GroundI.C.Internally Connected. Do not connect this pin.DLOVLow-Side Driver Supply. Bypass DLOV with a 1µF capacitor to GND.VHNPower Connection for the High-Side MOSFET Driver. Bypass VHP to VHN with a 1µF or greater ceramic
capacitor.DHIHigh-Side Power MOSFET (PMOS) Driver Output. Connect to the gate of the high-side step-down
MOSFET.VHPPower Connection for the High-Side MOSFET Driver. Bypass VHP to VHN with a 1µF or greater ceramic
capacitor.CSSNNegative Terminal for Current-Sense Resistor for Charger Current. Connect a 2.2µF capacitor from CSSN
to GND.CSSSNegative Terminal for Current-Sense Resistor for System Load CurrentCSSPPositive Terminal for Input Current-Sense Resistors. Connect a current-sense resistor from CSSP to
CSSN. Connect an equivalent sense resistor from CSSP to CSSS.DCINDC Supply Voltage Input. Bypass DCIN with a 1µF or greater ceramic capacitor to power ground.
PaddlePaddle. Connect to GND.
MAX1870AStep-Up/Step-Down
Li+ Battery Charger
MAX1870A4
VHP
VHN
CSSP
CSSN
DHI
DBST
CSIP
CSIN
BATT
DLOV
LDO
BLKP
CSSS
DCIN
REF
CLS
CCV
CCI
CCS
REFIN
ASNS
VCTL
ICTL
CELLS
IINP
PGND
ADAPTER
VDD
HOST
DIGITAL INPUT
D/A OUTPUT
D/A OUTPUT
HI-IMPEDANCE
OUTPUT
LOGIC OUTPUT
A/D INPUT
GND
SYSTEM LOAD
10kΩ
0.01µF
22µF
44µF
1µF
RS2
30mΩ
10µH
C11
1µF
C12
1µF
RS1b
30mΩ
GND
RS1a
30mΩ
33Ω
1µF
1µF
OPTIONAL REVERSE-
ADAPTER PROTECTION
2.2µF
2.2µF
10kΩ
0.01µF
0.01µF
0.01µF
SHDN
Figure 1. µC-Controlled Typical Application Circuit
MAX1870AStep-Up/Step-Down
Li+ Battery Charger476
VHP
VHN
CSSP
CSSN
DHI
DBST
CSIP
CSIN
BATT
DLOV
LDO
BLKP
CSSS
DCIN
REF
CELLS
CLS
PGND
REFIN9
VCTL11
ICTL12
ASNS10
IINP14
CCV5
SYSTEM LOAD
22µF
44µF
1µF
RS2
30mΩ
10µH
C11
1µF
C12
1µF
RS1b
30mΩ
GNDCCSCCI
RS1a
30mΩ
33Ω
1µF
1µF
2.2µF
2.2µF
OPEN
SHORT
OPEN
R10
OPEN
SHORT
R12
OPEN
LDO
10kΩ
10kΩ
0.01µF
0.01µF
0.01µF
0.01µF
SHDN
ADAPTEROPTIONAL
MAX1870A
OPTIONAL REVERSE-
ADAPTER PROTECTION
Figure 2. Stand-Alone Typical Application Circuit
MAX1870AStep-Up/Step-Down
Li+ Battery Charger
Detailed DescriptionThe MAX1870A includes all of the functions necessary
to charge Li+, NiMH, and NiCd batteries. A high-effi-
ciency 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 bat-
tery voltage. The MAX1870A includes analog control
inputs to limit the AC adapter current, charge current,
and battery voltage. An analog output (IINP) delivers a
current proportional to the source current. The Typical
Application Circuitshown in Figure 1 uses a microcon-
troller (µC) to control the charge current or voltage,
while Figure 2 shows a typical application with the
charge voltage and current fixed to specific values for
the application. The voltage at ICTL and the value of
RS2 set the charge current. The voltage at VCTL and
the CELLS inputs set the battery regulation voltage for
the charger. The voltage at CLS and the value of R3 and
R4 set the source current limit.
The MAX1870A features a voltage-regulation loop
(CCV) and two current-regulation loops (CCI and CCS).
CCV is the compensation point for the battery voltage
regulation loop. CCI and CCS are the compensation
points for the battery charge current and supply current
loops, respectively. The MAX1870A regulates the
adapter current by reducing battery charge current
according to system load demands.
Setting the Charge VoltageThe MAX1870A provides high-accuracy regulation of
the charge voltage. Apply a voltage to VCTL to adjust
the battery-cell voltage limit. Set VCTL to a voltage
between 0 and VREFINfor a 10% adjustment of the bat-
tery cell voltage, or connect VCTL to LDO for a default
setting of 4.2V per cell. The limited adjustment range
reduces the sensitivity of the charge voltage to external
resistor tolerances. The overall accuracy of the charge
voltage is better than ±1% when using ±1% resistors to
divide down the reference to establish VCTL. The per-
cell battery-termination voltage is a function of the bat-
tery chemistry and construction. Consult the battery
manufacturer to determine this voltage. Calculate bat-
tery voltage using the following equation:
where NCELLSis the cell count selected by CELLS.
VCTL is ratiometric with respect to REFIN to improve
accuracy when using resistive voltage-dividers.
Connect CELLS as shown in Table 1 to charge two,
three, or four cells. The cell count can either be hard-
wired or software controlled. The internal error amplifier
(GMV) maintains voltage regulation (see Figure 3 for
the Functional Diagram). Connect a 10kΩresistor in
series with a 0.01µF capacitor from CCV to GND to
compensate the battery voltage loop. See the Voltage
Loop Compensation section for more information.
Setting the Charge CurrentSet the maximum charge current using ICTL and the
current-sense resistor RS2 connected between CSIP
and CSIN. The current threshold is set by the ratio of
VICTL / VREFIN. Use the following equation to program
the battery charge current:
where VCSITis the full-scale charge current-sense
threshold, 73mV (typ). The input range for ICTL is
VREFIN / 32 to VREFIN. To shut down the MAX1870A,
force ICTL below VREFIN / 100.
The internal error amplifier (GMI) maintains charge-
current regulation (see Figure 3 for the Functional
Diagram). Connect a 0.01µF capacitor from CCI to GND
to compensate the charge-current loop. See the Charge-
Current Loop Compensationsection for more information.
Setting the Input Current LimitThe total input current, from a wall adapter or other DC
source, is a function of the system supply current and
the battery charge current. The MAX1870A limits the wall
adapter current by reducing the charge current when the
input current exceeds the input current-limit set point. As
the system supply current rises, the available charge
current decreases linearly to zero in proportion to the
system current. After the charge current has fallen to
zero, the MAX1870A cannot further limit the wall adapter
current if the system current continues to increase.VxVCHGCSIT
ICTL
REFINxVVxVBATTCELLS
VCTL
REFIN=+⎛⎜⎞⎟404.
CELLSCELL COUNTGND2
Float3
REFIN4
