MAX745EAP+ Fast Delivery |IC PHOENIX CO.,LIMITED

MAX745EAP+ ,Switch-Mode Lithium-Ion Battery-ChargerApplicationsMAX745C/D 0°C to +70°C Dice*MAX745EAP -40°C to +85°C 20 SSOPLi+ Battery PacksDesktop Cr ..
MAX745EAP+ ,Switch-Mode Lithium-Ion Battery-ChargerFeaturesThe MAX745 provides all functions necessary for ♦ Charges 1 to 4 Li+ Battery Cellscharging ..
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MAX745EAP+
Switch-Mode Lithium-Ion Battery-Charger
MAX745
Switch-Mode Lithium-Ion
Battery-Charger
General Description
The MAX745 provides all functions necessary for
charging lithium-ion (Li+) battery packs. It provides a
regulated charging current of up to 4A without getting
hot, and a regulated voltage with only ±0.75% total
error at the battery terminals. It uses low-cost, 1% resis-
tors to set the output voltage, and a low-cost N-channel
MOSFET as the power switch.
The MAX745 regulates the voltage set point and charg-
ing current using two loops that work together to transi-
tion smoothly between voltage and current regulation.
The per-cell battery voltage regulation limit is set
between 4V and 4.4V using standard 1% resistors, and
then the number of cells is set from 1 to 4 by pin-strap-
ping. Total output voltage error is less than ±0.75%.
For a similar device with an SMBus™ microcontroller
interface and the ability to charge NiCd and NiMH cells,
refer to the MAX1647 and MAX1648. For a low-cost Li+
charger using a linear-regulator control scheme, refer
to the MAX846A.
________________________Applications
Li+ Battery Packs
Desktop Cradle Chargers
Cellular Phones
Notebook Computers
Hand-Held Instruments
____________________________FeaturesCharges 1 to 4 Li+ Battery Cells±0.75% Voltage-Regulation Accuracy
Using 1% ResistorsProvides up to 4A without Excessive Heating90% EfficientUses Low-Cost Set Resistors and
N-Channel SwitchUp to 24V Input Up to 18V Maximum Battery Voltage300kHz Pulse-Width Modulated (PWM) Operation
Low-Noise, Small ComponentsStand-Alone Operation—No Microcontroller
Needed
Typical Operating Circuit
19-1182; Rev 3; 10/01
PART
MAX745EAP-40°C to +85°C
TEMP RANGEPIN-PACKAGE
20 SSOP
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
Ordering Information
Pin Configuration appears at end of data sheet.
MAX745C/D0°C to +70°CDice*
*Dice are tested at TA= +25°C.
(UP TO 24V)
REF
DCIN
VIN
BST
DHI
DLO
BATT
CELL
COUNT
SELECT
SET PER
CELL VOLTAGE
WITH 1% RESISTORS
OFF
VADJ
STATUS
SETI
CELL0
CELL1
CCIPGNDGNDIBATCCV
ICHARGE
RSENSE
VOUT
1–4 Li+ CELLS
(UP TO 18V)
MAX745
THM/SHDN
MAX745
Switch-Mode Lithium-Ion
Battery Charger
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDCIN= 18V, VBATT= 8.4V, 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.
DCINto GND............................................................-0.3V to 26V
BST, DHI to GND......................................................-0.3V to 30V
BST to LX....................................................................-0.3V to 6V
DHI to LX............................................(LX - 0.3V) to (BST + 0.3V)
LX to GND................................................-0.3V to (DCIN + 0.3V)
VL to GND...................................................................-0.3V to 6V
CELL0, CELL1, IBAT, STATUS, CCI, CCV, REF, SETI,
VADJ, DLO, THM/SHDNto GND.................-0.3V to (VL + 0.3V)
BATT, CS to GND.....................................................-0.3V to 20V
PGND to GND..........................................................-0.3V to 0.3V
VL Current...........................................................................50mA
Continuous Power Dissipation (TA= +70°C)
SSOP (derate 8.00mW/°C above +70°C)....................640mW
Operating Temperature Range...........................-40°C to +85°C
Storage Temperature.........................................-60°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
6.0V < VDCIN< 24V, logic inputs = VL
VL < 3.2V, VCS= 12V
VL < 3.2V, VBATT= 12V
Output high or low
0 < IREF< 1mA
6.0V < VDCIN< 24V, no load= +25°C
Output high or low
CONDITIONS019BATT, CS Input Voltage Range5CS Input Current
BATT Input Current614DLO On-Resistance47DHI On-Resistance46DCIN Quiescent Supply Current624DCIN Input Voltage Range8993DHI Maximum Duty Cycle
kHz270300330Oscillator Frequency
mV/mA1020REF Output Load Regulation5.155.405.65VL Output Voltage4.174.24.23REF Output Voltage
UNITSMINTYPMAXPARAMETER
4V < VBATT< 16V
6.0V < VDCIN< 24V
(Note 1)mV±1.5CS to BATT Offset Voltage
SETI = VREF(full scale)mV170185205CS to BATT
Current-Sense Voltage
Not including VADJresistor tolerance%-0.65+0.65Absolute Voltage AccuracyWith 1% tolerance VADJ resistors
-0.75+0.75
SWITCHING REGULATOR
SUPPLY AND REFERENCE
VL > 5.15V, VBATT= 12V
VL > 5.15V, VCS= 12V400
SETI = 400mV141822
MAX745
Switch-Mode Lithium-Ion
Battery Charger
Note 1:When VSETI= 0V, the battery charger turns off.
ELECTRICAL CHARACTERISTICS (continued)
(VDCIN= 18V, VBATT= 8.4V, TA= 0°C to +85°C. Typical values are at TA= +25°C, unless otherwise noted.)
ELECTRICAL CHARACTERISTICS
(VDCIN= 18V, VBATT= 8.4V,TA= -40°C to +85°C, unless otherwise noted. Limits over temperature are guaranteed by design.)
6.0V < VDCIN< 24V
6.0V < VDCIN< 24V, no load
Output high or low
Output high or low
CONDITIONS165205CS to BATT Full-Scale
Current-Sense Voltage
Not including VADJ resistors%-1.0+1.0Absolute Voltage Accuracy4.144.26REF Output Voltage5.105.70VL Output Voltage14DLO On-Resistance7DHI On-Resistance
kHz260340Oscillator Frequency
UNITSMINTYPMAXPARAMETER
IBAT Compliance Voltage Range02V
VIBAT= 2VIBATOutput Current vs.
Current-Sense Voltage0.9µA/mV
Charger in voltage-regulation mode,
VSTATUS= 5VSTATUSOutput Leakage Current1µA
Charger in current-regulation mode,
STATUSsinking 1mASTATUSOutput Low Voltage 0.2V
THM/SHDNFalling Threshold2.012.12.19V
THM/SHDNRising Threshold2.202.32.34V
1.1V < VCCI< 3.5VCCV Clamp Voltage with Respect to CCI
PARAMETERMINTYPMAXUNITS
GMV Amplifier Output Current±130µA
GMI Amplifier Transconductance200µA/V
GMI Amplifier Output Current±320 µA
CCI Clamp Voltage with Respect to CCV2580 200mV80 200mV
CELL0, CELL1 Input Bias Current-1 +1µA
SETI Input Voltage Range 0VREFV
SETI, VADJ Input Bias Current-10+10nA
VADJ Adjustment Range10%
CONDITIONS
VADJ Input Voltage Range0 VREF
1.1V < VCCV< 3.5V
(Note 1)
SWITCHING REGULATOR (Note 1)
SUPPLY AND REFERENCE
GMV Amplifier Transconductance800µA/V
CONTROL INPUTS/OUTPUTS
ERROR AMPLIFIERS
MAX745
Switch-Mode Lithium-Ion
Battery Charger
BATTERY VOLTAGE
vs. CHARGING CURRENT
MAX745/TOC-01
CHARGING CURRENT (A)
BATTERY VOLTAGE (V)
R1 = 0.2Ω
R16 = SHORT
R12 = OPEN CIRCUIT
CURRENT-SENSE VOLTAGE
vs. SETI VOLTAGE
MAX745/TOC-02
SETI VOLTAGE (V)
CURRENT-SENSE VOLTAGE (mV)
R1 = 0.2Ω
VOLTAGE LIMIT
vs. VADJ VOLTAGE
MAX745/TOC-03
VADJ VOLTAGE (V)
PER-CELL VOLTAGE LIMIT (V)
REFERENCE VOLTAGE
vs. TEMPERATURE
MAX745/TOC-06
TEMPERATURE (°C)
REFERENCE VOLTAGE (V)100
__________________________________________Typical Operating Characteristics
(TA= +25°C, VDCIN= 18V, VBATT= 4.2V, CELL0 = CELL1 = GND, CVL= 4.7µF CREF= 0.1µF. Circuit of Figure 1, unless otherwise
noted.)
VL LOAD REGULATION
MAX745/TOC-04
VL OUTPUT CURRENT (mA)
VL OUTPUT VOLTAGE (V)20
REFERENCE LOAD REGULATION
MAX745/TOC-05
REFERENCE CURRENT (μA)
REFERENCE VOLTAGE (V)
4.18
_______________Detailed Description
The MAX745 is a switch-mode, Li+ battery charger that
can achieve 90% efficiency. The charge voltage and
current are set independently by external resistor-
dividers at SETI and VADJ, and at pin connections at
CELL0 and CELL1. VADJ is connected to a resistor-
divider to set the charging voltage. The output voltage-
adjustment range is ±5%, eliminating the need for 0.1%
resistors while still achieving 0.75% set accuracy using
1% resistors.
The MAX745 consists of a current-mode, pulse-width-
modulated (PWM) controller and two transconductance
error amplifiers: one for regulating current (GMI) and
the other for regulating voltage (GMV) (Figure 2). The
error amplifiers are controlled through the SETI and
VADJ pins. Whether the MAX745 is controlling voltage
or current at any time depends on the battery state. If
the battery is discharged, the MAX745 output reaches
the current-regulation limit before the voltage limit,
causing the system to regulate current. As the battery
charges, the voltage rises to the point where the volt-
age limit is reached and the charger switches to regu-
lating voltage. The STATUS pin indicates whether the
charger is regulating current or voltage.
Voltage Control
To set the voltage limit on the battery, connect a resis-
tor- divider to VADJ from REF. A 0V to VREFchange at
VADJ sets a ±5% change in the battery limit voltage
around 4.2V. Since the 0 to 4.2V range on VADJ results
in only a 10% change on the voltage limit, the resistor-
divider’s accuracy does not need to be as high as the
output voltage accuracy. Using 1% resistors for the
voltage dividers typically results in no more than 0.1%
degradation in output voltage accuracy. VADJ is inter-
nally buffered so that high-value resistors can be used
to set the output voltage. When the voltage at VADJ is
MAX745
Switch-Mode Lithium-Ion
Battery Charger
______________________________________________________________Pin Description
IBATCurrent-Sense Amplifier’s Analog Current-Source Output. See the Monitoring Charge Currentsection for a
detailed description.DCINCharger Input Voltage. Bypass DCIN with a 0.1µF capacitor.VLChip Power Supply. Output of the 5.4V linear regulator from DCIN. Bypass VL with a 4.7µF capacitor.CCVVoltage-Regulation-Loop Compensation PointCCICurrent-Regulation-Loop Compensation PointVADJVoltage-Adjustment Pin. VADJ is tied to a 1% tolerance external resistor-divider to adjust the voltage set
point by 10%, eliminating the need for precision 0.1% resistors. The input voltage range is 0V to VREF. REF4.2V Reference Voltage Output. Bypass REF with a 0.1µF or greater capacitor. THM/
SHDN
Thermistor Sense-Voltage Input. THM/SHDNalso performs the shutdown function. If pulled low,
the charger turns off.STATUS
An open-drain MOSFET sinks current when in current-regulation mode, and is high impedance when in volt-
age-regulation mode. Connect STATUSto VL through a 1kΩ to 100kΩpullup resistor. STATUScan also drive
an LED for visual indication of regulation mode (see MAX745 EV kit). Leave STATUS floating if not used.
11, 12CELL1,
CELL0Logic Inputs to Select Cell Count. See Table 1 for cell-count programming.GNDAnalog GroundSETISETI is externally tied to the resistor-divider between REF and GND to set the charging current. BATTBattery-Voltage-Sense Input and Current-Sense Negative InputCSCurrent-Sense Positive InputPGNDPower GroundDLOLow-Side Power MOSFET Driver OutputDHIHigh-Side Power MOSFET Driver OutputLXPower Connection for the High-Side Power MOSFET SourceBSTPower Input for the High-Side Power MOSFET Driver
NAMEFUNCTIONPIN
MAX745
Switch-Mode Lithium-Ion
Battery Charger
VREF/ 2, the voltage limit is 4.2V. Table 1 defines the
battery cell count.
The battery limit voltage is set by the following:
Solving for VADJ, we get:
Set VADJby choosing a value for R11 (typically 100kΩ),
and determine R3 by:
R3 = [1 - (VADJ/ VREF)] x R11 (Figure 1)
where VREF= 4.2V and cell count is 1, 2, 3, 4 (Table 1).
The voltage-regulation loop is compensated at the CCV
pin. Typically, a series-resistor-capacitor combination
can be used to form a pole-zero doublet. The pole
introduced rolls off the gain starting at low frequencies.
The zero of the doublet provides sufficient AC gain at
mid-frequencies. The output capacitor (C1) rolls off the
mid-frequency gain to below unity. This guarantees sta-
bility before encountering the zero introduced by the
C1’s equivalent series resistance (ESR). The GMV
amplifier’s output is internally clamped to between one-
fourth and three-fourths of the voltage at REF.
Current Control
The charging current is set by a combination of the cur-
rent-sense resistor value and the SETI pin voltage. The
current-sense amplifier measures the voltage across
the current-sense resistor, between CS and BATT. The
current-sense amplifier’s gain is 6. The voltage on SETI
is buffered and then divided by 4. This voltage is com-
pared to the current-sense amplifier’s output.
Therefore, full-scale current is accomplished by con-
necting SETI to REF. The full-scale charging current
(IFS) is set by the following:
IFS= 185mV / R1 (Figure 1)
V = 9.523 V
cell count 9.023VADJBATTREF()− = cell count x V
V 1V
9.523BATTREF
ADJREF()+
CELL0CELL1
GNDGND1GND2
GNDVL3VL4
CELL COUNT
REF
(UP TO 24V)DCIN
VIN
BST
DHI
DLO
PGND
BATT
THM 1
VADJ
SETI
CCI
47nF
R11
100kΩ
100kΩ
R16C6
0.1μF
0.1μFM1A
1/2 IRF7303
M1BD6
MBRS
340T3
MBRS
340T3
0.2Ω
68μF
22μH
1/2 IRF7303
IN4148
R12
R15
10kΩ
0.1μF
4.7μFC2, 0.1μF10kΩ
GNDIBAT
CCV
MAX745
BATTERY
THM/SHDN
STATUS
Figure 1. Standard Application Circuit
Table 1. Cell-Count Programming Table

Partno	Mfg	Dc	Qty	Available	Descript
MAX745EAP+ \|MAX745EAP	MAX	N/a	27	avai	Switch-Mode Lithium-Ion Battery-Charger
MAX745EAP+ \|MAX745EAP	MAXIM	N/a	2500	avai	Switch-Mode Lithium-Ion Battery-Charger