MAX1640EEE+ ,Adjustable-Output, Switch-Mode Current Sources with Synchronous RectifierEVALUATION KIT AVAILABLE
MAX1640EEE+-MAX1640EEE+T-MAX1641EEE+
Adjustable-Output, Switch-Mode Current Sources with Synchronous Rectifier
AVAILABLE
EVALUATION KIT AVAILABLE
_______________General DescriptionThe MAX1640/MAX1641 CMOS, adjustable-output,
switch-mode current sources operate from a +5.5V to
+26V input, and are ideal for microprocessor-controlled
battery chargers. Charging current, maximum output
voltage, and pulse-trickle charge are programmed with
external resistors. Programming the off-time modifies
the switching frequency, suppressing undesirable har-
monics in noise-sensitive circuits. The MAX1640’s high-
side current sensing allows the load to connect directly
to ground, eliminating ground-potential errors. The
MAX1641 incorporates a low-side current sense.
The MAX1640/MAX1641 step-down pulse-width-modu-
lation (PWM) controllers use an external P-channel
MOSFET switch and an optional, external N-channel
MOSFET synchronous rectifier for increased efficiency.
An internal low-dropout linear regulator provides power
for the internal reference and circuitry as well as the
gate drive for the N-channel synchronous rectifier.
The MAX1640/MAX1641 are available in space-saving,
16-pin narrow QSOP packages.
________________________ApplicationsBattery-Powered Equipment
Laptop, Notebook, and Palmtop Computers
Handy Terminals
Portable Consumer Products
Cordless Phones
Cellular Phones
PCS Phones
Backup Battery Charger
____________________________Features95% Efficiency+5.5V to +26V Input Supply Range2V to 24V Adjustable-Output Voltage Range100% Maximum Duty Cycle (Low Dropout)Up to 500kHz PWM OperationOptional Synchronous Rectifier16-Pin QSOP PackageCurrent-Sense Accuracy:2% (MAX1641)
5.3% (MAX1640)
Adjustable-Output, Switch-Mode
Current Sources with Synchronous Rectifier
__________________Pin ConfigurationLDOLIN
LDOH
PDRV
NDRV
PGND
CS+
CS-
GND
TOP VIEW
MAX1640
MAX1641
QSOPTOFF
REF
SET
TERM
PART
MAX1640C/DMAX1640EEE+
MAX1641C/D0°C to +70°C
-40°C to +85°C
0°C to +70°C
TEMP RANGEPIN-PACKAGEDice*
16 QSOP
Dice*
______________Ordering Information*Dice are specified at TA= +25°C, DCparameters only.
+Denotes a lead(Pb)-free/RoHS-compliant package.
MAX1641EEE+-40°C to +85°C16 QSOPLDOH
PDRV
NDRV
PGND
CS+
CS-
TERM
LDOLGND
OUT
VIN = +5.5V TO +26V
TOFF
RTOFF
REF
SET
MAX1640
__________Typical Operating CircuitMAX1640/MAX1641
Adjustable-Output, Switch-Mode
Current Source with Synchronous Rectifier
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VIN= +12V, VOUT= 6V, Circuit of Figure 1, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
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.
IN to GND...............................................................-0.3V to +28V
LDOH to IN...............................................................+0.3V to -6V
LDOL to GND...........................................................-0.3V to +6V
PDRV to GND..............................(VLDOH- 0.3V) to (VIN+ 0.3V)
NDRV to GND.........................................-0.3V to (VLDOL+ 0.3V)
TOFF, REF, SET, TERM, CC to GND......-0.3V to (VLDOL+ 0.3V)
D0, D1 to GND.........................................................-0.3V to +6V
CS+, CS- to GND...................................................-0.3V to +28V
PGND to GND.....................................................................±0.3V
Continuous Power Dissipation (TA = +70°C)
QSOP (derate 9.6mW/°C above +70°C).....................772mW
Package Junction-to-Ambient Thermal Resistance (θJA)
(Note 1)..................................................................103.7°C/W
Package Junction-to-Case Thermal Resistance θJC)
(Note1).......................................................................37°C/W
Operating Temperature Range
MAX164_EEE...................................................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10sec)............................+300°C
IREF= 0 to 50µA
D0 = D1 = low
D0 = D1 = low (off mode)
D0 or D1 = high
VOUT= 2V to 24V
VIN= VOUT+ 0.5V to 26V
MAX1641
MAX1641
MAX1640
VIN= 5.5V to 26V, ILOAD= 0 to 20mA
VIN= 5.5V to 26V, ILOAD= 0 to 20mA
MAX1640
CONDITIONS1VSETInput Current410Reference Load Regulation1.962.002.04VREFReference Voltage4.054.204.35VLDOLUndervoltage Lockout1Output Current in Off Mode
Quiescent VINSupply Current
%/V0.10.4Output Current Compliance
%/V0.03Current-Sense Line Regulation37.541mV4248
147150153mV142 150158Full-Scale Current-Sense
ThresholdVIN-VIN-VIN-
5.55.04.5VLDOHLinear-Regulator Output
Voltage, VINReferenced4.5 5.05.5VLDOLLinear-Regulator Output
Voltage, Ground Referenced
UNITSMINTYPMAXSYMBOLPARAMETER5.526VINInput Voltage Range
FET Drive Output ResistancePFET and NFET drive12Ω
Off-Time Range110µs
Off-Time AccuracyRTOFF= 62kΩ1.72.22.7µs
Pulse-Trickle Mode Duty-Cycle
PeriodD0 = low, D1 = high, RTOFF= 100kΩ273340ms
Pulse-Trickle Mode Duty Cycle
(Note 2)D0 = low, D1 = high, RTOFF= 100kΩ12.5%
Quarter-Scale Current-Sense
Threshold
MAX1640
MAX1641
Note 1:Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal comsiderations, refer to /thermal-tutorial.
MAX1640/MAX1641
Adjustable-Output, Switch-Mode
Current Source with Synchronous Rectifier
ELECTRICAL CHARACTERISTICS(VIN= +12V, VOUT= 6V, Circuit of Figure 1, TA= -40°C to +85°C, unless otherwise noted.)
IREF= 0 to 50µA
VOUT= 2V to 24V (MAX1640)
D0 = D1 = low
D0 or D1 = high
FET Drive Output Resistance
MAX1641
MAX1640
VIN= 5.5V to 26V,
ILOAD= 0 to 20mA
VIN= 5.5V to 26V,
ILOAD= 0 to 20mA
MAX1640
CONDITIONS1VSETInput Current10Reference Load Regulation1.942.06VREFReference Voltage4.04.4VLDOLUndervoltage Lockout1Output Current in Off Mode4Quiescent VINSupply Current
%/V0.4Output Current Compliance48Quarter-Scale Current-Sense
ThresholdΩ
Off-Time Range5.526VINInput Voltage Range
1.58µs
Off-Time AccuracyRTOFF= 62kΩ1.52.5µs
Pulse-Trickle Mode Duty-Cycle
Period141 159Full-Scale Current-Sense
ThresholdVIN-VIN-
5.54.5VLDOHLinear-Regulator Output
Voltage, VINReferenced
D0 = low, D1 = high, RTOFF= 50kΩ2542ms4.5 5.5VLDOLLinear-Regulator Output
Voltage, Ground Referenced
UNITSMINTYPMAXSYMBOLPARAMETERPWM Maximum Duty Cycle100%
Input Low VoltageVILD0, D10.8V
Input High VoltageVIHD0, D12.4V
Input Leakage CurrentIIND0, D1±1µA42MAX1641
ELECTRICAL CHARACTERISTICS (continued)(VIN= +12V, VOUT= 6V, Circuit of Figure 1, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
CONDITIONSUNITSMINTYPMAXSYMBOLPARAMETERPWM Maximum Duty Cycle100%
Input Low VoltageVILD0, D10.8V
Input High VoltageVIHD0, D12.4V
Input Leakage CurrentIIND0, D1±1µA
Note 2:This ratio is generated by a 1:8 clock divider and is not an error source for current calculations.
MAX1640/MAX1641
Adjustable-Output, Switch-Mode
Current Source with Synchronous RectifierOFF-MODE SUPPLY CURRENT
(NO-LOAD)
MAX1640/41-TOC07
INPUT VOLTAGE (V)
OFF-MODE SUPPLY CURRENT (mA)
TA = -40°C
TA = +25°C
TA = +85°C
10,00050100150200250300350400
SWITCHING FREQUENCY vs. RTOFFMAX1640/41 TOC 08
TOFF (kΩ)
SWITCHING FREQUENCY (kHz)10
1000VOUT = +3V
VOUT = +6V
__________________________________________Typical Operating Characteristics(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)
EFFICIENCY vs. OUTPUT VOLTAGE
MAX1640/41-TOC01
OUTPUT VOLTAGE (V)
EFFICIENCY (%)
VIN = 12VVIN = 18VVIN = 26V
MAX1640
OUTPUT CURRENT vs. INPUT VOLTAGE
MAX1640/41 TOC02
INPUT VOLTAGE (V)
OUTPUT CURRENT (A)
TA = -40°C
(VOUT = 4V)
TA = +25°C
TA = +85°C
MAX1640
OUTPUT CURRENT vs. OUTPUT VOLTAGE
OUTPUT VOLTAGE (V)
OUTPUT CURRENT (A)
TA = -40°C
TA = +85°C
TA = +25°C
MAX1641
OUTPUT CURRENT vs. INPUT VOLTAGE
MAX1640/41 TOC04
INPUT VOLTAGE (V)
OUTPUT CURRENT (A)
TA = -40°C
(VOUT = 4V)
TA = +25°C
TA = +85°C
MAX1641
OUTPUT CURRENT vs. OUTPUT VOLTAGE
MAX1640/41-TOC05
VOUT (V)
OUTPUT CURRENT (A)
TA = -40°C
TA = +25°C
TA = +85°C
QUIESCENT CURRENT
vs. INPUT VOLTAGE (NO-LOAD)
MAX1640/41-TOC06
INPUT VOLTAGE (V)
QUIESCENT CURRENT (mA)
TA = -40°C
TA = +25°C
TA = +85°C
A: OUTPUT CURRENT, D1 = D0 = 1 1A/div
VLOAD = 3V
LINE-TRANSIENT RESPONSE2ms/div
MAX1640/41 TOC 09
MAX1640/MAX1641
Adjustable-Output, Switch-Mode
Current Source with Synchronous Rectifier
____________________________Typical Operating Characteristics (continued)(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)
A: OUTPUT CURRENT, D0 = D1 = 0 1A/div
VIN = 12V, VSET = 1V, RLOAD = 4Ω, NO OUTPUT CAPACITOR
B: LOAD VOLTAGE, AC coupled, 500mV/div
CURRENT-MODE CHANGE RESPONSE TIME2ms/div
MAX1640/41 TOC 10
EXITING OFF MODEMAX1640/41 TOC11
A: D0 = D1 = 1 2V/div
VIN = 12V, RLOAD = 4Ω
B: OUTPUT CURRENT, 0.5A/div
20μs/div
______________________________________________________________Pin Description
NAMEFUNCTIONLDOLInternal, Ground-Referenced Low-Dropout Linear Regulator Output.
Bypass LDOL with a 0.1µF capacitor in parallel with a 4.7µF capacitor to GND.TOFF
Off-Time Select Input. A resistor (RTOFF) connected from TOFF to GND programs the off-time for the hys-
teretic PWM step-down converter. This resistor also sets the period in duty-cycle mode. See Duty-Cycle
Mode and Programming the Off-Time.
PIN3, 4D1, D0Digital Inputs. Select mode of operation (Table 1).CCConstant-Current Loop Compensation Input. Bypass CC with a 0.01µF capacitor to GND.TERMMaximum Output Voltage Termination Input. When VTERMexceeds the reference voltage, the comparator
resets the internal PWM latch, shutting off the external P-channel FET.SETCurrent Select Input. Program the desired current level by applying a voltage at SET between 0V and VREF,
(I = VSET/ 13.3RSENSE). See Figure 2.REFReference Voltage Output (VREF= 2V). Bypass REF with a 0.1µF capacitor to GND.NDRVGate Drive for an optional N-channel FET synchronous rectifierPGNDHigh-Current Ground Return for the output driversCS+Positive Current-Sense Comparator InputCS-Negative Current-Sense Comparator InputGNDGroundPDRVGate Drive for the P-channel FETLDOHInternal, Input-Referenced Low-Dropout Linear Regulator Output.
Bypass LDOH with a 0.33µF capacitor to IN.INPower-Supply Input. Input of the internal, low-dropout linear regulators.
MAX1640/MAX1641
Adjustable-Output, Switch-Mode
Current Source with Synchronous RectifierMODE
CONTROLTOFFD0, D1
TERM
REF
SET
CS-
CS+
REG
PDRV
NDRV
PGNDLDOLLDOH
MUXSEL
MAX1640
MAX1641
_________________________________________________________Functional DiagramMAX1640/MAX1641
