19-1245; Rev 0; 7/97
Ad ju s t a b le -Ou t p u t , S w it c h -Mo d e
Cu rre n t S o u rc e s w it h S yn c h ro n o u s Re c t ifie r
0/MAX641
_______________Ge n e ra l De s c rip t io n
____________________________Fe a t u re s
♦ 95% Efficiency
The MAX1640/MAX1641 CMOS, a d jus ta b le -outp ut,
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 g round , e limina ting g round -p ote ntia l e rrors . The
MAX1641 incorporates a low-side current sense.
♦ +5.5V to +26V Input Supply Range
♦ 2V to 24V Adjustable-Output Voltage Range
♦ 100% Maximum Duty Cycle (Low Dropout)
♦ Up to 500kHz PWM Operation
♦ Optional Synchronous Rectifier
♦ 16-Pin QSOP Package
♦ Current-Sense Accuracy: 2% (MAX1641)
The MAX1640/MAX1641 step-down pulse-width-modu-
la tion (PWM) c ontrolle rs use a n e xte rna l P-c ha nne l
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.
5.3% (MAX1640)
______________Ord e rin g In fo rm a t io n
PART
TEMP. RANGE
0°C to +70°C
PIN-PACKAGE
Dice*
The MAX1640/MAX1641 are available in space-saving,
16-pin narrow QSOP packages.
MAX1640C/D
MAX1640EEE
MAX1641C/D
MAX1641EEE
-40°C to +85°C
0°C to +70°C
16 QSOP
Dice*
________________________Ap p lic a t io n s
-40°C to +85°C
16 QSOP
Battery-Powered Equipment
Laptop, Notebook, and Palmtop Computers
Handy Terminals
*Dice are specified at T = +25°C, DC parameters only.
A
Portable Consumer Products
Cordless Phones
__________Typ ic a l Op e ra t in g Circ u it
Cellular Phones
V
IN
= +5.5V TO +26V
PCS Phones
IN
LDOH
PDRV
Backup Battery Charger
D0
D1
P
__________________P in Co n fig u ra t io n
TOFF
REF
NDRV
PGND
CS+
R
TOFF
TOP VIEW
LDOL
TOFF
D1
1
2
3
4
5
6
7
8
16 IN
15 LDOH
14 PDRV
13 NDRV
12 PGND
11 CS+
10 CS-
SET
OUT
CS-
D0
MAX1640
MAX1641
CC
MAX1640
TERM
REF
SET
TERM
CC
GND
LDOL
9
GND
QSOP
________________________________________________________________ Maxim Integrated Products
1
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