19-1183; Rev 0; 6/97
Hig h -Effic ie n c y, S t e p -Up
DC-DC Co n ve rt e rs fo r 1 V In p u t s
2/MAX1643
_______________Ge n e ra l De s c rip t io n
____________________________Fe a t u re s
♦ Built-In Synchronous Rectifier
The MAX1642/MAX1643 are high-efficiency, low-voltage,
step-up DC-DC converters intended for devices pow-
ered by a single alkaline cell. They feature low quies-
cent supply currents and are supplied in the ultra-small
µMAX package, which is only 1.1mm high. The guaran-
teed start-up voltage is 0.88V.
♦ 0.88V Guaranteed Start-Up
♦ Ultra-Small µMAX Package: 1.1mm High
♦ 83% Efficiency
Ea c h d e vic e c ons is ts of a n inte rna l 1Ω, N-c ha nne l
MOSFET power switch; a built-in synchronous rectifier
that acts as the catch diode; an oscillator; a reference;
and pulse-frequency-modulation (PFM) control circuitry.
Both devices feature an independent undervoltage
comparator (PFI/PFO). The MAX1642 also includes a
2µA logic-controlled shutdown mode. The MAX1643
offers a dedicated low-battery detector (BATTLO) in
lieu of shutdown.
♦ 4µA Quiescent Supply Current into BATT Pin
♦ 2µA Logic-Controlled Shutdown (MAX1642)
♦ Two Undervoltage Detectors (MAX1643)
♦ 2V to 5.2V Output Range
♦ 20mA Output Current at 1.2V Input
♦ Reverse Battery Protection
The output voltage for each device is preset to 3.3V
±4%, or can be adjusted from +2V to +5.2V using only
two resistors.
______________Ord e rin g In fo rm a t io n
PART
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
Dice*
MAX1642C/D
MAX1642EUA
MAX1643C/D
MAX1643EUA
8 µMAX
Dice*
________________________Ap p lic a t io n s
8 µMAX
Pagers
*Dice are tested at T = +25°C.
A
Remote Controls
Note: To order these devices shipped in tape and reel, add a -T
to the part number.
Pointing Devices
Personal Medical Monitors
Single-Cell Battery-Powered Devices
_________________P in Co n fig u ra t io n s
TOP VIEW
1
2
3
4
8
7
6
5
OUT
LX
BATT
PFI
__________Typ ic a l Op e ra t in g Circ u it
MAX1642
µMAX
GND
FB
PFO
SHDN
INPUT
0.88V TO 1.65V
OUTPUT
3.3V
100µH
OUT
LX
22µF
22µF
MAX1642
BATT
1
2
3
4
8
7
6
5
OUT
LX
BATT
PFI
ON
SHDN
OFF
MAX1643
µMAX
PFI
GND
PFO
FB
LOW-BATTERY
DETECTOR INPUT
LOW-BATTERY
DETECTOR OUTPUT
GND
FB
BATTLO
PFO
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.