Rainbow Electronics MAX1678 - Manual

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.
General Description
The MAX1678 is a high-efficiency, low-voltage, syn-
chronous-rectified, step-up DC-DC converter intended
for use in devices powered by 1 to 3-cell alkaline,
NiMH, or NiCd batteries or a 1-cell lithium battery. It
guarantees a 0.87V start-up voltage and features a low
37µA quiescent supply current.
The device includes a 1
Ω
, N-channel MOSFET power
switch, a synchronous rectifier that acts as the catch
diode, a reference, pulse-frequency-modulation (PFM)
control circuitry, and circuitry to reduce inductor ring-
ing—all in an ultra-small, 1.1mm-high µMAX package.
The output voltage is preset to 3.3V or can be adjusted
from +2V to +5.5V using only two resistors. Efficiencies
up to 90% are achieved for loads up to 50mA. The
device also features an independent undervoltage
comparator (PFI/PFO) and a logic-controlled 2µA shut-
down mode.
Applications
Pagers
Remote Controls
Pointing Devices
Personal Medical Monitors
Single-Cell Battery-Powered Devices
Features
♦ 0.87V Guaranteed Start-Up
♦ Up to 90% Efficiency
♦ Built-In Synchronous Rectifier (no external diode)
♦ Ultra-Small µMAX Package, 1.1mm High
♦ 37µA Quiescent Current (85µA from 1.5V battery)
♦ 2µA Logic-Controlled Shutdown
♦ Power-Fail Detector
♦ Dual Mode™ Output: Fixed 3.3V
Adjustable 2V to 5.5V
♦ 45mA Output Current at 3.3V for 1-Cell Input
♦ 90mA Output Current at 3.3V for 2-Cell Input
♦ Inductor-Damping Switch Suppresses EMI
MAX1678
1-Cell to 2-Cell, Low-Noise,
High-Efficiency, Step-Up DC-DC Converter
________________________________________________________________ Maxim Integrated Products 1
1
2
3
4
8
7
6
5
OUT
LX
GND
FB SHDN
PFO
PFI
BATT
MAX1678
µ
MAX
TOP VIEW
OUT
OUTPUT
3.3V
INPUT
0.87V TO V
OUT
ON
LOW-BATTERY
DETECTOR INPUT
LOW-BATTERY
DETECTOR OUTPUT
OFF
PFO
BATT
LX
MAX1678
SHDN
PFI
GND FB
Typical Operating Circuit
19-1381; Rev 0; 7/98
PART
MAX1678EUA -40°C to +85°C
TEMP. RANGE PIN-PACKAGE
8 µMAX
EVALUATION KIT
AVAILABLE
Note: To order these devices shipped in tape-and-reel, add a -T
to the part number.
Pin Configuration
Ordering Information
Dual Mode is a trademark of Maxim Integrated Products.