Rainbow Electronics MAX1672 - Manual

________________General Description
The MAX1672 integrates a step-up DC-DC converter with a
linear regulator to provide step-up/down voltage conver-
sion. This device provides a constant output voltage for
inputs that vary above and below the output voltage. It has
a 1.8V to 11V input range and a preset 3.3V or 5V output.
The output can also be set from 1.25V to 5.5V using two
resistors. Typical efficiency is 85%.
The MAX1672’s step-up/linear-regulator configuration per-
mits the use of a single, physically smaller inductor than
can be used with competing SEPIC and flyback configura-
tions. Switch current is also selectable, permitting the use
of smaller inductors in low-current applications. The linear
regulator also acts as a filter to reduce output ripple voltage.
The MAX1672 has a low 85µA quiescent supply current, which
is further reduced to 0.1µA in logic-controlled shutdown. The
output voltage is disconnected from the input in shutdown.
The MAX1672 also has a PGI/PGO low-battery detector.
The MAX1672 comes in a 16-pin QSOP package (same size
as a standard 8-pin SO). For a larger device that delivers more
output current, refer to the MAX710/MAX711. The preassem-
bled MAX1672 evaluation kit is available to speed designs.
________________________Applications
Single-Cell, Lithium-Powered 2-Cell to 4-Cell AA Alkaline
Portable Devices Hand-Held Equipment
3.3V and Other Low-Voltage Battery-Powered Devices
Systems with AC Input Adapters
Digital Cameras
____________________________Features
♦ Step-Up/Down Voltage Conversion
♦ 1.8V to 11V Input Range
♦ 3.3V/5V or Adjustable Output Voltage Range
♦ Output Current:
300mA at 5V (V IN
≥
2.5V)
150mA at 5V (V IN
≥
1.8V)
♦ Smaller Inductor than SEPIC and Flybacks
♦ Load Disconnects from Input in Shutdown
♦ Supply Current from Battery:
85µA (No-Load)
0.1µA (Shutdown)
♦ PGI/
PGO
Low-Battery Comparator
♦ 16-Pin QSOP Package
(same footprint as 8-pin SO)
♦ No External FETs Required
♦ Thermal and Short-Circuit Protection
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.
MAX1672
Step-Up/Down DC-DC Converter
in QSOP Package
________________________________________________________________ Maxim Integrated Products 1
19-1307; Rev 0a; 11/97
EVALUATION KIT
AVAILABLE
______________Ordering Information
* Dice are tested at T A = +25°C.
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
LX LX
PGND
GND
REF
IN
PS
FB
OUT
TOP VIEW
MAX1672
QSOP
PGND
ONA
ILIM
PGO
PGI
3/5
ONB
__________________Pin Configuration
MAX1672
IN
ONA
PGI
ONB
OFF ON
PGND GND
PS
3.3V/5V
OUTPUT
INPUT
1.8V TO 11V
LOW-BATTERY
DETECTOR
OUTPUT
OUT
PG0
FB REF
LX
OFF
3/5
ILIM
5V
0.8A
ON
3.3V
0.5A
__________Typical Operating Circuit
PART
MAX1672C/D
MAX1672EEE -40°C to +85°C
0°C to +70°C
TEMP. RANGE PIN-PACKAGE
Dice*
16 QSOP