Datasheet

High-Efficiency, Low-Supply-Current,
Compact, Step-Up DC-DC Converters
TRANSISTOR COUNT: 751
Chip Information
Package Information
Optional External Rectifier
Although not required, a Schottky diode (such as the
MBR0520) connected between LX and OUT allows
lower start-up voltages (Figure 10) and is recommend-
ed when operating at input voltages below 1.3V. Note
that adding this diode provides no significant efficiency
improvement.
PC Board Layout and Grounding
Careful printed circuit layout is important for minimizing
ground bounce and noise. Keep the IC’s GND pin and
the ground leads of the input and output filter capaci-
tors less than 0.2in (5mm) apart. In addition, keep all
connections to the FB and LX pins as short as possi-
ble. In particular, when using external feedback resis-
tors, locate them as close to the FB as possible. To
maximize output power and efficiency and minimize
output ripple voltage, use a ground plane and solder
the IC’s GND directly to the ground plane.
MAX1674
MAX1675
MAX1676
BATT
(MAX1676)
V
IN
LBI
REF
GND
R3
R1
200Ω
R4
R2
100k
22µH
47µF
0.1µF
LX
LBO
FB
SHDN
OUT
LOW-BATTERY
OUTPUT
0.1µF
MBR0520
47µF
CLSEL
(MAX1676)
Figure 10. Adding a Schottky Diode for Low Input Voltage
Operation
10LUMAX.EPS
MAX1674/MAX1675/MAX1676
12
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Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical
Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
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2000 Maxim Integrated
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