MAX1700 Maxim, MAX1700 Datasheet - Page 9

• Manufacturer Part Number: MAX1700
• Description: 1-Cell to 3-Cell / High-Power 1A / Low-Noise / Step-Up DC-DC Converters
• Manufacturer: Maxim

The MAX1700/MAX1701 are highly efficient, low-noise
power supplies for portable RF and data acquisition
instruments. The MAX1700 combines a boost switching
regulator, N-channel power MOSFET, P-channel syn-
chronous rectifier, precision reference, and shutdown
control. The MAX1701 contains all of the MAX1700 fea-
tures plus a versatile gain amplifier, POK output, and a
low-battery comparator (Figure 1). The MAX1700/
MAX1701 come in a 16-pin QSOP package, which
occupies no more space than an 8-pin SO.
The switching DC-DC converter boosts a 1- to 3-cell
input to an adjustable output between 2.5V and 5.5V.
The MAX1700/MAX1701 start from a low 1.1V input and
remain operational down to 0.7V.
These devices are optimized for use in cellular phones
and other applications requiring low noise during full-
Figure 1. Functional Diagram
_______________Detailed Description
CLK/SEL
OUT
LBP*
LBN*
GND
ONA
ONB
AIN*
REF
FB
*MAX1701 ONLY
_______________________________________________________________________________________
2.25V
IC PWR
Low-Noise, Step-Up DC-DC Converters
1.25V
ON
REF
FEEDBACK AND
POWER-GOOD
REFERENCE
SELECT
UNDERVOLTAGE LOCKOUT
1-Cell to 3-Cell, High-Power (1A),
COMPARATOR
RDY
FEEDBACK
REF
EN
power operation, as well as low-quiescent current for
maximum battery life during standby and shutdown
modes. They feature constant-frequency (300kHz), low-
noise PWM operation with up to 800mA output capabili-
ty. See Table 1 for typical available output current. A
low-quiescent-current, low-power mode offers an out-
put up to 100mA and reduces quiescent power con-
sumption to 200µW. In shutdown mode, the quiescent
current is further reduced to just 3µA. Figure 2 shows
the
MAX1700/MAX1701.
Additional features include synchronous rectification for
high efficiency and improved battery life, a POK output,
and an uncommitted comparator for low-battery detec-
tion (MAX1701). A CLK input allows frequency synchro-
nization to reduce interference. Dual shutdown controls
allow shutdown using a momentary pushbutton switch
and microprocessor control (MAX1701).
OSCILLATOR
EN
GAIN
BLOCK
300kHz
OSCILLATOR
START-UP
standard
PFM/PWM
Q
application
D
EN
OSC
MODE
FB
CONTROLLER
PFM/PWM
Q
Q
N
N
N
circuit
PCH
0.25
NCH
0.13
POUT
LX
PGND
POK*
AO*
LBO*
for
the
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