Rainbow Electronics MAX1673 - Manual

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________________General Description
The MAX1673 charge-pump inverter provides a low-
cost, compact means of generating a regulated nega-
tive output from a positive input at up to 125mA. It
requires only three small capacitors, and only two resis-
tors to set its output voltage. The input range is 2V to
5.5V. The regulated output can be set from 0V to -V
IN
in
Skip regulation mode or -1.5V to -V IN in Linear (LIN)
regulation mode.
In Skip mode, the MAX1673 regulates by varying its
switching frequency as a function of load current. This
On-Demand™ switching gives the MAX1673 two
advantages: very small capacitors and very low quies-
cent supply current. At heavy loads, it transfers energy
from the input to the output by switching at up to
350kHz. It switches more slowly at light loads, using
only 35µA quiescent supply current.
In Linear mode, the MAX1673 switches at a constant
350kHz at all loads and regulates by controlling
the current-path resistance. This provides constant-
frequency ripple, which is easily filtered for low-noise
applications.
This device also features a 1µA logic-controlled shut-
down mode and is available in a standard 8-pin SO
package. For a device that delivers about 10mA and
fits in a smaller package, refer to the MAX868.
________________________Applications
Hard Disk Drives Measurement Instruments
Camcorders Modems
Analog Signal-Processing Digital Cameras
Applications
____________________________Features
♦ Regulated Negative Output Voltage
(up to -1 x V
IN
)
♦ 125mA Output Current
♦ 35µA Quiescent Supply Current
(Skip-mode regulation)
♦ 350kHz Fixed-Frequency, Low-Noise Output
(Linear-mode regulation)
♦ 2V to 5.5V Input Range
♦ 1µA Logic-Controlled Shutdown
MAX1673
Regulated, 125mA-Output,
Charge-Pump DC-DC Inverter
________________________________________________________________ Maxim Integrated Products 1
FB
OUT SHDN
1
2
8
7
IN
GND CAP+
CAP-
LIN/SKIP
SO
TOP VIEW
3
4
6
5
MAX1673
MAX1673
IN
INPUT 2V TO 5.5V
REGULATED
NEGATIVE
OUTPUT
(UP TO -1 x V IN ,
UP TO 125mA)
LIN/SKIP
FB
OUT
GND
CAP+
ON
OFF SHDN
CAP-
Typical Operating Circuit
___________________Pin Configuration
19-1334; Rev 0; 1/98
PART
MAX1673ESA -40°C to +85°C
TEMP. RANGE PIN-PACKAGE
8 SO
_______________Ordering Information
On-Demand™ is a trademark of Maxim Integrated Products.