MAX253ESA Datasheet Download

Part No.:
MAX253ESA
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Download Datasheet
Description:
[Transformer Driver for Isolated RS-485 Interface]
File Size:
232 K
Page:
16 Pages
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Manufacturer:
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
PCB Prototype
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19-0226; Rev 0; 1/94
Transformer Driver for
Isolated RS-485 Interface
_______________General Description
The MAX253 is a monolithic oscillator/power-driver,
specifically designed to provide isolated power for an
isolated RS-485 or RS-232 data interface. It
drives a center-tapped transformer primary from a 5V
or 3.3V DC power supply. The secondary can be
wound to provide any isolated voltage needed at power
levels up to 1W.
The MAX253 consists of a CMOS oscillator driving a
pair of N-channel power switches. The oscillator runs
at double the output frequency, driving a toggle flip-flop
to ensure 50% duty cycle to each of the switches.
Internal delays are arranged to ensure break-before-
make action between the two switches.
The SD pin puts the entire device into a low-power
shutdown state, disabling both the power switches and
oscillator.
____________________________Features
o
Power-Supply Transformer Driver for Isolated
RS-485/RS-232 Data-Interface Applications
o
Single +5V or +3.3V Supply
o
Low-Current Shutdown Mode: 0.4µA
o
Pin-Selectable Frequency: 350kHz or 200kHz
o
8-Pin DIP, SO, and µMAX Packages
MAX253
______________Ordering Information
PART
MAX253CPA
MAX253CSA
MAX253CUA
MAX253C/D
MAX253EPA
MAX253ESA
MAX253EUA
MAX253MJA
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
PIN-PACKAGE
8 Plastic DIP
8 SO
8 µMAX
Dice*
8 Plastic DIP
8 SO
8 µMAX
8 CERDIP**
________________________Applications
Isolated RS-485/RS-232 Power-Supply
Transformer Driver
High Noise-Immunity Communications Interface
Isolated and/or High-Voltage Power Supplies
Bridge Ground Differentials
Medical Equipment
Process Control
* Contact factory for dice specifications.
**Contact factory for availability and processing to MIL-STD-883.
__________Typical Operating Circuit
ON / OFF
4
SD
6
V
CC
D1
1
C3
C2
V
IN
5V
C1
OUTPUT
5V @ 200mA
__________________Pin Configuration
TOP VIEW
D1
GND1
1
2
8
7
D2
GND2
V
CC
N.C.
MAX253
3
FREQUENCY
SWITCH
FS
GND1
2
D2
GND2
7
8
FS
3
SD
4
MAX253
6
5
DIP/SO/µMAX
________________________________________________________________
Maxim Integrated Products
1
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