MAX253EPA ,Transformer Driver for Isolated RS-485 InterfaceApplicationsisolated RS-485 or RS-232 data interface. It' Single +5V or +3.3V Supplydrives a cente ..
MAX253EPA ,Transformer Driver for Isolated RS-485 InterfaceGeneral Description ________
MAX253EPA+ ,1W Primary-Side Transformer H-Bridge Driver for Isolated SuppliesFeaturesThe MAX253 monolithic oscillator/power-driver is• Simple Power-Supply Transformer Driver De ..
MAX253ESA ,Transformer Driver for Isolated RS-485 InterfaceApplicationsisolated RS-485 or RS-232 data interface. It' Single +5V or +3.3V Supplydrives a cente ..
MAX253ESA ,Transformer Driver for Isolated RS-485 InterfaceGeneral Description ________
MAX253ESA ,Transformer Driver for Isolated RS-485 InterfaceFeaturesThe MAX253 is a monolithic oscillator/power-driver,' Power-Supply Transformer Driver for Is ..
MAX5922CEUI+ ,+48V, Single-Port Network Power Switch For Power-Over-LANFeaturesThe MAX5922A/B/C is a single-port network power con-♦ IEEE 802.3af Complianttroller with an ..
MAX5924AEUB+ ,1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense ResistorFeaturesThe MAX5924/MAX5925/MAX5926 1V to 13.2V hot-swap ● Hot Swap 1V to 13.2V with V ≥ 2.25VCCcon ..
MAX5924AEUB+ ,1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense ResistorElectrical Characteristics(V , EN (MAX5924/MAX5925), EN1 (MAX5926) = +2.7V to +13.2V; EN2 (MAX5926) ..
MAX5924AEUB+T ,1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense ResistorApplications RCB● Base StationsCB SENSE GATE OUT● RAID● Remote-Access ServersVCC● Network Routers a ..
MAX5924BEUB ,1 V to 13.2 V, n-channel hot-swap controller require no sense resistorELECTRICAL CHARACTERISTICS(V , EN (MAX5924/MAX5925), EN1 (MAX5926) = +2.25V to +13.2V; EN2 (MAX5926 ..
MAX5925DEUB ,1 V to 13.2 V, n-channel hot-swap controller require no sense resistorApplicationsTYPICAL OPERATION WITHOUT RSENSEBase StationsBACKPLANE REMOVABLE CARDRAID NV1V TO V OUT ..
MAX253CPA-MAX253CSA-MAX253CUA-MAX253EPA-MAX253ESA-MAX253MJA
Transformer Driver for Isolated RS-485 Interface
_______________General DescriptionThe 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.
________________________ApplicationsIsolated 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
____________________________FeaturesPower-Supply Transformer Driver for Isolated
RS-485/RS-232 Data-Interface ApplicationsSingle +5V or +3.3V SupplyLow-Current Shutdown Mode: 0.4µAPin-Selectable Frequency: 350kHz or 200kHz8-Pin DIP, SO, and µMAX Packages
______________Ordering Information* Contact factory for dice specifications.
**Contact factory for availability and processing to MIL-STD-883.
MAX253ransformer Driver for
Isolated RS-485 Interface
________________________________________________________________Maxim Integrated Products1
__________________Pin Configuration
__________Typical Operating Circuit
Call toll free 1-800-998-8800 for free samples or literature.19-0226; Rev 0; 1/94
MAX253ransformer Driver for
Isolated RS-485 Interface_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VCC= 5V ±10%, TA= TMINto TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Note 1:Operating supply current is the current used by the MAX253 only, not including load current.
Note 2:Shutdown supply current includes output switch-leakage currents.
Supply Voltage (VCC)...............................................-0.3V to +7V
Control Input Voltages (SD, FS).................-0.3V to (VCC+ 0.3V)
Output Switch Voltage (D1, D2).............................................12V
Peak Output Switch Current (D1, D2)......................................1A
Average Output Switch Current (D1, D2).........................200mA
Continuous Power Dissipation (TA= +70°C)
Plastic DIP (derate 9.09mW/°C above +70°C).............727mW
SO (derate 5.88mW/°C above +70°C)..........................471mW
µMAX (derate 4.10mW/°C above +70°C).....................330mW
CERDIP (derate 8.00mW/°C above +70°C)..................640mW
Operating Temperature Ranges
MAX253C_ _........................................................0°C to +70°C
MAX253E_ _.....................................................-40°C to +85°C
MAX253MJA...................................................-55°C to +125°C
Junction Temperatures
MAX253C_ _/E_ _..........................................................+150°C
MAX253MJA.................................................................+175°C
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10sec).............................+300°C
MAX253ransformer Driver for
Isolated RS-485 Interface
_______________________________________________________________________________________3OUTPUT RESISTANCE vs. TEMPERATURE
(FS = LOW)
plot01
TEMPERATURE (°C)
OUTPUT RESISTANCE (100
OUTPUT RESISTANCE vs. TEMPERATURE
(FS = HIGH)
plot02
TEMPERATURE (°C)
OUTPUT RESISTANCE (100
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
plot03
TEMPERATURE (°C)
SHUTDOWN CURRENT (µA)100
D1, D2 FREQUENCY vs. TEMPERATURE
(FS = LOW)
plot04
TEMPERATURE (°C)
FREQUENCY (kHz)100
SUPPLY CURRENT vs. TEMPERATURE
(FS = HIGH)
plot07
TEMPERATURE (°C)
SUPPLY CURRENT (µA)100
D1, D2 FREQUENCY vs. TEMPERATURE
(FS = HIGH)
plot05
TEMPERATURE (°C)
FREQUENCY (kHz)100
SUPPLY CURRENT vs. TEMPERATURE
(FS = LOW)
plot06
TEMPERATURE (°C)
SUPPLY CURRENT (µA)100
10040120200
EFFICIENCY vs. LOAD CURRENT
(FS = LOW)20
80
plot08
LOAD CURRENT (mA)
EFFICIENCY (%)
80160
60
40
10
30
90
70
50
2060140100180
__________________________________________Typical Operating Characteristics(Circuit of Figure 6, VIN= 5V ±10%, TA = +25°C, unless otherwise noted.)
MAX253ransformer Driver for
Isolated RS-485 Interface_______________________________________________________________________________________40220
OUTPUT VOLTAGE vs. LOAD CURRENT
(FS = LOW)plot10
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)6014012010016018020040220
OUTPUT VOLTAGE vs. LOAD CURRENT
(FS = HIGH)plot11
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)60140120100160180200
____________________________Typical Operating Characteristics (continued)(Circuit of Figure 6, VIN= 5V ±10%, TA = +25°C, unless otherwise noted.)
10040120200
EFFICIENCY vs. LOAD CURRENT
(FS = HIGH)20
80
plot09
LOAD CURRENT (mA)
EFFICIENCY (%)
80160
60
40
10
30
90
70
50
2060140100180
MAX253ransformer Driver for
Isolated RS-485 Interface
_______________________________________________________________________________________5
_____________________Pin Description
_______________Detailed DescriptionThe MAX253 is an isolated power-supply transformer
driver specifically designed to form the heart of a fully
isolated RS-485 data interface. Completely isolated
communications are obtained by combining the
MAX253 with a linear regulator, a center-tapped trans-
former, optocouplers, and the appropriate Maxim inter-
face product (as described in the Isolated RS-485/RS-
232 Data Interfacesection).
The MAX253 consists of an RC oscillator followed by a
toggle flip-flop, which generates two 50% duty-cycle
square waves, out-of-phase at half the oscillator fre-
quency (see Figure 2). These two signals drive the
ground-referenced output switches. Internal delays
ensure break-before-make action between the two
switches.
Ground SD for normal operation. When high, SD dis-
ables all internal circuitry, including the oscillator and
both power switches.
Pulling FS low reduces the oscillator frequency and low-
ers the supply current (see Supply Current vs.
Temperature in the Typical Operating Characteristics).
FS includes a weak pull-up, so it will float to the high-fre-
quency state if not connected.
Figure 1. Test Circuit
MAX253ransformer Driver for
Isolated RS-485 Interface_______________________________________________________________________________________Figure 3. Typical RS-485 Application Circuit, 5V Configuration
MAX253ransformer Driver for
Isolated RS-485 Interface
_______________________________________________________________________________________7Figure 4. Typical RS-485 Application Circuit, 3.3V Configuration
MAX253ransformer Driver for
Isolated RS-485 Interface_______________________________________________________________________________________Figure 5. Typical RS-232 Application Circuit
