ADM3483E/ADM3486E/ADM3488E/ADM3490E/ADM3491ECIRCUIT DESCRIPTION
The ADM34xxE are low power transceivers for RS-485 and RS-422 communications. The ADM3483E/ADM3488E operate at data rates up to 250 kbps. The ADM3486E operates at data rates up to 2.5 Mbps, and the ADM3490E/ADM3491E transmit at up to 12 Mbps. The ADM3488E/ADM3490E/ADM3491E are full-duplex transceivers, and the ADM3483E/ADM3486E are half duplex. Driver enable (DE) and receiver enable (RE) pins are included on the ADM3483E/ADM3486E/ADM3491E. When disabled, the driver and receiver outputs are high impedance.
Table 12. Receiving Truth Table
Receiving Input A – B ≥ +0.2 V ≤ ?0.2 V Inputs open
Receiving Output RO 1 0 1
LOW POWER SHUTDOWN MODE—ADM3483E/ ADM3486E/ADM3491E
The ADM3483E/ADM3486E/ADM3491E are put into a low power shutdown mode by bringing both RE high and DE low. The devices do not shut down unless both the driver and the receiver are disabled (high impedance). In shutdown mode, the devices typically draw less than 1 μA of supply current. For these devices, the tPSH and the tPSL enable times assume the part was in the low power shutdown mode; the tPZH and the tPZL
enable times assume the receiver or the driver was disabled, but the part was not shut down.
DEVICES WITH RECEIVER/DRIVER ENABLE—ADM3483E/ ADM3486E/ ADM3491E
Table 9. Transmitting Truth Table Transmitting Inputs Transmitting Outputs DE DI A1, Y2 B1, Z2 RE 3Mode X 1 1 1 0 Normal 3X 1 0 0 1 Normal 0 0 X3 High-Z4 High-Z4 Normal 1 0 X3 High-Z4 High-Z4 Shutdown ADM3483E and ADM3486E only. 2
ADM3491E only. 3
X = don’t care. 4
High-Z = high impedance.
1
DRIVER OUTPUT PROTECTION
The ADM34xxE family implements two ways to prevent
excessive output current and power dissipation caused by faults or by bus contention. A current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range (see the Typical
Performance Characteristics section). In addition, a thermal shutdown circuit forces the driver outputs into a high impedance state if the die temperature rises excessively.
Table 10. Receiving Truth Table Receiving Inputs RE DE1 DE2 A – B 0 0 0 0 0 0 1 0 1
Receiving Output RO X ≥ +0.2 V 1 3X ≤ ?0.2 V 0 X3 Inputs open 1 33X XHigh-Z43Mode Normal Normal Normal ShutdownPROPAGATION DELAY
Figure 11, Figure 14, Figure 26, and Figure 27 show the typical propagation delays. Skew time is simply the difference between the low-to-high and the high-to-low propagation delays. Small driver/receiver skew times help maintain a symmetrical mark-space ratio (50% duty cycle).
The receiver skew time, |tPRHL – tPRHL|, is under 10 ns (20 ns for the ADM3483E/ADM3488E). The driver skew time is 8 ns for the ADM3490E/ADM3491E, 12 ns for the ADM3486E, and typically under 50 ns for the ADM3483E/ADM3488E.
ADM3483E and ADM3486E only. 2
ADM3491E only. 3
X = don’t care. 4
High-Z = high impedance.
DEVICES WITHOUT RECEIVER/DRIVER ENABLE― ADM3488E/ ADM3490E
Table 11. Transmitting Truth Table
Transmitting Input DI10
Transmitting Outputs Z Y
0 1
1 0
LINE LENGTH VS. DATA RATE
The RS-485/RS-422 standard covers line lengths up to 4000 feet.
For line lengths greater than 4000 feet, Figure 34 illustrates an example of a line repeater.
Rev. A | Page 14 of 20
ADM3483E/ADM3486E/ADM3488E/ADM3490E/ADM3491E
±15 kV ESD PROTECTION
Two coupling methods are used for ESD testing: con- tact discharge and air-gap discharge. Contact discharge calls for a direct connection to the unit being tested. Air-gap discharge uses a higher test voltage but does not make direct contact with the test unit. With air-gap discharge, the discharge gun is moved toward the unit under test, developing an arc across the air gap, therefore the term air- gap discharge. This method is influenced by humidity, temperature, barometric pressure, distance, and rate of closure of the discharge gun. The contact discharge method, while less realistic, is more repeatable and is gaining acceptance and preference over the air- gap method.
Although very little energy is contained within an ESD pulse, the extremely fast rise time, coupled with high voltages, can cause failures in unprotected semiconductors. Catastrophic destruction can occur immediately as a result of arcing or
heating. Even if catastrophic failure does not occur immediately, the device can suffer from parametric degradation that can result in degraded performance. The cumulative effects of continuous exposure can eventually lead to complete failure. Input/output lines are particularly vulnerable to ESD damage. Simply touching or connecting an input/output cable can result in a static discharge that can damage or completely destroy the interface product connected to the input/output port. It is extremely important, therefore, to have high levels of ESD protection on the input/output lines.
The ESD discharge can induce latch-up in the device under test, so it is important that ESD testing on the input/output pins be carried out while device power is applied. This type of testing is more representative of a real-world input/output discharge, which occurs when the equipment is operating normally. The transmitter outputs and receiver inputs of the ADM34xxE family are characterized for protection to a ±15 kV limit using the human body model.
HIGHVOLTAGEGENERATORR1R2DEVICEUNDERTESTC1ESD TEST METHODHUMAN BODY MODELESD ASSOC. STD 55.1R21.5k?C1100pF100?6.8%IPEAKtRLtDLTIMEtFigure 30. Human Body Model and Current Waveform
TYPICAL APPLICATIONS
The ADM3483E/ADM3486E/ADM3491E transceivers are designed for bidirectional data communications on multipoint bus transmission lines. The ADM3488E/ADM3490E full-duplex transceiver is designed to be used in a daisy-chain network topology or in a point-to-point application (see Figure 32). The ADM3483E/ADM3486E are half-duplex RS-485 transceivers that can be used in a multidrop bus configuration, as shown in Figure 31. The ADM3488E/ADM3490E/ADM3491E can also be used as a line repeater, for use with cable lengths longer than 4000 feet, as shown in Figure 34. To minimize reflections, the line must be terminated at both ends in its characteristic
impedance, and stub lengths off the main line should be kept as short as possible.
HUMAN BODY MODEL
Figure 30 shows the human body model and the current wave-form it generates when discharged into a low impedance. This model consists of a 100 pF capacitor charged to the ESD voltage of interest, which is then discharged into the test device through a 1.5 kΩ resistor.
Rev. A | Page 15 of 20
06284-016ADM3483E/ADM3486E/ADM3488E/ADM3490E/ADM3491E
ADM3483E/ADM3486ERORERTDEDIDBBDRTRAAADM3483E/ADM3486ERROREDEDIABABADM3483E/ADM3486EADM3483E/ADM3486ERDRDFigure 31. ADM3483E/ADM3486E Typical Half-Duplex RS-485 Network
Rev. A | Page 16 of 20
06284-017ROREDEDINOTES1.MAXIMUMNUMBER OFTRANSCEIVERS ONBUS:32.2.RT ISEQUALTOTHECHARACTERISTIC IMPEDANCE OFTHECABLEUSED.ROREDEDIADM3483E/ADM3486E/ADM3488E/ADM3490E/ADM3491E
MASTERSLAVEABRTYZADM3491EROREDEDIDRADM3491EDDEDIZYRTBARRORESLAVEABZYABZYSLAVERDRDADM3491EADM3491EROREDEDIROREDEDINOTES1.MAXIMUM NUMBER OF NODES: 32.2. RT IS EQUALTO THE CHARACTERISTIC IMPEDANCE OF THE CABLE USED.Figure 33. ADM3491E Full-Duplex RS-485 Network
ADM3488E/ADM3490E/ADM3491EARORBRTDATA INREDEZDIDYRTDATA OUTNOTES1.RT ISEQUALTOTHECHARACTERISTIC02 IMPEDANCE OFTHECABLEUSED.0-42.REANDDEPINS ONADM3491E ONLY.8260
Figure 34. Line Repeater for ADM3488E/ADM3490E/ADM3491E
Rev. A | Page 17 of 20
910-48260ADM3483E/ADM3486E/ADM3488E/ADM3490E/ADM3491EOUTLINE DIMENSIONS
5.00(0.1968)4.80(0.1890)4.00 (0.1574)3.80 (0.1497)81546.20 (0.2440)5.80 (0.2284)1.27 (0.0500)BSC0.25 (0.0098)0.10 (0.0040)COPLANARITY0.10SEATINGPLANE1.75 (0.0688)1.35 (0.0532)0.50 (0.0196)0.25 (0.0099)8°0°0.25 (0.0098)0.17 (0.0067)1.27 (0.0500)0.40 (0.0157)45°0.51 (0.0201)0.31 (0.0122)COMPLIANTTO JEDEC STANDARDS MS-012-AACONTROLLING DIMENSIONSARE IN MILLIMETERS; INCH DIMENSIONS(INPARENTHESES)ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FORREFERENCE ONLYANDARE NOTAPPROPRIATE FOR USE IN DESIGN.Figure 35. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
8.75 (0.3445)8.55 (0.3366)141874.00 (0.1575)3.80 (0.1496)6.20 (0.2441)5.80 (0.2283)1.27 (0.0500)BSC0.25 (0.0098)0.10 (0.0039)COPLANARITY0.100.51 (0.0201)0.31 (0.0122)1.75 (0.0689)1.35 (0.0531)SEATINGPLANE0.50 (0.0197)0.25 (0.0098)8°0°0.25 (0.0098)0.17 (0.0067)1.27 (0.0500)0.40 (0.0157)45°COMPLIANTTO JEDEC STANDARDS MS-012-ABCONTROLLING DIMENSIONSARE IN MILLIMETERS; INCH DIMENSIONS(INPARENTHESES)ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FORREFERENCE ONLYANDARE NOTAPPROPRIATE FOR USE IN DESIGN.060506-AFigure 36. 14-Lead Standard Small Outline Package [SOIC_N]
Narrow Body (R-14)
Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model
ADM3483EARZ1
ADM3483EARZ-REEL71ADM3486EARZ1
ADM3486EARZ-REEL71ADM3488EARZ1
ADM3488EARZ-REEL71ADM3490EARZ1
ADM3490EARZ-REEL71ADM3491EARZ1
ADM3491EARZ-REEL71
1
Temperature Range
–40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C
Package Description
8-Lead Standard Small Outline Package (SOIC_N) 8-Lead Standard Small Outline Package (SOIC_N) 8-Lead Standard Small Outline Package (SOIC_N) 8-Lead Standard Small Outline Package (SOIC_N) 8-Lead Standard Small Outline Package (SOIC_N) 8-Lead Standard Small Outline Package (SOIC_N) 8-Lead Standard Small Outline Package (SOIC_N) 8-Lead Standard Small Outline Package (SOIC_N) 14-Lead Standard Small Outline Package (SOIC_N) 14-Lead Standard Small Outline Package (SOIC_N) Package Option R-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 R-14 R-14
060606-AOrdering Quantity 1,000 1,000 1,000 1,000 1,000
Z = Pb-free part.
Rev. A | Page 18 of 20
MEMORY存储芯片ADM3490EARZ-REEL7中文规格书 - 图文
