MAX3221IDBR

Product Folder Sample & Buy Support & Community Tools & Software Technical Documents Reference Design MAX3221 SLLS348O – JUNE 1999 – REVISED JUNE 2015 MAX3221 3-V to 5.5-V RS-232 Line Driver and Receiver With ±15-kV ESD Protection 1 Features 3 Description • The MAX3221 device consists of one line driver, one line receiver with dedicated enable pin, and a dual charge-pump circuit with ±15-kV ESD protection pin to pin (serial-port connection pins, including GND). The device meets the requirements of TIA/EIA-232-F and provides the electrical interface between an asynchronous communication controller and the serial-port connector. The charge pump and four small external capacitors allow operation from a single 3-V to 5.5-V supply. These devices operate at data signaling rates up to 250 kbps and a maximum of 30-V/μs driver output slew rate. 1 • • • • • • • • • RS-232 Bus-Pin ESD Protection Exceeds ±15 kV Using Human Body Model (HBM) Meets or Exceeds the Requirements of TIA/EIA-232-F and ITU V.28 Standards Operates With 3-V to 5.5-V VCC Supply Operates up to 250 kbps One Driver and One Receiver Low Standby Current: 1 μA Typical External Capacitors: 4 × 0.1 μF Accepts 5-V Logic Input With 3.3-V Supply Alternative High-Speed Pin-Compatible Device (1 Mbps) – SNx5C3221 Automatic Power-Down Feature Automatically Disables Drivers for Power Savings Flexible control options for power management are available when the serial port is inactive. The automatic power-down feature functions when FORCEON is low and FORCEOFF is high. During this mode of operation, if the device does not sense a valid RS-232 signal on the receiver input, the driver output is disabled and the supply current is reduced to 1 μA. The INVALID output notifies the user if an RS-232 signal is present at the receiver input. 2 Applications • • • • Battery-Powered, Hand-Held, and Portable Equipment Notebooks, Subnotebooks, and Laptops Digital Cameras Mobile Phones and Wireless Devices Device Information(1) PART NUMBER PACKAGE BODY SIZE (NOM) MAX3221xDB SSOP (32) 6.20 mm × 5.30 mm MAX3221xPW TSSOP (32) 5.00 mm × 4.40 mm (1) For all available packages, see the orderable addendum at the end of the data sheet. Simplified Diagram 3.3 V, 5 V POWER EN [RX] FORCEON APD FORCEOFF DIN 1 1 TX DOUT RS232 1 ROUT INVALID RX 1 RIN RS232 STATUS 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. MAX3221 SLLS348O – JUNE 1999 – REVISED JUNE 2015 www.ti.com Table of Contents 1 2 3 4 5 6 7 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Pin Configuration and Functions ......................... Specifications......................................................... 1 1 1 2 3 4 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.10 6.11 6.12 4 4 4 5 5 5 6 6 6 7 7 7 Absolute Maximum Ratings ...................................... ESD Ratings.............................................................. Recommended Operating Conditions....................... Thermal Information .................................................. Electrical Characteristics – Power ............................ Electrical Characteristics – Driver ............................. Electrical Characteristics – Receiver ........................ Electrical Characteristics – Status ........................... Switching Characteristics – Driver ............................ Switching Characteristics – Receiver ..................... Switching Characteristics – Status.......................... Typical Characteristics ............................................ Parameter Measurement Information .................. 8 8 Detailed Description ............................................ 11 8.1 8.2 8.3 8.4 9 Overview ................................................................. Functional Block Diagram ....................................... Feature Description................................................. Device Functional Modes........................................ 11 11 11 12 Application and Implementation ........................ 13 9.1 Application Information............................................ 13 9.2 Typical Application .................................................. 13 10 Power Supply Recommendations ..................... 14 11 Layout................................................................... 15 11.1 Layout Guidelines ................................................. 15 11.2 Layout Example .................................................... 15 12 Device and Documentation Support ................. 16 12.1 12.2 12.3 12.4 Community Resources.......................................... Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 16 16 16 16 13 Mechanical, Packaging, and Orderable Information ........................................................... 16 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision N (January 2014) to Revision O • Page Added Pin Configuration and Functions section, ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section .............................. 1 Changes from Revision M (March 2004) to Revision N Page • Updated document to new TI data sheet format - no specification changes. ........................................................................ 1 • Deleted Ordering Information table. ....................................................................................................................................... 1 2 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: MAX3221 MAX3221 www.ti.com SLLS348O – JUNE 1999 – REVISED JUNE 2015 5 Pin Configuration and Functions DB or PW Package 16-Pin SSOP or TSSOP Top View EN C1+ V+ C1− C2+ C2− V− RIN 1 16 2 15 3 14 4 13 5 12 6 11 7 10 8 9 FORCEOFF VCC GND DOUT FORCEON DIN INVALID ROUT Pin Functions PIN NAME NO. I/O DESCRIPTION C1+ 2 C2+ 5 C1– 4 C2– 6 DIN 11 I Driver input DOUT 13 O RS-232 driver output EN 1 I Low input enables receiver ROUT output. High input sets ROUT to high impedance. FORCEOFF 16 I Automatic power-down control input FORCEON 12 I Automatic power-down control input GND 14 — Ground INVALID 10 O Invalid output pin. Output low when all RIN inputs are unpowered. RIN 8 I RS-232 receiver input ROUT 9 O Receiver output VCC 15 — 3-V to 5.5-V supply voltage V+ 3 O 5.5-V supply generated by the charge pump V– 7 O –5.5-V supply generated by the charge pump — Positive terminals of the voltage-doubler charge-pump capacitors — Negative terminals of the voltage-doubler charge-pump capacitors Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: MAX3221 3 MAX3221 SLLS348O – JUNE 1999 – REVISED JUNE 2015 www.ti.com 6 Specifications 6.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) MIN MAX VCC to GND –0.3 6 V+ to GND –0.3 7 V– to GND 0.3 –7 V+ + |V–| (2) VI Input voltage VO Output voltage TJ Junction temperature (3) Tstg Storage temperature range (1) (2) (3) UNIT V 13 DIN, EN, FORCEOFF , and FORCEON to GND –0.3 6 RIN to GND V ±25 DOUT to GND ±13.2 ROUT to GND –0.3 VCC + 0.3 150 –65 V °C 150 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 under Recommended Operating Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. V+ and V– can have maximum magnitudes of 7 V, but their absolute difference cannot exceed 13 V. Maximum power dissipation is a function of TJ(max), RθJA, and TA. The maximum allowable power dissipation at any allowable ambient temperature is PD = (TJ(max) – TA) / RθJA. Operating at the absolute maximum TJ of 150°C can affect reliability. 6.2 ESD Ratings VALUE V(ESD) Electrostatic discharge Human body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1) All pins except 8, 13 Pins 8, 13 ±15,000 Charged-device model (CDM), per JEDEC specification JESD22C101 (2) (1) (2) UNIT ±3000 V ±1500 JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. 6.3 Recommended Operating Conditions (see Figure 8) (1) VCC = 3.3 V Supply voltage VCC = 5 V VIH Driver high-level input voltage DIN, FORCEOFF, FORCEON, EN VIL Driver low-level input voltage DIN, FORCEOFF, FORCEON, EN Driver input voltage DIN, FORCEOFF, FORCEON, EN VI VCC = 3.3 V VCC = 5 V (1) 4 Operating free-air temperature NOM MAX 3 3.3 3.6 4.5 5 5.5 2 MAX3221C MAX3221I UNIT V V 2.4 0.8 Receiver input voltage TA MIN 0 5.5 –25 25 0 70 –40 85 V V °C Test conditions are C1–C4 = 0.1 μF at VCC = 3.3 V ± 0.3 V; C1 = 0.047 μF, C2–C4 = 0.33 μF at VCC = 5 V ± 0.5 V. Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: MAX3221 MAX3221 www.ti.com SLLS348O – JUNE 1999 – REVISED JUNE 2015 6.4 Thermal Information MAX3221 THERMAL METRIC (1) DB (SSOP) PW (TSSOP) 16 PINS 16 PINS UNIT RθJA Junction-to-ambient thermal resistance 98.0 106.4 °C/W RθJC(top) Junction-to-case (top) thermal resistance 48.3 41.1 °C/W RθJB Junction-to-board thermal resistance 48.7 51.4 °C/W ψJT Junction-to-top characterization parameter 10.1 3.9 °C/W ψJB Junction-to-board characterization parameter 48.1 50.9 °C/W (1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953. 6.5 Electrical Characteristics – Power over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted) (1) PARAMETER II Input leakage current Supply current ±0.01 ±1 µA 0.3 1 mA Powered off No load, FORCEOFF at GND 1 10 No load, FORCEOFF at VCC, FORCEON at GND, All RIN are open or grounded 1 10 No load, FORCEOFF and FORCEON at VCC No load, VCC = 3.3 V to 5 V Automatic power-down enabled (1) (2) MAX MIN FORCEOFF, FORCEON, EN Automatic power-down disabled ICC TYP (2) TEST CONDITIONS UNIT µA Test conditions are C1–C4 = 0.1 μF at VCC = 3.3 V ± 0.3 V; C1 = 0.047 μF, C2–C4 = 0.33 μF at VCC = 5 V ± 0.5 V. All typical values are at VCC = 3.3 V or VCC = 5 V, and TA = 25°C. 6.6 Electrical Characteristics – Driver over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted) (1) PARAMETER TEST CONDITIONS MIN TYP (2) MAX UNIT VOH High-level output voltage DOUT at RL = 3 kΩ to GND, DIN = GND 5 5.4 V VOL Low-level output voltage DOUT at RL = 3 kΩ to GND, DIN = VCC –5 –5.4 V IIH High-level input current VI = VCC ±0.01 ±1 μA IIL Low-level input current VI at GND ±0.01 ±1 μA IOS Short-circuit output current (3) rO Output resistance Ioff (1) (2) (3) Output leakage current VCC = 3.6 V VO = 0 V ±35 ±60 VCC = 5.5 V VO = 0 V ±35 ±60 VCC, V+, and V– = 0 V VO = ±2 V FORCEOFF = GND 300 mA Ω 10M VO = ±12 V, VCC = 3 V to 3.6 V ±25 VO = ±12 V, VCC = 4.5 V to 5.5 V ±25 µA Test conditions are C1–C4 = 0.1 μF at VCC = 3.3 V ± 0.3 V; C1 = 0.047 μF, C2–C4 = 0.33 μF at VCC = 5 V ± 0.5 All typical values are at VCC = 3.3 V or VCC = 5 V, and TA = 25°C. Short-circuit durations should be controlled to prevent exceeding the device absolute power dissipation ratings, and not more than one output should be shorted at a time. Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: MAX3221 5 MAX3221 SLLS348O – JUNE 1999 – REVISED JUNE 2015 www.ti.com 6.7 Electrical Characteristics – Receiver over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted) (1) PARAMETER VOH High-level output voltage IOH = –1 mA VOL Low-level output voltage IOL = 1.6 mA TYP (2) VCC – 0.6 VCC – 0.1 MAX VCC = 3.3 V 1.5 2.4 VCC = 5 V 1.8 2.4 Positive-going input threshold voltage VIT– Negative-going input threshold voltage Vhys Input hysteresis (VIT+ – VIT–) Ioff Output leakage current FORCEOFF = 0 V ri Input resistance VI = ±3 V to ±25 V VCC = 3.3 V 0.6 1.1 VCC = 5 V 0.8 1.4 V V V 0.5 3 UNIT V 0.4 VIT+ (1) (2) MIN TEST CONDITIONS V ±0.05 ±10 µA 5 7 kΩ Test conditions are C1–C4 = 0.1 μF at VCC = 3.3 V ± 0.3 V; C1 = 0.047 μF, C2–C4 = 0.33 μF at VCC = 5 V ± 0.5 V. All typical values are at VCC = 3.3 V or VCC = 5 V, and TA = 25°C. 6.8 Electrical Characteristics – Status over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted) (1) PARAMETER TEST CONDITIONS VT+(valid) Receiver input threshold for INVALID high-level output voltage FORCEON = GND, FORCEOFF = VCC VT–(valid) Receiver input threshold for INVALID high-level output voltage FORCEON = GND, FORCEOFF = VCC –2.7 VT(invalid) Receiver input threshold for INVALID low- FORCEON = GND, level output voltage FORCEOFF = VCC –0.3 VOH INVALID high-level output voltage IOH = –1 mA, FORCEON = GND, FORCEOFF = VCC VCC – 0.6 VOL INVALID low-level output voltage IOH = –1 mA, FORCEON = GND, FORCEOFF = VCC (1) (2) TYP (2) MIN MAX 2.7 UNIT V V 0.3 V V 0.4 V Test conditions are C1–C4 = 0.1 μF at VCC = 3.3 V ± 0.3 V; C1 = 0.047 μF, C2–C4 = 0.33 μF at VCC = 5 V ± 0.5 V. All typical values are at VCC = 3.3 V or VCC = 5 V, and TA = 25°C. 6.9 Switching Characteristics – Driver over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted) (1) PARAMETER TEST CONDITIONS Maximum data rate CL = 1000 pF, RL = 3 kΩ, see Figure 3 tsk(p) Pulse skew (3) CL = 150 to 2500 pF, RL = 3 kΩ to 7 kΩ, see Figure 4 SR(tr) Slew rate, transition region (see Figure 3) VCC = 3.3 V, RL = 3 kΩ to 7 kΩ (1) (2) (3) 6 MIN TYP (2) 150 250 kbps 100 ns MAX CL = 150 to 1000 pF 6 30 CL = 150 to 2500 pF 4 30 UNIT V/μs Test conditions are C1–C4 = 0.1 μF at VCC = 3.3 V ± 0.3 V; C1 = 0.047 μF, C2–C4 = 0.33 μF at VCC = 5 V ± 0.5 V. All typical values are at VCC = 3.3 V or VCC = 5 V, and TA = 25°C. Pulse skew is defined as |tPLH − tPHL| of each channel of the same device. Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: MAX3221 MAX3221 www.ti.com SLLS348O – JUNE 1999 – REVISED JUNE 2015 6.10 Switching Characteristics – Receiver over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted) (1) PARAMETER TEST CONDITIONS MIN TYP (2) MAX UNIT tPLH Propagation delay time, low- to high-level output CL = 150 pF, see Figure 5 150 ns tPHL Propagation delay time, high- to low-level output CL = 150 pF, see Figure 5 150 ns ten Output enable time CL = 150 pF, RL = 3 kΩ, see Figure 6 200 ns tdis Output disable time CL = 150 pF, RL = 3 kΩ, see Figure 6 200 ns tsk(p) Pulse skew (3) See Figure 5 50 ns (1) (2) (3) Test conditions are C1–C4 = 0.1 μF at VCC = 3.3 V ± 0.3 V; C1 = 0.047 μF, C2–C4 = 0.33 μF at VCC = 5 V ± 0.5 V. All typical values are at VCC = 3.3 V or VCC = 5 V, and TA = 25°C. Pulse skew is defined as |tPLH − tPHL| of each channel of the same device. 6.11 Switching Characteristics – Status over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted) (1) PARAMETER MIN TYP (2) MAX UNIT tvalid Propagation delay time, low- to high-level output 1 µs tinvalid Propagation delay time, high- to low-level output 30 µs ten Supply enable time 100 µs (1) (2) Test conditions are C1–C4 = 0.1 μF at VCC = 3.3 V ± 0.3 V; C1 = 0.047 μF, C2–C4 = 0.33 μF at VCC = 5 V ± 0.5 V. All typical values are at VCC = 3.3 V or VCC = 5 V, and TA = 25°C. 6.12 Typical Characteristics VCC = 3.3 V 0 6 VOH VOL ±1 DOUT Voltage (V) DOUT Voltage (V) 5 4 3 2 1 ±2 ±3 ±4 ±5 0 ±6 0 5 10 15 20 DOUT Current (mA) 25 0 C001 Figure 1. DOUT VOH vs Load Current 5 10 15 20 DOUT Current (mA) Product Folder Links: MAX3221 C001 Figure 2. DOUT VOL vs Load Current Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated 25 7 MAX3221 SLLS348O – JUNE 1999 – REVISED JUNE 2015 www.ti.com 7 Parameter Measurement Information 3V Generator (see Note B) Input RS-232 Output 50 Ω RL tTHL CL (see Note A) 3V FORCEOFF TEST CIRCUIT 0V tTLH 3V 3V Output −3 V −3 V 6V SR(tr) = t THL or t TLH VOH VOL VOLTAGE WAVEFORMS A. CL includes probe and jig capacitance. B. The pulse generator has the following characteristics: PRR = 250 kbps, ZO = 50 Ω, 50% duty cycle, tr ≤ 10 ns, tf ≤ 10 ns. Figure 3. Driver Slew Rate 3V Generator (see Note B) RS-232 Output 50 Ω RL Input 1.5 V 1.5 V 0V CL (see Note A) tPHL tPLH VOH 3V FORCEOFF 50% 50% Output VOL TEST CIRCUIT VOLTAGE WAVEFORMS A. CL includes probe and jig capacitance. B. The pulse generator has the following characteristics: PRR = 250 kbps, ZO = 50 Ω, 50% duty cycle, tr ≤ 10 ns, tf ≤ 10 ns. Figure 4. Driver Pulse Skew 3 V or 0 V FORCEON 3V Input 1.5 V 1.5 V −3 V Output Generator (see Note B) 50 Ω 3V FORCEOFF tPHL CL (see Note A) tPLH VOH 50% Output 50% VOL TEST CIRCUIT VOLTAGE WAVEFORMS A. CL includes probe and jig capacitance. B. The pulse generator has the following characteristics: ZO = 50 Ω, 50% duty cycle, tr ≤ 10 ns, tf ≤ 10 ns. Figure 5. Receiver Propagation Delay Times 8 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: MAX3221 MAX3221 www.ti.com SLLS348O – JUNE 1999 – REVISED JUNE 2015 Parameter Measurement Information (continued) 3V Input 3 V or 0 V FORCEON VCC S1 1.5 V GND 0V tPZH (S1 at GND) tPHZ (S1 at GND) RL 3 V or 0 V 1.5 V VOH Output 50% Output CL (see Note A) EN Generator (see Note B) 50 Ω 0.3 V tPZL (S1 at VCC) tPLZ (S1 at VCC) 0.3 V Output 50% VOL TEST CIRCUIT VOLTAGE WAVEFORMS A. CL includes probe and jig capacitance. B. The pulse generator has the following characteristics: ZO = 50 Ω, 50% duty cycle, tr ≤ 10 ns, tf ≤ 10 ns. C. tPLZ and tPHZ are the same as tdis. D. tPZL and tPZH are the same as ten. Figure 6. Receiver Enable and Disable Times Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: MAX3221 9 MAX3221 SLLS348O – JUNE 1999 – REVISED JUNE 2015 www.ti.com Parameter Measurement Information (continued) 2.7 V 2.7 V 0V Receiver Input ROUT Generator (see Note B) 3V 0V −2.7 V −2.7 V −3 V 50 Ω tvalid tinvalid VCC Autopowerdown INVALID CL = 30 pF (see Note A) FORCEOFF FORCEON DIN DOUT INVALID Output 50% VCC 50% VCC 0V ten V+ ≈V+ Supply Voltages 0.3 V VCC 0V 0.3 V V− TEST CIRCUIT ≈V− VOLTAGE WAVEFORMS Valid RS-232 Level, INVALID High 2.7 V Indeterminate 0.3 V 0V If Signal Remains Within This Region For More Than 30 µs, INVALID Is Low† −0.3 V Indeterminate −2.7 V Valid RS-232 Level, INVALID High † Auto-powerdown disables drivers and reduces supply current to 1 µA. Figure 7. INVALID Propagation Delay Times and Driver Enabling Time 10 Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: MAX3221 MAX3221 www.ti.com SLLS348O – JUNE 1999 – REVISED JUNE 2015 8 Detailed Description 8.1 Overview The MAX3221 device is a one-driver and one-receiver RS-232 interface device. All RS-232 inputs and outputs are protected to ±15 kV using the Human Body Model. The charge pump requires only four small 0.1-μF capacitors for operation from a 3.3-V supply. The MAX3221 is capable of running at data rates up to 250 kbps, while maintaining RS-232-compliant output levels. Automatic power-down can be disabled when FORCEON and FORCEOFF are high. With automatic power-down plus enabled, the device activates automatically when a valid signal is applied to any receiver input. The device can automatically power down the driver to save power when the RIN input is unpowered. INVALID is high (valid data) if receiver input voltage is greater than 2.7 V or less than –2.7 V, or has been between –0.3 V and 0.3 V for less than 30 μs. INVALID is low (invalid data) if receiver input voltages are between –0.3 V and 0.3 V for more than 30 μs. Refer to Figure 7 for receiver input levels. 8.2 Functional Block Diagram 3.3V, 5V POWER EN [RX] FORCEON APD FORCEOFF DIN ROUT INVALID 1 1 TX RX 1 DOUT RS232 1 RIN RS232 STATUS 8.3 Feature Description 8.3.1 Power The power block increases, inverts, and regulates voltage at V+ and V- pins using a charge pump that requires four external capacitors. Auto-power-down feature for driver is controlled by FORCEON and FORCEOFF inputs. Receiver is controlled by EN input. See Table 1 and Table 2 When MAX3221 is unpowered, it can be safely connected to an active remote RS232 device. 8.3.2 RS232 Driver One driver interfaces standard logic level to RS232 levels. DIN input must be valid high or low. 8.3.3 RS232 Receiver One receiver interfaces RS232 levels to standard logic levels. An open input will result in a high output on ROUT. RIN input includes an internal standard RS232 load. A logic high input on the EN pin will shutdown the receiver output. 8.3.4 RS232 Status The INVALID output goes low when RIN input is unpowered for more than 30 μs. The INVALID output goes high when receiver has a valid input. The INVALID output is active when Vcc is powered irregardless of FORCEON and FORCEOFF inputs (see Table 3). Submit Documentation Feedback Copyright © 1999–2015, Texas Instruments Incorporated Product Folder Links: MAX3221 11 MAX3221 SLLS348O – JUNE 1999 – REVISED JUNE 2015 www.ti.com 8.4 Device Functional Modes Table 1, Table 2, and Table 3 show the behavior of the driver, receiver, and INVALID(activelow) features under all possible relevant combinations of inputs. Table 1. Driver (1) INPUTS (1) OUTPUT DRIVER STATUS DIN FORCEON FORCEOFF VALID RIN RS-232 LEVEL X X L X Z Powered off Normal operation with automatic power down disabled DOUT L H H X H H H H X L L L H Yes H H L H Yes L L L H No Z H L H No Z Normal operation with automatic power down enabled Powered off by automatic power down feature H = high level, L = low level, X = irrelevant, Z = high impedance, Yes = |RIN| > 2.7 V, No = |RIN|