Product details


Drivers per package 1 Receivers per package 1 Logic voltage (Min) (V) 3.3 Data rate (Max) (kbps) 1000 Main supply voltage (Nom) (V) 3.3, 5 Features Auto-Powerdown ESD HBM (kV) 15 Rating Catalog Operating temperature range (C) -40 to 85 open-in-new Find other RS-232 transceivers

Package | Pins | Size

SSOP (DB) 16 48 mm² 6.2 x 7.8 TSSOP (PW) 16 22 mm² 4.4 x 5 open-in-new Find other RS-232 transceivers


  • Operate With 3-V to 5.5-V VCC Supply
  • Operate up to 1 Mbit/s
  • Low Standby Current ...1 µA Typical
  • External Capacitors ...4 × 0.1 µF
  • Accepts 5-V Logic Input With 3.3-V Supply
  • RS-232 Bus-Pin ESD Protection Exceedsb ±15 kV Using Human-Body Model (HBM)
  • Auto-Powerdown Feature Automatically Disables Drivers for Power Savings
  • Applications
    • Battery-Powered, Hand-Held, and Portable Equipment
    • PDAs and Palmtop PCs
    • Notebooks, Sub-Notebooks, and Laptops
    • Digital Cameras
    • Mobile Phones and Wireless Devices

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The SN65C3221 and SN75C3221 consist of one line driver, one line receiver, and a dual charge-pump circuit with ±15-kV ESD protection pin to pin (serial-port connection pins, including GND). These devices provide 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 1 Mbit/s and a driver output slew rate of 24 V/µs to 150 V/µs.

Flexible control options for power management are available when the serial port is inactive. The auto-powerdown feature functions when FORCEON is low and FORCEOFF\ is high. During this mode of operation, if the devices do not sense a valid RS-232 signal on the receiver input, the driver output is disabled. If FORCEOFF\ is set low and EN\ is high, both the driver and receiver are shut off, and the supply current is reduced to 1 µA. Disconnecting the serial port or turning off the peripheral drivers causes the auto-powerdown condition to occur. Auto-powerdown can be disabled when FORCEON and FORCEOFF\ are high. With auto-powerdown enabled, the device is activated automatically when a valid signal is applied to the receiver input. The INVALID\ output notifies the user if an RS-232 signal is present at the receiver input. INVALID\ is high (valid data) if the 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 the receiver input voltage is between –0.3 V and 0.3 V for more than 30 µs. Refer to Figure 5 for receiver input levels.

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Exact equivalent in functionality and parametrics to the compared device:
SN65C3221E ACTIVE 3-V To 5.5-V Single Channel RS-232 1 Mbit/s Line Driver/Receiver TI recommends the SN65C3221E in new designs. The SN65C3221E is an improved direct drop-in replacement for the SN65C3221.
TRSF3221 ACTIVE 3-V to 5.5-V Single-Channel RS-232 Compatible Line Driver/Receiver The industrial temp version is an EXACT EQUIVALENT in functionality and parametrics to the compared device.
Same functionality and pinout but is not an equivalent to the compared device:
TRSF3221E ACTIVE 3-V to 5.5-V Single-Channel RS-232 1-Mbit/s Line Driver/Receiver With +/-15-kV IEC ESD Protection The industrial temp device has the SAME FUNCTIONALITY/PINOUT as the compared device but includes enhanced IEC61000-4-2 ESD Protection.

Technical documentation

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Type Title Date
* Datasheet SN65C3221, SN75C3221 datasheet (Rev. E) Oct. 19, 2004

Design & development

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Reference designs

360W Phase Shift Full Bridge Resonant LLC with High Side Low Side Driver Reference Design
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document-generic Schematic
340W Digital Controlled LLC Resonant Half-Bridge DC-to-DC Power Conversion Reference Design
TIDA-00512 This design is a LLC resonant half-bridge DC-DC power converter with digital control using 3138ACC32EVM-149 daughter-card. The daughter-card control functions with preloaded firmware providing the required control functions for a LLC resonant half-bridge converter.  The TIDA-00512 (...)
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SSOP (DB) 16 View options
TSSOP (PW) 16 View options

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