Supertex inc.
MD0101
High Voltage Protection T/R Switch
with Clamp Diodes
Features
►► Up to ±100V input voltage protection
►► Low on resistance - 15Ω typical
►► Integrated clamp diodes
►► Fast switching speed
►► Four electrically isolated channels
►► No external supplies needed
Applications
►► Medical ultrasound imaging
►► NDT applications
►► Fast resettable fuses
►► High side switches
►► Data acquisition
General Description
The Supertex MD0101 is a four channel, high voltage, current limiting
protection device. It is designed to protect a low noise receiver from the
high voltage transmit pulses in ultrasound applications and is commonly
referred to as a T/R (transmit and receive) switch. Each channel has
three terminals; Tx, Rx, and RGND. The analog switch terminals are
Tx and Rx. Rx has integrated clamping diodes to RGND to protect the
receiver against high voltages. Voltages greater than ±0.6V will start
forward biasing the clamp diodes to RGND.
The MD0101 can be considered as a normally closed switch with a
typical switch resistance of 15Ω, allowing small signals to pass. Once
the voltage drop across the switch exceeds a nominal value of ±1.0V,
the device will start to turn off. In the off state, the MD0101 can withstand
up to ±100V across its terminals. A small amount of current, 200µA, is
allowed to flow through.
The MD0101 is not limited to just ultrasound applications. It can also
be used for resettable fuses to protect power lines, output short circuit
protection, and data acquisition. The MD0101 is available in an 18-
Lead, 5x5mm DFN package as a four channel device for high density
requirements.
Typical Application Circuit
One of 128 Channels
+90V
Logic
Control
and
Signal
Processing
Transmitter
TX
-90V
RX
Receiver
RX MD0101 TX
RGND
T/R Switch
Piezo
Transducers
High Voltage
Switches
Supertex inc. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: 408-222-8888 ● www.supertex.com