THS7320 Datasheet, PDF (27/35 Pages) Texas Instruments – 3-Channel ED Filter Video Amplifier with 4-V/V Gain

THS7320
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EVALUATION MODULE
SBOS565B – JULY 2011 – REVISED SEPTEMBER 2012
To evaluate the THS7320, an evaluation module (EVM) is available. The EVM allows dc-coupled input and
output configurations. Inputs and outputs include BNC connectors commonly found in video systems along with
75-Ω effective input termination resistors, 75-Ω series source termination resistors, and 75-Ω characteristic
impedance traces. This EVM is designed to be used with a single supply from 2.6 V up to 5 V.
The EVM input configuration sets all channels for dc input coupling. The input signal must be within 0 V to
approximately 0.75 V for proper operation. Failure to be within this range saturates and/or clips the output signal.
Refer to the Application Information section for further information.
The THS7320 incorporates an easy method to configure the enable mode. JP1 controls the enable feature.
Connecting JP1 to GND applies 0 V to the enable pin and the THS7320 is placed into shutdown mode
consuming nominally 0.15 μA of quiescent current. Moving JP1 to +V_S causes the THS7320 to be in normal
operation mode where the quiescent current should be nominally 3.4 mA for the entire EVM. This quiescent
current is with no load or no signal applied on the input. Adding a load or input signal causes the quiescent
current to vary accordingly.
An example procedure to confirm proper device operation with standard lab equipment is described in the
following sections.
REQUIRED EQUIPMENT
• One dc power supply: +3.0 V, 50-mA output (minimum) is recommended
• One dc current meter: resolution to 1 mA, capable of maximum current the dc power supply can supply
• Function or arbitrary waveform generator
• Oscilloscope: 50-MHz bandwidth (minimum) is recommended
• Banana-to-banana patch cords
• BNC test cables
BASIC SETUP
1. Set the dc power supply to +3.0 V. Set the current limit on the dc power supply to 50 mA.
2. Connect the positive (+) terminal of the power supply to the positive (+) terminal of the current meter.
3. Connect the negative (–) terminal of the current meter to the V_S+ terminal of the EVM (J7).
4. Connect the common ground terminal of the power supply to the ground (GND) terminal on the EVM (J8).
5. Connect the output of the waveform generator to the channel 1 input on the EVM (J1)
6. Connect the probe ground to the GND of the EVM.
TESTING THE EVM
The EVM can be tested by following these steps:
1. Enable the 3.0-V_DC power supply.
2. Verify that the current meter is reading nominally 3.5 mA (2.7 mA to 4.7 mA, minimum and maximum).
3. Set the function generator such that a 1-MHz, 0.5-V_PP sine wave (with an 0.40-V_DC offset) appears on the
THS7320 input pin. The function generator ac and dc levels may have to be adjusted to ensure the proper
voltage appears on the THS7320 input pins because most function generators have a 50-Ω source
impedance and the THS7320 incorporates a double 37.4-Ω resistor termination divider scheme for a total 75-
Ω termination.
4. Probe the device side of R12, which is connected to the THS7320 channel 1 output pin.
5. Verify that the oscilloscope displays the THS7320 channel 1 output voltage amplitude as 2.0 V_PP ±0.1 V with
a nominal 1.75-V_DC offset.
6. Repeat steps 3 through 5 for channels 2 and 3.
7. When confirmed, turn off the function generator and power supply.
8. Note that if video equipment is used with the THS7320EVM, the proper input and output 75-Ω terminations
already exist on the EVM along with the proper input voltage divider. This functionality makes the EVM very
easy to test video signals with no modifications to the EVM.
Copyright © 2011–2012, Texas Instruments Incorporated
Product Folder Links: THS7320
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