Datasheet

6 TSW7001 EVM Introduction
6.1 Jumper Settings
6.2 Input/Output Connectors
6.3 USB Interface
www.ti.com TSW7001 EVM Introduction
Figure 9. Output of TSW7001 With Arbitrary Gain Profile
The TSW7001 was designed to provide an easy way to test the VCA824 in a high-performance,
voltage-controlled gain application. The EVM includes a16-bit DAC8831 voltage-controlled DAC to
precisely control the voltage-controlled gain of the VCA824. An optional high-impedance input stage,
consisting of an OPA656 circuit, can be enabled to implement a transimpedance function for connection to
a photodiode application. The output of the VCA is designed to drive out to 50- Ω test equipment.
Two solder jumpers can be used to bypass the OPA656 (default) or enable the OPA656 in the signal path.
SJP5 and SJP6 must be in the 1-2 position by default to bypass, or in 2-3 position to enable the OPA656.
Optional external power supplies can be used for the OPA656 and VCA824. This requires that some
ferrite beads be removed to isolate the V+ and V– supplies.
Table 1 lists the input and output connectors.
Table 1. Input and Output Connections
REFERENCE LABEL CONNECTOR DESCRIPTION
DESIGNATOR TYPE
J26 IN SMA Input ac signal / Connection for external photodiode
J27 OUT SMA Output from VCA824 – 50- Ω source impedance
J13 USB USB CONN USB input
J12 CONN JACK PWR Power Jack Power input for 6-V wall supply
J24 6.0V IN Banana Jack +6-V input banana jack
J25 GND Banana Jack GND
The TSW7001 contains a 4-pin, USB port connector to interface to a USB 1.1 or later compliant USB port.
Programming the DAC8831 control voltage is accomplished through this connector.
SLWU058 – August 2008 Voltage-Controlled Amplifier Evaluation Kit 11
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