Texas Instruments PGA2505 Evaluation Module PGA2505EVM PGA2505EVM 데이터 시트
제품 코드
PGA2505EVM
2.2
PGA2505EVM Features
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Introduction
The zero-crossing control bit, ZC in the serial control word, is provided for enabling and disabling the
internal zero-crossing detector function. Setting the ZC bitt high enables the function. Zero-crossing
detection is used to ensure gain changes on zero crossings of the analog input signal. This limits the glitch
energy associated with the switched gain network, thereby minimizing audible artifacts at the preamplifier
output. Because zero-crossing detection can add some delay when performing gain changes (up to 16ms
maximum for a detector timeout event), there may be some cases where the user may wish to disable this
function. Forcing the ZC bit low disables zero-crossing detection, and gain changes will occur immediately
when programmed.
internal zero-crossing detector function. Setting the ZC bitt high enables the function. Zero-crossing
detection is used to ensure gain changes on zero crossings of the analog input signal. This limits the glitch
energy associated with the switched gain network, thereby minimizing audible artifacts at the preamplifier
output. Because zero-crossing detection can add some delay when performing gain changes (up to 16ms
maximum for a detector timeout event), there may be some cases where the user may wish to disable this
function. Forcing the ZC bit low disables zero-crossing detection, and gain changes will occur immediately
when programmed.
A timeout function is implemented when ZC is held low, ensuring a maximum timeout detection limit of
16ms.
16ms.
An over-range indicator output, OVR, is provided at pin 6. The over-range output is forced high when the
preamplifier output voltage exceeds one of two preset thresholds. The threshold is programmed through
the serial port interface using the OR bit. If OR = '0', then the threshold is set to 5.1V
preamplifier output voltage exceeds one of two preset thresholds. The threshold is programmed through
the serial port interface using the OR bit. If OR = '0', then the threshold is set to 5.1V
RMS
differential, which
is approximately 1dB below the specified output voltage range. If OR = '1', then the threshold is set to
4.0V
4.0V
RMS
differential, which is approximately 3dB below the maximum specified output voltage range.
The PGA2505 includes four general-purpose programmable digital outputs, named GPO1 through GPO4
(pins 2 through 5, respectively), which are controlled via the serial port interface. All four pins are
CMOS-logic-level outputs. These pins may be used to control relay drivers or switches used for external
preamplifier functions, including input pads, filtering, polarity reversal, or phantom power.
(pins 2 through 5, respectively), which are controlled via the serial port interface. All four pins are
CMOS-logic-level outputs. These pins may be used to control relay drivers or switches used for external
preamplifier functions, including input pads, filtering, polarity reversal, or phantom power.
The PGA2505EVM provides a convenient platform for evaluating the performance and features of the
PGA2505 device. Key EVM features include the following:
PGA2505 device. Key EVM features include the following:
•
Accepts either XLR- or TRS-balanced input connections
•
Configurable front-end circuit options for prototyping pads and filters
•
XLR-balanced output with flexible output loading options
•
Buffered PC parallel and DATA_IN ports provide host interface connections
•
DATA_OUT port allows daisy-chaining of multiple PGA2505EVM boards
•
Register readback function supports host interface diagnostic capability
•
LED indicators for GPOs and the over-range output (OVR)
•
Common-mode voltage input (V
COM
IN) terminal
•
Includes applications software that is compatible with most personal computers with a built-in parallel
port and equipped with Microsoft Windows 9x, 2000, or XP operating systems
port and equipped with Microsoft Windows 9x, 2000, or XP operating systems
•
Requires +5V and –5V analog supplies, as well as a +5V digital supply
SBOU078 – June 2009
PGA2505EVM
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