TS472 STMICROELECTRONICS | Alldatasheet
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 20
Technical content
Very Low Noise Microphone Preamplifier with 2V Biased Output and Active Low Standby Mode ■ Low noise: 10nV/√Hz typ. equivalent input noise @ F = 1kHz ■ Fully differential input/output ■ 2.2V to 5.5V single supply operation ■ Low power consumption @20dB: 1.8mA ■ Fast start up time @ 0dB: 5ms typ. ■ Low distortion: 0.1% typ. ■ 40kHz bandwidth @ -3dB and adjustable ■ Active low standby mode function (1 µA max) ■ Low noise 2.0V microphone bias output ■ Available in flip-chip lead-free package ■ ESD protection (2kV)
Description
The TS472 is a differential-input microphone preamplifier optimized for high-performance, PDA and notebook audio systems. This device features an adjustable gain from 0dB to 40dB with excellent power-supply and common-mode rejection ratios. In addition, the TS472 has a very low-noise microphone bias generator of 2V. It also includes a complete shutdown function, with active low standby mode.
Applications
■ Video and photo cameras with sound input ■ Sound acquisition & voice recognition ■ Video conference systems ■ Notebook computers and PDAs Order Codes IN+ IN- GND OUT+ C2C1 OUTPUT BIAS GS VCC OUT- STDBY BYPASS Flip-chip - 12 bumps Pin Connections (top view) Part Number Temperature Range Package Packing Marking TS472EIJT -40, +85°C Flip-Chip T ape & Reel 472
1 Typical Application Schematic
gain see Chapter 4.5: Gain settings on page 14. Table 1. External component descriptions Figure 1. Application schematic and determine Lower cut-off frequency. output terminal (pins C2 and D2) and determine Lower cut-off frequency. Output load resistors which allow to charged the output coupling capacitors Cout. Cs Supply Bypass capacitor which provides power supply filtering. Cb Bypass pin capacitor which provides half supply filtering. C1, C2 Low pass filter capacitors which can determine Higher cut-off frequency . C3 Bias output capacitor which keeps voltage stabilized and provides 2.0V bias filtering.
2 Absolute Maximum Ratings
Table 2. Key parameters and their absolute maximum ratings Table 3. Operating conditions
- All voltages values are measured with respect to the ground pin.
3 Electrical Characteristics
Table 4. V CC = 3V, GND = 0V, Tamb = 25°C (unless otherwise specified) Table 5. Bias output: V CC = 3V, GND = 0V, Tamb = 25°C (unless otherwise specified)
Table 6. Differential RMS noise voltage Table 7. Bias output RMS noise voltage Table 8. SNR (signal to noise ratio), THD+N < 0.5%
Table 9. Index of graphics
4 Application Information
4.1 Differential configuration principle
maximize the input dynamic voltage range.
- Very high PSRR (Power Supply Rejection Ratio).
- High common mode noise rejection.
- In theory, the filtering of the internal bias by an external bypass capacitor is not necessary. But, to reach maximum performances in all tolerance situations, it’s better to keep this option.
4.2 Higher cut-off frequency
For example, FCH is almost 20kHz with C 1,2=100pF. Figure 30. Higher cut-off frequency vs. output capacitors
4.3 Lower cut-off frequency
a application because of DC voltage blocking.
4.4 Low-noise microphone bias source
determined by the internal resistance 100 Ω (for detailed load regulation curves see Figure 6). Figure 31. Lower cut-off frequency vs. Figure 32. Lower cut-off frequency vs.
4.5 Gain settings
- the sensitivity of the microphone,
- the distance to the microphone,
- the audio level of the sound,
- the desired output level. The sensitivity of the microphone is generally expressed in dB/Pa, referenced to 1V/Pa. For example, the microphone used in testing had an output voltage of 6.3 mV for a sound pressure of 1 Pa (where Pa is the pressure unit, Pascal). Expressed in dB, the sensitivity is: 20Log(0.0063) = -44 dB/Pa To facilitate the first approach, the following table gives voltages and gains used with a low cost omnidirectional Electret Condenser Microphone of -44dB/Pa. The gain of the TS472 microphone preamplifier can be set: 1. From -1.5 dB to 41 dB by connecting an external grounded resistor R GS to the GS pin. It allows to adapt more precisely the gain to each application.
Table 10. Typical TS472 gain vs. distance to the microphone (sensitivity -44dB/Pa) Table 11. Selected gain vs. gain select resistor Figure 33. Gain in dB vs. gain select Figure 34. Gain in V/V vs. gain select
- To 20dB by applying VGS > 1VDC on Gain Select (GS) pin. This setting can help to reduce
4.6 Wake-up time
Figure 35. Gain vs. gain select voltage Figure 36. Wake-up time in the typical application vs. input capacitors
40 Tamb=25 °C
4.7 Standby mode
4.8 Layout considerations
4.9 Demoboard
A demoboard for the TS472 is available. Figure 37. Top layer Figure 38. Bottom layer Figure 39. Component location
Figure 40. Demoboard schematic
5 Package Mechanical Data
Figure 41. TS472 footprint recommendation Figure 42. Pin-out (top view) Figure 43. Marking (top view)
6 Revision History
July 2005 1 First Release corresponding to the product preview version. Oct. 2005 2 First release of fully mature product datasheet. Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this p ublication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicr oelectronics. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners © 2005 STMicroelectronics - All rights reserved STMicroelectronics group of companies Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Ital y - Japan - Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America