ST AN2862 APPLICATION NOTE
AN2862
Application note
Demonstration board user guidelines for the TS2007FC
3 W filter-free class D audio amplifier with 6-12 dB fixed gain select
Introduction
This application note concerns the TS2007FC demonstration board, designed to evaluate
the class D audio differential amplifier TS2007FC.
This document provides:
■ a brief description of the TS2007FC device.
■ a description of the demonstration board and all of its components.
■ the layout of the demonstration board.
About the TS2007FC
The TS2007FC is an audio power class D amplifier that can drive up to 1.4 W into an 8 Ω
load at 5 V. It achieves better efficiency compared to a typical class AB audio power
amplifier.
This device allows switching between two different gains: 6 or 12 dB via a logic signal on the
GS pin. Pop and click reduction circuitry provides low on/off switch noise while allowing the
device to start within 1 ms. A standby function (active low) reduces the current consumption
to 1 μA typical. The TS2007FC also integrates an output short-circuit protection mechanism
and thermal shutdown protection to avoid damage to the amplifier.
Key features of the TS2007FC
■ Operating range from V
■ Standby mode active low.
■ Output power: 1.4 W at 5 V or 0.5 W at 3.0 V into 8 Ω with 1% THD+N maximum.
■ Output power: 2.3 W at 5 V or 0.75 W at 3.0 V into 4 Ω with 1% THD+N maximum.
■ Two fixed gain selects: 6 or 12 dB.
■ Low current consumption.
■ Efficiency: 88% typical.
■ Signal-to-noise ratio: 90 dB typical.
■ PSRR: 68 dB typical at 217 Hz with 6 dB gain.
■ PWM base frequency: 280 kHz
■ Low pop and click noise.
■ Thermal shutdown protection.
■ Output short-circuit protection.
■ Flip-chip lead-free 9-bump package.
Refer to the datasheet for complete information on the TS2007FC.
= 2.4 to 5.5 V.
CC
February 2009 Rev 1 1/7
www.st.com
Description of the evaluation board AN2862
1 Description of the evaluation board
The TS2007FC demonstration board is designed for the TS2007FC class D audio
differential amplifier. The TS2007FC device, in a flip-chip package, is mounted on a twolayer PCB. Easily-accessible connectors on the board allow changing or driving the gain
select and standby control pins, as well as changing the input configuration of the
TS2007FC.
The TS2007FC’s gain can be set to either 6 or 12 dB via the P1 connector (see Tab l e 1 ).
The input configuration is either capacitor-coupled or common-mode feedback. On the
evaluation board, the JP3 and JP4 connectors allow you to change the input configuration.
In the capacitor-coupled configuration, the -3 dB cut-off frequency in Hz is:
1
----------------------------------- -
⋅⋅
2π Z
inC1
1
----------------------------------- -=
2π ZinC
⋅⋅
2
with Z
in Ω (Zin=75kΩ typically), C in Farads and C1 = C2.
in
More information about component calculations is available in the TS2007FC datasheet.
Table 1. Evaluation board connectors
Connector(s) Description
JP1 Input signal connector (GND, In+, In-, GND).
JP1 Output signal connector (GND, Out-, Out+, GND).
Input configuration:
JP3, JP4
P1
P2
– capacitor-coupled when JP3 and JP4 are open.
– common-mode feedback when JP3 and JP4 are shorted by jumpers.
Gain select control connector:
`
– pins 1 and 2 are shorted or pin 2 is floating, the gain is 6 dB.
123
`
– pins 2 and 3 are shorted, the gain is 12 dB.
123
The connector pins are connected as follows:
– 1 to V
CC
– 2 to GS of the TS2007FC
– 3 to GND
Standby control connector:
`
– pins 1 and 2 are shorted, the TS2007FC is in operation mode.
123
`
– pins 2 and 3 are shorted, the TS2007FC is in standby mode.
123
The connector pins are connected as follows:
– 1 to V
CC
– 2 to STANDBY of the TS2007FC
– 3 to GND
JP5 Power connector (V
and GND). Power supply voltage from 2.4 to 5.5 V.
CC
Caution: When you apply the power supply through JP5, do not invert the polarity since this will
irreversibly damage the U1 amplifier.
2/7
AN2862 Description of the evaluation board
Figure 1. Schematic diagram
GND
IN IN +
GND
JP1
VCC
P1
1
2
JP3
1
2
C1
1
2
3
4
220nF
C2
220nF
JP4
1
2
3
A2C2
U1 TS2007
GS Vcc
C1
A1
IN -
Gain
Select
IN +
Standby
Control
VCC
P2
-
+
Standby Gnd
C3
1uF
B1
Vcc
Oscillator
VCC
PWM
B3
B2
H
Bridge
Prot ection
Circuit
JP5
1
2
OUT+
OUT-
C3
A3
JP2
GND
1
OUT+
2
OUT-
3
GND
4
1
2
3
Table 2. Component list for the demonstration board
Designation Quantity Description
C1, C2 2 220 nF/16 V, SMD ceramic capacitors, 0603
C3 1 1 µF/16 V, SMD ceramic capacitor, 0603
JP1, JP2 2 4-pin header 2.54 mm pitch
JP3, JP4, JP5 3 2-pin header 2.54 mm pitch
P1, P2 2 3-pin header 2.54 mm pitch
U1 1 TS2007EIJT
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