Texas Instruments DRV601EVM - DRV601 Evaluation Module DRV601EVM DRV601EVM Datenbogen
Produktcode
DRV601EVM
www.ti.com
4.2
Decoupling Capacitors
4.3
Supply Voltage Limiting at 4.5 V
4.4
Using the DRV601 as a Second-Order Low-Pass Filter
C1
R1
R3
R2
C2
+
-
C3
Component Selection
The DRV601 is a DirectPath™ line driver amplifier that requires adequate power supply decoupling to
ensure that the noise and total harmonic distortion (THD) are low. A good low equivalent-series-resistance
(ESR) ceramic capacitor, C12, typical 1
ensure that the noise and total harmonic distortion (THD) are low. A good low equivalent-series-resistance
(ESR) ceramic capacitor, C12, typical 1
µ
F, placed as close as possible to the device V
DD
leads works
best. Placing this decoupling capacitor close to the DRV601 is important for the performance of the
amplifier. For filtering lower frequency noise signals, a 10-
amplifier. For filtering lower frequency noise signals, a 10-
µ
F or greater capacitor placed near the audio
amplifier also helps, but is not required in most applications because of the high PSRR of this device.
The charge pump circuit does apply ripple current on the V
DD
line, and a LC or RC filter may be needed if
noise-sensitive audio devices share the V
DD
supply.
The DRV601 has a build-in charge pump which serves to generate a negative rail for the line driver.
Because the line driver operates from a positive and negative voltage supply, circuitry has been
implemented to protect the devices in the amplifier from an overvoltage condition. Once the supply is
above 4.5 V, the DRV601 can shut down in an overvoltage protection mode to prevent damage to the
device.
Because the line driver operates from a positive and negative voltage supply, circuitry has been
implemented to protect the devices in the amplifier from an overvoltage condition. Once the supply is
above 4.5 V, the DRV601 can shut down in an overvoltage protection mode to prevent damage to the
device.
Many of the audio DACs used today require an external low-pass filter, to remove band noise. This is
possible with the DRV601, and the EVM is configured as a 40-kHz second-order, active Butterworth filter.
The topology chosen is the MFB Single-Ended. Further, the DRV601 needs a ac-coupling capacitor to
remove dc-content from the source.
possible with the DRV601, and the EVM is configured as a 40-kHz second-order, active Butterworth filter.
The topology chosen is the MFB Single-Ended. Further, the DRV601 needs a ac-coupling capacitor to
remove dc-content from the source.
Figure 5. Second-Order, Active Low-Pass Filter
The component values can be calculated with the help of the TI FilterPro™ program available on:
In
, various proposals for the filter and gain settings can be found.
Table 3. DRV601EVM Specification
Gain
High Pass
Low Pass
C1
C2
C3
R1
R2
R3
–1 V/V
16 Hz
40 kHz
100 pF
680 pF
1
µ
F
10 kR
10 kR
24 kR
-1.5 V/V
19 Hz
40 kHz
68 pF
680 pF
1
µ
F
8.2 kR
12 kR
30 kR
-2 V/V
11 Hz
40 kHz
33 pF
330 pF
1
µ
F
15 kR
30 kR
47 kR
–2 V/V
11 Hz
30 kHz
47 pF
470 pF
1
µ
F
15 kR
30 kR
43 kR
–3.33 V/V
12 Hz
40 kHz
33 pF
470 pF
1
µ
F
13 kR
43 kR
43 kR
-10 V/V
15 Hz
30 kHz
22 pF
1 nF
2.2
µ
F
4.7 kR
47 kR
27 kR
The resistor values should be low value to get low noise, but should be high value to get a small size
ac-coupling capacitor. With the proposed values, 15k, 30k, and47k, a DYR of 105 dB can be achieved
with a small 1-
ac-coupling capacitor. With the proposed values, 15k, 30k, and47k, a DYR of 105 dB can be achieved
with a small 1-
µ
F input ac-coupling capacitor.
DRV601EVM
6
SLOU215 – January 2008