DRV604 Datasheet, PDF (11/21 Pages) Texas Instruments – DirectPath™ 2Vrms Line Driver and HP Amp With Adjustable Gain

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DRV604
SLOS659 – JANUARY 2010
Ex_UVP
25
Comparator
1.25 V
Bandgap
PVDD_LD 23
PVDD_HP 20
Comparator
Internal PVDD
AMP Enable
The selected thresholds can be determined as follows:
(R11 + R12)
V_UVP = 1.25 V ´
R12
(1)
V_Hysteresis
= 5 μA × R13 ×
æ
çè
R11
R12
ö
+1_÷ø
(2)
With the condition R13 >> R11||R12
For example, to obtain V_UVP = 4.5 V and 400 mV hysteresis, use R11 = 10 kΩ, R12 = 3 kΩ and R13 = 22kΩ.
To filter supply spikes and noise a capacitor across R12 can be added.
External
Sense
Voltage
5 mA
R11
R13 ^Ex_UVP
25
R12
DRV604
Comparator
1.25 V
Bandgap
Input-Blocking Capacitors
DC input-blocking capacitors are required to be added in series with the audio signal into the input pins of the
DRV604. These capacitors block the DC portion of the audio source and allow the DRV604 inputs to be properly
biased to provide maximum performance. The input blocking capacitors also limit the DC gain to 1, limiting the
DC-offset voltage at the output.
These capacitors form a high-pass filter with the input resistor, R_in. The cutoff frequency is calculated using
Equation 1. For this calculation, the capacitance used is the input-blocking capacitor and the resistance is the
input resistor chosen from Table 1, then the frequency and/or capacitance can be determined when one of the
two values are given.
1
1
fc_in = _{2p ´ Rin ´ Cin}
C_in = _{2p ´ fcin ´ Rin}
(3)
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