Knowles Acoustics,
a division of Knowles Electronics, LLC.
Revision: C
6 of 10
SPM0103ND3
C1 (set by customer)
R1 = 22kΩ
R3 (set by customer)
R2 = 2.4kΩ
V+
Term 1 = Output
Term 2 = Gain Control Term 3 = Ground
Term 4 = Vdd
Vout
9. RECOMMENDED INTERFACE CIRCUIT
Setting Gain Formulas:
Gain of non-inverting Op-Amp is determined as:
G=1+ {R1 / (R2 + R3)} Gain(dB) = 20 * log(G)
High-pass-filter Corner Frequency:
C.F. = 1 / {2*p*(R2 + R3) * C1}
Add R3 and C1. Use formulas provided to calculate
settings, or contact Knowles for support.
Adjustable Gain
Tie Terminal 2 through C1 (0.47uF) to Ground.20dB Gain
Tie Terminal 2 directly to Output (Terminal 1). Unity Gain (0dB)
Pin 2 Termination MethodDesired Gain
