TDA8941P Datasheet, PDF (4/21 Pages) NXP Semiconductors – 1.5 W mono Bridge Tied Load BTL audio amplifier

Philips Semiconductors
TDA8941P
1.5 W mono BTL audio amplifier
The input cut-off frequency is:
f _{i(cut – off )} = -₂---_π----₍--_R----¹_i---_×-----_C----_i--₎
(1)
For R_i = 45 kΩ and C_i = 220 nF:
f _{i(cut – off )} = -₂---_π---₍---₄---₅----_×-----₁---₀---₃---¹-_×-----₂---₂---₀----_×-----₁---₀---_–---₉--₎- = 16 Hz
(2)
As shown in Equation 1 and 2, large capacitor values for the inputs are not
necessary; so the switch-on delay during charging of the input capacitors, can be
minimized. This results in a good low frequency response and good switch-on
behaviour.
Remark: To prevent HF oscillations do not leave the inputs open, connect a capacitor
of at least 1.5 nF across the input pins close to the device.
8.2 Power amplifier
The power amplifier is a Bridge Tied Load (BTL) amplifier with an all-NPN output
stage, capable of delivering a peak output current of 2 A.
The BTL principle offers the following advantages:
• Lower peak value of the supply current
• The ripple frequency on the supply voltage is twice the signal frequency
• No expensive DC-blocking capacitor
• Good low frequency performance.
8.2.1 Output power measurement
The output power as a function of the supply voltage is measured on the output pins
at THD = 10%; see Figure 8. The maximum output power is limited by the maximum
power dissipation in the plastic package.
8.2.2 Headroom
Typical CD music requires at least 12 dB (factor 15.85) dynamic headroom –
compared to the average power output – for transferring the loudest parts without
distortion. At V_CC = 9 V, R_L = 16 Ω and P_o = 1 W at THD = 1% (see Figure 6), the
Average Listening Level (ALL) – music power – without any distortion yields:
P_o(ALL) = 1 W/15.85 = 63 mW.
The power dissipation can be derived from Figure 11 on page 10 for 0 dB
respectively 12 dB headroom.
9397 750 06864
Product specification
Rev. 02 — 7 April 2000
© Philips Electronics N.V. 2000. All rights reserved.
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