lv4985vh Sanyo Semiconductor Corporation, lv4985vh Datasheet - Page 8

• Manufacturer Part Number: lv4985vh
• Description: Bi-cmos Ic For Portable Electronic Device Use 1.2w ? 2ch Btl Power Amplifier
• Manufacturer: Sanyo Semiconductor Corporation

Continued from preceding page.
Usage Note
1. Input coupling capacitor (C1 and C2)
2. Input coupling capacitors (C3 and C4) in the power amplifier block
3. BTL voltage gain of the power amplifier block
Pin No.
C1 (C2) is an input coupling capacitor that is used to cut the DC component. The input coupling capacitor C1 (C2) and
the input resisters of 20kΩ (15kΩ + 5kΩ) make up a high-pass filter, attenuating the bass frequency. Therefore, the
capacitance value must be selected with due consideration of the cut-off frequency.
The cut-off frequencies are expressed by the following formulas.
This capacitor affects the pop noise at startup. Note with care that increasing the capacitance value lengthens the
charging time of the capacitor, which will make the pop noise louder.
C3 (C4) is an input coupling capacitor that is used to cut the DC component. The input coupling capacitor C3 (C4) and
the input resistor R1 (R3) make up a high-pass filter, attenuating the bass frequency. Therefore, the capacitance value
must be selected with due consideration of the cut-off frequency.
The cut-off frequencies are expressed by the following formulas.
This capacitor affects the pop noise at startup. Note with care that increasing the capacitance value lengthens the
charging time of the capacitor, which will make the pop noise louder.
The voltage gain of the first amplifier is determined by the ratio between the resistors R1 and R2 (R3 and R4).
Therefore, the BTL voltage gain of the power amplifier block is expressed by the following formulas.
The BTL voltage gain of the power amplifier block must be set in the range of 0 to 26dB.
10
9
1ch ⇒ fc1 = 1/ (2π × C1 × 20000)
2ch ⇒ fc2 = 1/ (2π × C2 × 20000)
1ch ⇒ fc3 = 1/ (2π × C3 × R1)
2ch ⇒ fc4 = 1/ (2π × C4 × R3)
1ch ⇒ Vg1 = 20 × log (R2/R1) … unit : dB
2ch ⇒ Vg2 = 20 × log (R4/R3) … unit : dB
1ch ⇒ VgBTL1 = 6 + 20 × log (R2/R1) … unit : dB
2ch ⇒ VgBTL2 = 6 + 20 × log (R4/R3) … unit : dB
STBY
VOL
Pin Name
External apply
External apply
Pin Voltage
V CC = 5V
Standby/2nd amplifier stop control pin.
Volume control pin.
0 to 0.3V ⇒ Standby mode
1.3 to 1.7V ⇒ SE mode
2.3 to V CC ⇒ BTL mode
Description
LV4985VH
10
9
V CC
V CC
150kΩ
30kΩ
Equivalent Circuit
VB1
+
-
No.A1568-8/15
V CC
GND
V CC
GND