SANYO LA4906 Datasheet

Overview

The LA4906 is a BTL two-channel power amplifier for use in car audio systems. It uses a signal-following switching technique in the power supply for the amplifier output stage and a newly-developed nonlinear amplifier that features nonlinear characteristics in the signal system. These features hold increases in the number of external components to a minimum, and reduce power dissipation (and thus heat generation) in the practical operating region to about 1/2 that of earlier class B amplifier ICs. This can contribute significantly to miniaturization and weight reduction in the heat sink and to reduction of the heat generated within the end product case.

Features

• Power dissipation reduced by 50% (for music at average power levels, as compared to earlier Sanyo products)

• The number of required signal-following switching circuits has been reduced to just one circuit for two channels, reducing the number of external components.

• The output is a pure analog signal; no switching noise whatsoever appears on the output lines.

• Uses a single-voltage power supply from 8 to 18 V.

• Provides a full range of built-in protection circuits, including shorting of output pin to VCC, shorting of output pin to ground, overvoltage, and thermal shutdown protection.

• Built-in standby switch

• Clipping detection function

Package Dimensions

unit: mm

3160-SIP23HZ

Monolithic Linear IC

Ordering number : EN *5714

73097HA(OT) No. 5714-1/10

Preliminary

SANYO: SIP23HZ

[LA4906]

SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters

TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN

17-W, 2-Channel BTL AF High-Efficiency

Power Amplifier for Car Audio Systems

LA4906

Parameter Symbol Conditions Ratings Unit

Maximum supply voltage

max1 With no signal, t = 1 minute 18 V

max2 16 V

Maximum output current I

Peak Per channel 4.5 A Allowable power dissipation Pd max With an arbitrarily large heat sink 37.5 W Operating temperature Topr –35 to +85 °C Storage temperature Tstg –40 to +150 °C

Specifications

Absolute Maximum Ratings at Ta = 25°C

Notes: 1. Set VCCand RLto be in the range where Pd max does not exceed 37.5 W.

2. The overvoltage protection circuit operates at V

= 26 V or higher.

No. 5714-2/10

LA4906

Parameter Symbol Conditions

Ratings

Unit

min typ max

Quiescent current drain I

0 RL= ∞, VIN= 0 80 110 150 mA Standby current Ist 0 10 µA Voltage gain VG V

= 0 dBm 28 30 32 dB

Total harmonic distortion THD P

= 1 W, LPF = 30 kHz 0.07 0.2 %

Output power

1 THD = 10 %, RL = 4 Ω 14 17 W

2 THD = 10 %, RL = 2 Ω 25 W Output noise voltage V

Rg = 0, BPF = 20 Hz to 20 kHz 0.10 0.3 mVrms

Ripple rejection ratio SVRR

Rg = 0, V

CCR

= 0 dBm,

60 75 dB

BPF = 20 Hz to 20 kHz

Channel separation CH sep

Rg = 10 kΩ, V

= 0 dBm,

45 60 dB

BPF = 20 Hz to 20 kHz

Input resistance Ri 21 30 39 kΩ Output offset voltage VN offset Rg = 0 –200 +200 mV Standby on voltage V

STH

AMP = on, applied through a 10 kΩ resistor 3 V

Clipping detect off current I

DOFF

THD = 1 % 1 10 µA

Clipping detect on current I

DON

THD = 10 % 100 150 200 µA

Operating Characteristics

at Ta = 25°C, VCC= 13.2 V, RL= 4 Ω, f = 1 kHz, RG = 600 Ω, in the recommended circuit

Parameter Symbol Conditions Ratings Unit

Recommended supply voltage V

13.2 V

Allowable operating voltage range V

op 8 to 16 V Recommended load resistance R

4 Ω

Recommended load resistance range R

op 2 to 4 Ω

Operating Conditions at Ta = 25°C

Note: Set VCCand RLto be in the range where Pd max does not exceed 37.5 W.

Allowable power dissipation, Pd max – W

Heat sink thermal resistance,

θf – °C/W

Heat sink area, Sf – cm

Ambient temperature, Ta – °C

With an arbitrarily large heat sink

Al heat sink, t = 1.5 mm Tightening torque: 39 N·cm With silicone grease applied.

No. 5714-3/10

LA4906

Technologies for Increased Efficiency Used in the LA4906

• Nonlinear amplifier The LA4906 adopts a nonlinear amplifier, which has the nonlinear characteristics shown in Figure 2, in the signal system. The LA4906 dispenses with the lower side switching regulator by using a low 2 V as the midpoint voltage instead of the 1/2 VCC used in normal amplifiers.

This nonlinear amplifier is basically formed from a differential amplifier that has a symmetrical negative feedback circuit. Although the BTL output stage positive and reverse phase output waveforms have a half-wave waveform that, when referenced to ground, is expanded and compressed as shown in Figure 3, the combined output waveform at the load terminals is identical to that of earlier products.

• Signal-following switching technique The LA4906 uses a switching regulator for the power supply for the amplifier output stage. The LA4906 significantly reduces power dissipation by having the switching regulator output voltage follow the signal. Also, the LA4906 restricts the number of switching regulators required to just one circuit even though it implements a BTL 2-channel amplifier by using the switching regulator in combination with the nonlinear amplifier described below. (See Figure 1.)

Figure 1 Overview Block Diagram

Figure 2 Nonlinear Amplifier

Input/Output Characteristics

Figure 3 Output Waveforms

Figure 4

RL = 4 Ω f = 1 kHz Rg = 600 Ω With both channels driven. Calculated at Pd = VCC × ICC – 2 P

Regulator output

Amplifier

output

stage

Nonlinear

amplifier

Loss in the output transistor

Regulator output (point C)

Positive phase output (point A) Center point Ground

Reverse phase output (point B) Center point Ground

Waveform between the outputs (Between A and B)

Power dissipation, Pd – W

Output power, PO– W

High-efficiency

LA4906

Earlier SANYO products (class B amplifiers)

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