SA7267 Datasheet, PDF (4/10 Pages) Silan Microelectronics Joint-stock – 2CH AUDIO POWER AMPLIFIER(20W X 2)

SA7267
(Continued)
Pin No.
HSIP-11 HSIP-15
6
8
7
9
8
10
9
12
10
13
11
14
1,4,11,15
Pin Name
-Vs
IN+(2)
IN-(2)
GND
IN-(1)
IN+(1)
NC
FUNCTION DESCRIPTION
I/O
Pin Description
--
Negative power
I
Inverting Input 2
I
Non inverting input 2
--
Ground
I
Non inverting input 1
I
Inverting input 1
--
Not connected
MUTE STAND-BY FUNCTION
The MUTE/ST-BY controls the amplifier status by two different thresholds, referred to +Vs.
Ø When MUTE/ST-BY higher than +Vs - 2.5V, the amplifier is in Stand-by mode and the final stage
generators are off.
Ø When MUTE/ST-BY is between +Vs - 2.5V and +Vs- 6V, the final stage current generators are
switched on and the amplifier is in mute mode
Ø When MUTE/ST-BY is lower than +Vs - 6V, the amplifier is in play mode.
Power Dissipation and Heat Sinking
The SA7267 must always be operated with a heat sink. In order to determine the appropriate heat sink for a
given application, the power dissipation of the SA7267 in that application must be known. When the load is a
resistor, the maximum average power of the IC is approximately:
PD(MAX)=Vs²/π²RL+PQ
Where VS is the total power supply voltage across the SA7267, RL is the load resistance and PQ is the
quiescent power dissipation of the amplifier. The above equation is only an approximation which assumes an
“ideal”class B output stage and constant power dissipation in all other parts of the circuit. The curves of “Power
Dissipation vs. Power Output”give a better representation of the behavior of the SA7267 with various power
supply voltages and resistors. As an example, if the SA7267 is operated on a ±15V power supply with a
resistance of 4Ω, it can develop up to 24.5W of internal power dissipation. If the die temperature is to remain
below 150°C for ambient temperatures up to 50°C, the total junction-to-ambient thermal resistance must be less
than:
(150°Cˉ50°C)/24.5W˙4.1°C/W
Using Rth(j-c) = 2°C /W, the sum of the case-to-heat-sink interface thermal resistance and the heat-sink-to-
ambient thermal resistance must be less than 2.1°C/W. The case-to-heat-sink thermal resistance of the HSIP-11
package varies with the mounting method used. A metal-to-metal interface will be about 1°C /W if use the thermal
resistance, and about 1.2°C /W if not.
If a mica insulator is used, the thermal resistance will be about 1.6°C /W lubricated and 3.4°C /W dry. For this
example, we assume a lubricated mica insulator between the SA7267 and the heat sink. The heat sink thermal
resistance must then be less than:
4.1°C/W-2°C/W-1.6°C/W˙0.5°C/W
HANGZHOU SILAN MICROELECTRONICS CO.,LTD
Http: www.silan.com.cn
REV:1.1 2006.05.25
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