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參數(shù)資料
| 型號： | G1421 |
| 英文描述： | 2-W stereo audio power OP amplifier with no headphone coupling capacitor function.|OP Amplifier Series |
| 中文描述： | 2 - W型立體聲音頻功率運算放大器，耦合電容沒有耳機功能。|任擇議定書放大器系列 |
| 文件頁數(shù)： | 30/31頁 |
| 文件大?。?/td> | 825K |
| 代理商： | G1421 |
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Ver: 1.1
May 23, 2003
TEL: 886-3-5788833
http://www.gmt.com.tw
30
G1421
Global Mixed-mode Technology Inc.
Optimizing DEPOP Operation
Circuitry has been implemented in G1421 to mini-
mize the amount of popping heard at power-up and
when coming out of shutdown mode. Popping oc-
curs whenever a voltage step is applied to the
speaker and making the differential voltage gener-
ated at the two ends of the speaker. To avoid the
popping heard, the bypass capacitor should be
chosen promptly, 1/(C
B
x100k
)
≦
1/(C
I
*(R
I
+R
F
)).
Where 100k
is the output impedance of the
mid-rail generator, C
B
is the mid-rail bypass capaci-
tor, C
I
is the input coupling capacitor, R
I
is the input
impedance, R
F
is the gain setting impedance which
is on the feedback path. C
B
is the most important
capacitor. Besides it is used to reduce the popping,
C
B
can also determine the rate at which the amplifier
starts up during startup or recovery from shutdown
mode.
De-popping circuitry of G1421 is shown on Figure 5.
The PNP transistor limits the voltage drop across
the 50k
by slewing the internal node slowly when
power is applied. At start-up, the voltage at
BYPASS capacitor is 0. The PNP is ON to pull the
mid-point of the bias circuit down. So the capacitor
sees a lower effective voltage, and thus the charg-
ing is slower. This appears as a linear ramp (while
the PNP transistor is conducting), followed by the
expected exponential ramp of an R-C circuit.
Junction Temperature Measurement
Characterizing a PCB layout with respect to thermal
impedance is very difficult, as it is usually impossi-
ble to know the junction temperature of the IC.
G1421 TJ (pin 2) sources a current inversely pro-
portional to the junction temperature. Typically TJ
sources–120
μ
A for a 5V supply at 25
°C
. And the
slope is approximately 0.22
μ
A/
°C
. As the resistors
have a tolerance of
±
20%, these values should be
calibrated on each device. When the temperature
sensing function is not used, TJ pin can be left
floating or tied to VDD to reduce the current con-
sumption.
Temperature sensing circuit is shown on Figure 6.
Bypass
VDD
100 k
100 k
50 k
Figure 5
TJ
VDD
R
R
5R
Figure 6
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| G1421F | 制造商:GMT 制造商全稱:Global Mixed-mode Technology Inc 功能描述:2W Stereo Audio Amplifier with No Headphone Coupling Capacitor Function |
| G1422 | 功能描述:安裝硬件 RG 2.5-68-2 2.875 DIA BLACK RoHS:否 制造商:Harwin 類型:SMT Cable Clip 材料:Phosphor Bronze 安裝孔大小: 長度:5 mm 外徑: 內(nèi)徑: 厚度: 電鍍:Tin 螺紋大小: |
| G1-422-057 | 制造商:HECON / DANAHER 功能描述: |
| G1-422-122 | 制造商:HECON / DANAHER 功能描述: |
| G1422E10NF1.5A | 制造商:Glenair Inc 功能描述:ADAPTER - Bulk 制造商: 功能描述: 制造商:undefined 功能描述: |
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