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参数资料
| 型号： | G1420F31U |
| 厂商： | Global Mixed-mode Technology Inc. |
| 元件分类： | 音频放大器 |
| 英文描述： | 2W Stereo Audio Amplifier |
| 中文描述： | 2W立体声音频放大器 |
| 文件页数： | 11/20页 |
| 文件大小： | 386K |
| 代理商： | G1420F31U |
Ver: 1.5
Aug 04, 2005
TEL: 886-3-5788833
http://www.gmt.com.tw
19
G1420
Global Mixed-mode Technology Inc.
MUTE and SHUTDOWN Mode Operations
G1420 implements the mute and shutdown mode
operations to reduce supply current, IDD, to the ab-
solute minimum level during nonuse periods for
battery-power conservation. When the shutdown
pin (pin 8) is pulled high, all linear amplifiers will be
deactivated to mute the amplifier outputs. And
G1420 enters an extra low current consumption
state, IDD is smaller than 5A. If pulling mute-in pin
(pin 11) high, it will force the activated linear ampli-
fier to supply the VDD/2 dc voltage on the output to
mute the AC performance. In mute mode operation,
the current consumption will be a little different be-
tween BTL, SE. (SE < BTL) Typically, the supply
current is about 2.5mA in BTL mute operation.
Shutdown and Mute-In pins should never be left
unconnected, this floating condition will cause the
amplifier operations unpredictable.
Optimizing DEPOP Operation
Circuitry has been implemented in G1420 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/(CBx100kΩ) ≦ 1/(CI*(RI+RF)).
Where 100k
Ω is the output impedance of the
mid-rail generator, CB is the mid-rail bypass ca-
pacitor, CI is the input coupling capacitor, RI is the
input impedance, RF is the gain setting impedance
which is on the feedback path. CB is the most im-
portant capacitor. Besides it is used to reduce the
popping, CB can also determine the rate at which
the amplifier starts up during startup or recovery
from shutdown mode.
De-popping circuitry of G1420 is shown on Figure D.
The PNP transistor limits the voltage drop across
the 50k
Ω 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.
G1420 TJ (pin 2) sources a current inversely pro-
portional to the junction temperature. Typically TJ
sources–120A for a 5V supply at 25°C. And the
slope is approximately 0.22A/°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 E.
Bypass
VDD
100 k
Ω
100 k
Ω
50 k
Ω
Figure D
Bypass
VDD
100 k
Ω
100 k
Ω
50 k
Ω
Figure D
TJ
VDD
R
5R
Figure E
TJ
VDD
R
5R
Figure E
相关PDF资料 |
PDF描述 |
|---|---|
| G1420 | 2W Stereo Audio Amplifier |
| G1421F | 2W Stereo Audio Amplifier with No Headphone Coupling Capacitor Function |
| G1422F2UF | 2W Stereo Audio Amplifier |
| G1422F2U | 2W Stereo Audio Amplifier |
| G1422 | 2W Stereo Audio Amplifier |
相关代理商/技术参数 |
参数描述 |
|---|---|
| G1420F31UF | 制造商:GMT 制造商全称:Global Mixed-mode Technology Inc 功能描述:2W Stereo Audio Amplifier |
| G1421 | 功能描述:安装硬件 RG 2.58-64-8 3.000 DIA BLACK RoHS:否 制造商:Harwin 类型:SMT Cable Clip 材料:Phosphor Bronze 安装孔大小: 长度:5 mm 外径: 内径: 厚度: 电镀:Tin 螺纹大小: |
| G1421F | 制造商:GMT 制造商全称:Global Mixed-mode Technology Inc 功能描述:2W Stereo Audio Amplifier with No Headphone Coupling Capacitor Function |
| G1422 | 功能描述:安装硬件 RG 2.5-68-2 2.875 DIA BLACK RoHS:否 制造商:Harwin 类型:SMT Cable Clip 材料:Phosphor Bronze 安装孔大小: 长度:5 mm 外径: 内径: 厚度: 电镀:Tin 螺纹大小: |
| G1-422-057 | 制造商:HECON / DANAHER 功能描述: |
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