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參數資料
| 型號： | LA1781M |
| 元件分類： | 接收器 |
| 英文描述： | AM/FM, AUDIO SINGLE CHIP RECEIVER, PQFP64 |
| 封裝： | 14 X 14 MM, QIP-64 |
| 文件頁數： | 25/48頁 |
| 文件大小： | 508K |
| 代理商： | LA1781M |
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LA1781M
No.6038-31/48
Hall detection
The Hall detection function detects the level of the pin 36 quadrature input signal and then applies peak detection to
that result. The result is output from pin 33. This circuit has three effects.
(1) It assures that muting will be applied for weak inputs with an antenna input of under 5dB
μ. The amount of
attenuation is referenced to an antenna input of 60dB
μ, fm = 1kHz, and a 22.5kHz dev output, and is variable from
10dB to 40dB when there is no input. Thus one feature of this circuit is that the weak input noise attenuation and
the -3dB limiting sensitivity for over 5dB
μ inputs can be set independently.
(2) When the pin 36 quadrature input is a saturated input, the pin 36 noise level (Va) is detected and a peak-hold
function is applied to pin 33 (Vb) for locations rapid field strength variations and severe multipath occurs for
fields that result in an antenna input level of over 5dB
μ.
Fig. 26
(3) Unique features
One unique feature of the LA1781M is that if there are adjacent stations such that f1 = 98.1MHz and f2 =
97.9MHz, a search operation will not stop at 98.0MHz. Since VAFC = 0V and VSM = 3.6V at 98.0MHz in the
situations shown in figure 27 and 28, even though Hall detection would normally not operate and SD would be
high, in this IC the Hall detection circuit will operate, VMute will be set to 1.2V (over 0.7V) and the SD signal
will go low, thus preventing incorrect stopping of the search.
36
33
+
00
0.1
μF
Va
Vb
Hall Detection Output -- Antenna Input Characteristics
0
2
3
4
1
5
--20
--10
20
10
030
Antenna input -- dB
μ
V
38pin
-
V
Area muted by Hall detection
Fig. 25
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LA1781M_09 | 制造商:SANYO 制造商全稱:Sanyo Semicon Device 功能描述:For Car Radios Single-Chip Tuner IC |
| LA1781MA-MPB-E | 功能描述:調諧器 RoHS:否 制造商:NXP Semiconductors 功能: 噪聲系數: 工作電源電壓: 最小工作溫度: 最大工作溫度: |
| LA1781MD-A-MPB-E | 制造商:ON Semiconductor 功能描述:ANALOG CAR RADIO TUNER - Trays |
| LA1781MD-B-MPB-E | 功能描述:調諧器 RoHS:否 制造商:NXP Semiconductors 功能: 噪聲系數: 工作電源電壓: 最小工作溫度: 最大工作溫度: |
| LA1781ML-MPB-E | 功能描述:調諧器 RoHS:否 制造商:NXP Semiconductors 功能: 噪聲系數: 工作電源電壓: 最小工作溫度: 最大工作溫度: |
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