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參數(shù)資料
| 型號： | L4979MD |
| 廠商： | 意法半導(dǎo)體 |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | LOW DROP VOLTAGE REGULATOR |
| 中文描述： | 低壓差穩(wěn)壓器 |
| 文件頁數(shù)： | 6/10頁 |
| 文件大小： | 268K |
| 代理商： | L4979MD |
L4979MD L4979D
6/10
and reset pulse delay trd is given by:
t
rd
= 512 x T
osc
Figure 5. Reset Time Diagram.
4
The watchdog input Wi monitors a connected microcontroller. If pulses are missing, the reset output Res is
set to low. The pulse sequence time can be set within a wide range thorough the external capacitor C
tw
. The
watchdog circuit discharges the capacitor C
tw
with the constant current Icwd. If the lower threshold Vwlth is
reached, a watchdog reset is generated. To prevent this reset, the microcontroller must generate a positive edge
during the discharge of the capacitor before the voltage has reached the threshold V
wlth
. In order to calculate
the minimum time Tdis during which the microcontroller must generate the positive edge, the following equation
can be used:
(V
whth
- V
wlth
) x C
tw
= I
cwd
x T
dis
Each W
i
positive edge switches the current source from discharging to charging; the same happens when the
lower V
wlth
threshold is reached. When the voltage reaches the upper threshold V
whth
the current switches from
charging to discharging. The result is a saw tooth voltage at the watchdog timer capacitor C
tw
.
WATCHDOG
Figure 6. Watchdog time diagram
T
osc
V
--------------------–
V
I
cr
)
C
tr
[
]
V
--------------------–
V
I
dr
)
C
tr
[
]
+
=
trr
< trr
trd = 512 Tosc
Tosc
Vrhth
Vrlth
Res
Vcr
Vo
Wi
Vout_th
Wi
Res
Vcw
Vwlth
Vwhth
twol
Twop
Tdis
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| L4979MD013TR | 功能描述:低壓差穩(wěn)壓器 - LDO 5.0 Volt 0.5 Amp RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| L4979MD13TR | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:LOW DROP VOLTAGE REGULATOR |
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| L497D1 | 功能描述:馬達/運動/點火控制器和驅(qū)動器 Hall Effect Control RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Stepper Motor Controllers / Drivers 類型:2 Phase Stepper Motor Driver 工作電源電壓:8 V to 45 V 電源電流:0.5 mA 工作溫度:- 25 C to + 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:HTSSOP-28 封裝:Tube |
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