參數(shù)資料
型號: TL7712
廠商: Texas Instruments, Inc.
英文描述: Supply voltage Supervisor
中文描述: 電源電壓監(jiān)控
文件頁數(shù): 5/17頁
文件大小: 340K
代理商: TL7712
Supply voltage Supervisor TL77xx Series
1
Supply Voltage Supervisor TL77xx Series
ABSTRACT
After power-on a digital system must be forced into a definite initial state. For microcomputers and microprocessors a
Reset input is provided to which, in simple applications, an R/C network is connected. After power-on, this circuitry
maintains the logic level at this input high (or low), until the supply voltage has reached its nominal value, and the
internal logic of the microcomputer has executed the Reset. However, this simple circuit does not work well under all
conditions, or during short drops of the supply voltage. This applications report describes the operation and the
application of the supply voltage supervisor circuits series TL77xx, which has been specially designed to solve these
applications problems.
1. Introduction
After power-on a digital system must normally be forced into a definite initial state. For microcomputers
and microprocessors a reset input is provided to which, in simple applications, an R/C network is
connected. After power-on, this circuitry maintains the logic level at this input high (or low), until the supply
voltage has reached its nominal value, and the internal logic of the microcomputer has executed the
initialization of the system.
Figure 1. Reset circuit
However, this circuit does not work well during short drops of the supply voltage. In this case, the capacitor
C must be quickly discharged via the diode D, which will occur only if the supply voltage V
cc
goes below the
threshold voltage (1
2 Volt) of the Reset input. A small decrease of V
cc
under the recommended
minimum supply voltage can destroy the content of the memory and registers and yet not activate the reset
circuit. This may have catastrophic consequences.
The following program example (8080 assembler code) tests an input:
WAIT
LOOP
LXI
LDAX
ANI
JNZ
B,INPUT
B
MASK
LOOP
;load address
;read input
;mask bit
;test
If, during the execution of the loop, the content of the B/C register is affected by a short voltage drop
(causing an incorrect input to be read), an incorrect condition will be tested and an incorrect decision will
be the consequence. Alternatively the addressed input will show a value which can never give a positive
test result: the execution of the program seems to be stopped.
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相關代理商/技術參數(shù)
參數(shù)描述
TL7712A 制造商:TI 制造商全稱:Texas Instruments 功能描述:SUPPLY-VOLTAGE SUPERVISORS
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TL7712ACD 制造商:Texas Instruments 功能描述:IC SVS SINGLE PROG SMD SOIC8 制造商:Texas Instruments 功能描述:IC, SVS, SINGLE, PROG, SMD, SOIC8
TL7712ACDE4 功能描述:監(jiān)控電路 Sngl SVS For 12V Sys w/Prg Time Delay RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關:No Backup 上電復位延遲(典型值):10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel
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