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參數(shù)資料
| 型號(hào)： | MAX7705 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | μP Power-Supply Monitor with Reset(具復(fù)位功能的μP電源監(jiān)控器) |
| 中文描述： | 微處理器電源監(jiān)視器與復(fù)位 |
| 文件頁(yè)數(shù)： | 4/8頁(yè) |
| 文件大?。?/td> | 83K |
| 代理商： | MAX7705 |
M
μP Power-S upply Monitor
with Reset
4
_______________________________________________________________________________________
__________Applic ations Information
Replac ing the T L7705 with a MAX 7705
in an Existing Design
The MAX7705 has only three active pins: V
, GND,
and
RESET
. When using a TL7705 with a μP that has
a
RESET
input, simply plug the MAX7705 into the
same socket and omit the
RESET
pull-up resistor, reset
timing capacitor, and reference bypass capacitor (see
the Typical Operating Circuit.
The MAX7705 monitors the V
voltage and asserts
reset whenever V
falls below the reset threshold.
The reset power-up delay is created by an internal
fixed oscillator. This delay is 100% tested and guaran-
teed over the full temperature range. The
RESET
out-
put both sources and sinks current (see
RESET
Output
Voltage in the Electrical Characteristics).
Negative-Going V
CC
T ransients
The MAX7705 asserts
RESET
during power-up,
power-down, and brownout conditions. However, it is
relatively immune to short-duration negative-going V
CC
transients (glitches).
Figure 1 shows typical transient duration vs. reset com-
parator overdrive for which the MAX7705 does
not
gen-
erate a reset pulse. The graph was generated using a
fast-edge, negative-going pulse applied to V
, starting
1.5V above the actual reset threshold and ending below
the reset threshold by the magnitude indicated (reset
comparator overdrive). It indicates the typical maxi-
mum pulse width a negative-going V
transient may
have without causing a reset pulse to be issued. As
the magnitude of the transient increases (goes farther
below the reset threshold), the maximum allowable
pulse width decreases. Typically, a V
transient that
goes 100mV below the reset threshold and lasts 40μs
or less will not cause a reset pulse to be issued.
A 0.1μF bypass capacitor mounted as close as possible
to pin 2 (V
CC
) provides additional transient immunity.
Ensuring a V alid
RESET
Output
Down to V
CC
= 0V
When V
falls below 1V, the MAX7705
RESET
output
no longer sinks current; it becomes high impedance.
Therefore, high-impedance CMOS logic inputs con-
nected to the
RESET
output can drift to indeterminate
voltages. In most applications this presents no prob-
lem, as μP and other circuitry is generally inoperative
with V
below 1V. In applications where the
RESET
output must be valid down to 0V, adding a pull-down
resistor to the
RESET
pin (as shown in Figure 2) will
cause any stray leakage currents to flow to ground,
holding
RESET
low. The resistance value of R1 is not
critical. It should be about 100k
, which is large
enough not to load
RESET
and small enough to pull
RESET
to ground.
150
0
10
100
10k
50
100
RESET COMPARATOR OVERDRIVE, V
TH
- V
CC
(mV)
M
μ
s
1k
T
A
= +25°C
10ns
R1
V
CC
GND
MAX7705
RESET
Figure 1. Maximum Transient Duration without Causing a
Reset Pulse vs. Reset Comparator Overdrive
Figure 2.
RESET
Valid to V
CC
= Ground Circuit
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX7705CPA | 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過(guò)電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開(kāi)關(guān):No Backup 上電復(fù)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(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX7705CPA+ | 功能描述:監(jiān)控電路 uPower P-Supply Monitor RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過(guò)電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開(kāi)關(guān):No Backup 上電復(fù)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(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX7705CSA | 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過(guò)電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開(kāi)關(guān):No Backup 上電復(fù)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(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX7705CSA+ | 功能描述:監(jiān)控電路 uPower P-Supply Monitor RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過(guò)電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開(kāi)關(guān):No Backup 上電復(fù)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(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX7705CSA+T | 功能描述:監(jiān)控電路 uPower P-Supply Monitor RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過(guò)電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開(kāi)關(guān):No Backup 上電復(fù)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(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
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