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參數(shù)資料
| 型號： | LTC2903-1 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | Octal Buffer/Driver With 3-State OUtputs 20-SO -40 to 85 |
| 中文描述： | 精密四電源監(jiān)視器6引腳SOT - 23 |
| 文件頁數(shù)： | 12/16頁 |
| 文件大?。?/td> | 187K |
| 代理商： | LTC2903-1 |
12
LTC2903-1
29031f
APPLICATIU
In any supervisory application, supply noise riding on the
monitored DC voltage can cause spurious resets, particu-
larly when the monitored voltage approaches the reset
threshold. A less than desirable but commonly used
technique used to mitigate this problem adds hysteresis to
the input comparator. The amount of added hysteresis,
usually specified as a percentage of the trip threshold,
effectively degrades the advertised accuracy of the part.
To maintain high accuracy, the LTC2903-1 does not use
hysteresis.
To minimize spurious resets while maintaining threshold
accuracy, the LTC2903-1 employs two forms of noise
filtering. The first line of defense incorporates proprietary
tailoring of the comparator transient response. Transient
events receive electronic integration in the comparator
and must exceed a certain magnitude and duration to
cause the comparator to switch. Figure 5 illustrates the
typical transient duration versus comparator overdrive
(as a percentage of the trip threshold V
RT
) required to trip
the comparators. Once any comparator is switched, the
reset line pulls low. The reset time-out counter starts once
all inputs return above threshold. The nominal reset delay
time is 200ms. The counter clears whenever any input
W
U
U
drops back below threshold. This reset delay time effec-
tively provides further filtering of the voltage inputs. A
noisy input with frequency components of sufficient mag-
nitude above f = 1/t
RST
= 5Hz holds the reset line low,
preventing oscillatory behavior on the reset line.
Although all four comparators have built-in glitch filtering,
use bypass capacitors on the V1 and V2 inputs because
the greater of V1 or V2 supplies the V
CC
for the part (a
0.1
μ
F ceramic capacitor satisfies most applications). Ap-
ply filter capacitors on the V3 and V4 inputs in extremely
noisy situations.
Reset Output Rise and Fall Time Estimation
The reset output line contains a weak pull-up current
source to the V2 supply. Use an external pull-up resistor
when the output needs to pull to another voltage and/or
when the reset output needs a faster rise time. The open-
drain output allows for wired-OR connections when more
than one signal needs to pull down on the reset line.
Estimate output rise time for the open-drain output with-
out an external pull-up using:
t
RISE
≈
2.2 R
PU
C
LOAD
where R
PU
is the on-resistance of the pull-up transistor
and C
LOAD
is the external load capacitance on the pin. At
room temperature, the average R
PU
is approximately
50k
. When externally pulling up to voltages higher than
V2, an internal network automatically protects the weak
pull-up circuitry from reverse currents.
The reset output has very strong pull-down capability.
Estimate the output fall time using:
t
FALL
≈
2.2 R
PD
C
LOAD
where R
PD
is the on-resistance of the pull-down transistor
and C
LOAD
is the external load capacitance on the pin. At
room temperature, the average R
PD
is approximately 40
.
With a 150pF load capacitance the reset line can pull down
in about 13ns.
Figure 5. Typical Transient Duration vs Overdrive
Required to Trip Comparator
RESET COMPARATOR OVERDRIVE (% OF V
RTX
)
0.1
250
T
μ
s
300
350
400
1
10
100
29031 F05
200
150
50
0
100
RESET OCCURS
ABOVE CURVE
T
A
= 25
°
C
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| LTC2903CS6-A1 | 制造商:Linear Technology 功能描述:Volt Supervisor Monitor 1.8V/2.5V/3.3V 6-Pin TSOT-23 |
| LTC2903CS6-A1#PBF | 制造商:Linear Technology 功能描述:Volt Supervisor Monitor 1.8V/2.5V/3.3V 6-Pin TSOT-23 |
| LTC2903CS6-A1#TR | 功能描述:IC MONITOR SUPPLY QUAD SOT23-6 RoHS:否 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 標(biāo)準(zhǔn)包裝:400 系列:- 類型:備用電池電路 監(jiān)視電壓數(shù)目:1 輸出:開路漏極，推挽式 復(fù)位:高有效/低有效 復(fù)位超時:最小為 35 ms 電壓 - 閥值:4.65V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:16-SOIC W 包裝:帶卷 (TR) 其它名稱:ADM691ARZ-REEL7TR |
| LTC2903CS6-A1#TRM | 功能描述:IC QUAD SPLY MONITOR ADJ SOT23-6 RoHS:否 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 標(biāo)準(zhǔn)包裝:400 系列:- 類型:備用電池電路 監(jiān)視電壓數(shù)目:1 輸出:開路漏極，推挽式 復(fù)位:高有效/低有效 復(fù)位超時:最小為 35 ms 電壓 - 閥值:4.65V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:16-SOIC W 包裝:帶卷 (TR) 其它名稱:ADM691ARZ-REEL7TR |
| LTC2903CS6-A1#TRMPBF | 功能描述:IC QUAD SUPPLY MONITOR TSOT23-6 RoHS:是 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 標(biāo)準(zhǔn)包裝:100 系列:- 類型:簡單復(fù)位/加電復(fù)位 監(jiān)視電壓數(shù)目:1 輸出:開路漏極，開路漏極 復(fù)位:高有效/低有效 復(fù)位超時:最小為 250 ms 電壓 - 閥值:4.37V，4.62V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應(yīng)商設(shè)備封裝:8-SOIC 包裝:管件 產(chǎn)品目錄頁面:1337 (CN2011-ZH PDF) |
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