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参数资料
| 型号： | LTC2908ITS8-B1#TRM |
| 厂商： | Linear Technology |
| 文件页数： | 12/18页 |
| 文件大小： | 0K |
| 描述： | IC MON SIX SUPPLY PREC TSOT23-8 |
| 标准包装： | 500 |
| 类型： | 多压监控器 |
| 监视电压数目： | 6 |
| 输出： | 开路漏极或开路集电极 |
| 复位： | 低有效 |
| 复位超时： | 最小为 160 ms |
| 电压 - 阀值： | 1.403V，1.683V，2.338V，3.086V，可调，可调 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | SOT-23-8 薄型，TSOT-23-8 |
| 供应商设备封装： | TSOT-23-8 |
| 包装： | 带卷 (TR) |
| 其它名称： | LTC2908ITS8-B1 LTC2908ITS8-B1-ND |
LTC2908
APPLICATIONS INFORMATION
With this variation of reset threshold in mind, the nominal
reset threshold of the supervisor resides below the
minimum supply voltage; just enough so that the reset
threshold band and the power supply tolerance bands
do not overlap. If the two bands overlap, the supervisor
could generate a false or nuisance reset when the power
supply remains within its speci?ed tolerance band (for
example at 4.8V).
Adding half of the reset threshold accuracy spread (1.5%)
to the ideal 5% thresholds puts the LTC2908 thresholds at
6.5% (typ) below the nominal input voltage. For example,
the 5V typical threshold is 4.675V, or 75mV below the
ideal threshold of 4.750V. The guaranteed threshold lies
in the band between 4.600V (8% below 5V) and 4.750V
(5% below 5V) overtemperature.
The powered system must work reliably down to the lowest
voltage in the threshold band or risk malfunction before
the reset line falls. In the 5V example, using the 1.5%
accurate supervisor, the system ICs must work down to
4.60V (8% below 5V). System ICs working with a ±2.5%
accurate supervisor must operate down to 4.50V (10%
below 5V), increasing the required system voltage margin
and the probability of system malfunction.
In any supervisory application, supply noise riding on
the monitored DC voltage can cause spurious resets,
particularly when the monitored voltage is near the reset
threshold. A less desirable but common solution to this
problem is to introduce hysteresis around the nominal
threshold. Notice however, this hysteresis introduces an
error term in the threshold accuracy. Therefore, a ±2.5%
accurate monitor with ±1% hysteresis is equivalent to a
±3.5% monitor with no hysteresis.
Therefore, the LTC2908 takes a different approach to solv-
ing this problem of supply noise causing spurious reset.
The ?rst line of defense against this spurious reset is a
?rst order lowpass ?lter at the output of the comparators.
Therefore, each comparator output is integrated over time
before triggering the output logic. Therefore, any kind of
transient at the input of the comparator needs to be of
suf ?cient magnitude and duration before it can trigger a
change in the output logic.
The second line of defense is the 200ms delay time t RST .
This delay eliminates the effect of any supply noise, whose
frequency is above 1/200ms = 5Hz, on the RST output.
When any one of the supply voltages drops below its
threshold, the RST pin asserts low. When the supply
recovers above its threshold, the reset-pulse-generator
timer starts counting.
If all the supplies remain above their corresponding thresh-
old when the timer ?nishes counting, the RST pin weakly
pulls high. However, if any of the supplies falls below its
threshold any time during the period when the timer is still
counting, the timer resets and it starts fresh when all the
supplies rise above their corresponding threshold.
Note that this second line of defense is only effective
for a rising supply and does not affect the sensitivity of
the system to a falling supply. Therefore, the ?rst line of
defense that works for both cases of rising and falling is
necessary. These two approaches prevent spurious reset
caused by supply noise without sacri?cing the threshold
accuracy.
Although all six comparators for the six inputs have built-
in glitch ?ltering, use bypass capacitors on the V1 and
V2 inputs because the greater of V1 or V2 supplies the
V CC for the part (a 0.1μF ceramic capacitor satis?es most
applications). Apply ?lter capacitors on the V3, V4, V ADJ1 ,
V ADJ2 , V ADJ3 , V ADJ4 and V ADJ5 inputs in extremely noisy
situations.
2908fd
12
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相关代理商/技术参数 |
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| LTC2908ITS8-C1#PBF | 制造商:Linear Technology 功能描述: 制造商:Linear Technology 功能描述:MONITOR HEX ACT LW / OP DR 8TSOT23 制造商:Linear Technology 功能描述:MONITOR, HEX, ACT LW / OP DR, 8TSOT23 制造商:Linear Technology 功能描述:MS-System Monitor/Supervisor, Cut Tape Six Supply Monitor SOT-23 |
| LTC2908ITS8-C1#TRMPBF | 功能描述:IC SUPPLY MON 6-IN TSOT23-8 RoHS:是 类别:集成电路 (IC) >> PMIC - 监控器 系列:- 标准包装:100 系列:- 类型:简单复位/加电复位 监视电压数目:1 输出:开路漏极，开路漏极 复位:高有效/低有效 复位超时:最小为 250 ms 电压 - 阀值:4.37V，4.62V 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 供应商设备封装:8-SOIC 包装:管件 产品目录页面:1337 (CN2011-ZH PDF) |
| LTC2908ITS8-C1#TRPBF | 功能描述:IC MON SIX SUPPLY PREC TSOT23-8 RoHS:是 类别:集成电路 (IC) >> PMIC - 监控器 系列:- 标准包装:1 系列:- 类型:简单复位/加电复位 监视电压数目:1 输出:开路漏极或开路集电极 复位:高有效 复位超时:- 电压 - 阀值:1.8V 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:6-TSOP（0.059"，1.50mm 宽）5 引线 供应商设备封装:5-TSOP 包装:剪切带 (CT) 其它名称:NCP301HSN18T1GOSCT |
| LTC2909CDDB-2.5#PBF | 制造商:Linear Technology 功能描述:MONITOR TRIPLE 2.213VTH 8DF 制造商:Linear Technology 功能描述:MONITOR, TRIPLE, 2.213VTH, 8DFN |
| LTC2909CDDB-2.5#TRMPBF | 功能描述:IC MONITOR PREC 2.5V 8-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 监控器 系列:- 标准包装:1 系列:- 类型:简单复位/加电复位 监视电压数目:1 输出:推挽式，图腾柱 复位:低有效 复位超时:最小为 140 ms 电压 - 阀值:4.63V 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:TO-236-3，SC-59，SOT-23-3 供应商设备封装:SOT-23-3 包装:Digi-Reel® 产品目录页面:662 (CN2011-ZH PDF) 其它名称:TCM809LVNB713DKR |
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