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参数资料
| 型号： | LTC2905HDDB#TRMPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8 |
| 封装： | 3 X 2 MM, LEAD FREE, PLASTIC, MO-229WECD-1, DFN-8 |
| 文件页数： | 4/16页 |
| 文件大小： | 151K |
| 代理商： | LTC2905HDDB#TRMPBF |
LTC2904/LTC2905
12
29045fd
APPLICATIONS INFORMATION
Output Rise and Fall Time Estimation
The RST and RST outputs have strong pull-down capabil-
ity. The following formula estimates the output fall time
(90% to 10%) for a particular external load capacitance
(CLOAD):
tFALL ≈ 2.2 RPD CLOAD
where RPD is the on-resistance of the internal pull-down
transistor estimated to be typically 40Ω at room tempera-
ture (25°C) and CLOAD is the external load capacitance on
the pin. Assuming a 150pF load capacitance, the fall time
is about 13ns.
The rise time, on the RST and RST pins is limited by weak
internal pull-up current sources to VCC. The following
formula estimates the output rise time (10% to 90%) at
the RST and RST pins:
tRISE ≈ 2.2 RPU CLOAD
where RPU is the on-resistance of the pull-up transistor.
Notice that this pull-up transistor is modeled as a
6μA current source in the Block Diagram as a typical
representation.
The on-resistance as a function of the VCC = Max (V1, V2)
voltage (for VCC > 1V) at room temperature is estimated
as follows:
R
MAX V V
V
PU =Ω
610
12
1
5
(,
) –
At VCC = 3.3V, RPU is about 260k. Using 150pF for load
capacitance, the rise time is 86μs. An external pull-up
resistor may be used if the output needs to pull up faster
and/or to a higher voltage, for example: the rise time re-
duces to 3.3μs for a 150pF load capacitance, when using
a 10k pull-up resistor.
RST and RST Output Characteristics
The DC characteristics of the RST and RST pull-up and
pull-down strength are shown in the Typical Performance
Characteristics section. Both RST and RST have a weak
internal pull-up to VCC = Max (V1, V2) and a strong pull-
down to ground.
The weak pull-up and strong pull-down arrangement allow
these two pins to have open-drain behavior while possess-
ing several other benecial characteristics.
The weak pull-ups eliminate the need for external pull-up
resistors when the rise time on these pins is not critical. On
the other hand, the open-drain RST conguration allows
for wired-OR connections and can be useful when more
than one signal needs to pull down on the RST line.
As noted in the Power-Up and Power-Down sections the
circuits that drive RST and RST are powered by VCC. During
fault condition, VCC of at least 1V guarantees a maximum
VOL = 0.4V at RST. However, at VCC = 1V the weak pull-up
current on RST is barely turned on. Therefore, an external
pull-up resistor of no more than 100k is recommended on
the RST pin if the state and pull-up strength of the RST
pin is crucial at very low VCC.
Note however, by adding an external pull-up resistor, the
pull-up strength on the RST pin is increased. Therefore,
if it is connected in a wired-OR connection, the pull-down
strength of any single device needs to accommodate this
additional pull-up strength.
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相关代理商/技术参数 |
参数描述 |
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| LTC2905HTS8#PBF | 制造商:Linear Technology 功能描述:IC SUPPLY MONITOR 65A 5.5V TSOT23-8 制造商:Linear Technology 功能描述:MS-System Monitor/Supervisor, Cut Tape Dual Supply Monitor 制造商:Linear Technology 功能描述:IC, SUPPLY MONITOR, 65 uA, 5.5V, TSOT23-8, Threshold Voltage:4.75V, No. of Supervisors / Monitors:2, Supply Voltage Min:1V, Supply Voltage Max:5.5V, Reset Type:Active-Low, Open-Drain, Digital IC Case Style:TSOT-23, No. of Pins:8 , RoHS Compliant: Yes |
| LTC2905HTS8#TRMPBF | 功能描述:IC PWR SUPPLY MON DUAL TSOT23-8 RoHS:是 类别:集成电路 (IC) >> PMIC - 监控器 系列:- 标准包装:400 系列:- 类型:备用电池电路 监视电压数目:1 输出:开路漏极，推挽式 复位:高有效/低有效 复位超时:最小为 35 ms 电压 - 阀值:4.65V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:16-SOIC（0.295"，7.50mm 宽） 供应商设备封装:16-SOIC W 包装:带卷 (TR) 其它名称:ADM691ARZ-REEL7TR |
| LTC2905HTS8#TRPBF | 功能描述:IC PWR SUPPLY MON DUAL TSOT23-8 RoHS:是 类别:集成电路 (IC) >> PMIC - 监控器 系列:- 标准包装:400 系列:- 类型:备用电池电路 监视电压数目:1 输出:开路漏极，推挽式 复位:高有效/低有效 复位超时:最小为 35 ms 电压 - 阀值:4.65V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:16-SOIC（0.295"，7.50mm 宽） 供应商设备封装:16-SOIC W 包装:带卷 (TR) 其它名称:ADM691ARZ-REEL7TR |
| LTC2905IDDB#PBF | 制造商:Linear Technology 功能描述:MONITOR 60uA 7V DFN-8 制造商:Linear Technology 功能描述:MONITOR, 60uA, 7V, DFN-8 制造商:Linear Technology 功能描述:MS-System Monitor/Supervisor, Cut Tape Dual Supply Monitor 制造商:Linear Technology 功能描述:MONITOR, 60uA, 7V, DFN-8, No. of Supervisors / Monitors:2, Supply Voltage Min:1V, Supply Voltage Max:7V, Reset Type:Active-Low, Open-Drain, Digital IC Case Style:DFN, No. of Pins:8, Supply Current:65A, Operating Temperature Max:85C, RoHS Compliant: Yes |
| LTC2905IDDB#TR | 功能描述:IC MONITOR DUAL SUPPLY PREC 8DFN RoHS:否 类别:集成电路 (IC) >> PMIC - 监控器 系列:- 标准包装:400 系列:- 类型:备用电池电路 监视电压数目:1 输出:开路漏极，推挽式 复位:高有效/低有效 复位超时:最小为 35 ms 电压 - 阀值:4.65V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:16-SOIC（0.295"，7.50mm 宽） 供应商设备封装:16-SOIC W 包装:带卷 (TR) 其它名称:ADM691ARZ-REEL7TR |
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