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参数资料
| 型号： | LTC695IN-3.3#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDIP16 |
| 封装： | 0.300 INCH, LEAD FREE, PLASTIC, DIP-16 |
| 文件页数： | 5/20页 |
| 文件大小： | 189K |
| 代理商： | LTC695IN-3.3#TRPBF |
LTC694-3.3/LTC695-3.3
13
69453fb
APPLICATIONS INFORMATION
Example 1: The circuit in Figure 8 demonstrates the use
of the power-fail comparator to monitor the unregulated
power supply input. Assuming the the rate of decay of the
supply input VINis100mV/msandthetotaltimetoexecutea
shutdown procedure is 8ms. Also the noise of VINis200mV.
With these assumptions in mind, we can reasonably set
VL = 5V which is 1.6V greater than the sum of maximum
reset voltage threshold and the dropout voltage of the
LT1129-3.3 (3V + 0.4V) and VHYSTERESIS = 850mV.
VHYSTERESIS = 3.3V
R1
R3
= 850mV
R3 ≈ 3.88 R1
Choose R3 = 200k and R1 = 51k. Also select R4 = 10k
which is much smaller than R3.
5V =1.3V 1
51k
R2
(3.3V
1.3V)51k
1.3V(210k)
R2 = 15.8k, Choose nearest 5% resistor 16k and recal-
culate VL,
VL = 1.3V 1+
51k
16k
(3.3V
1.3V)51k
1.3V(210k)
= 4.96 V
VH = 1.3V 1+
51k
16 k
+
51k
2 00k
=
5.77 V
(4.96V
3.4V)
100mV / ms
= 15.6ms
VHYSTERESIS = 5.77V – 4.96V = 810mV
The 15.6ms allows enough time to execute shutdown pro-
cedure for microprocessor and 810mV of hysteresis would
prevent PFO from going low due to the noise of VIN.
Example 2: The circuit in Figure 9 can be used to measure
the regulated 3.3V supply to provide early warning of
power failure. Because of variations in the PFI threshold,
this circuit requires adjustment to ensure the PFI compara-
tor trips before the reset threshold is reached. Adjust R5
such that the PFO output goes low when the VCC supply
reaches the desired level (e.g., 3.1V).
Monitoring the Status of the Battery
C3 can also monitor the status of the memory back-up
battery (Figure 10). If desired, the CE OUT can be used to
apply a test load to the battery. Since CE OUT is forced high
in battery back-up mode, the test load will not be applied
to the battery while it is in use, even if the microprocessor
is not powered.
2.4V
3.3V
694/5-3.3 F10
R1
1M
RL
20k
R2
1.6M
OPTIONAL TEST LOAD
LOW-BATTERY SIGNAL
T0 μP I/O PIN
I/O PIN
VCC
VBATT
GND
PFI
LTC695-3.3
CE IN
PFO
CE OUT
Figure 10. Back-Up Battery Monitor with Optional Test Load
Watchdog Timer
The LTC694-3.3/LTC695-3.3 provide a watchdog timer
function to monitor the activity of the microprocessor. If
the microprocessor does not toggle the watchdog input
(WDI) within a selected timeout period, RESET is forced
to active low for a minimum of 140ms. The reset active
time is adjustable on the LTC695-3.3. Since many systems
can not service the watchdog timer immediately after a
reset, the LTC695-3.3 has a longer timeout period (1.0
second minimum) right after a reset is issued. The normal
timeout period (70ms minimum) becomes effective follow-
ing the first transition of WDI after RESET is inactive. The
watchdog timeout period is fixed at 1.0 second minimum
on the LTC694-3.3. Figure 11 shows the timing diagram
of watchdog timeout period and reset active time. The
watchdog timeout period is restarted as soon as RESET is
inactive. When either a high-to-low or low-to-high transi-
tion occurs at the WDI pin prior to timeout, the watchdog
time is reset and begins to time out again. To ensure the
watchdog time does not time out, either a high-to-low or
low-to-high transition on the WDI pin must occur at or
less than the minimum timeout period. If the input to the
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC695INPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Microprocessor Supervisory Circuits |
| LTC695IN-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Microprocessor Supervisory Circuits |
| LTC695IS | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Power Supply Supervisor |
| LTC695IS-3.3 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Power Supply Supervisor |
| LTC695ISW | 功能描述:IC MPU SUPERVISRY CIRCUIT 16SOIC RoHS:否 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 |
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