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參數(shù)資料
| 型號(hào)： | LTC1726EMS8-2.5 |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 電源管理 |
| 英文描述： | Triple Supply Monitor and uP Supervisor with Adjustable Reset and Watchdog Timer |
| 中文描述： | 3-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO8 |
| 封裝： | PLASTIC, MSOP-8 |
| 文件頁(yè)數(shù)： | 8/12頁(yè) |
| 文件大小： | 172K |
| 代理商： | LTC1726EMS8-2.5 |
8
LTC1726
Figure 4. RST Output Voltage
Characteristics of the Circuit in Figure 3
Figure 3. LTC1726-5 Monitoring a Single 5V
Supply. D1 Used to Avoid RST High Near 3.1V
to 4V (See Figure 2).
V
CC3
V
CC5
V
CCA
GND
6
1
2
3
4
RST
LTC1726-5
1726 F03
TO SYSTEM
RESET
R1
10k
5V
0.1
μ
F
D1
D1: MMBD914 OR EQUIVALENT
PINS 5, 7 AND 8 NOT SHOWN FOR CLARITY
V
CC5
(V)
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
R
1726 F04
5
4
3
2
1
0
V
CC5
= V
CCA
= 0V TO 5V
10k PULL-UP FROM RST TO V
CC5
T
A
= 25
°
C
Figure 3 contains a simple circuit for 5V systems that can’t
risk the RST output going high in the 3.1V to 4.15V range
(possibly due to very slow rise time on the 5V supply).
Diode D1 powers the LTC1726-5 while dropping
≈
0.6V
from the V
CC5
pin to the V
CC3
pin. This prevents the part’s
internal override circuit from being activated. Without the
override circuit active, the RST pin stays low until V
CC5
reaches V
RT5
4.675V. (See Figure 4.)
Watchdog Timer
The watchdog circuit monitors a
μ
P’s activity. The
μ
P is
required to change the logic state of the WDI pin on a
periodic basis in order to clear the watchdog timer and
prevent the LTC1726 from issuing a reset.
During power-up, the watchdog timer remains cleared
while reset is asserted. As soon as the reset timer times
out, the watchdog timer is started. The watchdog timer will
continue to run until a transition is detected on the WDI
input or until the watchdog timer times out. Once the
watchdog timer times out, the internal circuitry asserts the
reset and starts the reset timer. When the reset timer times
out and reset is deasserted, the watchdog timer is again
started. If no WDI transition is received within the watch-
dog time-out period, the reset will be reasserted at the end
of the watchdog time-out period. If a transition is received
on the WDI input during the watchdog time-out period, the
watchdog timer will be restarted and reset will remain
deasserted.
Selecting the Reset and Watchdog
Time-Out Capacitors
The reset time-out period is adjustable in order to accom-
modate a variety of
μ
P applications. The reset time-out
period, t
RT
, is adjusted by connecting a capacitor, C
RT
,
between the RT pin and ground. The value of this capacitor
is determined as follows:
C
RT
= t
RT
/3.30
with C
RT
in pF and t
RT
in
μ
s (i.e., 1500pF
4.95ms).
The watchdog period is also adjustable so that the watch-
dog time-out period can be optimized for software execu-
tion. The watchdog time-out period, t
WT
, is adjusted by
connecting a capacitor, C
WT
, between the WT pin and
ground. Once the optimum watchdog time-out period
(t
WT
) is determined, the value of the capacitor is calculated
as follows:
C
WT
= t
WT
/21.8
with C
WT
in pF and t
WT
in
μ
s (i.e., 1500pF
32.7ms).
LTC1726-2.5 Override Functions
The V
CCA
pin, if unused, can be tied to either V
CC3
or V
CC25
.
This is an obvious solution since the trip points for V
CC3
and V
CC25
will always be greater than the trip point for
V
CCA
. Likewise, the V
CC25
, if unused, can be tied to V
CC3
.
V
CC3
must always be used. Tying V
CC3
to V
CC25
and
operating off of a 2.5V supply will result in the continuous
assertion of RST.
APPLICATIOU
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U
U
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參數(shù)描述 |
|---|---|
| LTC1726EMS8-5 | 功能描述:IC TRPL SUPPLY MONITOR 5V 8-MSOP 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(kāi)路漏極，推挽式 復(fù)位:高有效/低有效 復(fù)位超時(shí):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 |
| LTC1726EMS8-5#PBF | 功能描述:IC TRPL SUPPLY MONITOR 5V 8-MSOP RoHS:是 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(kāi)路漏極，推挽式 復(fù)位:高有效/低有效 復(fù)位超時(shí):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 |
| LTC1726EMS8-5#TR | 功能描述:IC MON TRPL SPPLY SUPERVSR 8MSOP 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(kāi)路漏極，推挽式 復(fù)位:高有效/低有效 復(fù)位超時(shí):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 |
| LTC1726EMS8-5#TRPBF | 功能描述:IC TRPL SUPPLY MONITOR 5V 8-MSOP RoHS:是 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(kāi)路漏極，推挽式 復(fù)位:高有效/低有效 復(fù)位超時(shí):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 |
| LTC1726EMS8-5PBF | 制造商:Linear Technology 功能描述:Processor Supervisor 3.3V/5V/Adj MSOP8 |
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