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參數(shù)資料
| 型號： | LTC1235CS |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 電源管理 |
| 英文描述： | Microprocessor Supervisory Circuit |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO16 |
| 封裝： | PLASTIC, SOL-16 |
| 文件頁數(shù)： | 10/16頁 |
| 文件大?。?/td> | 295K |
| 代理商： | LTC1235CS |
10
LTC1235
U
S
A
O
PPLICATI
U
U
Replacing the Backup Battery with Power On
When changing the backup battery with system power on,
spurious resets can occur while battery is removed due to
battery standby current. Although battery standby current
is only a tiny leakage current, it can still charge up the stray
capacitance on the V
BATT
pin. The oscillation cycle is as
follows: When V
BATT
reaches within 50mV of V
CC
, the
LTC1235 switches to battery backup or battery saving
mode. In either case, the battery supply current pulls
V
BATT
low and the device goes back to normal operation.
The leakage current then charges up the V
BATT
pin again
and the cycle repeats.
If spurious resets during battery replacement pose no
problems, then no action is required. Otherwise, two
methods can be used to eliminate this problem. First, a
capacitor from V
BATT
to GND will allow time for battery
replacement by slowing the charge rate. For example, the
battery standby current is 1
μ
A maximum over tempera-
ture and the external capacitor required to slow the charge
rate is:
C
T
V
– V
CC
BATT
where T
REQ'D
is the maximum time required to replace the
backup battery. With V
CC
= 4.5V, V
BATT
= 3V and T
REQ'D
=
3 sec, the value for external capacitor is 2
μ
F. Second, a
resistor from V
BATT
to GND will hold the pin low while
changing the battery. For example, the battery standby
current is 1
μ
A maximum over temperature and the exter-
nal resistor required to hold V
BATT
below V
CC
is:
V
– 50mV
1 A
With V
CC
= 4.5V, a 4.3M
resistor will work. With a 3V
battery, this resistor will draw only 0.7
μ
A from the battery,
which is negligible in most cases.
If the battery connections are made with long wires or PC
traces, inductive spikes can be generated during battery
replacement. Even if a resistor is used to prevent spurious
resets as described above, these spikes can take the V
BATT
pin below GND violating the LTC1235 absolute maximum
ratings. A 0.1
μ
F capacitor from V
BATT
to GND is recom-
mended to eliminate these potential spikes when battery
replacement is made through long wires.
Figure 5. Charging External Battery Through V
OUT
The operating voltage at the V
BATT
pin ranges from 2.0V to
4.25V. High value capacitors, such as electrolytic or farad-
size double layer capacitors, can be used for short term
memory backup instead of a battery. For capacitor backup,
see Typical Applications. The charging resistor for re-
charging rechargeable batteries should be connected to
V
OUT
through a diode since this eliminates the discharge
path that exists when V
CC
collapses and RAM is not backed
up (Figure 5).
Figure 4. Conditional Battery Backup Operation
+5V
+3V
0.1μF
0.1μF
V
BATT
V
CC
LTC1235
V
OUT
GND
4
LTC1235 F05
V
OUT
– V
BATT
– V
D
R
I =
R
BACKUP
I/O LINE
μP
RAM
1N4148
V
OUT
IN BATTERY SAVING MODE
LOGIC LOW
BACKUP
V
CC
RESET VOLTAGE THRESHOLD
V
OUT
Hi-Z
V
BATT
V
OUT
IN BATTERY BACKUP MODE
LOGIC
HIGH
RESET VOLTAGE THRESHOLD
V
BATT
BACKUP
V
CC
V
OUT
V
OUT
= V
BATT
LTC1235 F04
1 A
EXT
REQ'D
≥
R
CC
≤
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| LTC1235CSW | 功能描述:IC MPU SUPERVISRY CIRCUIT 16SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 標(biāo)準(zhǔn)包裝:1 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:開路漏極或開路集電極 復(fù)位:高有效 復(fù)位超時:- 電壓 - 閥值:1.8V 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:6-TSOP（0.059"，1.50mm 寬）5 引線 供應(yīng)商設(shè)備封裝:5-TSOP 包裝:剪切帶 (CT) 其它名稱:NCP301HSN18T1GOSCT |
| LTC1235CSW#PBF | 功能描述:IC MPU SUPERVISRY CIRCUIT 16SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 其它有關(guān)文件:STM6905 View All Specifications 標(biāo)準(zhǔn)包裝:1 系列:- 類型:多壓監(jiān)控器 監(jiān)視電壓數(shù)目:5 輸出:開路漏極或開路集電極 復(fù)位:低有效 復(fù)位超時:最小為 140 ms 電壓 - 閥值:2.188V，2.955V，可調(diào)，可調(diào)，可調(diào) 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-TSSOP，8-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:8-TSSOP 包裝:Digi-Reel® 產(chǎn)品目錄頁面:1197 (CN2011-ZH PDF) 其它名稱:497-8728-6 |
| LTC1235CSW#TR | 功能描述:IC MPU SUPERVISRY CIRCUIT 16SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 標(biāo)準(zhǔn)包裝:1 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:開路漏極或開路集電極 復(fù)位:高有效 復(fù)位超時:- 電壓 - 閥值:1.8V 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:6-TSOP（0.059"，1.50mm 寬）5 引線 供應(yīng)商設(shè)備封裝:5-TSOP 包裝:剪切帶 (CT) 其它名稱:NCP301HSN18T1GOSCT |
| LTC1235CSW#TRPBF | 功能描述:IC MPU SUPERVISRY CIRCUIT 16SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 標(biāo)準(zhǔn)包裝:1 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:開路漏極或開路集電極 復(fù)位:高有效 復(fù)位超時:- 電壓 - 閥值:1.8V 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:6-TSOP（0.059"，1.50mm 寬）5 引線 供應(yīng)商設(shè)備封裝:5-TSOP 包裝:剪切帶 (CT) 其它名稱:NCP301HSN18T1GOSCT |
| LTC1235CSWPBF | 制造商:Linear Technology 功能描述:Supervisor 4.65V Reset Watchdog SOIC16W |
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