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參數資料
| 型號： | LTC4252-2IMS8 |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 電源管理 |
| 英文描述： | Negative Voltage Hot Swap Controllers |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8 |
| 封裝： | PLASTIC, MSOP-8 |
| 文件頁數： | 13/32頁 |
| 文件大?。?/td> | 327K |
| 代理商： | LTC4252-2IMS8 |
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LTC4252-1/LTC4252-2
13
425212f
APPLICATIU
SHUNT REGULATOR
A fast responding regulator shunts the LTC4252 V
IN
pin.
Power is derived from –48RTN by an external current
limiting resistor. The shunt regulator clamps V
IN
to 13V
(V
Z
). A 1
μ
F decoupling capacitor at V
IN
filters supply
transients and contributes a short delay at start-up. R
IN
should be chosen to accommodate both V
IN
supply cur-
rent and the drive required for an optocoupler if the
PWRGD function on the 10-pin MS package is used.
Higher current through R
IN
results in higher dissipation
for R
IN
and the LTC4252. An alternative is a separate NPN
buffer driving the optocoupler as shown in Figure 3.
Multiple 1/4W resistors can replace a single higher power
R
IN
resistor.
W
U
U
INTERNAL UNDERVOLTAGE LOCKOUT (UVLO)
A hysteretic comparator, UVLO, monitors V
IN
for
undervoltage. The thresholds are defined by V
LKO
and its
hysteresis, V
LKH
. When V
IN
rises above 9.2V (V
LKO
) the
chip is enabled; below 8.2V (V
LKO
– V
LKH
) it is disabled and
GATE is pulled low. The UVLO function at V
IN
should not
be confused with the UV/OV pin(s). These are completely
separate functions.
UV/OV COMPARATORS
An UV hysteretic comparator detects undervoltage condi-
tions at the UV pin, with the following thresholds:
UV low-to-high (V
UVHI
) = 3.225V
UV high-to-low (V
UVLO
) = 2.925V
An OV hysteretic comparator detects overvoltage condi-
tions at the OV pin, with the following thresholds:
OV low-to-high (V
OVHI
) = 6.150V
OV high-to-low (V
OVLO
) = 5.550V
The UV and OV trip point ratio is designed to match the
standard telecom operating range of 43V to 75V when
connected together as in Figure 2. A divider (R1, R2) is
used to scale the supply voltage. Using R1 = 402k and R2
= 32.4k gives a typical operating range of 43.2V to 74.4V.
The under- and overvoltage shutdown thresholds are then
39.2V and 82.5V. 1% divider resistors are recommended
to preserve threshold accuracy.
The R1-R2 divider values shown in the Typical Application
set a standing current of slightly more than 100
μ
A and
define an impedance at UV/OV of 30k
. In most applica-
tions, 30k
impedance coupled with 300mV UV hyster-
esis makes the LTC4252 insensitive to noise. If more noise
immunity is desired, add a 1nF to 10nF filter capacitor from
UV/OV to V
EE
.
Separate UV and OV pins are available in the 10-pin MS
package and can be used for a wider operating range such
as 35.5V to 76V as shown in Figure 3. Other combinations
are possible with different resistor arrangements.
4252-1/2 F03
GND
UV
OV
V
EE
V
IN
SENSE
SS
TIMER
GATE
PWRGD
DRAIN
LTC4252-1
R1
432k
1%
R3
32.4k
1%
R2
14k
1%
C
330nF
C
68nF
C
18nF
–48V
R
0.02
Q1
IRF530S
R
C
10
R5
2.2k
Q2
R
IN
10k
1/2W
1
9
8
10
3
2
7
6
4
5
C2
10nF
C
IN
1
μ
F
C
L
100
μ
F
GND
(SHORT PIN)
+
R
D
1M
LOAD
EN
R4
22k
*
* M0C207
Q2: MMBT5551LT1
Figure 3. –48V/2.5A Application with Wider Input Operating Range
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LTC4252-2IMS8#PBF | 功能描述:IC CNTRLR HOTSWAP NEGVOLT 8-MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 標準包裝:50 系列:- 類型:熱交換控制器 應用:-48V 遠程電力系統，AdvancedTCA ? 系統，高可用性 內部開關:無 電流限制:可調 電源電壓:11.5 V ~ 14.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應商設備封裝:10-MSOP 包裝:管件 |
| LTC4252-2IMS8#TR | 功能描述:IC CNTRLR HOTSWAP NEGVOLT 8-MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 標準包裝:50 系列:- 類型:熱交換控制器 應用:-48V 遠程電力系統，AdvancedTCA ? 系統，高可用性 內部開關:無 電流限制:可調 電源電壓:11.5 V ~ 14.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應商設備封裝:10-MSOP 包裝:管件 |
| LTC4252-2IMS8#TRPBF | 功能描述:IC CNTRLR HOTSWAP NEGVOLT 8-MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 標準包裝:50 系列:- 類型:熱交換控制器 應用:-48V 遠程電力系統，AdvancedTCA ? 系統，高可用性 內部開關:無 電流限制:可調 電源電壓:11.5 V ~ 14.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應商設備封裝:10-MSOP 包裝:管件 |
| LTC4252-2IMS8PBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Negative Voltage Hot Swap Controllers |
| LTC4252-2IMS8TR | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Negative Voltage Hot Swap Controllers |
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