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參數(shù)資料
| 型號： | LTC4267IGN |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
| 中文描述： | 1 A SWITCHING CONTROLLER, 240 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 0.150 INCHES, PLASTIC, SSOP-16 |
| 文件頁數(shù)： | 14/32頁 |
| 文件大小： | 1975K |
| 代理商： | LTC4267IGN |
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LTC4267
14
4267f
PWRGD
C1
5μF
MIN
V
PORTN
P
OUT
1.125V
300k
300k
R9
100k
LTC4267
THERMAL SHUTDOWN
UVLO
4267 F06
TO
PSE
+
–
+
+
I
TH
/RUN
PGND
PGND
the LTC4267 will attempt to quickly charge capacitor C1
using an internal secondary current limit circuit. In this
scenario, the PSE current limit should provide the overall
limit for the circuit. For slower rising inputs, the 375mA
current limit in the LTC4267 will set the charge rate of the
capacitor C1. In either case, the
P
W
R
G
D signal may go
inactive briefly while the capacitor is charged up to the
new line voltage. In the design of a PD, it is necessary
to determine if a step in the input voltage will cause the
P
W
R
G
D signal to go inactive and how to respond to this
event. In some designs, it may be desirable to filter the
P
W
R
G
D signal so that intermittent power bad conditions
are ignored. Figure 7 demonstrates a method to insert a
lowpass filter on the power good interface.
For PD designs that use a large load capacitor and also
consume a lot of power, it is important to delay activation
of the switching regulator with the
P
W
R
G
D signal. If the
regulator is not disabled during the current-limited turn-on
sequence, the PD circuitry will rob current intended for
charging up the load capacitor and create a slow rising
input, possibly causing the LTC4267 to go into thermal
shutdown.
The
P
W
R
G
D pin connects to an internal open drain, 100V
transistor capable of sinking 1mA. Low impedance to
V
PORTN
indicates power is good.
P
W
R
G
D is high imped-
ance during signature and classification probing and in
the event of a thermal overload. During turn-off,
P
W
R
G
D
is deactivated when the input voltage drops below 30V.
In addition,
P
W
R
G
D may go active briefly at turn-on for
fast rising input waveforms.
P
W
R
G
D is referenced to the
V
PORTN
pin and when active, will be near the V
PORTN
po-
tential. Connect the
P
W
R
G
D pin to the switching regulator
circuitry as shown in Figure 7.
Figure 6. LTC4267 Power Good
APPLICATIOU
W
U
U
Figure 7. Power Good Interface Examples
PD Interface Thermal Protection
The LTC4267 PD Interface includes thermal overload
protection in order to provide full device functionality
in a miniature package while maintaining safe operat-
ing temperatures. Several factors create the possibility
of significant power dissipation within the LTC4267. At
turn-on, before the load capacitor has charged up, the
instantaneous power dissipated by the LTC4267 can be
as much as 10W. As the load capacitor charges up, the
power dissipation in the LTC4267 will decrease until it
reaches a steady-state value dependent on the DC load
current. The size of the load capacitor determines how
fast the power dissipation in the LTC4267 will subside. At
room temperature, the LTC4267 can typically handle load
capacitors as large as 800μF without going into thermal
shutdown. With large load capacitors, the LTC4267 die
temperature will increase by as much as 50°C during a
single turn-on sequence. If for some reason power were
removed from the part and then quickly reapplied so that
the LTC4267 had to charge up the load capacitor again, the
temperature rise would be excessive if safety precautions
were not implemented.
The LTC4267 PD interface protects itself from thermal
damage by monitoring the die temperature. If the die
4267 F07
LTC4267
V
PORTN
P
OUT
PGND
V
PORTP
PWRGD
I
TH
/RUN
I
TH
/RUN
TO
PSE
–48V
+
C1
5μF
100V
ALTERNATE ACTIVE-HIGH ENABLE FOR P
PIN
SEE APPLICATIONS INFORMATION SECTION
ACTIVE-HIGH ENABLE FOR RUN PIN WITH INTERNAL PULL-UP
R18
10k
R9
100k
D6
MMBD4148
C15
0.047μF
Q1
2N7002
LTC3803
GND
OPTIONAL
AUXILIARY
SWITCHING
REGULATOR
PGND
LTC4267
V
PORTN
P
OUT
PGND
V
PORTP
PWRGD
P
VCC
TO
PSE
–48V
+
C1
5μF
100V
R18
10k
R9
100k
D6
MMBD4148
C15
0.047μF
Q1
2N7002
PGND
R
START
C
PVCC
C17
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC4267IGN#PBF | 功能描述:IC POE 802.3AF INTERFACE 16SSOP RoHS:是 類別:集成電路 (IC) >> 接口 - 控制器 系列:- 標(biāo)準(zhǔn)包裝:2,450 系列:- 控制器類型:SPI 總線至 I²C 總線橋接 接口:I²C，串行，SPI 電源電壓:2.4 V ~ 3.6 V 電流 - 電源:11mA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-HVQFN（4x4） 包裝:托盤 配用:568-3511-ND - DEMO BOARD SPI TO I2C 其它名稱:935286452157SC18IS600IBSSC18IS600IBS-ND |
| LTC4267IGN#TRPBF | 功能描述:IC POE 802.3AF INTERFACE 16SSOP RoHS:是 類別:集成電路 (IC) >> 接口 - 控制器 系列:- 標(biāo)準(zhǔn)包裝:2,450 系列:- 控制器類型:SPI 總線至 I²C 總線橋接 接口:I²C，串行，SPI 電源電壓:2.4 V ~ 3.6 V 電流 - 電源:11mA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-HVQFN（4x4） 包裝:托盤 配用:568-3511-ND - DEMO BOARD SPI TO I2C 其它名稱:935286452157SC18IS600IBSSC18IS600IBS-ND |
| LTC4267IGN-1 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Power over Ethernet IEEE 802.3af PD Interface with Integrated Switching Regulator |
| LTC4267IGN-1#PBF | 功能描述:IC POE 802.3AF 16-SSOP RoHS:是 類別:集成電路 (IC) >> 接口 - 控制器 系列:- 標(biāo)準(zhǔn)包裝:2,450 系列:- 控制器類型:SPI 總線至 I²C 總線橋接 接口:I²C，串行，SPI 電源電壓:2.4 V ~ 3.6 V 電流 - 電源:11mA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-HVQFN（4x4） 包裝:托盤 配用:568-3511-ND - DEMO BOARD SPI TO I2C 其它名稱:935286452157SC18IS600IBSSC18IS600IBS-ND |
| LTC4267IGN-1#TRPBF | 功能描述:IC POE 802.3AF INTERFACE 16SSOP RoHS:是 類別:集成電路 (IC) >> 接口 - 控制器 系列:- 標(biāo)準(zhǔn)包裝:2,450 系列:- 控制器類型:SPI 總線至 I²C 總線橋接 接口:I²C，串行，SPI 電源電壓:2.4 V ~ 3.6 V 電流 - 電源:11mA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-HVQFN（4x4） 包裝:托盤 配用:568-3511-ND - DEMO BOARD SPI TO I2C 其它名稱:935286452157SC18IS600IBSSC18IS600IBS-ND |
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