Datasheet > DI-101

DI-101

更新时间： 2022-04-23 23:00:11

品牌	Logo	应用领域
帕沃英蒂格盛 - POWERINT		/
页数	文件大小	规格书
2页	241K
描述
Under-Voltage with Wide Hysteresis

阅读下载

获取价格

数据手册

如果您发现信息不准确，欢迎纠错

DI-101 数据手册

Design Idea DI-101

DPA-Switch^®Under-Voltage with

Wide Hysteresis

Application

Device

Power Output

Input Voltage

Output Voltage

Topology

PoE/VoIP

DPA423G

34-57 VDC

Design Highlights

37 VDC (350 mA × 20 Ω). A minimum of 7 VDC under-

voltage hysteresis is required to accommodate the cable drop

voltage and prevent nuisance lockouts from occurring.

• High hysteresis under-voltage lockout for Power over

Ethernet (PoE) Powered Devices (PDs)

• Turn-on threshold of 42 VDC and turn-off threshold of

34 VDC

Operation

• CompliancetoPoEstandard(IEEE802.3af)overcomplete

voltagewindowensurescompatibilitywithPSEequipment.

Tested by University of New Hampshire Interoperability

Consortium (UNH-IOC)*

This circuit takes advantage of accurate DPA-Switch L-pin

current sensing as the basis for a new composite threshold,

programmed for 42 VDC turn-on and 34 VDC turn-off.

The DPA-Switch detects the input voltage via current in the

L-pin resistor R_LS. Above an UV-on threshold (50 µA), the

DPA-Switch begins switching and below an UV-off threshold

(47 µA), the DPA-Switch is disabled. Transistor Q1 is turned

on via bias resistor R2, causing a voltage drop across R3 and

subtracting a ﬁxed current of approximately 10 µA(moving the

effective threshold to 60 µA) from the L-pin. When the power

supply becomes operational, the bias voltage pulls up via R1,

turning off Q1, cutting off the R3 current and returning to the

default UV-off threshold (47 µA).

Wide Hysteresis Under-Voltage

Thedefaultunder-voltagelockoutandovervoltageshutdown

thresholds of the DPA-Switch are programmed with a single

resistor (R_LS) connected from the positive input voltage

to the L-pin. The default overvoltage and under-voltage

thresholds have a ﬁxed ratio (ratio approximately 2.7:1).

In a PoE system, the Power Sourcing Equipment (PSE)

provides a minimum operating voltage of 44 VDC.

However, the PoE speciﬁcation allows CAT-5 (Ethernet)

cable lengths up to 100 meters/ 300 ft (with up to

20 Ω of cable impedance). At peak operating current

(350 mA), the voltage at the PD can drop to approximately

I_UV(ON)

I_OV(OFF)

R_LSOnly

OFF

R_LS

649 kΩ

100

131 µA

125

150

I_L

47 µA

135 µA

174 kΩ

10 kΩ

DC Input

Voltage

Bias

Voltage

MMST3906

10 µA

CONTROL

R_LSwith

Q1 Circuit

DPA-Switch

10 kΩ

OFF

PI-4064-111005

60 µA

100

125

150

I_L

Figure 1. DPA-Switch with Wide Hysteresis UVLO.

PI-4068-111005

L Pin Current (µA)

Figure 2. L-Pin Current without/with Wide UVLO Circuit.

*UNH-IOC test reports are available on the PI website www.powerint.com/poe

DI-101

November 2005

www.powerint.com

下载PDF

与DI-101相关器件

型号	品牌	描述	获取价格	数据表
DI1010	PANJIT	DUAL-IN-LINE GLASS PASSIVATED SINGLE-PHASE BRIDGE RECTIFIER(VOLTAGE - 50 to 1000 Volts CUR	获取价格
DI1010	TRSYS	DUAL-IN-LINE GLASS PASSIVATED SINGLE-PHASE BRIDGE RECTIFIER	获取价格
DI1010	CTC	GLASS PASSIVATED BRIDGE RECTIFIERS	获取价格
DI1010S	CTC	GLASS PASSIVATED BRIDGE RECTIFIERS	获取价格
DI1010S	FORMOSA	Surface Mount Bridge Rectifier - Glass passivated type	获取价格
DI1010S	PANJIT	SURFACE MOUNT GLASS PASSIVATED SINGLE-PHASE BRIDGE RECTIFIER	获取价格