protection for Powered Devices (PDs) utilizing the IEEE802.3af
protocol. As the most complete PD Power Manager available,
the HV110 features a 400mA inrush limit and fault current limit,
as well as minimum current shutdown to ensure additional
protection and reliability to expensive equipment connected to
the PD switch. The internal power switch uses scaled current-
mirror technology, which eliminates the need for an external
sense resistor and provides highly accurate current sensing
at the high and low end operating conditions.
The HV110 uses a rugged high voltage junction isolated
process, which eliminates the need for any external high
voltage protection devices at the input of these controllers.
Circuit isolation also reduces the chance of tripping on
system noise. A 90V open drain PWRGD pin provides status
information and can be used to enable the DC/DC power
supplies.
The HV110 is available in a thermally rugged 5-Lead D-PAK
package that provides improved thermal resistance when
compared to 8-Lead SOIC based solutions.
Applications
►
►
►
►
►
►
IP phones
Wireless access points
End-spans and mid-spans
PoE routers, switches
Chargers
Security peripherals & cameras
Typical Application Circuit
O
GND
bs
ol
Discovery
and
Classification
et
12V
23.7kΩ
e
C
PORT
+
VPP
UVLO/
PWRGD
ENABLE
ENABLE
Features
General Description
PHY
PSE
-48V
CAT-5
Cable
PHY
953Ω
0.47µF
DC/DC
Converter
3.3/5V
HV110
VNN
DRAIN
Note: A decoupling capacitor may be connected across VPP and VNN pins when used with long CAT-5 cables.
HV110
Ordering Information
Device
HV110
-G indicates package is RoHS compliant (‘Green’)
Pin Configuration
Package Option
5-Lead TO-252 (D-PAK)
HV110K4-G
VNN
Absolute Maximum Ratings
Parameter
Supply voltage, V
PP
1
Operating temperature range
Storage temperature range
5-Lead D-PAK thermal resistance R
θja
(minimum footprint)
UVLO/Enable input
1
PWRGD open collector input
1
-0.5V to +90V
-40°C to +85°C
-65° to +150°C
ol
110°C/W
6.0V
90V
PWRGD
A
Note:
1. The HV110 will work in both positive and negative voltage applications, the maxi-
mum differential voltage between the VPP and VNN pins must not be exceeded.
bs
Parameter
Supply voltage
1
Supply current
Internal UVLO threshold (turn-off)
2
Internal UVLO threshold (turn-on)
2
UVLO comparator hysteresis
UVLO comparator threshold
UVLO input resistance
MOSFET on-resistance
Output leakage current
Operating output current
Inrush current limit
Over load current limiting
Minimum current threshold
Slew rate to enable turn-on timers
Absolute Maximum Ratings are those values beyond which damage to devicemay occur.
Functional operation under these conditions is not implied. Continuous operation of the
device at the absolute rating level my affect reliability. All voltages are references to
VNN pin.
Electrical Characteristics
(at 0°C < T
Sym
V
PP
I
PP
< +75°C, unless otherwise specified)
Min
36
-
30
38
-
1.1
-
-
-
-
300
300
1.0
-
O
V
UVLO
V
HYS
V
UVHO
V
UVTH
R
DS
I
LEAK
I
OUT
R
UVLO
I
INRUSH
I
OC
I
MIN
V
SLEW
Notes:
1. The HV110 will work in both positive and negative voltage applications, the maximum differential voltage between the VPP and VNN pins must not be exceeded.
2. UVLO Threshold to be modified using external resistors, when a Zener diode is connected to VPP pin. (See Signature Detection)
et
e
VPP
UVLO/
ENABLE
5-Lead
TO-252 (D-PAK)
TO-252 (D-PAK) (K4)
(top view)
Pin Description
Pin
VPP
Value
Function
Positive voltage supply input
VNN
Negative voltage power supply input
DRAIN
Internal N-channel MOSFET drain
output
Active-low power good output
UV/ENABLE Under voltage lockout input
Product Marking
YYWW
HV110K4
LLLLLLL
YY = Year Sealed
WW = Week Sealed
L = Lot Number
= “Green” Packaging
5-Lead TO-252 (D-PAK)
Max
57
1.0
34
42
-
1.3
-
1.6
10
350
400
400
20
-
Units Conditions
V
mA
V
V
V
V
kΩ
Ω
µA
mA
mA
mA
mA
V/ms
V
PP
referenced to V
NN
V
PP
= -48V, standby mode. MOSFET off.
V
PP
referenced to V
NN
V
PP
referenced to V
NN
---
Referenced to V
NN
---
Measured at 25
O
C and I
DS
= 200mA
Internal MOSFET off
---
---
---
---
Enables timers
Typ
-
-
32
40
8.0
1.2
100
1.0
-
-
350
350
10
4.25
2
PWRGD
DRAIN
HV110
Electrical Characteristics
(cont.) (at 0°C < T
Sym
IOH
PWRGD
t
SC
t
UC
t
OC
t
LIMIT
t
POR
t
RESTART
T
OT
T
HYS
Parameter
PWRGD output leakage current
Shorted-circuit timer
3
Under-current timer
4
Over-current timer
5
Current limit delay time
6
POR timer
Restart timer
Over temperature trip limit
Temperature hysteresis
VOL
PWRGD
PWRGD output low voltage
-
-
-
-
-
-
-
-
-
-
A
< +75°C, unless otherwise specified)
Min
Typ
-
-
60
60
350
10
Max
0.4
10
-
-
-
-
-
-
-
-
Units Conditions
V
µA
ms
ms
ms
µs
ms
O
O
I = 3.0mA; Referenced to V
NN
V = 5.0V; Referenced to V
NN
Measured at T
A
= 25°C
Measured at T
A
= 25°C
Measured at T
A
= 25°C
Measured at T
A
= 25°C
Functional Block Diagram
VPP
bs
24MΩ
UVLO
UVLO
116kΩ
POR
Timer
Restart
Timer
VNN
ol
Regulator
Control
Logic
3
Notes:
1. The HV110 will work in both positive and negative voltage applications, the maximum differential voltage between the VPP and VNN pins must not be exceeded.
2. UVLO Threshold to be modified using external resistors, when a Zener diode is connected to VPP pin. (See Signature Detection)
3. Shorted-circuit timer starts after POR timer. If V
OUT
does not charge at least 90% V
IN
before t
SC
then a shorted-circuit condition exists.
4. Under-current timer starts when I
OUT
goes below I
MIN
. If I
OUT
stays below I
MIN
longer than t
UC
then MOSFET is turned off due to under current condition.
5. If the output current is in an overload or shorted load condition then the output immediately goes to current limit and starts the over-current timer. If I
OUT
does not drop
back below I
LIMIT
before the timer expires then an over current condition exists. The timer is immediately reset when a fault is cleared.
6. Time for fast return to limit circuit to react.
O
Powered Ethernet Requirements
Power-over-LAN (sometimes called Powered Ethernet or
Powered VoIP) is the general concept of providing high volt-
age (48VDC) power over existing networking cables, such
as Ethernet cables. This is accomplished either by using
the CAT5 Ethernet Cable’s unused spare pairs or the signal
pairs (ENV B vs. ENV A).
In Power-over-LAN applications there are two main types of
equipment: the Power Sourcing Equipment (PSE) and the
Powered Device (PD). There is a third type called Mid-Span
equipment that plugs in line and converts a conventional
router into a PSE.
The IEEE802.3af standard specifies the requirements, fea-
tures and characteristics of the PSE and PD devices for use
in PoE applications. The HV110 is a PD controller IC, ca-
pable of handling all the current and timing requirements of
the IEEE802.3af standard.
A PD designed to this standard and within its range of avail-
able power, can obtain both power and data for operation via
the standard LAN cables and therefore will not require any
additional power sources or connections.
et
e
Measured at T
A
= 25°C
3.5
9.0
20
sec
C
C
Measured at T
A
= 25°C
---
---
140
HV110
Temperature
Sensor
PWRGD
DRAIN
HV110
Power-over-Ethernet (PoE) Standards
IEEE802.3af standard, DTE Power via MDI, deals with the
specification of the interface that can supply/draw power us-
ing the same generic cabling as that used for data trans-
mission. It allows both power and data to flow through the
Media Dependent Interface (MDI) (like 10Base-T, 100Base
TX or 1000BaseT) to the Data Terminal Equipment (DTE)
safely and effectively. It defines the functional and electri-
cal characteristics of two optional power (non-data) entities
– the Powered Device (PD) and the Power Sourcing Equip-
ment (PSE) that makes this single interface possible. The
mechanical and electrical interface between PSE and PD
and the transmission line is achieved through the Power In-
terface (PI) Devices (usually the LAN cables).
subsequently. The reason for all of this is that high voltages
(-48V) connected to many legacy devices can cause equip-
ment damage. For this reason discovery takes place at volt-
ages compatible with existing legacy equipment and high
voltage DC is only applied once discovery is satisfied. The
IEEE802.3af discovery is based upon the sensing of a char-
acteristic impedance. This impedance is defined nominally
as 25k (23.5k to 26.25k) with no more than 0.1µF of ca-
pacitance in parallel with the impedance, in a voltage range
from 2.8V to 10V. The presence of diode rectification at the
PD end forces a slope impedance method, requiring at least
two operating point measurements, to eliminate the effect of
diode level shift.
bs
Even though the HV110 is a PD device, it is closely associ-
ated with the operation of PSE, in fact it is dependent on the
PSE for its normal operation. The HV110, however, unlike
many other PD controllers, provides redundant PSE protec-
tions and timings for maximum protection while ensuring
compliance. Hence certain basic functionalities of the PSE
are included in this data sheet for better understanding some
of the features and operation of PDs.
PSE Power Standards
O
PSE powers a single link. It searches the link for a PD and
supplies power to the link only after a PD Signature is de-
tected. The PSE will reject any links with an invalid PD Sig-
nature. When the PD is removed, the PSE will also remove
the power from the link.
PSE may be able to do an optional classification of the PD,
to detect the maximum power drawn by the PD, to do some
high level Power Management. PSE is limited to a continu-
ous maximum output of 15.4W.
ol
Class
0
1
2
3
4
PSE is defined as a device that provides a single portion
of the link (10BASE-T, 100BASE_TX or 1000BASE_T) with
both the data it requires and the power to process this data.
PSEs may be placed with the DTE/Repeater/Mid-Span. A
PSE that is located along with the DTE/Repeater is called
Endpoint PSE, while a PSE that is located within the link,
between the MDIs is called a Mid-Span PSE. All the specifi-
cations for the PSE sitting in the End Point (e.g. the router)
may not apply for the Mid span PSE.
Discovery
Key to all Power-over-Ethernet methods is discovery. Dis-
covery is the method used to determine if a device at the
end of the cable is capable of receiving high voltage DC,
before applying high voltage. Discovery also is used for de-
termining when a PD device is disconnected or removed
et
e
Classification (optional)
Table 1. PD Power Classification
Usage
Default
Optional
Optional
Optional
As per the IEEE802.3af standards, the PSE has to deliver a
minimum of 15.4W to a PD connected to it while limited by
the 350mA maximum operating current. Not all PD devices,
however, require this much power to operate. For example
an IP Phone with a monochrome screen will require far less
power than an IP Phone with color display. By identifying
the power drawn through each port, PSE can assist in the
System Power Management protocol to determine the total
number of PDs it can support, depending on the output ca-
pacity of the system power supply.
To achieve this type of power management an optional step
was added to the IEEE802.3af standard called ‘Classifi-
cation’. Classification allows a device to communicate the
maximum power it will ever demand to the PSE so that the
Power Management Protocol can allocate the unused power
to other ports, enabling the full utilization of the installed ca-
pacity. Table 1 identifies the different Classifications included
in the IEEE802.3af standard.
PD Power (W)
0.44 – 12.95
0.44 – 12.95
3.84 – 6.49
6.49 – 12.95
In order to identify the class of the PD connected, the PSE
sends a second voltage signal of 15 to 20V, slightly higher
than signature detection voltage and measures the current.
Depending on the magnitude of the current drawn, the PSE
will classify the load to one of the four Classes as shown in
Table 2, and will assume that the load will not draw any ad-
ditional power than shown for the given Class.
HV110
Table 2. Classification signature measured at PD con-
nector
Class
0
1
2
3
Probe
Voltage (V)
15 - 20
15 - 20
15 - 20
15 - 20
Min
(mA)
0.5
9.0
17
26
Max
(mA)
4.0
12
20
30
PD Application
IEEE Electrical & Timing Requirements
Below are of the major features of the HV110, some of which
are usually found only in PSE devices.
►
Provides an internal current limit for inrush, normal op-
eration and overload conditions.
►
Limits the input current to less than 10µA that will not
interfere with Discovery from 2.6V to 10V (with Zener as
shown on page 1).
►
Meets the turn-on and turn-off thresholds for the PD de-
vice & has a built-in 8.0V hysteresis (with PNP transistor
as shown on page 9).
►
Protects the device from thermal run away, with thermal
shut down and built in 9 sec restart timer.
►
UVLO & POR provides hot-swapping/de-bounce capa-
bilities and inrush current limit.
►
PWRGD (active LOW) provides enable signal to DC/DC
converter.
►
Complies with the timing requirements for IEEE 802.3af
standard.
►
Classification can be easily implemented, as shown on
page 9.
In addition to operating as a PD controller, the HV110 can
function as a redundant protective element to assure reliable
operation and compliance to IEEE802.3af standard for the
PD, even in cases where the PD is powered from an auxil-
iary power source, as shown on page 10.
Disconnect
bs
The PSE must be able to remove the power from a port once
the PD is removed. The purpose of this is to prevent dam-
age to non-compatible devices connected to the same link
at a later time. As per the DC disconnect requirements, the
PSE may disconnect load if the current is between 5mA and
10mA and must disconnect between 0-5mA, if the condition
persists for more than 300ms. Although not required by a
PD device, the HV110 includes a “minimum circuit breaker”
which when the current is in a range less than 20mA will
cause a shutdown after the 300ms if the PSE does not re-
act.
O
PD Power Standards
According to the IEEE802.3af standards, the PD must op-
erate from 36V to account for a potential 8.0V line drop
across the impedance of the network during inrush (400mA
max current x 20W line-impedance). The UVLO must allow
a 44V max turn-on and a 30V minimum turn off. A PD de-
vice may draw a maximum power of 12.95W. The maximum
power that can be expected is limited by the 20W line re-
sistance carrying the 350mA current to the PD at the mini-
mum input voltage of 44V (power delivered is 12.95W [{44
– (20*0.35)}*0.35].
ol
5
Note that Class 0 default will work for all devices & Classifi-
cation is only needed in the rare instance when a multi-port
switch or router wants to rate the system supply lower than
the combined Class 0 port output; a situation which will re-
duce it’s potential classification base. In fact most of the PD
devices, like Wireless Access Points, in the market today are
Class 0 devices and hence do not require any classification
methods. The HV110 therefore does not force the use of
resistors and wasted silicon area to implement a Classifica-
tion current source. The HV110, however, can be made to be
compatible with classification by utilizing low cost circuitry as
shown on page 6.
et
e
Thermal Shutdown
Auto Restart
The HV110 is designed with a built in Thermal Shutdown
feature to assure higher levels of reliability. It will shutdown
if the temperature on the die reaches 140°C and will try to
restart when the temperature drops to 120°C.
Any fault condition will cause the device to shut down and
enable a 9 second auto-restart timer. This will occur indefi-
nitely and is strong protection against PSE error when the
the HV110 is used in PD applications.
Note that a 9 second auto-restart will disconnect the PD due
to under current conditions, and will also turn off the PSE,
since the PSE will not see the minimum current for greater
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
