NCP1091DBG ON Semiconductor, NCP1091DBG Datasheet - Page 7

• Manufacturer Part Number: NCP1091DBG
• Description: IC INTERFACE CTLR POE-PD 8-TSSOP
• Manufacturer: ON Semiconductor
• Series: HIPO™r

Specifications of NCP1091DBG

• Controller Type: PoE-PD Interface
• Interface: IEEE 802.3af
• Current - Supply: 500mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-TSSOP
• Output Voltage: 9.8 V
• Output Current: 500 mA
• Operating Temperature Range: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Number Of Outputs: 8
• Input Voltage: 57V
• Supply Current: 500mA
• Digital Ic Case Style: TSSOP
• No. Of Pins: 8
• Svhc: No SVHC (20-Jun-2011)
• Base Number: 1091
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Supply: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: NCP1091DBGOS

Description of Operation
Powered Device Interface
defined operating modes: detection signature, current
source classification, undervoltage lockout, inrush and
operating current limits. The following sections give an
overview of these previous processes.
Detection
resistance seen by the PSE through the cable must be in the
IEEE 802.3af standard specification range (23.70 kW to
26.30 kW) for a PSE voltage from 2.7 V to 10.1 V. In order
to compensate for the non−linear effect of the diode bridge
and satisfy the specification at low PSE voltage, the
NCP1090/91/92 present a suitable impedance in parallel
with the 24.9 kW Rdet external resistor. For some types of
diodes (especially Schottky diodes), it may be necessary to
adjust this external resistor.
DET pins. During the detection phase, the DET pin is pulled
to ground and goes in high impedance mode (open−drain)
once the device exit this mode, reducing thus the current
consumption on the cable.
Classification
classification process begins. In classification, the PD
regulates a constant current source that is set by the external
resistor RCLASS value on the CLASS pin. Figure 4 shows
the schematic overview of the classification block. The
current source is defined as:
Power Mode
PSE and PD devices move into the operating mode.
The integrated PD interface supports the IEEE 802.3af
During the detection phase, the incremental equivalent
The Rdet resistor has to be inserted between VPORTP and
Once the PSE device has detected the PD device, the
When the classification hand−shake is completed, the
VPORTP
VPORTN
Figure 4. Classification Block Diagram
CLASS
9.8 V
Iclass +
VPORTP
Rclass
9.8 V
EN
Class_enable
1.2 V
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Under Voltage Lock Out (UVLO)
lock out (ULVO) circuit which monitors the input voltage
and determines when to turn on the pass switch and charge
the dc−dc converter input capacitor before the power up of
the application.
threshold depending if the UVLO pin is used or not. In
Figure 5, the UVLO pin is strapped to ground and the
Vuvlo_on threshold is defined by the internal level.
must be connected to the center of an external resistor
divider between VPORTP and VPORTN as shown in
Figure 6.
equivalent input resistor made of the Ruvlo1, Ruvlo2 and
Rdet should be equal to 24.9 kW.
Ruvlo1 and Ruvlo2 can be calculated using the following
equations:
with
and
With:
The NCP1090/91/92 incorporate a fixed under voltage
The NCP1091 offers a fixed or adjustable Vuvlo_on
To define the UVLO threshold externally, the ULVO pin
In order to guarantee the detection signature, the
For a Vuvlo_on desired turn−on voltage threshold,
Vuvlo_on: Desired Turn−On voltage threshold
VPORT
Figure 5. Default Internal UVLO Configuration
Figure 6. Default Internal UVLO Configuration
Ruvlo1
Ruvlo2
VPORT
Ruvlo +
Ruvlo1 ) Ruvlo2 + Ruvlo
Ruvlo2 +
(NCP1091 only)
(NCP1091 only)
Rdet
Rdet * 24.9 k
24.9 k @ Rdet
Vuvlo_on
1.2
VPORTP
UVLO
VPORTN1,2
@ Ruvlo
VPORTP
DET
UVLO
VPORTN1,2
NCP1091