ncp1083 ON Semiconductor, ncp1083 Datasheet - Page 5

• Manufacturer Part Number: ncp1083
• Description: Integrated High Power Poe-pd Interface & Dc-dc Converter Controller With 9v Auxiliary Supply Support
• Manufacturer: ON Semiconductor

Table 1. Pin Descriptions
VPORTP
VPORTN1
VPORTN2
RTN
ARTN
VDDH
VDDL
CLASS
INRUSH
ILIM1
UVLO
GATE
OSC
nCLASS_AT
COMP
FB
CS
SS
AUX
TEST
EP
Name
Pin No.
6,8
14
16
17
15
13
18
19
12
20
10
11
1
7
2
4
5
3
9
Open Drain
Ground
Ground
Ground
Output,
Supply
Supply
Supply
Output
Type
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
I/O
Positive input power. Voltage with respect to VPORTN
Negative input power. Connected to the source of the internal pass−switch.
DC−DC controller power return. Connected to the drain of the internal pass−switch. It must
be connected to ARTN. This pin is also the drain of the internal pass−switch.
DC−DC controller ground pin. Must be connected to RTN as a single point ground connection
for improved noise immunity.
Output of the 9 V LDO internal regulator. Voltage with respect to ARTN. Supplies the internal
gate driver. VDDH must be bypassed to ARTN with a 1 mF or 2.2 mF ceramic capacitor with
low ESR.
Output of the 3.3 V LDO internal regulator. Voltage with respect to ARTN. This pin can be
used to bias an external low−power LED (1 mA max.) connected to nCLASS_AT, and can
also be used to add extra biasing current in the external opto−coupler. VDDL must be by-
passed to ARTN with a 330 nF or 470 nF ceramic capacitor with low ESR.
Classification current programming pin. Connect a resistor between CLASS and VPORTN
Inrush current limit programming pin. Connect a resistor between INRUSH and VPORTN
Operational current limit programming pin. Connect a resistor between ILIM1 and
VPORTN
DC−DC controller under−voltage lockout input. Voltage with respect to VPORTN
a resistor−divider from VPORTP to UVLO to VPORTN
DC−DC controller gate driver output pin.
Internal oscillator frequency programming pin. Connect a resistor between OSC and ARTN.
Active−low, open−drain Layer 1 dual−finger classification indicator.
Output of the internal error amplifier of the DC−DC controller. COMP is pulled−up internally to
VDDL with a 5 kW resistor. In isolated applications, COMP is connected to the collector of the
opto−coupler. Voltage with respect to ARTN.
DC−DC controller inverting input of the internal error amplifier. In isolated applications, the pin
should be strapped to ARTN to disable the internal error amplifier.
Current−sense input for the DC−DC controller. Voltage with respect to ARTN.
Soft−start input for the DC−DC controller. A capacitor between SS and ARTN determines the
soft−start timing.
When the pin is pulled up, the IEEE detection mode is disabled and the device can be sup-
plied by an auxiliary supply. Voltage with respect to VPORTN
ary supply through a resistor divider.
Digital test pin must always be connected to VPORTN
Exposed pad. Connected to VPORTN
1,2
.
http://onsemi.com
5
1,2
Description
ground.
1,2
1,2
1,2
.
.
to set an external UVLO threshold.
1,2
. Connect the pin to the auxili-
1,2
. Connect
1,2
1,2
.
.