EVBUM2528/D
8
I/O Connectors
There are 7 I/O connectors described in Table 2 below.
The
m
C (or, PWM control IC) output (J3, J4), the XVDD and
XGND (J1, J2) and the XEN (J5) signals are noted as
“primary” ground referenced. There is no true “primary”
and “secondary” ground but there is 1.5 kV galvanic
isolation across the isolation boundary. It is especially
important to maintain isolation in high
−
side, high
−
voltage,
switching applications where the “secondary” VDD (J6, J7)
floats VDD volts above the power supply input voltage:
Table 2. I/O CONNECTOR DESCRIPTIONS
Ref Des
Name
I/O
GND Ref
Type
Description
Value (V)
J1
XGND
Input
Primary
Plated Hole
External primary ground from PWM side
0
J2
XVDD
Input
Primary
Plated Hole
External VDD from PWM side (isolator bias)
5
(Note 1)
J3
IN+
Input
Primary
Plated Hole
Non
−
inverting, PWM input
3.3<V
IN+
<5
(Note 1)
J4
IN
−
Input
Primary
Plated Hole
Inverting PWM input
3.3<V
IN
-
<5
(Note 1)
J5
XEN
Output
Primary
Plated Hole
XEN fault flag or sync signal from NCP51705
5
J6
VDD
Input
Secondary
Plated Hole
NCP51705 VDD
<20
J7
GND
Input
Secondary
Plated Hole
NCP51705 secondary ground
0
J8
XGND
Input
Primary
Plated Hole
External primary ground from PWM side
0
1. The digital isolator, U2, requires that the amplitude of the PWM input (IN+ or IN
−
) be equal to VDD (XVDD) and less than or equal to 5 V.