MCP18480
DS20091B-page 34
?2003 Microchip Technology Inc.
V
REFOUT
6
O
A
Reference output.
Internal reference output voltage (typically 2.5V). Usually tied back to
the V
REFIN
pin unless an external high-precision reference voltage is
desired.
V
REFIN
7
I
A
Reference input.
This pin allows a high-precision reference voltage for the following
functions:
" Undervoltage Comparator
" Overvoltage Comparator
" DRAIN Comparator
" Current Limit Timer
If the precision of the V
REFOUT
output voltage is acceptable, tie the
V
REFOUT
pin to the V
REFIN
pin.
CL
8
I
A
Current Limit.
Input used to set the maximum current limit threshold allowed by the
system via a resistor divider network (with the resistor R
CL1
between
the V
REFIN
pin and the CL pin and resistor R
CL
between the V
NEG
pin
and the CL pin). If the voltage across the sense resistor exceeds the
voltage on the CL pin, it implies that there is excessive current over the
allowed limit and forces the GATE pin to the V
NEG
pin voltage level
without delay.
I
SET
9
I
A
Current source set.
Establishes the internal I
SOURCE
for the following:
" Undervoltage Delay
" Current Limit Timer
" GATE Pin Source Current
An external resistor R
ISET
from the I
SET
pin must be connected to
either the V
NEG
pin or the V
REFIN
pin to set I
BIAS
, which will then estab-
lish the current sources throughout the device. The I
BIAS
current is the
same for either connection.
Connecting the R
ISET
resistor to the V
NEG
pin will establish the
PWRGOOD pin output polarity to be active-high. Connecting the R
ISET
resistor to the V
REFIN
pin will establish the PWRGOOD pin output
polarity to be active-low.
TABLE 3-1:
MCP18480 PIN DESCRIPTIONS (CONTINUED)
Pin Name
Pin
Number
Pin
Direction
Buffer
Type
Description
SSOP
Legend: TTL = TTL compatible input
ST = Schmitt Trigger input with CMOS levels
I = Input
O = Output
P = Power
CMOS = CMOS-compatible input
A = Analog
D = Digital