LTC4245CUHF
6
low can lead to a PGI fault causing
all FETs to be turned off.
JP6 to JP9 ADR0 to ADR3: Selects 1 of
32 possible addresses for the LTC4245
I
2
C interface by strapping the ad-
dress pins high, low or allowing them
to float. An address table is shown
in the datasheet and the Help menu of
the evaluation software. The software
can automatically scan and identify
the I
2
C address, regardless of the
pin setting.
LEDs
D1 to D8: D1 to D4 indicate if the
input supplies are high. D5 to D8
light up when the supply outputs
power up, after the FET switches turn
on.
D9 HEALTHY#: This should light up at
the end of the start-up timing cycle
after all the supply outputs power
up. It will turn off as soon as any
FET switch is turned off or if any
output falls out of tolerance.
D10 LOCAL_PCI_RST#: This LED normally
flashes briefly during start-up and
power-down. This is because it is
powered off +3.3V OUT and the pin is
released at the end of the start-up
timing cycle. It will be lit continu-
ously if +3.3V OUT is high and
PCI_RST# is set low with JP2.
D11 ALERT#: The ALERT# pin pulls low
and turns on this LED if a fault oc-
curs and that fault’s alert is en-
abled in the ALERT register. The
alert can be cleared either by reset-
ting bit B3 in the ALERT register or
writing to the LTC4245 alert response
address (ARA).
SOFTWARE SETUP
Communicating with the LTC4245 I
2
C
interface requires the QuickEval Sys-
tem software and a DC590 board. The
QuickEval software is available from
the website www.linear.com/software.
The QuickEval software talks to the
DC590 board through the USB port of
the PC. The DC590 is connected to the
I
2
C port (P2) on the DC985A-B with
the supplied 14-wire ribbon cable
(Figure 2). When connected, the
QuickEval software identifies the
DC985 and brings up the LTC4245 in-
terface as shown in Figure 3. When
experiencing problems with the soft-
ware, try unplugging and plugging the
DC590 board from the PC. Also refer
the DC590 Quick Start guide.
I
2
C ADDRESS SELECTION
Select in the drop down list box the
Write address byte of the LTC4245
that is to be communicated with. The
address pins to I
2
C address map can
be found in the Help menu. Easier
still, the Auto Find button will scan
through the 32 individual LTC4245 ad-
dresses and list which addresses re-
sponded with an acknowledge. If mul-
tiple LTC4245s are on the bus lines,
the Mass Write address 2Eh can be se-
lected to write to all LTC4245s at
the same time. The ARA button sends
the Alert Response protocol address
and displays the address of the de-
vice holding its ALERT# pin low.
5V ADC LSB AND -12V ON CONTROL
Select the radio button that corre-
sponds with the CFG pin jumper, JP4,
