LTC4261 LINER [Linear Technology], LTC4261 Datasheet - Page 21

• Manufacturer Part Number: LTC4261
• Description: Negative Voltage Hot Swap Controllers with ADC and I2C Monitoring
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
Ejector Switch or Loop-Through Connection Sense.
Floating switch contacts or a connection sense loop also
work well with the ON pin, replacing the phototransistor
in Figure 8a. If an insertion debounce delay is desired,
use the EN pin as shown in Figure 8c. Like Figures 8a
and 8b, this circuit works on either side of the backplane
connector.
Short Pin to RTN. Figure 8d uses the UV divider string to
detect board insertion. This method works equally well in
both backplane and board resident applications.
AdvancedTCA Style Control. Figure 2 shows an ATCA
application using EN as the interface to the LTC4261.
Register bit A4 allows the I
of EN and by setting C4 high, bit B4 can generate an alert
to instantly report any changes in the state of EN.
I
fi guration shown in Figure 8e and control the GATE pin
with register bit D3. The circuit defaults off at power up.
To default on, connect the ON pin to INTV
or PGIO can be used as an input to monitor a connection
sense or other control signal. PGIO is confi gured as an
input by setting register bits D6 and D7 high; its input
state is stored at location B6. FLTIN is always an input
whose state is available from register bit B7. FLTIN gen-
erates an alert if C7 is set high.
2
C Only Control. To lock out EN and ON, use the con-
–48V
5V
1k
(8a) Optoisolator Control
INPUT
–48V
–48V
RTN
(8d) Short Pin Connection Sense to RTN
47k
INTV
ON
2
LTC4261
CC
C port to monitor the status
V
EE
EN
453k
28.7k
UVL
UVH
CC
Figure 8. On/Off Control of the LTC4261
–48V
. Either FLTIN
LTC4261
V
EE
INTV
(8b) Logic Control
ON
EN
CC
INTV
ON
LTC4261
CC
V
EE
Data Converter
The LTC4261/LTC4261-2 incorporates a 10-bit analog-
to-digital converter (ADC) that continuously monitors
three different voltages at (in the sequence of) SENSE,
ADIN2/OV (SSOP/QFN) and ADIN. The voltage between
the SENSE pin and V
scale and 62.5µV resolution, and the data is stored in
registers E and F. The ADIN and the ADIN2/OV pins are
monitored with a 2.56V full scale and 2.5mV resolution.
The data for the ADIN2/OV pin is stored in registers G
and H. The data for the ADIN pin is stored in registers I
and J.
The results in registers E, F, G, H, I and J are updated at
a frequency of 7.3Hz. Setting CONTROL register bit D5
invokes a test mode that halts updating of these registers
so that they can be written to and read from for software
testing. By invoking the test mode right before reading
the ADC data registers, the 10-bit data separated in two
registers are synchronized.
The ADIN and ADIN2 pins can be used to monitor input
and output voltages of the Hot Swap controller as shown
in Figures 1 and 2.
EN
–48V
DEFAULT
DEFAULT
OFF
ON
–48V
LOOP OR
SWITCH
(8e) I
(8c) Contact Debounce Delay Upon
Insertion for Use with an Ejector
Switch or Loop-Through Style
Connection Sense
LTC4261/LTC4261-2
2
C-Only Control
INTV
ON
EN
EE
CC
LTC4261
is monitored with a 64mV full
1M
100k
V
EE
10nF
SDAO
SDAI
42612 F08
SCL
EN
LTC4261
INTV
V
EE
CC
I
2
C
ON
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