7
Rev. 0
CONNECTOR FUNCTIONS
CONNECTOR
NAME
DESCRIPTION
J1, J2
SPI Master, Cell
Monitors
isoSPI connectors.
Pin 1 (iso–) and Pin 2 (iso+) of both connectors are connected in parallel. Thus, any of the two
connectors can be used as the interface to the isoSPI master. For clarity, they are still named differently to indicate
one connector can be used to interface to the isoSPI master and one to a cell monitor. Having two connectors
allows the DC2732A to be easily inserted into the isoSPI bus between a LTC6820 and a LTC681x/ADBMS681x cell
monitor by using two standard Ethernet cables. Physically the LTC2949 is then connected in parallel to this isoSPI
bus and the isoSPI termination resistor (see JP1) must be disabled.
J3
EXT
General purpose I/O connector.
Allows connection to LTC2949’s analog inputs V2 to V7, VBATP, VBATM, general
purpose I/Os V8 to V10, reference output V
REF
and supply voltage A/DV
CC
. See Pin Functions or schematic for
pin assignment.
J4
QuikEval
Linduino QuikEval connector.
Connect the 14-pin flat ribbon cable between this connector and Linduino for
nonisolated SPI operation. Keep in mind that the Linduino has an isolated USB interface, meaning also in this setup
the DC2732A is isolated from the PCs USB port.
Also note, that the Linduino’s default VCCIO output voltage setting (Pin 2) is 5V, whereas LTC2949’s max. IOV
CC
operating voltage is 4.5V. The absolute maximum voltage for IOV
CC
of LTC2949 is 5V plus some safety margin
Analog Devices puts on such parameters, thus no damage will happen even with Linduino’s VCCIO tolerances. Still,
for operation within LTC2949’s specifications, it is recommended to set the jumper JP3 of the Linduino to any of
EXT, 2.5V or 3.3V. It is also allowed to remove the jumper which sets VCCIO to 1.8V. In case EXT is selected, an
external voltage of 1.8V to 4.5V must be applied to JP1 of Linduino or to test point IOV
CC
of DC2732A.
J5
I
2
C
I2C test points.
Allows to connect a scope or 2nd I
2
C master to the onboard I
2
C EEPROM for debugging purposes.
J6
EXTCLK
External clock interface.
In case the internal oscillator and the optional onboard 4MHz crystal is not used, an
external oscillator between 10kHz and 25MHz can be connected to those test points.
J7
NTC (V1)
External NTC connection.
The DC2732A, as default, has an onboard NTC that is connected to V1 and to IM
(negative shunt terminal). This allows a good thermal (via big copper plane) connection to the shunt for sensing its
temperature. As the NTC is put into a voltage divider between V
REF
and GND, it requires the shunt to be configured
for low side sensing (IM connected to GND via JP8). To allow the temperature measurement of the shunt also in
high side current sensing applications, it is possible to remove the onboard NTC R1 and connect an external, wired
NTC to J7. For tight thermal coupling the external NTC can then be clued to the shunt (electrical isolated).
If shunt temperature measurement is not required in high side sensing applications, it is not necessary to remove
the onboard NTC. Still, if leaving the NTC R1 populated, the analog input V1 can’t be used for other purposes. To
allow usage of V1 for other analog input signals, the NTC R1 and the reference resistor R3 must be removed.
J8
GPO
Isolated digital interface to LTC2949’s alert signals (heart-beat signals DO4, DO5).
If enabled, the heart beat
signals of LTC2949 toggle at 400kHz at normal operation. They are transferred via capacitors and the dual isolation
transformer T4 over the isolation barrier, rectified and buffered via the dual comparator LT6700. The open-drain
output signals are driven to V
CC
by weak 150k pull-up resistors, as long the heart beat signals are toggling. The
weak pull-up resistors allow to connect low-ohmic (e.g., 3.3k) external pull-up signals to a different I/O voltage if
required. In case of an alert (e.g., over current), the associated heart beat signals stop, and the comparator’s output
is pulled low indicating the alert on the isolated, low voltage side. See LTC2949’s data sheet for details on the heart
beat signals.
J9
Heart Beat
Test points to the heart beat signals after the isolation transformer and before the rectifier.
For debugging
purposes only.
J8, J9
In addition to the alert and heart-beat signals, those connectors also allow access to the supply voltage input V
CC
and LGND of the onboard flyback converter.
HARDWARE DESCRIPTION
