User Manual – 16 V and 48 V Modules
– Doc. No. 1008491.13
© 2014 Maxwell Technologies, Inc.
Page 6
2.86V maximum
3.
The Overvoltage Alarm Signal (Pin 2) is an open collector output indicating when the voltage
management electronics are active. In order to use the signal, the user must connect a pull-up
resistor (≥1kΩ) between Pin 2 and a nominal 5V (maximum 5.5V) supply. In this
configuration, the voltage at Pin 2 will be ~ 5V when the circuit is not active. When a cell in the
module goes into an overvoltage condition, the output of Pin 2 goes low. The Overvoltage
Alarm can be used as a signal to the system electronics to stop charging in order to protect
cells from damage. When an acceptable cell voltage is reached, the output goes high again
and can be used as a signal to resume charging. Figure 4 shows a typical connection to use
this system.
4.
The Overvoltage Alarm circuit can sink up to 5 mA with a V
OL
of no more than 0.4V. The
leakage current when the output is off is 50 nA. The proper value of the pull-up resistor
should be calculated based upon overall system circuit design.
Fig. 4 – Typical connection to the monitor cable. (Users to verify values based on their circuit
design)
The temperature output operates at any module voltage including zero volts.
The TEMP output is via a NTC thermistor and can be measured between pin 4 and pin 1 (GND) of
the connector. The resistance of the thermistor varies with temperature to provide the actual
temperature of the module. The thermistor is located inside the module. Under normal operating
conditions the temperature output should represent the module’s hottest location. The resistance
measured through the thermistor relates to temperature according to a US Sensor thermistor with
a nominal value of 10K
@ 25ºC (reference temperature chart for the 103JM1A.)
http://www.ussensor.com/rt charts/103JM1A.htm
A mating connector for these signals is provided with 6” (15 cm) of cable length. Additional 22
gauge wire may be spliced for longer wire length up to 6 feet (1.8 m). For lengths longer than 6
feet (1.8 m) shielded 4 conductor wire is recommended.
Thermal Performance
3.3
Low internal resistance of the energy storage modules enables low heat generation within the
modules during use. As with any electronic component, the cooler the part operates the longer
the service life. In most applications natural air convection should provide adequate cooling. In
severe applications requiring maximum service life, forced airflow or a liquid-cooled cold plate may
be required.
The thermal resistance,
R
TH
, of the units has been experimentally determined assuming free
convection at ambient temperature (~ 25
o
C). The R
TH
value provided on the datasheet is useful
for determining the operating limits for the units. Using the R
th
value a module temperature rise
can be determined based upon any current and duty cycle. The temperature rise can be
expressed by the following equation.
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