BQ33100_15 Datasheet, PDF (55/67 Pages) Texas Instruments – Super Capacitor Manager

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bq33100
SLUS987B – JANUARY 2011 – REVISED DECEMBER 2015
9.2.1 Design Requirements
The bq33100 comes programmed to support 4 series capacitor systems with cell balancing enabled. Other key
configuration defaults are shown in Table 96.
Table 96. Design Parameters
DESIGN PARAMETER
Number of Series Cells
Design Capacitance
Design ESR
Cell Balancing
V CHG Nominal
V CHG A
V CHG
V CHG MAX
Learn Frequency
Learn Delta Voltage
EXAMPLE VALUE
4
250 F
320 mΩ
Enabled
8400 mV
8900 mV
9500 mV
10000 mV
2 weeks
500 mV
Use the bqEVSW tool to update the settings to meet the specific application or pack configuration requirements.
9.2.2 Detailed Design Procedure
This section provides information on selecting key device configuration options. More information on these and
other configuration options is available in bq33100 Super Capacitor Manager - Top 13 Design Considerations,
SLUA751.
9.2.2.1 Selecting Number of Series Capacitor Support
The bq33100 can support 2 to 5 series capacitors when Operation Cfg [STACK] = 0 or 2 to 9 series capacitors
when [STACK] = 1. The main difference is that when [STACK] = 1 the bq33100 will not perform cell balancing.
9.2.2.2 Selecting Charging Voltage Values
The bq33100 learning algorithm requires that the capacitors not be charged to their maximum charging value, for
example: 2.5 V, under normal conditions. This allows for the bq33100 to charge up the capacitors a small
amount and then enable a discharge as part of the learning process. The value to which the capacitors must
charge up to is configured in V Learn Max and is expected to the be the maximum charging voltage as specified
by the capacitor manufacturer, for example: 2.5 V. This is typically also the V CHG MAX value although some
capacitor manufactures will allow a higher voltage for the short learning period compared to the DC value it is
held at during normal charging.
The nominal charging voltage must be selected to enable the capacitor array to provide the required amount of
energy from the capacitance at that voltage. This data is available from the capacitor manufacturer data sheet.
The default value is 2.1 V per capacitor and as the device is configured as a 4 series system then the
programmed value in V Chg Nominal is 8400 mV.
V CHG A and V CHG B must be selected to be evenly spread between V CHG Nominal and V Chg Max, for
example: V CHG A = 8900 mV (2.225 V per cap) and V CHG B = 9500 (2.375 V per cap).
9.2.2.3 Learning Frequency Selection
The default learning frequency of the bq33100 is set to 2 weeks. The capacitance and ESR changes relatively
slowly over time so selecting a period such as 2 weeks or longer allows for a change to be detected.
Setting an automatic update to occur on a very slow rate, for: 2 weeks, and then enabling the host system to
update at a faster, for example: each day, or synchronized to a host system event, for example, after a host
system reboot, is common.
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