Datasheet

bq34z100
www.ti.com SLUSAU1B –MAY 2012–REVISED DECEMBER 2012
X10 MODE
The bq34z100 supports high current and high capacity batteries above 32.76 Amperes and 32.76 Ampere-Hours
by switching to a times-ten mode where currents and capacities are internally handled correctly, but various
reported units and configuration quantities are rescaled to tens of milliamps and tens of milliamp-hours. The need
for this is due to the standardization of a two byte data command having a maximum representation of +/–32767.
When the X10 bit (Bit 7) is set in the Pack Configuration register, all of the mAh, cWh, and mWh settings will take
on a value of ten times normal. When this bit is set, the actual units for all capacity and energy parameters will
be 10 mAh or Wh. This includes reporting of Remaining Capacity. This bit will also be used to rescale the current
reporting to 10 times normal, up to +/–327 A. The actual resolution in that case becomes 10 mA.
It is important to know that setting the X10 flag does not actually change anything in the operation of the gauge.
It serves as a notice to the host that the various reported values should be reinterpreted ten times higher. X10
Current measurement is achieved by calibrating the current gain to a value X10 lower than actually applied.
Because the flag has no actual effect, it can be used to represent other scaling values. See Design Energy
Scale.
REMAINING STATE OF CHARGE LED INDICATION
The bq34z100 supports multiple options for using one to sixteen LEDs as an output device to display the
remaining state of charge. The LED/Comm Configuration register determines the behavior.
Table 13. LED/COMM Configuration Bits
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
XLED3 XLED2 XLED1 XLED0 LEDON Mode2 Mode1 Mode0
Bits 0, 1, 2 are a code for one of five modes. 0 = No LED, 1 = Single LED, 2 = Four LEDs, 3 = External LEDs
with I
2
C comm, 4 = External LEDs with HDQ comm.
Setting Bit 3, LEDON, will cause the LED display to be always on, except in Single LED mode. When clear
(default), the LED pattern will only be displayed after holding an LED display button for one to two seconds. The
button applies 2.5 V from REG25 pin 7 to VEN pin 2 (refer to APPLICATION SCHEMATICS). The LED Hold
Time parameter may be used to configure how long the LED display remains on if LEDON is clear. LED Hold
Time configures the update interval for the LED display if LEDON is set.
Bits 4, 5, 6, and 7 are a binary code for number of external LEDs. Code 0 is reserved. Codes 1 through 15
represents 2~16 external LEDs. So, number of External LEDs is 1 + Value of the 4-bit binary code. Display of
Remaining Capacity will be evenly divided among the selected number of LEDs.
Upon detecting A/D value representing 2.5 V on VEN pin, Single LED mode will toggle the LED as duty cycle on
within a period of one second. So, for example 10% RSOC will have the LED on for 100 ms and off for 900 ms.
90% RSOC will have the LED on for 900 ms and off for 100 ms. Any value >90% will display as 90%.
Upon detecting A/D value representing 2.5 V on VEN pin, Four-LED mode will display the RSOC by driving pins
RC2(LED1), RC0(LED2), RA1(LED3),RA2(LED4) in a proportional manner where each LED represents 25% of
the remaining state of charge. For example, if RSOC = 67%, three LEDs will be illuminated.
Upon detecting A/D value representing 2.5 V on the VEN pin, External LED mode will transmit the RSOC into an
SN74HC164 (for 2~8 LEDs) or two SN74HC164 devices (for 9~16 LEDs) using a bit-banged approach with RC2
as Clock and RC0 as Data (see Figure 9). LEDs will be lit for number of seconds as defined in a data flash
parameter. Refer to the SN54HC164, SN74HC164 8-Bit Parallel-Out Serial Shift Registers Data Sheet
(SCLS115E) for detail on these devices.
Extended commands are available to turn the LEDs on and off for test purposes.
ALERT SIGNAL
Based on the selected LED mode, various options are available for the hardware implementation of an Alert
signal. Software configuration of the Alert Configuration register determines which alert conditions will assert the
ALERT pin.
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