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bq77pl900
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  • Forum Post: bq77PL900 Vout output voltage?

    sean lee11942
    The bq77PL900 Vout output voltage is below 0.975v or 1.2v when sending out the cell voltage. Most MCU have 5V or 3.3V as their ADC rference voltage, so this will decrease resolution of cell voltage. Why bq77PL900 use such design? what 's the benifit? Any suggestion when use a 5V or 3.3V ADC...
    on May 14, 2009

  • Forum Post: bq77PL900 Vout calibration and measurement

    sean lee11942
    When I try to calibrate the vout by changing CAL2-0 and following the step 1-6 listed in datasheet. In each step , I get vout from a MCU A/D input. I found it need "some delay time" to read the actually vout in each step. I think that EV board has a 0.1uf on vout pin, which make the need...
    on May 26, 2009

  • Forum Post: bq77pl900, host control mode - does it continue to monitor cell V for under-voltage automatically? Or only when I measure a cell V myself?

    Brian Myers
    I suspect that it continues to monitor the cells at a 50 millisecond sample rate, just as in standalone mode (Otherwise, what's the point of the FS bit in OUTPUT_CONTROL?) A fellow engineer believes that in host-control-mode, it only measure cell V's when the host measures cell voltage at V_OUT...
    on Jul 10, 2009

  • Forum Post: bq77pl900 problem with vout

    Piotr Bigaj
    Hello, I am having problems with obtaining a Vout signal from bq77pl900. I put bq77pl900 into host-controlled mode and enable cell voltage amplifier (bit VAEN in FUNCTION_CONTROLL) . The STATUS_REGISTER has only CHG and DSG bit set to '1' - the rest is set to '0' (VGOOD bit is '0'...
    on Sep 28, 2009

  • Forum Post: Re: bq77PL900 Vout calibration and measurement

    WM5295
    There are 2 measurement systems, the safety system which runs on the 50ms sample period and is always on, and the cell monitor output (Vout) system which is user selectable. The user selectable cell monitor system samples on the ~ 1.25ms interval. Gas gauges which use a similar architecture AFE use...
    on Oct 16, 2009

  • Forum Post: bq77pl900 EEPROM register question

    Brian Myers
    I have noticed that after writing (or attempting to write) the configuration registers, register 0x0b (EEPROM) retains the value 0xE2 - fair enough. Accordingly, I have put in code after my programming routine that sets this register back to zero. I have not yet actually used my code to re-program...
    on Nov 5, 2009

  • Forum Post: BQ77PL900 cell balancing function

    Lee19407
    Hi I tested cell balancing function of BQ77PL900. test condition: 8S1P 2200mAh , imbalance state, charge to 4.110V at 7th-cell, other cells voltage : 4.010V. imbalance voltage :0.1V , stand-alone mode, OVP set 4.25V , hysteresis 100mV , CBEN set 1, after charge to 33.6V(CC/CV mode), state is...
    on Dec 2, 2009

  • Forum Post: Re: BQ77PL900 cell balancing function

    WM5295
    It certainly seems the balancing is not functioning. The cell voltage drops seem small even for relaxation. If you are monitoring the state of the the status register, be sure the software has not inadvertently put the device in host mode. In host mode balancing is controlled by the host control of...
    on Dec 7, 2009

  • Forum Post: Re: 7 cell li-lion battery

    BatteryBorne
    hello Bajybukn, please look into the features of the bq77PL900. bq77PL900 - multi cell charge, voltage and temperature protector with cell balancing http://focus.ti.com/docs/prod/folders/print/bq77pl900.html Regards, Matthew
    on Dec 16, 2009

  • Forum Post: bq77lp900 ground

    Doug Heermann
    Should the GND pins of the BQ77LP900 be connected to the negative terminal of the battery or the pack (which side of the current sense resistor)? The BQ77LP900 eval kit has them connected to the battery side but has options for both. App notes and reference designs for other BMS chips (e.g. SLUA340B...
    on Feb 24, 2010

  • Forum Post: Re: bq77lp900 ground

    WM5295
    In systems with a gas gauge, external communication is a key part of the system. Having the ground reference at the pack side of the sense resistor keeps the sense resistor from modulating the communication lines with load current changes. The bq77PL900 is anticipated to be used in systems with high...
    on Feb 26, 2010

  • Forum Post: Re: BQ77PL900: EEPROM programming

    WM5295
    You should be able to program with cells attached and at a battery voltage >14V (and less than the device maximum). If you can not adjust your battery voltage to >14V you should disconnect the cells and provide a power supply to device during programming. The 20V is a nice round number with...
    on May 6, 2010

  • Forum Post: bq77pl900

    Larry Shilkoff
    I'm trying to use the evaluation software to exercise the bq77pl900 battery protector. I haven't been able to get the chip to respond to the software. I can see the I2C signals on the comm line, and the clock and data are on the correct lines. I'm delivering ~8 vdc to pin 9 (Batt). According...
    on May 11, 2010

  • Forum Post: Re: bq77pl900

    WM5295
    Be sure you are connected to the I2C connection of the EV2300, the SMBUS connector will not work for the bq77PL900. Once you have your 8V on BAT, you also need to provide a startup voltage to the PACK pin to wake up the part. The 8V should work well there also. Check to see that he regulator voltages...
    on May 12, 2010

  • Forum Post: BQ27510 Production Code

    Nick Moore
    I have written the firmware to program the BQ27510 from the three page flow chart from Going to Production with the bq2750x. However, every time I read register 0x66 to see if the data=0x00 I get the data to equal 0x37. Does anyone have any idea why this might be happening? I'm thinking maybe...
    on Jun 22, 2010

  • Wiki Page: Can I implement multiple temperature thresholds using the bq77PL900?

    WM5295
    Can I implement multiple temperature thresholds using the bq77PL900? by 17523 Can I implement multiple temperature thresholds using the bq77PL900? The bq77PL900 protector has a single temperature input and threshold. A voltage derived from an external thermistor is input to the TIN pin and compared...
    on Aug 24, 2010

  • Wiki Page: FAQ - bq77PL900 FET drive information

    WM5295
    FAQ - bq77PL900 FET drive information by 17523 What is the intended application of the internal FET drive circuit of the bq77PL900 and what additional information is available so I can interface to my FETs? The FET driver was expected to drive through a nominal 5k external resistor to the gate...
    on Aug 24, 2010

  • Wiki Page: bq77PL900 UV and UVH limit and test

    WM5295
    bq77PL900 UV and UVH limit and test by 17523 The paragraph before table 12 in the datasheet SLUS844B reads as follows: " When the undervoltage threshold and the hysteresis values are high, then undervoltage recovery may not occur. To avoid this, Table 12 should be used for assistance in configuration...
    on Aug 24, 2010

  • Forum Post: Interfacing BQ77pl900 with MSP430f1611

    KoroB
    I'm trying to read status register (protocol B), but nothing works out. The code im trying to run on MSP430f1611: #include "msp430f1611.h" char TXData = 0x00; // status register addr char RXData,i; void main (void) { WDTCTL = WDTPW+WDTHOLD; // Stop Watchdog BCSCTL1 &= ~XT2OFF;...
    on Aug 31, 2010

  • Forum Post: Re: Interfacing BQ77pl900 with MSP430f1611

    WM5295
    From a hardware perspective there are a number of things to check, likely with a scope: Is the bq77PL900 awake, out of reset and have FETs on so there is a non-zero status to read? Is VLOG supplied? When the code is run, do the I2C lines toggle at the VLOG level, or at all? Is the resulting...
    on Sep 2, 2010

  • Forum Post: Re: My bq77PL900 is powered up but won't communicate over the serial communication bus. What could be wrong?

    WM5295
    Apply a battery and pack voltage sufficient for both regulators to be up. VLOG must be tied to one of them, Vreg1 as you indicate is fine. XRST should be high. A host should then be able to communicate with the part through the SCLK and SDATA lines. The device block diagram in the datasheet and the EVM...
    on Sep 3, 2010

  • Forum Post: BQ77PL900: standalone mode without programming EEPROM

    Gabba
    Hello! I have a question about bq77pl900: if i write configuration registers from 0x06 to 0x0a (OV_CFG, UV_LEVEL,OCV&UV_DELAY,OC_DELAY, SCD_CFG), can i use the IC'protection features without programming EEPROM?? I want to load these registers with correct values at every start-up of the...
    on Sep 7, 2010

  • Wiki Page: bq77PL900 prewriting data readback

    WM5295
    The bq77PL900 datasheet indicates prewriting data is available when the EEPROM register is set to 0x62. What does this mean and why is it important? Values to be written to the EEPROM are loaded to corresponding register locations. All the EEPROM registers are then written at one time by the EEPROM...
    on Sep 8, 2010

  • Forum Post: Re: BQ77PL900: standalone mode without programming EEPROM

    WM5295
    The bq77PL900 operates from the EEPROM settings. Host mode does not allow dynamic re-configuration of the protection thresholds, but if the host is monitoring the battery parameters, it can take more restrictive actions. Once the EEPROM is written the settings are used in both standalone and host mode...
    on Sep 8, 2010

  • Forum Post: BQ77PL900: problem with reading pack/ batt voltage in host mode

    Gabba
    Hi, I have a problem with the reading of the voltage at pack/bat pin, even if i read the correct voltage of each single cell(then ADC works fine). Using a 12 bit ADC with 3.3V full scale range,i calculate the pack/batt voltage with the formula: (ADC_bits / 4096)* 3.3 * 50. Is it correct? ...
    on Sep 30, 2010
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