BQ34Z100 VEN ON with REG 30mA Current . Why increase Current at VEN ON ??

Jasper,

We recommend placing a 1 kohm resistor in series with the switch connecting REG15 to VEN to limit the current. Please reference the schematic in Figure 7 of the bq34z100 datasheet.

Regards
Tom

Dear Tom 

Now  I used  BQ34Z100  EVM and measured current about this REG Current 30mA  Issues. 

【　Question　】

 Dose BQ34Z100 EVM has this 1k Ohm on EVM Board?? 

 Because of  I could not found 1k Ohm Resister at VEN on EVM.

 But Data Sheet schematic has this 1k ohm as R38.

And  we need Reason for this phenomenon and  cause relation between VEN 1K Ohm and REG.

I think this is some relation to internal function block .

For Instance

    VEN  Function  is  Open Drain or   Push Pull  .... or something.

Regard

Jasper 

Hi  Tom 

I checked  REG25 Current with  this Resister between 1K  and 10k Ohm.

Resister Value(ohm)          REG2.5 Current (mA) 

     0   ohm                                32.8mA

    1k  ohm                                4.25mA

    5K ohm                                2.38mA   

  10k  ohm                               2.13mA   

We wants  Maximum Resister value for VEN .

Because of we need save consumption current at LED Gage Status.  

Could you tell us about this Maximum Resister Value? 

Thanks and Regard

Jasper 

Jasper,

I did not conduct the original analysis to select the resistance value. I an out of the office through Friday, but I will look at it next week. Also, the resistor was added to the newer version of the EVM. You must be using the old one.

Tom

Dear Tom 

Thank you very much.

We want to know just these one.

1)   Why relation this REG25 Current increase with VEN  Resister setting (= Current setting ) ??

2)   Could you tell us about VEN internal Function ??      Pushpull , or Internal Pull Down Resister value.... etc. 

3)   About this resister setting finale value decide by  High Level keep  minimum current for VEN.

     This mean  , almost device has V_IL , V_IH, I_IL and  I_IH spec.    I think need I_IH spec  VEN for this device.

Any way can I contact  to you directory??

Regard

Jasper 

Dear Tom 

Thank you very much.

Thanks and Regard

Jasper in Japan 

Dear Tom 

Thank you very much about this Resistance and Current Value.

But we need more some information about this Answer.

Question 

1)  This VEN Port internal easy Block and Structure.  * What type input Port structure? 

    Because of we need how to calculate about this Resister value with Min Current. 

Thanks and Regard

Jasper 

Jasper

The pin has a totem pole output structure to provide gate drive to the external FET network that disables the BAT sense circuit when the voltage measurement is not in progress. The pin also have an analog input buffer and you have to force current into the pin to overdrive the internal low-side FET. The series resistance needs to be 33 kohm or smaller to overdrive the FET and actuate the LEDs.

Regards

Tom

Dear Tom 

Thank you very much.  

I understood VEN structure.

 Thanks and Regard

Jasper in Japan

Hi,

I am also trying to use the BQ34 in the led configuration : 5 leds ,I2C bus

- Pack Configuraton = 0x0141

- Pack Configuration  B = 0xFF

- Pack Configuration C  = 0x30

- Led_Comm Configuration = 0x43

- Number of cells = 0x01

The schematic to enable the I2C communication is quite similar to the one shown at page 46 of the  Bq34Z100 - G1 data sheet but when I press the button no communication occurs.Really  I don't understand what is my mistake .

Moreover the VEN pin goes high every 1 sec. for about 150 mS and when the button is pressed I can detect the 2,5 V on one side of 1K resistor but on the other side (VEN)  I only see the 1 second transition of VEN pin

Thanks

Giuliano