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LM96000: LM96000 PWM output and TACH input

Terry Wu2
Expert 2110 points
Part Number: LM96000

Hello Sirs,

We need to use two LM96000 at same SMBUS system for six PWM and six TACH meter.

So need to pull correct level for PWM3/ADD_enable and TACH4/ADD_sel .

Do you have comment for :

LM96000#1  pull up 10K to 3.3V for PWM1~3  . Slave address is default "0x2e"

LM96000#2  pull up 10K to 3.3V for PWM1~2 . How to treat PWM3/ADD_enable for this is open-drain pin ?   How to treat  TACH4/ADD_sel ? What's slave address for this device ?

Many thanks !

I hear this description. Does it mean I can't use TACH4 and PWM3 for 2nd LM96000 ??

When using the non-default addresses the TACH4
and PWM3 will not function. As shown in the timing diagram the Address Enable pin must remain low in order for
the latched address to remain in effect. If the address enable pin is pulled high after the first SMBus
communication, then the LM96000 SMBus address will revert to the default value (2Eh) after the first five clocks
of next SMBus communication

  • 0
    TI__Expert 6715 points
    Terry,

    I will need to think about this one and get back to you.

    -Kelvin
  • 0 in reply to Kelvin Le THS
    TI__Expert 6715 points
    Terry,

    Unfortunately, it looks like when you are using two LM96000s on the same SMBus you can only control up to 5 fans because the second device's TACH4 and PWM3 will not function as you noticed in the datasheet.

    Device #1 pull up 10K to 3.3V for PWM1~3 . Slave address is default 0x2E.
    Device #2 pull up 10K to 3.3V for PWM1~2 .

    Pull down 10k to GND for PWM3 for Address Enable mode and
    pull up or down on TACH4 for Address Select depending on your preference of the SMBus slave address.
    Pull down TACH4 for 0x2C or pull up TACH4 for 0x2D. Please refer to the address table on pg.9 of the datasheet.

    -Kelvin
  • 0 in reply to Kelvin Le THS
    Expert 2110 points
    Hello Kelvin,

    Can't believe it ... I need to add extra component for this ?

    Many thanks your help so much ~