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MSP430FR6047: LCD Current Consumption Issue in MSP430FR6047

Rohan Sharma
Prodigy 20 points
Part Number: MSP430FR6047
Other Parts Discussed in Thread: TLV8802

Tool/software:

Hello all,
I am working on a MSP430FR6047 microcontroller and I have an issue related to LCD consumption.
I am using LCD glass which takes consumption of just 160nA according to manufacturer and have cross verified. But when integrating it with my controller and in case of all segments on it takes 10.7uA and when all segments are off it takes 5.9uA  and the current of controller is 1.1uA(LPM3 mode). In these cases, my charge pump is disabled and the LCD is being clocked by ACLK, and it is of 8MUX,1/3 bias ,Frame =64Hz ,FLcd =1024Hz and supply of 3.6V.
Glass - SR9028
Below given are the experiments done-
1)  Controller sleep current  - 1.1uA
With internal Biasing
2)Controller current with LCD driver initialization and all segments off -
  Without Glass - 1.5uA
  With  Glass - 5.9uA
3)LCD initialization as per MCU datasheet page no. 35, fLCD = 256 Hz, 4-mux
    At 3V - 1.4uA typically
   We are getting-
   3V - 1.25uA
   3.6V- 1.4UA  with the same setting as per datasheet.
4) Now with our settings , all segments on with panel glass-
   10.6uA.
External biasing-
1)  Internal Reference Voltage, TLV8802 opamp with 6M ohm ladder with our default settings-
Case 1: Glass : SR9028, Internal Reference Voltage, TLV8802 opamp with 6M ohm ladder
At 3.6 V Module Current All Seg ON
All Seg On 7.3 uA LCD R33 3.6 uA
Taking from LCD cap R33 internal supply
Total = LCD + Sleep Mode Opamp 1.5 uA Going to opamp
Ladder 0.6 uA Going in divider
Sleep Mode 1.4 uA W/O Opamp
2) 
Case 2:  External Reference Voltage, TLV8802 opamp 2M ohm ladder
At 3.6 V Module Current All Seg ON
All Seg On 7.3 uA LCD Full 6.15 uA
Checked on LCD external supply
Total = LCD Full + Sleep Mode LCD R33 1.2 uA
Going to LCD cap R33 internal
Sum of all 3 should be equal to above LCD, but it is not
Opamp 1.5 uA Opamp current
Ladder 0.6 uA
Sleep Mode 1.15 uA
 

3) Internal Reference Voltage, TLV8802 opamp with 6M ohm ladder, fLCD = 512 Hz, fFrame = 32 Hz at 3.6V

   All segments on - 5.2uA
Apart from these experiments we have done many more like switching to VLO, pin configurations etc.
We are only able to reduce current consumption only by changing frame frequency and supply.But we don't want to go with this approach.
 
Problem Statement -
We are not able to understand why the controller is taking a current of 10.6uA with all segments on? 
We have verified glass consumption. It takes 160nA with all segments on.
  • 0
    TI__Genius 9105 points

    Hi Rohan,

    I'm out of office today and will come back with this thread in next days of this week.

  • 0 in reply to Pengfei Xie
    TI__Genius 9105 points

    Hi Rohan,

    Sorry for late reply. 

    To be notice, the MCU power consumption with LCD in datasheet page 35 is tested without LCD panel. So it is only related to MCU internal current, and I think you also checked about the value in datasheet in your test.

    So I believe the 10.6uA is mostly contributed by the external circuit. The whole LCD consumption could be much different in different active mode.  

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