Sunday, June 16, 2013

[work log] U1 (C8051F501) reprogramming failed analysis report (upload figure)

U1(C8051F501) reprogramming failed analysis report

1. Failed phenomena:

  U1 has F/W inside. Function of board is OK. The device (U1) can not been reprogram F/W, the programmer can't detect this device.

 

2. Fail Rate

  More than 1.5%, total ~80 pcs, verify ~40 pcs by ourself.

 

3. 1st level analysis by repair team

  Action1: use 1 pcs new IC to replace the failed one on the board, then pass;

  Action2: heat up this IC, can resume programming function, but still failed when cold down.

 

4. Repeat the 1st level analysis action and verify

  Take 2 pcs failed sample for example, S/N: L12A008354 and L12A008367, result is as below:

  4.1 Heat U1 (NG: L12A008354), can connect to programmer and reprogram F/W, but after the temperature of U1 is down,still failed (can't connect to programmer and reprogram F/W).

  4.2 Heat U2(NG:L12A008367), still failed. Retry to heat 1 time, failed again.

  4.3 Change 1 pcs new IC on NG board, then pass

 

5. 2nd level analysis based on board/circuit diagram, check the basic working condition

  The U1 is a microcontroller, so the basic working condition is power supply and oscillator. After measure the frequency and voltage by Osc, the basic condition can meet U1 requirement.

 

6. 3rd level analysis, signal check

  6.1 Measure and compare the signal of P1 that uses to connect to programmer.

 

 

Good Board

NG Board

PIN#

Connected

Disconnected

Connected

Disconnected

#1

3.3

3.3

3.3

3.3

#2

0

0

0

0

#3

0

0

0

0

#4

5

5

5

5

#5

2.5

2.5

2.5

2.5

#6

2.5

2.5

2.5

2.5

#7

5

5

0~0.999

5

#8

0

0

0

0

#9

0

0

0

0

#10

5

-3.3

5

-3.3

 

Measure the voltage between GND by DMM

 

PIN7 of P1 connector connect to PIN12 of U1 directly. Pin12 is the reset signal and low voltage is active. But when NG board connect to programmer, this signal keep "0" all the time, but disconnect to programmer, the signal is OK.

Refer to datasheet of C8051F501 


    6.2 Check the interface (C2) and the key signal from U1 (C8051F501)

  C2 Interface: C8051F50x-F51x devices include an on-chip Silicon Labs 2-Wire (C2) debug interface to allow Flash programming and in-system debugging with the production part installed in the end application. The C2 interface uses a clock signal (C2CK) and a bi-directional C2 data signal (C2D) to transfer information between the device and a host system. See the C2 Interface Specification for details on the C2 protocol. (Refer to section 28 of datasheet)


The result is as below:

Item

Sample #

U1 Signal Pin

Picture name#

Status

1

OK(L12A008367)

PIN12

ALL0000/ALL0001

Connected

2

OK(L12A008367)

PIN11

ALL0002/ALL0003

Connected

3

OK(L12A008367)

PIN11

ALL0004

Disconnected

4

NG(L12A008354)

PIN12

ALL0005

Connected

5

NG(L12A008354)

PIN11

ALL0006/ALL0007/ALL0008/ALL0009

Connected

6

NG(E13A021033)

PIN12

ALL0010/ALL0011

Connected

7

NG(E13A021033)

PIN11

ALL0012

Connected


  (Pin12 Good board) Vs. (Pin12 NG board)    

 

 (Pin11 Good board) Vs. (Pin11 NG board)


7. Conclusion and next action

  7.1 Conclusion is that raw material is bad.

  7.2 Send the failed chip samples to supplier for further failure analysis on chip level.


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