U1(C8051F501) reprogramming failure 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
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 #
|
Status
|
1
|
OK(L12A008367)
|
PIN12(Reset/clk)
|
ALL0000/ALL0001
|
Connected
|
2
|
OK(L12A008367)
|
PIN11(Data)
|
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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