Author Topic: Identifying RF chip  (Read 1778 times)

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Offline IanMacdonald

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Identifying RF chip
« on: October 02, 2017, 10:28:11 am »
Anyone able to identify this chip? It's an RF output amp from a car key fob. Fortunately it seems like the encoder chip is OK since that would be manufacturer-specific. This is the RF out chip, and it's leaking such that the battery is discharged in a few days.

Looks like 7507 6228 5RYC

6 is a bit indistinct, others clear.

Assuming the dot is 1:
2: signal in
4: Gnd
7: 12k to gnd
10,11: loop antenna
12: V+ (3v)

 

Offline CJay

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Re: Identifying RF chip
« Reply #1 on: October 02, 2017, 10:32:09 am »
Doubtful it's an RF amp, it's likely to be a microcontroller with RF circuitry built in.

Common fault on keyfobs is leaky switches and a build up of conductive 'crud' in the fob.

I assume you've cleaned it thoroughly, even desoldered the switches?

 

Offline IanMacdonald

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Re: Identifying RF chip
« Reply #2 on: October 02, 2017, 08:15:57 pm »
The other chip to the left is the controller, which seems to be working OK. Buttons desoldered and entire board well washed. Gently warming the RF chip greatly increases the leakage current.
 

Offline nighthunter

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Re: Identifying RF chip
« Reply #3 on: October 04, 2017, 06:21:54 am »
Hi, try to look at Silabs datasheets maybe some Silabs one. On what frequency and modulation does it transmitt?
 

Offline mauda

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Re: Identifying RF chip
« Reply #4 on: December 12, 2019, 08:54:57 am »
Hello, I have also problems with this kind of key fobs. Did you find the datasheet or the solution? Thank you for your reply.
 

Offline fzabkar

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Re: Identifying RF chip
« Reply #5 on: December 12, 2019, 08:32:52 pm »
@mauda, what are the markings on your chip? By comparing them, we may be able to eliminate the date and batch codes.

What are the markings on the other chip? What is the make of vehicle? Japanese car manufacturers would tend to use Japanese ICs, and American cars would tend to use US ICs.





 

Offline nali

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Re: Identifying RF chip
« Reply #6 on: December 12, 2019, 08:48:02 pm »
MC33493 may or may not be the original, but seems to match the pinout

https://www.nxp.com/docs/en/data-sheet/MC33493.pdf

Quote
1 DATACLK Clock output to the microcontroller
2 DATA Data input
3 BAND Frequency band selection
4 GND Ground
5 XTAL1 Reference oscillator input
6 XTAL0 Reference oscillator output
7 REXT Power amplifier output current setting input
8 CFSK FSK switch output
9 VCC Power supply
10 RFOUT Power amplifier output
11 GNDRF Power amplifier ground
12 VCC Power supply
13 ENABLE Enable input
14 MODE Modulation type selection input
 

Offline Yansi

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Re: Identifying RF chip
« Reply #7 on: December 12, 2019, 09:11:37 pm »
A chip from NXP, but hard to guess which one.  You won't get much if any documentation for it anyway, if it is any of the more recent chips, that includes the RFID immobilizer, especially the key-less entry one.
« Last Edit: December 12, 2019, 09:14:56 pm by Yansi »
 

Offline mauda

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Re: Identifying RF chip
« Reply #8 on: December 13, 2019, 08:05:33 am »
It is a common Citroen key fob for Berlingo, Xsara, Picasso, Saxo, etc. usually marked as 73372217A or 73372217B.
I have 4 of them and the chips is marked 7507 6228 ... + other four (non-important) letters are like 5XZ1 or 5LXS or 5XZ1 or 5VBZ.
« Last Edit: December 13, 2019, 08:07:48 am by mauda »
 

Offline fzabkar

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Re: Identifying RF chip
« Reply #9 on: December 13, 2019, 11:56:43 pm »
75076228 looks like an in-house part number. It has the same number of digits as the part number for the key fob.

In the following forum it is described as a Motorola MCU, but that can't be right, can it?

https://www.digital-kaos.co.uk/forums/showthread.php/325914-Reusing-old-Peugeot-Citroen-remotes-type-73373067B-C/page16

 

Offline mauda

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Re: Identifying RF chip
« Reply #10 on: January 04, 2020, 05:33:15 pm »
I ordered theese 7507 chips from Aliexpress (https://bit.ly/2SRTJJL) and they works fine  :-+ Thank you for any help.
 


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