Identifying RF chip - Page 1
Forum section: electronics / repair

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: October 02, 2017, 10:28:11 am
content: 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 5RYC6 is a bit indistinct, others clear.Assuming the dot is 1:2: signal in4: Gnd7: 12k to gnd10,11: loop antenna12: V+ (3v)

author: CJay
author_rank: Super Contributor
timestamp: October 02, 2017, 10:32:09 am
content: 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?

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: October 02, 2017, 08:15:57 pm
content: 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.

author: nighthunter
author_rank: Newbie
timestamp: October 04, 2017, 06:21:54 am
content: Hi, try to look at Silabs datasheets maybe some Silabs one. On what frequency and modulation does it transmitt?

author: mauda
author_rank: Newbie
timestamp: December 12, 2019, 08:54:57 am
content: Hello, I have also problems with this kind of key fobs. Did you find the datasheet or the solution? Thank you for your reply.

author: fzabkar
author_rank: Super Contributor
timestamp: December 12, 2019, 08:32:52 pm
content: @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.

author: nali
author_rank: Frequent Contributor
timestamp: December 12, 2019, 08:48:02 pm
content: MC33493 may or may not be the original, but seems to match the pinouthttps://www.nxp.com/docs/en/data-sheet/MC33493.pdfQuote

author: Yansi
author_rank: Super Contributor
timestamp: December 12, 2019, 09:11:37 pm
content: 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.

author: mauda
author_rank: Newbie
timestamp: December 13, 2019, 08:05:33 am
content: 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 marked7507 6228... + other four (non-important) letters are like 5XZ1 or 5LXS or 5XZ1 or 5VBZ.

author: fzabkar
author_rank: Super Contributor
timestamp: December 13, 2019, 11:56:43 pm
content: 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

author: mauda
author_rank: Newbie
timestamp: January 04, 2020, 05:33:15 pm
content: I ordered theese 7507 chips from Aliexpress (https://bit.ly/2SRTJJL) and they works fineThank you for any help.

author: luisaco
author_rank: Newbie
timestamp: August 21, 2024, 07:24:37 pm
content: Hello friends,You were finally able to repair the keys by changing the 75076228, I have 2 Berlingo keys and neither of them emits RF and at least one of them when measuring voltage between GND and pin 12 gives me 3v and on pins 10 and 11 which are the antenna also gives me 3v is that normal?

author: luisaco
author_rank: Newbie
timestamp: August 22, 2024, 04:41:37 pm
content: Hello friends,You were finally able to repair the keys by changing the 75076228, I have 2 Berlingo keys and neither of them emits RF and at least one of them when measuring voltage between GND and pin 12 gives me 3v and on pins 10 and 11 which are the antenna also gives me 3v is that normal?