RAZR V3 will not charge by simply supplying 5V through USB (it's possible to use common USB cable for charging if you are using Motorola special PC driver software).
Motorola uses the #4 to sense what device is attached to the mini-USB port. Shorting Pin #3 to #2 and #4 causes the phone to go into handsfree/carkit mode and the LCD backlight will ignore timeout settings and stay on.
Shorting pin 4 to pin 2 and to pin 5 via R=200KOhm causes the phone to go into charge mode.
In Order to make your PC charge your phone through a usb cable w/o installing any special drivers or software: Short pins 2 and 3, then put a 200K Ohm resistor between pins 4 and 5.
- The phone supplies ~2.14Vdc to pin X before anything is plugged into it. It needs to be dropped 1V to approx 1.16Vdc. Putting a 200K Ohm resistor between Pins 4 and 5 will bring that voltage down to around 1.16Vdc.
- The wall charger has pins 2 and 3 shorted together. Not sure if it's a safe practice shorting the USB DATA lines together on your PC, so do at your own risk. However, it does work on my terminal with out any ill effects.
| AC adapter Pin |
Name | Direction | Description |
|---|---|---|---|
| 1 | +5 VDC | -?- | PC USB Pin 1 (+5 VDC). |
| 2 | USB Data | -?- | shorted to pin 4 in charger cable. |
| 3 | USB Data | -?- | not connected |
| 4 | -?- | Shorted to pin 2 + shorted to pin 4 via R=200KOhm in charge cable. (R=165KOhm?) | |
| 5 | GND | -?- | PC USB pin 4 (GND). Shorted to pin 4 via R=200KOhm in charge cable. (R=165KOhm?) |
Comment by Darrin
A standard Motorola USB charger puts ~1.4vdc onto the x pin of the mini USB plug. A 200k resistor between pin 2 and 4 produces ~1.9vdc on the 4 pin. This works for Motorola Q (which works from ~1.2vdc to ~1.9vdc), but not for Razr V3m. I had to lower the resistor to 165k. This produces ~1.5vdc and allows the charger to become authorized.
Comment by Andre
After many trial and error, the working pinout for my RAZR V3C was to short 2 and 3 THEN Short 4 and Gnd with a 200KOhm resistor. Work good on my unbranded USB car charger and with a PC without any driver installed.
Here is a schematic :
1 _____________ +5V ____________
2 _______,
PHONE SIDE 3_______/ USB / Power Supply side
4_________/\/200Kohm /\__,_ GND __
5_____________________/
Comment by Eric
Andre's schematic also works for the motorola IC502. I used a 220kohm resistor(that's what I had laying around). Thanks Andre.
Comment by kaputnik
Andre's schematic also works for the V3x. According to the spec sheet for the Enhanced Mini USB interface circuit, shorting pin 2 to pin 3 (the data lines) and putting a resistor of 200kOhm on the ID pin 4 to pin GND will put the phone into Dumb Mid-Rate Charger (500mA) mode with 1.225 volts on pin 4. Putting a 440kOhm resistor on pin x to pin GND will put the phone into Dumb Fast Charger (1.25A) mode with 1.68 volts on pin 4.
Comment by Alex
I just broke my RAZR V3i original car charger and it have the following: 1 +5V, 2 shortened to 3, 4 goes to GND via 440kOhm.
Comment by Tom Maneiro
I have tested with a 260K resistor (i only had these in this range) with a standard Motorola wall-wart charger (the MiniUSB plug on it was broken), and it works with V3c, V3m, U6, U6c... but not with my K1m (it only says Unable to charge).
Comment by Jiri
As reingeneered from V360 charger: 200kR between 4-5 and short circuit between 2-3. It is interesting, configuration with shorten 2-4 (and 4-5 via 200k resistor), as sometimes specified, didn't work. Without short circuit between 2-3 the phone detects charger as a computer. Few trials on resistor: 150k is too small (identified as a computer), 200k is OK, 430k is OK. Sorry, I didn't check charging currents for similarity to V3x observations by Kaputnik.
Steve:
I have got my v3 to charger by shorting pins 2&3, then soldering a 20K potentiometer across 1 and 5 with the wiper connected to 4. Adjusting this potentiometer will put the phone into charging mode, the charging rate can be varied by adjusting the pot. I have used this to make pc and 12V car chargers for the phone. If you measure the voltage on pin 4 with the charger unplugged, you can set the voltage as described in Kaputnik's post and set it to mid or fast charge.
Comment by Ron:
The two resistor values for 500 mA or 1.2 amp power pack is the current limiting level within the switching regulator power pack. Normal phone charger relies on this current limit level to avoid excessive heat dissipation of a linear charge regulator within the phone.
This means the power pack's current limit is matched to the phone battery capacity. Regular Razr has a relatively small mA-H battery, in order of 700 mA Hr so the 500 mA current limit is appropriate charge current level. Smart phone has 1500 mA Hr battery and the larger 1.2 amp current limit battery pack is used.
If a 1.2 amp power pack is used on Razr smaller battery the charge current will be regulated within the phone but at a lower level then even the 500 mA of the proper power pack. This is to avoid too much series pass regulator transistor heating within phone and to also not exceed max charge current of smaller mA-Hr battery.
Note that the charging cable supplied with the phone has the resistor built in to the mini-USB connector, so all you have to do is short pins 2&3 on the USB end of the cable.
Comment by Ton:
For all of you where the Motorola charger broke, I have good news: Get another 5V charger and cut the mini-USB plus with whatever length of cable you want from the Motorola original charger. Notice that the original charger cable is marked: the +Vdd has stripes of about 1 cm long while the GND has letters and numbers writtin on it. Ensure that your new 5V supply can source 500mA and that the actual delivered voltage is not much over 5V ! With a too high input voltage the RAZR refuses to charge. Also when the power supply can't provide the current and the voltage drops below 3.8 V or so it, the phone refuses to charge. Then connect the old mini-usb to your new power supply cable (soldering a bit), and please note the polarity! And there you go: the phone charges again. I *think* (?) that in the original mini-USB plug the circuits shown above are built-in. When I tried connecting with another mini-USB plug the phone did not charge!
Comment by Rik:
By cutting off a 5-wire USB-mini extension cable in two pieces I analysed, with the femal side connected to an original Motorola 5V charger, the conditions required for my RAZR:
White/green (signal) shortcircuited and not otherwise connected to red or black, yellow (id) connected to black (gnd) via 200k.
With the male side of the extension cable connected this way to a USB plug I built an USB charge cable.
As an aside it was quite an effort to purchase an extension cable with the fifth pin connected. A suitable address in Germany is adaptare.de
correct
incorrect