I have bought a no-brand, passive HDMI Male to VGA Female adapter, to link up a PC with a more dated monitor. It did not work.
After doing some reading, I have learned that buying such an adapter is often discouraged because in many cases it will not convert the signal from Digital to Analog, or the Motherboard/CPU on a specific computer might not be compatible with that particular adapter.
So my question is: seeing how there are so many of these passive adapters on the market, are there circumstances under which they actually do suffice to connect an HDMI output to a VGA input? Or are they generally just a rip-off?
Example of the kind of adapter I bought:
41 Answer
are there circumstances under which they actually do suffice to connect an HDMI output to a VGA input?
There are no "passive" HDMI to VGA adapters. It requires active signal conversion. HDMI uses digital data sent over differential pairs, VGA uses analog voltage levels sent over single signal wires per colour channel.
I use a cheap plug and play, line-powered, HDMI to VGA adapter to connect a Raspberry Pi 4 to an old VGA monitor. It works well, needs no external power, no drivers, no setup, but it is not passive ("Supports output up to UXGA/1080p with 10-bit DAC").
Not much larger than a VGA connector but large enough to contain active circuitry powered from HDMI pin 18
Compare
PIN CONNECTIONS FOR TYPE A HDMI CONNECTOR HDMI PIN NUMBER SIGNAL 1 TMDS Data 2+ 2 TMDS Data 2 shield 3 TMDS Data 2- 4 TMDS Data 1+ 5 TMDS Data 1 shield 6 TMDS Data 1- 7 TMDS Data 0+ 8 TMDS Data 0 shield 9 TMDS Data 0- 10 TMDS Clock+ 11 TMDS Clock shield 12 TMDS Clock- 13 CEC 14 HEC Data- 15 SCL (Serial Clock for DDC 16 SDA (Serial Data Line for DDC 17 DDC / CEC / HEC Ground 18 +5 V Power (50 mA max) 19 Hot Plug Detect (1.3) / HEC Data+ (1.4) with
VGA Pinout Configuration Pin No. Pin Name Description 1 RED Red video (75 ohm, 0.7V peak-to-peak) 2 GREEN Green video (75 ohm, 0.7V peak-to-peak) 3 BLUE Blue video (75 ohm, 0.7V peak-to-peak) 4 ID2 / RES Monitor ID Bit 2 / Reserved 5 GND Ground 6 RGND Red Ground 7 GGND Green Ground 8 BGND Blue Ground 9 KEY +5V DC output from graphic card 10 SGND Sync Ground 11 ID0 / RES Monitor ID Bit 0 / Reserved 12 ID1 / SDA Monitor ID Bit 1 / I2C bi-directional data line 13 HSYNC Horizontal Sync 14 VSYNC Vertical Sync 15 ID3 / SCL Monitor ID Bit 3 / I2C data clock So far as I can tell, there is nothing in common that could usefully be passed through using a passive connector.
