Af-Assist Lamp On/Off - Canon 580EXII Service Manual

4) EFIDO Terminal Circuit (Camera to Speedlite Transmission Terminal)
(1) EFIDO is input to IC102S pin 26, and is compared with the IC102S internal reference
voltage (2.6V).
(2) If the input voltage of EFIDO is less than 2.6V, "L" is output to IC102S pin 15, and "L" is
input to IC107S pin 14. If it is 2.6V or more, "H" is output, and IC107S recognizes this
signal as a serial input data and commands from the camera.
(3) EFIDO is input to IC102S pin 26. If the input is "H", "L" is output to IC102S pin 22 and
the AVEFI signal is selected to IC102S pin 23. (AVEFI can be output.)
If input of EFIDO is "L", "H" is output to IC102S pin 22, and "L" is output to IC102S pin
23. (AVEFI cannot be output).
<Operation Sequence>
(1) → (2), (3)
5) CCC Terminal Circuit (AF LED [Focus-Assist] ON/OFF)
(1) When CCC's output is "H", it passes through R87 and turns on Q23. Also, it passes
through R88 to IC107S pin 49 (A-D detection terminal). When CCC's output is "L", Q23
turns off.
(2) When Q23 is on, IC102S pin 22 turns off and AVEFI output is enabled.
When Q23 is off, IC102S pin 22 turns on and AVEFI output is disabled.
(3) When "H" is output from IC107S pin 4, RQ11 turns on. When pin 4 is "L", RQ11 turns
off.
(4) If RQ11 is on, R84's current flows from CCC.
<Operation Sequence>
(1) → (2), (3) → (4)

. AF-Assist Lamp ON/OFF

(1) When the camera requires the AF-assist light, 2.2V or higher voltage is input from the
CCC terminal. It passes through R88 and enters IC107S pin 49 (A-D detection terminal).
(A pulse signal is sent from the CCC. This is repeated up to 10 times until AF is achieved.)
(2) If the camera's focusing point is set to the center focusing point, IC107S pin 3 is set
to "H" and RQ8 (L), RQ106S, and RQ103S are turned on to turn on the AF-assist lamp
(PDI). If the EOS-3's Area AF is used, IC107S pin 2 is set to "H" and RQ8 (R), RQ 16, Q4
and RQ31 are turned on to turn on the AF-assist lamps (PD2, PD9) corresponding to the
active focusing point.
(If CCC is lower than 2.2V, IC107S pins 2 and 3 are set to "L" and RQ8 (L&R) turns off.)
IC108S and R132S stabilize the current going to PD1. Also, the current going to PD2 and
PD9 is stabilized by operation amp IC108S, R4 and R5.
(3) In wireless slave mode, IC107S pin 95 is set to H, RQ22 turns off, IC108S pin 3 is set to
0.1V, and the current through PD1 is set to 100mA.
<Operation Sequence>
(1) → (2) → (3)

Technical Information