Canon 580EX - Speedlite II - Hot-shoe clip-on..., Service Manual, Page: 29 / 97

Technical Information
. SE Timer
(1) With the wireless mode set to OFF or MASTER, if no operation is executed for about
90 seconds (Maximum 15 minutes, if it is overheated) after the Power SW is turned on,
IC107S pin 115 becomes "L" and IC15, IC17 and RQ100S turn off to cut off the power
source. This also occurs when the no-operation-time is 60 seconds with the wireless
mode set to SLAVE.
(2) When IC107S pin 114 goes off, oscillation stops.
(3) The Speedlite restarts (SE mode canceled) when the test button (TEST SW) is pressed or
when there is a signal (CCC and EFIDO terminal is "H") from the camera. This inputs an
"L" to IC107S pin 117 and pin 14.
(4) IC107S pin 115 thereby goes "H" and the Speedlite restarts.
<Operation Sequence>
(1) → (2) → (3) → (4)
.9 Flash Firing Operations
1) Trigger output
Trigger output is executed when the Speedlite is fully recharged and the flash is fired with the
test firing button (TEST SW) or with a firing command from the camera.
(1) With the firing command, "H" is output from IC107S pin 10.
(2) This signal turns on SCRI, and C21 starts to discharge.
(3) The voltage stepped up by T2 is applied to Xe. (Trigger voltage)
(4) Also, with the firing command, "H" is output from IC107S pin 112, Q 18 turns on and
Q17 turns on.
(5) When Q17 turns on, the 30V is generated by Q20, Q 19, and ZD3 passes through Q15
and it is applied to IT1's gate. IT1 thereby turns on.
(6) When IT1 turns on, Xe discharged electric current passes.
<Operation Sequence>
(1) → (2) → (3)
(4) → (5)
(6)
2) Flat Firing (Preflash, Main Flat Firing)
The preflash fires at the preflash command from the camera regardless of whether bounce
flash has been set.
(1) By the firing instruction from the camera, serial data communications using IC107S pin
57 (chip select), pin 58 (chip select), pin 37 (clock sync) and pin 36 (command data)
start, and serial data is sent respectively to IC102S pin 7 (chip select), pin 8 (chip select),
pin 10 (clock sync) and pin 9 (command data).
(2) Serial data (firing control value (A/D converter voltage), firing command) is sent to
IC102S from IC107S according to the firing wave height value data from the camera and
the firing mode (regular (no firing), flat firing, flash firing, TTL firing).
Also, "H" is output to IC107S pin 56, and input to IC102S pin 11.
(3) If "L" outputs from IC107pin 41, the voltage corresponding to the firing intensity in the
flat firing mode is generated at pin 31 by the PD10 metering sensor selected in IC20.
(4) That voltage is compared with the firing control value (A/D converter voltage). If the
voltage is lower than the internal reference voltage (1.6V), "H" is output to IC102S pin
17. If it is higher, "L" is output.