Oki ML670100, User Manual, Page: 37 / 94

Chapter 3 Setup and Operation
Page 3-7
3.1.4 V
ref
Selection Switch (VREFSEL)
This switch specifies the reference voltage source for the Board's analog-to-digital
converter: the in3.3-volt power supply or the user application system. (GND <
V
ref
≤
VDD)
Figure 3.7. V
ref
Selection Switch (VREFSEL)
Setting this switch to its SYSTEM position connects the ML670100 V
ref
pin to the
in3.3-volt power supply; the USER position, to the corresponding user interface
connector pin.
Figure 3.8 shows the related circuitry.
Figure 3.8. V
ref
Selection Switch (VREFSEL) Circuits
USER SYSTEM
VREFSEL
VREFSEL
SYSTEM
USER
+3.3V
USER_Vref
(CNU1 pin6)
V
ref
ML670100