© 2013
PAGE 9
WTC3293
www.teamwavelength.com
WTC3293-00400-I
STEP 9: ADJUSTING THE TEMPERATURE SETPOINT VOLTAGE
The setpoint voltage can be adjusted either by using the evaluation board’s onboard SET T trimpot or
by connecting a remote voltage source or potentiometer to the RSET or HSET inputs. When under
control, the setpoint voltage matches the sensor voltage at the desired temperature.
To use only the onboard SET T trimpot
, place the VSET SOURCE jumper on the bottom of the WTC3293
evaluation board in the “
T
” position, and do not connect an external voltage source. The SET T trimpot
will allow the setpoint to be adjusted from 0 V to 5 V. Figure 6 shows the jumper location. To get above
4.5 V, increase V
DD
to a minimum of 5.5 V.
To use only an external voltage source for the setpoint
, either place the VSET SOURCE jumper on the
bottom of the WTC3293 board to the “
X
” position and connect the external setpoint voltage source to
RSET on TB3, or remove the jumper and connect the external setpoint voltage source to the HSET
terminal on TB2. When the VSET SOURCE jumper is in the “
X
” position or removed, the voltage dialed
in using the SET T trimpot on the WTC3293 is ignored. Figure 6 shows the jumper location.
The RSET input is subject to the DAQ Failsafe Protection circuit. If RSET drops below 0.3 V, the
setpoint will be overridden and set to 1 V. See the Application Notes section for changing these
defaults. RSET is limited to 0-6.5 V.
The HSET remote setpoint input is not subject to
the DAQ Failsafe Protection circuit. It is limited
to 0 to V
DD
- 2.5 V.
Connecting An External Potentiometer:
RSET:
Set the VSET SOURCE jumper in the
“
X
” position (subject to DAC Failsafe Protection
circuit). Place the potentiometer’s CW terminal in
the pin marked 2.5 V. Connect the potentiometer’s
wiper (W) to the pin marked RSET and CCW
terminal to the pin marked COM. Do not use less
than 2 k
Ω
resistance, or the 2.5 V will droop.
HSET:
Remove the VSET SOURCE jumper
(not subject to DAC Failsafe Protection circuit).
Place the potentiometer’s CW terminal in the pin
marked 2.5 V. Connect the potentiometer’s wiper
(W) to the pin marked HSET and CCW terminal
to the pin marked COM. Do not use less than
2 k
Ω
resistance, or the 2.5 V will droop.
STEP 10: ENABLING AND DISABLING THE OUTPUT CURRENT
The WTC3243 output current can be enabled and disabled using the onboard toggle switch. The
output is enabled when the green ON LED indicator is lit. An external enable signal to REN (TB2)
can be used.
0 V =
ENABLED
Floating or >3 V =
DISABLED
The onboard switch overrides the external signal.
If there is no power to V
S
, the enable LED will not light.
CONFIGURING THE EVALUATION BOARD
(-)
(+) FAN
REN
HSET
COM
W
CW
CCW
2.5 V
TB2
SET T
ACT T
LIMA
LIMB
COM
RSET
TB3
Figure 9
Example Wiring --
External Setpoint Adjustment -- RSET
