PRODUCT SPECIFICATION
TMC3033
Pin Descriptions
(continued)
Pin Number
Pin Name
V
REF
PLCC
38
LQFP
35
Value
+1.235 V
Description
Voltage Reference output/input.
An internal voltage
source of +1.235 Volts is output on this pin. An external
+1.235 Volt reference may be applied here which
overrides the internal reference. Decoupling V
REF
to GND
with a 0.1
µ
F ceramic capacitor is required.
Current-setting resistor.
The full-scale output current of
each D/A converter is determined by the value of the
resistor connected between R
REF
and GND. The nominal
value for R
REF
is found from:
R
REF
= 9.1( V
REF
/I
FS
),
but is optimized to be 572
Ω
. I
FS
is the full-scale (white)
output current (in amps) from an output without sync. Sync
current is 0.4 * I
FS
.
D/A full-scale (white) current may also be calculated from:
I
FS
= V
FS
/ R
L
Where V
FS
is the white voltage level and R
L
is the total
resistive load (in ohms) on each D/A converter. V
FS
is the
blank to full-scale voltage.
COMP
37
34
0.1
µ
F
Compensation capacitor.
A 0.1
µ
F ceramic capacitor
must be connected between COMP and V
DD
to stabilize
internal bias circuitry.
Power supply
Ground
Voltage Reference
R
REF
39
36
572
Ω
Power and Ground
V
DD
GND
18, 33, 34
30, 31
12, 30, 31
27, 28
+3.3 V
0.0 V
Equivalent Circuits
V
DD
V
DD
p
Digital
Input
n
OUT
GND
GND
27014C
27013B
n
V
DD
p
Figure 2. Equivalent Digital Input Circuit
Figure 3. Equivalent Analog Output Circuit
5
CADEKA [ CADEKA MICROCIRCUITS LLC. ]
