Integrator's Manual GR47/GR48

5. SYSTEM CONNECTOR INTERFACE
46
LZT 123 7589 R1A
5.16.1 Digital to Analogue Converter - DAC
The DAC is an 8-bit converter. Conversion takes place when an AT
command is sent to the radio device. The radio device sends the resulting
analogue value to the DAC pin.
Tolerance on this internal voltage is ± 5 %
DAC output electrical characteristics are given in the following table.
(6)
Tolerance on this internal voltage is ± 5 %
(7)
Referred to the ideal conversion characteristic.
(8)
See Figure 5.11, page 46
Figure 5.11 DAC loads
Parameter Limit Units
Resolution 8 Bits
Output voltage for code = 0
(2.75
(6)
x 0.05) ± 0.05
V
Output voltage for code = 255
(2.75
(6)
x 0.95) ± 0.05
V
Nominal step size
(2.75
(6)
x 0.9)/256
mV
Absolute error
(7)
≤ ± 0.5 mV
Output wide-band noise and clock
feed-through 0 - 1.1 MHz
≤ 0.5 mV
rms
Power-supply rejection ratio 50 Hz - 10 kHz ≥ 40 dB
Conversion rate ± 0.5 LSB
≤ 2 (Load A)
(8)
ms
≤ 50 (Load B)
(8)
ms
Output buffer impedance when disabled ≥ 50 k
Ω
Output current source or sink ≥ 1 mA
Current consumption (active) ≤ 1.0 mA
1k
DGND
DAC
1nF
10nF
Load B
100k
DGND
DAC
100 - 200pF
Load A