TDC-GP2 acam messelectronic gmbh, TDC-GP2 Datasheet - Page 12

• Manufacturer Part Number: TDC-GP2
• Description: Precision Time Interval Measurement
• Manufacturer: acam messelectronic gmbh

2.5 Power supply
2.5.1 Supply voltage
Although the TDC-GP2 is a fully digital circuit, some analog measures affect the circuit. The reason is that the TDC is
based on the internal analog measure 'propagation delay time' which is influenced by temperature and supply voltage. A
good layout of the supply voltage is essential for good measurement results. It should be high capacitive and of low in-
ductance.
The TDC-GP2 provides two pairs of power supply terminals:
All ground pins should be connected to a ground plane on the printed circuit board. Vio and Vcc should be provided by a
battery or fixed linear voltage regulator. Do not use switched regulators to avoid disturbances caused by the I/O sup-
ply.
2.5.2 Current consumption
The current consumption is the sum from different parties (all data for Vio = Vcc = 3.6V):
I
I
I
I
I
I
ddq
32
hs
tmu
alu
T
< 150 nA
typ. 4.5 µA
typ. 260 µA/s * (active runtime).
typ. 15 mA/s * (active measuring time)
typ. 7 nA per calculation
typ. 2.5 µAs * measure rate
Vio
Vcc
acam-messelectronic gmbh - Am Hasenbiel 27 - D-76297 Stutensee-Blankenloch - Germany - www.acam.de
- I/O supply voltage
- Core supply voltage
Quiescent current,
Current into the 32 kHz oscillator, turned on only if the 32 kHz
oscillator is connected
Current into the high speed oscillator,
Example: In ultrasonic flow-meters the high-speed oscillator is on
for about 2ms only.
The average current consumption is 260 µA/s * 2 ms = 0.52 µA
Current into the time measuring unit,
In measurement range 1 the time measuring unit is active for the
start-stop time interval plus the calibration time interval of 2 periods
of the reference clock per measurement.
In measurement range 2 the time measuring unit is on for average 4
periods of the reference clock per measurement, two for the time
measurement and two for calibration.
Example: With 10 measurements per second in measurement range
2 and a 4 MHz reference clock the time measuring unit is active for
only about 10 µs.
The average current is 15 mA/s * 10 µs = 0.150 µA.
Current into ALU during data proccesing including a calibration
calculation.
Example: At 1000 measurements per second with 3 stops per start
the ALU average current is 7 nA * 3000 = 21 µA.
The current for a full temperature measurement is typ- 2.5µAs. In
heat-meters the temperature is measured typically once every 30
seconds. The average current is about 0.085 µA
12
TDC-GP2
2.5 Power suppl y