Appendix A - Specifications
Specifications at 25 degrees C and Vusb/Vext = 5.0V, except where noted.
Parameter
Conditions
Min
Typical
Max
Units
General
USB Cable Length
5
meters
Supply Voltage
4
5
5.25
volts
Supply Current (1)
Hardware V1.21+
50
mA
Operating Temperature
-40
85
°C
Clock Error
-40 to 85 °C
1.5
%
Typ. Command Execution Time (2)
USB high-high
0.6
ms
USB other
4
ms
VS Outputs
Typical Voltage (3)
Self-Powered
4.75
5
5.25
volts
Bus-Powered
4
5
5.25
Maximum Currrent (3)
Self-Powered
450
mA
Bus-Powered
50
mA
(1) Typical current drawn by the U3 itself, not including any user connections.
(2) Total typical time to execute a single Feedback function with no analog inputs. Measured by timing a
Windows application that performs 1000 calls to the Feedback function. See Section 3.1 for more timing
information.
(3) These specifications are related to the power provided by the host/hub. Self- and bus-powered
describes the host/hub, not the U3. Self-powered would apply to USB hubs with a power supply, all known
desktop computer USB hosts, and some notebook computer USB hosts. An example of bus-powered
would be a hub with no power supply, or many PDA ports. The current rating is the maximum current that
should be sources through the U3 and out of the Vs terminals.
Parameter
Conditions
Min
Typical
Max
Units
Analog Inputs
Typical input Range (4)
Single-Ended, LV
0
2.44
volts
Differential, LV
-2.44
2.44
volts
Special, LV
0
3.6
volts
Single-Ended, HV
-10.3
10.3
volts
Special, HV
-10.3
20.1
volts
Max AIN Voltage to GND (5)
Valid Readings, LV
-0.3
3.6
volts
Max AIN Voltage to GND (6)
No Damage, FIO
-10
10
volts
No Damage, EIO
-6
6
volts
No Damage, HV
-40
40
volts
Input Impedance (7)
LV
40
MΩ
HV
1.3
MΩ
Source Impedance (7)
LongSettling Off, LV
10
kΩ
LongSettling On, LV
200
kΩ
LongSettling Off, HV
1
kΩ
LongSettling On, HV
1
kΩ
Resolution
12
bits
Integral Linearity Error
±0.05
% FS
Differential Linearity Error
±1
counts
Absolute Accuracy
Single-Ended
±0.13
% FS
Differential
±0.25
% FS
Special 0-3.6
±0.25
% FS
Temperature Drift
15
ppm/°C
Noise (Peak-To-Peak) (8)
QuickSample Off
±1
counts
QuickSample On
±2
counts
Effective Resolution (RMS) (9)
QuickSample Off
>12
bits
Noise-Free Resolution (8)
QuickSample Off
11
bits
Single-Ended, LV
1.2
mV
Diff., Special, LV
2.4
mV
Single-Ended, HV
9.8
mV
Special, HV
19.5
mV
Command/Response Speed
See Section 3.1
Stream Perfromance
See Section 3.2
(4) With DAC1 disabled on hardware version < 1.30
(5) This is the maximum voltage on any AIN pin compared to ground for valid measurements. Note that a
differential channel has a minimum voltage of -2.44 volts, meaning that the positive channel can be 2.44
volts less than the negative channel, but no AIN pin can go more than 0.3 volts below ground.
(6) Maximum voltage, compared to ground, to avoid damage to the device. Protection level is the same
whether the device is powered or not.
(7) The low-voltage analog inputs essentially connect directly to a SAR ADC on the U3, presenting a
capacitive load to the signal source. The high-voltage inputs connect first to a resistive level-shifter/divider.
The key specification in both cases is the maximum source impedance. As long as the source impedance
is not over this value, there will be no substantial errors due to impedance problems.
(8) Measurements taken with AIN connected to a 2.048 reference (REF191 from Analog Devices) or GND.
All "counts" data are aligned as 12-bit values. Noise-free data is determined by taking 128 readings and
subtracting the minimum value from the maximum value.
(9) Effective (RMS) data is determined from the standard deviation of 128 readings. In other words, this
data represents _most_ readings, whereas noise-free data represents all readings.
Parameter
Conditions
Min
Typical
Max
Units
Analog Outputs (DAC)
Nominal Output Range (10)
No Load
0.04
4.95
volts
@ ±2.5 mA
0.225
4.775
volts
Resolution
10
bits
Absolute Accuracy
5% to 95% FS
±5
% FS
Integral Linearity Error
±1
counts
Differential Linearity Error
±1
counts
Error Due To Loading
@ 100 µA
0.1
%
@ 1 mA
1
%
Source Impedance
50
Ω
Short Circuit Current (11)
Max to GND
45
mA
Slew Rate
0.4
V/ms
Digital I/O, Timers, Counters
Low Level Input Voltage
-0.3
0.8
volts
Hight Level Input Voltage
2
5.8
volts
Maximum Input Voltage (12)
FIO
-10
10
volts
EIO/CIO
-6
6
volts
Output Low Voltage (13)
No Load
0
volts
--- FIO
Sinking 1 mA
0.55
volts
--- EIO/CIO
Sinking 1 mA
0.18
volts
--- EIO/CIO
Sinking 5 mA
0.9
volts
Output High Voltage (13)
No Load
3.3
volts
--- FIO
Sourcing 1 mA
2.75
volts
--- EIO/CIO
Sourcing 1 mA
3.12
volts
--- EIO/CIO
Sourcing 5 mA
2.4
volts
Short Circuit Current (13)
FIO
6
mA
EIO/CIO
18
mA
Output Impedance (13)
FIO
550
Ω
EIO/CIO
180
Ω
Counter Input Frequency (14)
Hardware V1.21+
8
MHz
61
