Key Digital ES381 - Manual (Page 29)

Isolation rating: 300V CAT II, 500V CAT I between BNC
ground and USB ground
Transient isolation
17
: BNC ground to USB ground +/-2.5KV
4.4.2 Performance
Measurement modes:
Frequency and Period
RUN mode:
Continuous readings
STOP mode: Readings frozen
ONCE mode: Single reading returning to STOP
Input
connector: BNC
Input DC resistance: 1Meg to GND for inputs between (GND-0.4V)
and (INPUT SUPPLY + 0.4V). Outside these
ranges DC resistance approximately 90KOhms
Input capacitance: 20pF typical
Input 3dB bandwidth: 100MHz typical
Input protection: ±30V max to GND
Input supply: 1.50V to 5.00V in 256 steps of 13.7mV to suit
external logic environments (see 2.2)
Main counter:
28-Bits with overflow detect bit
Maximum count rate: Guaranteed 50MHz, typically 100MHz with
input signal suitable to trigger input threshold
Master clock:
12.50MHz, initial accuracy ±0.01%, ageing and
drift after 1 year ±0.005%, temp coefficient
±0.005% /oC
Master clock skew: For 2 or more stacked USBcount50s, typical 2ns
between units
Internal reference clocks:
100MHz, 10MHz, 1MHz from internal PLL
clocked by master clock
Internal reference periods: 0.1s, 1s, 10s divided from master clock
Period edge detection: FALLING->FALLING, RISING->FALLING,
FALLING->RISING, RISING->RISING
4.4.3 Miscelaneous
USB transfer rate:
USB 1.1
18
Full Speed 12MBits/sec
USB device ID: 10C4 F004
17 This figure derives from the 300V CAT II isolation rating and defines the peak transient voltage that
can be safely tolerated between the BNC ground and the USB ground.
18 Works in USB 1.1 or USB 2.0 hosts using the 12MBits/sec full speed mode
Elan Digital Systems Ltd. 29 USBcount50 USER’S GUIDE Iss1