Key Digital ES381 User Manual download pdf (Page 29)

Isolation rating: 300V CAT II, 500V CAT I between BNC

ground and USB ground

Transient isolation

: 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

Full Speed 12MBits/sec

USB device ID: 10C4 F004

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.

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

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Key Digital ES381 User Manual Page 29