Gamry Instruments EIS Box, Operator'S Manual, Page: 45 / 52

Appendix A: EIS Box Specifications
45
Channel Characteristics
Mode Active
Channel switching time <10 ms
Cell current 5 A Maximum carried
Counter electrode voltage  6.5 V
maximum
Measured versus EIS Box chassis ground.
Channel Isolation
Current leakage <2 nA maximum To active channel pin from any source.
Impedance
>500 MΩ
<20 pF
Equiv. impedance to EIS Box chassis ground.
NOTES:
1.
Measured in galvanostatic mode with a high-power 2.4  load resistor connected from the counter to the
working electrode leads. The compliance voltage is measured using an external voltmeter across the 2.4 
load. Under these conditions, the output current is approximately 2.72 A.
2. Measured with a high-power 1

load resistor connected between the counter and working electrode
leads, in potentiostatic mode.
3. Unity gain bandwidth and slew rate are correlated. Each has five settings, with the highest slew rate
occurring at the highest bandwidth, down to the lowest slew rate occurring at lowest bandwidth. Both are
measured with 2 k

between counter and reference, and 20

between the reference and the working
and working sense leads.
4. Cell resistor 90
Ω
connected between the counter and working electrode leads, in potentiostatic mode.
5. The A/D and signal-processing chain in the EIS Box allows measurement of voltage signals as large as
±
6.5536 V. The voltage on the Work Sense lead can be as high as
±
0.51 V when measuring 5A using a 60
cm cell cable. This implies a maximum voltage input on the differential electrometer of
±6.04 V.
6. This specification is tested using a 2 G  resistor switched into the input and measuring the voltage
difference with and without the input resistance.
7. The differential impedance is measured between the Reference and Work Sense inputs. This is the
impedance you measure when you record the EIS spectrum of an infinite impedance (open lead) cell.
There is also a common-mode resistance and capacitance associated with the differential electrometer
inputs. These values tell you how much the electrometer response is modified by a resistance in series with
the source.
8. The bandwidth is for a sine-wave source with a 50 Ω output impedance driving either input. The
bandwidth is well in excess of this specification, which is limited by the measurement equipment used in
routine testing of the EIS Box.
9. CMRR is common-mode rejection ratio. It specifies the ability of the differential electrometer to reject
signals connected to both inputs. The CMRR is measured driving both inputs with a sine-wave source with
a 50
Ω output impedance, and measuring the error as a function of frequency. Resistance in either input
will cause a loss of CMRR.
10. Voltage measurement is performed with a nominal  6 V signal input to the ADC signal chain. The actual
full scale is 6.5536 V.
11. The total error in a voltage measurement is:
Error = Zero Offset Error + Gain Error × Voltage
For a 1 V signal the theoretical error can be as high as 2.5 mV. This error is typically less than 0.2 mV.
12. Offsets are summed into the signal. Offset inaccuracy is approximately
±
0.05% of the setting plus
±
0.5
mV.
13. There are six hardware current ranges, separated in sensitivity by decades. The ranges are 50 µ A, 500 µA,
5 mA, 50 mA, 500 mA and 5 A full scale. The ×10 and ×100 gains add two virtual ranges of 5  A and 500
nA full scale.