ES51919/ES51920
Features
•
19,999/1,999 counts dual LCD display
•
Current consumption: Typ. 25mA @ 100kHz
•
QFP-100L package for ES51919
•
SSOP-48L package for ES51920
•
•
•
•
•
LCR meter chipset
Application
Handheld LCR bridge meter
Description
The chipset of ES51919/ES51920 is suitable
4-wire terminal with guarding measurement
for LCR bridge application. By using
AutoLCR smart check and measurement
ES51919/ES51920 to implement the LCR
bridge meter, the complicated PCB design is
Series/Parallel modes are selectable
not necessary. The ES51920 is the analog frond
Ls/Lp/Cs/Cp with D/Q/θ/ESR parameters
end chip with resistor switches network to
Open/Short calibration for AC impedance
provide different ranges control. It also
measurement is allowed:
provides a high performance integrated circuit
Open condition requirement: Impedance is
by the signal with different frequency to
larger than 9.5MΩ @ 1kHz
measure the complex impedance of the DUT
Short condition requirement: Impedance is less
by 5-terminals architecture. The ES51919 is
than 1.1Ω
the mix-mode processing chip to handle the
calculation of the D/Q/ESR/θ parameter with
Ls/Lp/Cs/Cp values. It also provides the user
interface and LCD drivers to support dual
display operation. Tolerance mode and relative
mode are including in the dual display
operation. A multiple-level battery detection
and auto power-off scheme are built-in to help
the improvement of battery life. The high
performance of 4.5digits ADC circuit design is
implemented in the ES51919/ES51920 chipset.
A fully smart measurement for L/C/R is
possible. User could measure the DUT
impedance simply without change function key
at the AUTOLCR smart mode
•
Support DCR mode 200.00Ω~200.0MΩ
•
Five different test frequency are available:
100/120/1k/10k/100k Hz
•
Test ac signal level: 0.6mV
RMS
typ.
•
6 range resistor range used
•
Test range:
L: 20.000
µH
~ 2000 H
C: 200.00 pF ~ 20.00 mF
R: 20.000
Ω
~ 200.0 MΩ
•
Multi-level battery voltage detector
•
Support Backlight & Buzzer sound driver
•
Source resistance depends on range
Min: 120Ω typical
Max:1MΩ typical
Ver 2.3
1
12/03/01
Introduction
The ES51919/ES51920 chipset is a total solution for high accuracy LCR meter
which could measure Inductance/Capacitance/Resistance with secondary parameters
including dissipation factor(D), quality factor(Q), phase angle(θ), equivalent
series/parallel resistance(ESR or Rp). The chipset is fully auto ranging operation for AC
impedance & DC resistance measurement. Because of high integrated circuit design, a
smart measurement for L/C/R is possible (AUTOLCR mode). It means the user could
measure the L/C/R components directly at AUTOLCR smart mode without changing the
function key. User could also select the target test frequencies of
100Hz/120Hz/1kHz/10kHz/100kHz depending on DUT type. Components could be
measured in series or parallel mode according to the DUT impedance automatically.
The LCR chipset built-in a 4.5 digits ADC operates at 1.2/s updating rate nominally
for L/C/R mode. The chipset operates at 0.5/s updating rate for DCR mode.
The general DMM could measure DC resistance only, but the LCR meter could
measure DC resistance and AC impedance. The impedance consists of resistance (real
part) and reactance (imaginary part). For example, Zs represents the impedance in series
mode. Zs can be defined a combination of resistance Rs and reactance Xs. It also could
be defined as a |Z| of magnitude with a phase angle
θ.
Imaginary axis
Xs
| Zs |
(series mode)
Zs = Rs + jXs
θ
>0
θ
θ
1
Rs
1
θ
1
< 0
Rs
Real axis
Xs
1
Zs
1
= Rs
1
+ jXs
1
Zs = Rs + jXs or |Zs|∠θ
Ver 2.1
2
12/03/01
|Z| =
Rs
2
+
Xs
2
Rs = |Zs| cosθ
Xs = |Zs| sinθ
Xs/Rs = tanθ
θ
= tan
-1
(Xs/Rs)
If
θ
> 0, the reactance is inductive. In other words, if
θ
< 0, the reactance is capacitive.
There are two types for reactance. The one is the inductive reactance X
L
and the
other is the capacitive reactance X
C
. They could be defined as: (f = signal frequency)
X
L
= 2πf L (L = Inductance)
X
C
=
1
(C = Capacitance)
2
π
f
C
Measurement mode
The impedance could be measured in series or parallel mode. The impedance
Z
in
parallel mode could be represented as reciprocal of admittance
Y.
The admittance could
be defined as Y = G + jB. The G is the conductance and the B is the susceptance.
Impedance in serial mode
Rs
jXs
Admittance in parallel mode
Rp
Z = Rs + jXs
Rs: Resistance in series mode
Xs: Reactance in series mode
Cs: Capacitance in series mode
Ls: Inductance in series mode
jXp
Rp: Resistance in parallel mode
Xp: Reactance in parallel mode
Cp: Capacitance in parallel mode
Lp: Inductance in parallel mode
Y = 1/Z = 1/Rp + 1/jXp = G + jB
There are two factors to provide the ratio of real part and imaginary part. Usually
the quality factor
Q
is used for inductance measurement and the dissipation factor
D
is
used for capacitance measurement.
D
factor is defined as a reciprocal of
Q
factor.
Q = 1 / D = tanθ
Q = Xs / Rs = 2πf Ls / Rs = 1 / 2πf Cs Rs
Q = B / G = Rp / | Xp | = Rp / 2πf Lp = 2πf Cp Rp
Ver 2.1
3
12/03/01
Actually, Rs and Rp are existed in the equivalent circuit of capacitor or inductor. If
the capacitor is small, Rp is more important than Rs. If capacitor is large, the Rs is more
important also. Therefore, use parallel mode to measure lower value capacitor and use
series mode to measure higher value capacitor. For inductor, the impedance relationship
is different from capacitor. If the inductor is small, Rp is almost no effect. If inductor is
large, the Rs is no effect also. Therefore, use series mode to measure lower value
inductor and use parallel mode to measure higher value inductor.
Open/short calibration
The ES51919/ES51920 chipset provides the open/short calibration process to get the
better accuracy for high/low impedance measurement. The purpose of open/short
calibration is to reduce the parasitic effect of the test fixture.
Z
M
is defined as total impedance measured to DUT by the special test fixture which
1
has some parasitic impedance. Z
M
= (Rs + jωLs) + (
|| Z
DUT
)
Go
+
j
ω
Co
Z
OUT
is the target impedance user wants to realize. It is necessary to use the
open/short calibration process to cancel the effect of Rs + jωLs and Go+jωCo.
Ver 2.1
4
12/03/01
Equivalent circuit
Z
SHORT
Z
M
Y
OPEN
Z
DUT
Z
DUT
=
Z
M
– Z
SHORT
1-(Z
M
-Z
SHORT
)Y
OPEN
Ver 2.1
5
12/03/01
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