Datasheet

UNISONIC TECHNOLOGIES CO., LTD
GF2140
LINEAR INTEGRATED CIRCUIT
LOW POWER TWO-WIRE
GROUND FAULT INTERRUPTER

DESCRIPTION
As a low power controller for AC output appliance leakage current
interrupters, the UTC GF2140 can detect hazardous current paths to
ground, and trigger SCR to protect.

SOP-8
FEATURES
* Directly powered from the AC line
* Build-in bridge rectifer
* Interface to SCR
* Adjustable trip current and time delay
* Minimum external components
* For two-wire system
* Be used in 110V or 220V system

ORDERING INFORMATION
Ordering Number
GF2140G-S08-R

Package
SOP-8
Packing
Tape Reel
MARKING
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GF2140
LINEAR INTEGRATED CIRCUIT

PIN CONNECTIONS

PIN DESCRIPTION
PIN
1
2
3
4
5
6
7
8

PIN NAME
RSET
VFB
VREF
GND
Line
Neutral
SCR Trigger
C Delay
I/O
O
I
I
I
I
O
PIN FUNCTION
Output of Leakage current first
Input of leakage current
Reference voltage
Ground
Line input
Neutral input
SCR Trigger
The Delay time
BLOCK DIAGRAM
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GF2140

LINEAR INTEGRATED CIRCUIT
ELECTRICAL CHARACTERISTICS (ILINE=1.2mA, TA=25°C, RSET=290kΩ)
PARAMETER
Shunt Regulator (PIN 5-4)
SYMBOL
CONDITIONS
MIN
TYP
MAX UNITS
Regulator Voltage
VREG
I2-3=11μA
ILINE=700μA, I2-3=9μA
6.1
6.1
6.5
6.5
7.5
7.5
Sense Amplifier (PIN 2-3)
Offset Voltage
Input Bias Current
Gain Bandwidth
SCR Trigger (PIN 7-6)
VI(OFF)
II(BIAS)
fT
Design Value
Design Value
Design Value
-3.0
0
15
3.44
+3.0
30
mV
nA
MHZ
Output Voltage
VOUT
Output Current
Output Resistance
Reference Voltage (PIN 3-4)
Reference Voltage
Delay Time (PIN 8-4)
Delay Current
Delay Time
IOUT
ZO
I2-3=9μA
I2-3=11μA
V7-6=0V, I2-3=11μA
V5-6=open, I2-3=0
0
1.4
300
4.0
0.1
2.0
420
4.7
10
2.6
600
5.4
mV
V
μA
KΩ
VREF
ILINE=700μA
2.6
2.9
3.4
V
I2-3=11μA
C8-4=20nF
23
30
2.0
43
μA
ms
ID
tD
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GF2140

LINEAR INTEGRATED CIRCUIT
FUNCTIONAL DESCRIPTION
(Refer to Block Diagram and Figure 1)
The shunt regulator generated by a 6.5V zener diode is built into the internal bridge rectifier. It is divided to create
an internal reference voltage of 2.9V connected to pin 3. The secondary of the sense transformer is AC coupled to
the inverting input of the sense amplifier at pin 2; the non-inverting input is referenced to pin 3. A current feedback
loop around the sense amplifier ensures a virtual ground will be presented to the secondary of the sense transformer.
In this manner it acts as a current transformer instead of a voltage transformer. In this mode, the transformer’s
characteristics are very predictable and circuit adjustments are not necessary in production.
The AC coupled transformer secondary current then flows through the sense amplifier’s feedback loop, creating a
full wave rectified version of the secondary fault current. This current passes through RSET at pin 1, generating a
voltage equal to RSET times the peak fault current divided by the sense transformer turns ratio. This voltage is
compared with the reference voltage at pin 3.
If the voltage at pin 1 is greater than pin 3, a comparator will charge C2 through a 29uA current source at pin 8. If
the voltage at pin 1 exceeds pin 3 for longer than the delay time, a 400uA current will pulse between pins 7 and 6
which will trigger the gate of the SCR.
If the voltage at pin 1 exceeds pin 3 for less than the delay time, the SCR will not trigger.
The fault current at which the controller triggers the SCR is dependent on the value of RSET and the time delay
determined by C2.
UL 943 requires the circuit interrupter trip when the ground fault exceeds 6mA and not trip when the fault current is
less than 4mA.
Supply Current Requirements
The UTC GF2140 has a built-in diode bridge rectifier that provides power to the chip independent of the polarity of
the AC line. This eliminates the external rectifier required for previous GFCI controllers.
RLlNE limits the shunt regulator current to 2mA. The recommended value is 47K to 91K for 110V systems and 91K
to 150K for 220V systems. The recommended maximum peak line current through RLlNE is 7mA.
DO NOT connect a filter capacitor between pins 5 and 6 in an attempt to filter the supply voltage at the UTC
GF2140. Proper operaton of the UTC GF2140 requires the internal supply voltage to be unfiltered.
SCR Driver
The SCR must have a high dV/dt rating to ensure that line noise (generated by electrically noisy appliances) does
not falsely trigger the SCR. Also, the SCR must have a gate drive requirement less than 200uA. C3 is a noise filter
that prevents high frequency line pulses from triggering the SCR.
The relay solenoid used should have a 3 ms or less response time to meet the UL 943 timing requirement.
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GF2140

LINEAR INTEGRATED CIRCUIT
TYPICAL APPLICATION CIRCUIT
Mov
RTEST=15K
TEST
1 500ZCT
Line
Load
Hot
Neutral
Relay
C2 =0.02μF
RSET
290K
C1=10μF
1
8
SCR
7
2
3
RLINE=91K
GF2140
4
C3=10nF
6
5
C4=0.1μF
Figure 1. Appliance Leakage Detector Circuit Application
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
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www.unisonic.com.tw
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