LM1851M National Semiconductor, LM1851M Datasheet - Page 4

• Manufacturer Part Number: LM1851M
• Description: IC,Ground Fault Interrupter,BIPOLAR,SOP,8PIN,PLASTIC
• Manufacturer: National Semiconductor

Specifications of LM1851M

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Typical Performance Characteristics
Circuit Description
(Refer to Block and Connection Diagram)
The LM1851 operates from 26V as set by an internal shunt
regulator D3 In the absence of a fault (I
path status signal (V
conditions the capacitor discharge current I
cently at three times its threshold value I
induced charge on the timing capacitor will be rapidly re-
moved When a fault current I
of the external sense transformer the operational amplifier
A1 uses feedback to force a virtual ground at the input as it
S
) is correspondingly zero Under these
Average Trip Time vs
Fault Current
Output Drive Current vs
Output Voltage
f
is induced in the secondary
f
e
TH
0) the feedback
1
so that noise
sits quies-
4
extracts I
cause V
I
both half-cycles of the line I
during the half-cycle in which I
half-cycle I
the other half-cycle I
voltage reaches 17 5V the latch engages and turns off Q3
permitting I
TH
Although I
S
f
to go high which in turn changes I
f
2
The presence of I
–I
Normal Fault Current
Threshold vs R
Pin 1 Saturation Voltage vs
External Load Current I
to drive the gate of an SCR
TH
TH
charges the timing capacitor while during
discharges the timing capacitor during
TH
discharges it When the capacitor
SET
f
f
f
exits pin 2 Thus during one
only charges the capacitor
during either half-cycle will
L
TL H 5177 – 4
1
from 3I
TH
to