fs6611 Fortune Semiconductor Corporation, fs6611 Datasheet - Page 18

• Manufacturer Part Number: fs6611
• Description: Energy Metering Ic With Impulse Output
• Manufacturer: Fortune Semiconductor Corporation

FS6611
13.10 No Load Threshold
The FS6611 also includes a “no load threshold” and
“startup current” feature that will eliminate any creep
effects in the meter. The FS6611 is designed to
issue a minimum output frequency on all modes
except when SCF = 0 and S1 = S0 = 1. The no load
detection threshold is disabled on this output mode
to accommodate specialized application of the
FS6611. Any load generating a frequency lowers
than this minimum frequency will not cause a pulse
to be issued on F1, F2, or CF. The minimum output
frequency is given as 0.0014% of the full scale
output frequency for each of the F
frequency
1–4
selections (see Table II). For example, an energy
meter with a meter constant of 100imp/kWhr on F1
and F2, using F2 (3.4Hz), the maximum output
frequency at F1 or F2 would be 0.0014% of 3.4Hz or
–5
–3
4.76×10
Hz. This would be 3.05×10
Hz at CF (64
×F1 Hz). In this example, the no-load threshold is
equivalent to 1.7W of load or a start up current of
8mA at 220V. IEC1036 states that the meter must
start up with a load current equal to or less than
0.4% I
. For a 5A (I
) meter, 0.4% I
is equivalent to
b
b
b
20mA. The start up current of this design therefore
satisfies the IEC requirement. As illustrated from this
example, the choice of F
and the ratio of the
1–4
stepper motor display will determine the start up
current.
Rev. 1.1
18/20