IR2277S IRF [International Rectifier], IR2277S Datasheet - Page 17

• Manufacturer Part Number: IR2277S
• Description: Phase Current Sensor IC for AC motor control
• Manufacturer: IRF [International Rectifier]

1.6 Input filter gain setting
G0 and G1 pins are used to change the time
constant of the integrators of the high side input
filter.
To avoid internal saturation of the input filter, G0
and G1 must be connect according to SYNC
frequency as shown in Table 1. A too small time
constant may saturate the internal integrator, while
a large time constant may reduce accuracy.
G0 and G1 do not affect the overall current sensor
gain.
17
*
Table 1: G0, G1 gain settings
f
> 16 kHz *
16 / 10 kHz
10 / 6 kHz
< 6 kHz
PWM
40 kHz
G0
V
V
V
V
Figure 19: Even harmonic cancellation principle
B
S
B
S
G1
V
V
V
V
B
B
S
S
2
2.1 Bootstrap supply
The V
side drivers circuitry of the IR2277S/IR2177S. V
supply sit on top of the V
floating.
The bootstrap method to generate V
be used with IR2277S/IR2177S current sensors.
The bootstrap supply is formed by a diode and a
capacitor connected as in Figure 20.
Third
Third
Third
Third
harmonic
harmonic
harmonic
harmonic
harmonic
harmonic
harmonic
harmonic
SYNC 1
SYNC 1
SYNC 2
SYNC 2
Phase voltage
Phase voltage
Phase current
Phase current
Current Mean
Current Mean
Fundamental
Fundamental
Fundamental
Fundamental
Switching level
Switching level
Figure 20: bootstrap supply schematic
Triangular
Triangular
Error
Error
BS1,2,3
Sizing tips
voltage provides the supply to the high
instant
instant
instant
instant
Sampling
Sampling
Sampling
Sampling
harmonic only)
Stage 1 input:
IR2277S/IR2177S(PbF)
Input signal
components
(1
Stage 1
st
output
and 2
nd
S
voltage and so it must be
BS
www.irf.com
supply can
BS