Datasheet
MCP19111
DS22331A-page 42 2013 Microchip Technology Inc.
6.7 Slope Compensation
A negative voltage slope is added to the output of the
error amplifier. This is done to prevent subharmonic
instability when:
1. the operating duty cycle is greater than 50%
2. wide changes in the duty cycle occur.
The amount of negative slope added to the error ampli-
fier output is controlled by Register 6-7.
The slope compensation is enabled by setting the
SLCPBY bit in the ABECON register.
6.7.1 SLPS<3:0> CONFIGURATION
The SLPS<3:0> directly controls the V/t of the
added ramp. This byte should be set proportional to
the switching frequency according to the following
equation.
6.7.2 SLPG<3:0> CONFIGURATION
The SLPG<3:0> controls the amplitude of the added
ramp. The values listed above correspond to a 50%
duty cycle waveform and is true only if the SLPS<3:0>
bits are set according to the equation in Section 6.7.1
“SLPS<3:0> Configuration”. If less amplitude is
required, the SLPS<3:0> bits can be adjusted to a
lower switching frequency.
REGISTER 6-7: SLPCRCON: SLOPE COMPENSATION RAMP CONTROL REGISTER
R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x
SLPG3 SLPG2 SLPG1 SLPG0 SLPS3 SLPS2 SLPS1 SLPS0
bit 7 bit 0
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
bit 7-4 SLPG<3:0>: Slope Compensation Amplitude Configuration bits
0000 = 0.017 V
PK-PK
, measured for 50% duty cycle waveform
0001 = 0.022 V
PK-PK
, measured for 50% duty cycle waveform
0010 = 0.030 V
PK-PK
, measured for 50% duty cycle waveform
0011 = 0.040 V
PK-PK
, measured for 50% duty cycle waveform
0100 = 0.053 V
PK-PK
, measured for 50% duty cycle waveform
0101 = 0.070 V
PK-PK
, measured for 50% duty cycle waveform
0110 = 0.094 V
PK-PK
, measured for 50% duty cycle waveform
0111 = 0.125 V
PK-PK
, measured for 50% duty cycle waveform
1000 = 0.170 V
PK-PK
, measured for 50% duty cycle waveform
1001 = 0.220 V
PK-PK
, measured for 50% duty cycle waveform
1010 = 0.300 V
PK-PK
, measured for 50% duty cycle waveform
1011 = 0.400 V
PK-PK
, measured for 50% duty cycle waveform
1100 = 0.530 V
PK-PK
, measured for 50% duty cycle waveform
1101 = 0.700 V
PK-PK
, measured for 50% duty cycle waveform
1110 = 0.940 V
PK-PK
, measured for 50% duty cycle waveform
1111 = 1.250 V
PK-PK
, measured for 50% duty cycle waveform
bit 3-0 SLPS<3:0>: Slope Compensation V/t Configuration bits
n
F
SW
100 000
---------------------
1–=
Where:
F
SW
= Device switching frequency
n = Decimal equivalent of SLPS<3:0>