MC33099CDW FREESCALE [Freescale Semiconductor, Inc], MC33099CDW Datasheet - Page 12

• Manufacturer Part Number: MC33099CDW
• Description: Adaptive Alternator Voltage Regulator
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

PWM GATE frequency. Thus, the rates are accelerated by a
factor of 16.
LOW-PASS FILTER, DAC, AND ANALOG DUTY
CYCLE REGULATOR COMPARATOR
coupled to an input of a 300 Hz low-pass filter (Rf, Cf) to
remove high-frequency components of system noise at V
and thus associated with voltages V
the low-pass filter is coupled to a unity-gain buffer FB that
provides a filter buffer FB output.
generate a 4-bit 395 Hz voltage waveform having
16 descending 1.75 mV steps, ramping from V
28 mV], where V
output voltage waveform to the voltage at the FB output (V
When voltage V
comparator C
When voltage V
outputs a logic [0] for a 0% duty cycle. When (V
defined by the High / Low output voltage ratio for each period
(about 2.54 ms) of the DAC output voltage waveform.
BASIC SYSTEM VOLTAGE REGULATION
V
respectively, are scaled to the Remote Sense and Local
Sense inputs as voltages V
transferred to the FB output as voltage V
compared to the DAC output voltage waveform to generate
the ON and OFF time of the analog duty cycle waveform.
When voltage V
comparator C
through an AND3 GATE, an OR1 GATE, and an AND4 GATE
to activate switch S3, generating a fully ON or High GATE
drive voltage. When voltage V
output of comparator C
propagates through the AND3 GATE, the OR1 GATE, and
the AND4 GATE to activate switch S3 to generate a fully OFF
or low GATE drive voltage. Assuming voltage V
and V
factor is 7.45, the external MOSFET provides a fully ON field
current when the system voltage is less than 7.45
(V
when the system voltage is greater than 7.45 (V
14.9 V. When voltage V
waveform voltage, comparator C
an ON field current. When voltage V
portion of the DAC waveform voltage, comparator C
is low to produce an OFF field current. Thus the system
feedback will regulate the PWM duty cycle of the field current
from 0% to 100% over about a 210 mV system regulation
voltage range (dVreg). The system voltage is centered at
14.8 V, where a 50% duty cycle field current results for an
average system load current, and the duty cycle regulation
12
33099
TYPICAL APPLICATIONS
28 mV) < V
rem
ref
The output voltage V
The 4 MSBs of the 8-bit counter causes the DAC to
An analog duty cycle comparator (C
From a system voltage regulation viewpoint, the voltages
- 28 mV), or 14.6 V. The field current is also fully OFF
and V
fb
= V
l
rs
fb
from the Remote or Local connections,
, and the local or remote input resistive scale
dc
dc
< V
fb
fb
fb
is in a high state. This high state propagates
outputs a logic [1], for a 100% duty cycle.
ref
ref
is less then voltage [V
is greater than V
is less than V
is the 2.0 V reference voltage.
, comparator C
dc
o
fb
of combiners CB1 and CB2 is
is less than any portion of the DAC
is in a low state. This low state
rs
and V
fb
ref
is greater than V
dc
- 28 mV, the output of
ref
dc
output is high to produce
ls
ls
fb
, comparator C
, or V
respectively and
dc
outputs a duty cycle
is greater than any
) compares the DAC
ref
fb
. Voltage V
rs
- 28 mV],
. The output of
ref
ref
ref
ref
ref
to [V
-
), or
is 2.0 V
dc
, the
dc
fb
output
ref
is
fb
bat
-
).
frequency is (f
negative TC, voltage V
temperature coefficient (TC
INPUT PHASE AND FREQUENCY SWITCH
RESPONSE
AC output voltage being applied to the PHASE input pin.
A phase detection threshold voltage (V
4.0 V due to the 1.25 V phase reference voltage for the phase
comparator (C
the phase input resistor divider. The phase input resistance
(R
the input of Comparator C
filter capacitance when filtering of high frequency phase
noise is desired. A typical value of .003 µF to AGND provides
for an input phase 3.0 db roll-off frequency of about 10 kHz.
Comparator C
the PHASE input pin. Comparator C
phase signal binary output voltage having a phase frequency
of f
Switch F1 outputs a logic [1] when frequency f
phase detection frequency f
frequency f
frequency. Switch F2 outputs a logic [1] when the frequency
f
Frequency f
101 kHz oscillator frequency. These frequency switches are
used to define the Load Response Control region of
operation, an undervoltage at a high RPM fault condition, and
a low RPM fault condition due to a broken or loose belt.
LOAD RESPONSE CONTROL (LRC)
an analog/digital (A/D) duty cycle comparator and tracking
circuit, an up/down control switch, an up/down (U/D) counter,
a programmable divider (Np), and a multiplexer (MUX).
During normal operation, the LRC circuit becomes active and
generates digital duty cycle control of the GATE drive when
frequency f
LRC response becomes inactive and the analog duty cycle
controls the GATE drive when frequency f
frequency f
engine start, the LRC response is in effect, independent of
frequency f
V
the 8-bit counter as input and generates 11 discrete digital
duty cycles on 11 output lines. The frequency of each duty
cycle waveform is about 395 Hz (f
MSB of the 8-bit division of the 101 kHz OSC clock
frequency. The minimum duty cycle on the first output line is
31.25% and the maximum duty cycle on the eleventh output
line is 93.75%. The duty cycle difference between each
incremental duty cycle is 6.25%. All 11 duty cycle generator
output lines are coupled as data inputs to the MUX.
ph
set
ph
The phase voltage V
The LRC circuit consists of a digital duty cycle generator,
The digital duty cycle generator receives the 4 MSBs from
ph
is greater then the low/high transition frequency f
.
) is typically 60 kΩ. A PHASE FILTER pin is coupled to
and is applied to digital frequency switches F1 and F2.
ph
msb
2
ph
2
(f
, until system voltage is regulating at voltage
is equal to frequency 3f
is less than frequency f
osc
ph
1
ph
/ 8, or 49.3 Hz for a 101 kHz oscillator
< f
) and the 3.22 voltage ratio associated with
also provides about 480 mV of hysteresis at
/ 256), or 395 Hz. Since voltage V
ph
< f
Analog Integrated Circuit Device Data
set
ph
2
). During initial ignition and initial
ph
will also have a regulation voltage
results from the alternator's stator
Vreg
, providing for an external phase
1
. Frequency f
) of about -11 mV/ °C.
msb
Freescale Semiconductor
ph
2
), which results from the
msb
(f
Tph
further provides a
1
< f
/4, or 296 Hz for a
ph
) is approximately
1
ph
is equal to
is greater than
ph
< f
2
is less then
). The slow
ref
2
.
has a