MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
33099
9
APPLICATIONS
Introduction
The 33099 is an alternator voltage regulator designed with
internal level shifting resistors to control the voltage in a 12 V
automotive system that uses a three-phase alternator with a
rotating field winding. The system shown in
Figure 2
includes
an alternator with its associated field coil, stator coils and
rectifiers, an automotive battery, a fault indicator lamp, an
ignition switch, a field flyback diode, and the 33099.
Figure 2. 33099 Simplified Application
The 12 V system voltage (V
bat
) is connected to a REMOTE
input by a remote wire, which provides the IC regulator with an
external Kelvin connection directly to the battery to provide
REMOTE voltage, V
rem
. The system voltage at the BAT
terminal is also sensed by an internal Local IC connection as
Local voltage V
l
. The Local connection is provided in the event
the remote wire or remote connection becomes faulty such as
being resistive, an open, or shorted to ground.
The PHASE input is normally connected to a tap on one
corner of the alternator's stator winding, which provides an AC
phase voltage (V
ph
) for the IC to determine the rotational
frequency (f
ph
) of the alternator rotor. Two frequency
comparators (F1 and F2) monitor voltage V
ph
to determine a
phase rotation detection frequency (f
1
) and a Low/High RPM
transition phase frequency (f
2
), respectively. A PHASE FILTER
terminal is provided for externally providing a filter capacitance
for filtering phase input noise.
The regulated DC system set voltage (V
set
) is achieved by
employing feedback to compare a ratioed value of V
set
to an
internal IC bandgap voltage reference having a negative
temperature coefficient (TC). The GATE drive of an external
N-channel MOSFET is regulated by the IC to control the field
current in the alternator field coil as an alternating ON or OFF
state dependent on load current conditions affecting voltage
V
set
. The external MOSFET receives GATE-to-source voltage
drive from between the GATE and SOURCE output terminals of
the IC. The GATE-to-source voltage is a Pulse Width
Modulated (PWM) waveform having a variable ON/OFF duty
cycle ratio that is determined by an analog or a digital duty cycle
control circuitry that responds to variations in the system
voltage due to variations in system load current. The PWM
F
Field
M
Ignition
Stator
M
Ground
Battery
Low
0.6 V
Over
Detect
1.25 V
Bandgap
Regulator
IVreg
and Bias
Charge
Min Duty
Cycle
OR1
LD
OV
Remote
Local
Phase
Batt
Gate
GATE
V
Vef
(5.0 V)
1.25 V
S1
S2
CB1
CB2
LB
FB
Css
Z1
VTssc
A
N
D
4
S3
Vg
R1
R2
R3
R4
R5
RF
Cf
Vo
UV
Ign
Gate
Polling
Local
4 LSB
4MSB
8-Bit Counter
Digital
Duty Cycle
U/D
Counter
Np
Control
Switch
Up/Down
MUX
1.25 V
F2
DAC
A
N
D
3
1.25V
Batt
Polling
Drain
Lamp
Driver
Circuit
OR2
A
N
D
1
LCR1 LCR2
LRC2
Gnd
Lamp
Drain
Lamp
Gate
IGN
Cds
Dtl
Z2
Rs
To
Polling
Lamp
A
N
D
2
u/d
u/d
F1
A/D
Limit
Limit
Batt
DD
VTigmIign
VTdsc
f
LCR TEST
(OTC)
f
Osc
Remote
Phase
Alternate S tator
Configuration
P
16
P
256
Source
CF
Boundry for IC
MC33099
lpd
lpu
Vem
Vs
Vs
Cph
V
Cs
Vhvl
Vdac
Cdc
Cuv
Vb
Cgn
VBat
33099
REMOTE
FILTER
PHASE
GND
AGND
LAMP
GATE
LAMP
DRAIN
IGN
SOURCE
F
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
.