Data Sheet AS8446
AS 8446
Programmable PWM DC Motor Driver / Controller
DATA SHEET
Key Features
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Programmable PWM DC Motor Driver / Controller with µP
Interface (Three Wire Interface)
Programmable Functions and Parameters for Motor
Current, Voltage and Speed Regulation
Single Voltage Supply in the range
Vbat = 6.0 V to 18 V (Vbat,max = 30 V)
1
Total Power Efficiency up to 96 %
Low RF Emission within the whole frequency range due to
an integrated special EMC optimized driver
Dynamically self-adjusting slew rate regulated switching
technology
Fully protected by programmable failure handling
procedures via µP
Fast Over Current and Over / Under Voltage Detection
and Protection, Battery Voltage Monitoring
External and On Chip Temperature Detection and
Protection
Motor Current and Speed Measurement with a shunt
resistor and capability of trimming the chip for an external
shunt value
Programmable Parameters:
•
EMC compliant Driver Functions
•
Over Current, Over / Under Voltage
Threshold Values
•
Motor Failure Threshold Levels
•
Motor Current Measurement Range
•
Trimming for the current measurement shunt
WakeUp
It is an advanced PWM DC motor controller subsystem with
an excellent EMC behavior targeted especially for high
current automotive applications. The optimization of the EMC
behavior of the entire module only by software changes
makes it easier to implement it in harsh environments.
The programmability of parameters and functions allows the
adaptation of the AS8446 to a wide range of applications.
So the system can act either as a motor current or motor
speed or motor voltage regulator. Also a full diagnosis of
motor failures and power FET failures, over temperature and
over/under voltage can be formed by programmable failure
handling procedures using the motor characteristic and the
real time measured motor current, motor speed and battery
voltage.
Applications
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Fan cooler
Air conditioning
Fuel pumps
Water and oil pumps
General purpose DC Motor Regulators
Typical Application Diagram
Control part
Power part
Cbat
1
2
3
4
5
Vbat
AS8446
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OSC1
VDD
CLK
GND
Port1
Port2
9
10
11
12
Wake-up
n.c.
Test1
Test2
Iref
20
RESET
19
WD
18
Test3
17
PWM
16
CLK
15
Rref
R
T1
R
NTC
Sleep / Wake-up Mode system controlled by the
µP
and
the Wake-up Pin
SOIC 28 Package
CVDD
•
PWM Frequency, Charge Pump Monitor
Charge Pump to control high side drivers
Integrated 5 V Power Supply for external components
(µP, etc.)
Standby and Wake-up capability
CMN
CMP
VMO
Vbat
TP
FAIL
CS
ADC
VSS
28
GND_P
27
OUT
26
Tr1
CP12
CP0
Rmeas
Vpump
25
CP2
24
CP1
23
VDDctrl
22
VDD
21
VDD = 5 V
PWMout
INR
CS
ANA
6
7
8
µP
(optional)
Q1
OSC2
D1
M+
M
M-
VSS
RESET
Tout
SPIout
SPIin
13
DATAin
14
DATAout
General Description
The AS8446 is a complete and fully protected PWM DC motor
driver/controller, which can be implemented by interfacing a
low cost 8-bit
µP
and a high-side N-channel power FET
switch.
GND_P
1
Low-Batttery-mode between 6.0 V and 6.5 V
Revision 1.8, Date 2005-03-17
Page 1 of 35
Data Sheet AS8446
Functional Description
Overview
The AS8446 is a complex integrated circuit, which contains
both low and high voltage circuitry to regulate PWM brush DC
motors with an external n-channel power FET and an
8-bit
µP.
The regulation loop is a closed loop environment
where a
µP
is connected to the device with a Three-Wire
Interface. The AS8446 measures and delivers the motor
current as an analog value to the
µP.
The
µP
uses a special
algorithm to calculate the motor speed by considering the
motor current as a function of time. This technique allows the
system to act either as a
motor current
or a
motor speed
regulator.
The AS8446 also monitors and delivers the battery
voltage to the
µP
as an analog value and by leveraging this
voltage-monitoring feature a
motor voltage regulator
could
be implemented also. A full diagnosis of motor and power FET
failures is performed automatically by the programmable
failure handling functions after carefully analyzing the motor
characteristics, real-time motor current, motor speed and
battery voltage.
The dynamically self-adjusting slew rate regulated switching
technology (patented) is one of the most important features of
this ASSP in automotive applications. This technology
enables two features of the PWM DC motor regulator, which
were up till now impossible to realize:
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Excellent EMC behavior (very low RF emission in the
whole frequency range)
AS8446 into a power save mode. It is controlled via the
specified wake-up pin.
A short overview of the main features follows.
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programmable PWM DC motor current, speed or voltage
regulator
single voltage supply in the range Vbat = 6.0V to 18V
(Vbat,max = 30 V)
Low-Battery-Mode guarantees operation also when
battery voltage is between 6.0V and 6.5V; In this mode
the output driver is constantly on (100% PWM),
Vpump-Vbat
≥
4.0V.
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applicable directly to the automotive battery supply
(burst, surge, load dump)
closed loop regulation of the motor speed, motor current
or motor voltage with a
µP.
high power efficiency of the whole regulator module (up
to 96 % @ f
PWM
= 20 kHz)
low RF emission within the whole frequency range
fully protected by programmable failure handling
procedures (see below: Security Functions)
fast over current and over / under voltage detection and
protection
motor current and motor speed measurement with only
one shunt resistor (typ. measurement voltage at nominal
motor current: 50 mV)
on chip trimming capability of the external shunt resistor
Sleep/wake up mode system controlled by the
µP
and
the wake-up pin
Three Wire Interface
programming possibilities of the following regulator
parameters inside of the AS8446:
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PWM frequency (generated by
µP,
e.g. 20 kHz)
charge pump voltage monitoring and protection
slew rate control parameters (EMC behavior)
power FET Gate driver currents up to 500 mA
over current threshold level
over / under voltage threshold level
motor current measurement range and trimming of
the external current measurement resistor
programming possibilities of the following regulator
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High power efficiency up to 96 % @ f
PWM
= 20 kHz
(fall / rise time down up to < 150 ns)
Most of the parameters (e.g. PWM frequency, slew rate, over
current threshold, current measurement range, etc.) of the
AS8446 can be programmed (setting up the internal registers)
through the Three-Wire Interface, which makes the regulator
a versatile and easily adaptable device to a wide range of
regulation modes and motors.
The field programmability option of the slew rate regulation
parameters makes it easier to comply with the system level
EMC behavior (regulator board, motor, power cables, etc.)
A bandgap is used as a reference for a Low Drop Voltage
Regulator with a nominal output voltage of 5 V.
This regulator is capable to deliver a supply current of up to
40 mA. Higher current is possible with an external bipolar
transistor.
The device is bundled with a set of software to handle the
regulation loop, motor speed measurement and failure
detection. A sleep/wake up system is integrated to bring the
parameters / functions via the
µP
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motor failure threshold levels (motor currents and
voltages) for all motor failures: blocked motor, open
wire, no load, shorted motor segments, etc.
failure handling procedures for all motor failures,
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over / under voltage and for over temperature (type
of reaction and timing)
sleep mode criteria and sleep mode signal to the
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AS8446
Revision 1.8, Date 2005-03-17
Page 2 of 35
Data Sheet AS8446
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closed loop regulation timing with
µP
for speed,
current and voltage control
special features e.g. suppression of particular motor
speeds, dynamical change of the over current
threshold level, etc.
Security Functions
Extensive diagnosis of the DC motor and the power FET as
well as failure handling procedures are programmable via a
µP.
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over current detection and protection
no load detection of the motor
open wire detection (motor or power switch)
short circuit of the power switch detection
blocked motor detection and protection
short circuited motor segments detection and protection
protection of the power FET and the AS8446, if the
motor works in generator mode
battery voltage monitoring and over / under voltage
detection and protection
two over temperature detection and protection modes
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external temperature sensor
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on chip temperature sensor
Item (Start up values)
Over Voltage Threshold
Under Voltage Threshold
Minimum Charge Pump Voltage
Over Current Threshold (Shunt
Measurement Voltage)
Mode after Start up
AS 8446
40.0 V
2.5 V
4.0 V
125 mV
sleep
mode
Table 1
Start up values of the AS 8446
Revision 1.8, Date 2005-03-17
Page 3 of 35
Data Sheet AS8446
Pin Description
The AS8446 Motor Driver/Controller contains the
driver/controller chip in a SOIC28 package
The complete PWM DC Motor Regulator board needs an
additional
µP
to close the regulation loop and control the
whole regulator (dual package solution, free choice of the
controlling
µP).
Pin Name
1
2
3
4
5
6
CMN
CMP
VMO
Vbat
TP
FAIL
CS
ADC
Wake-up
n.c.
Tst 1
Tst 2
DATAin
DATAout
Clk
PWM
Tst 3
WD
RESET
Iref
VDD
VDDctrl
Type
HV AI
HV AI
HV AI
S
HV AI
LV DO
LV DIPU
HV AO
HV AIO
LV DIPU
LV DO
LV DIPD
Note
Current Measurement Input
(negative side)
Current Measurement Input
(positive side)
Motor Voltage Input
Battery Voltage, Main Supply
Temperature Sensor Input
Error Status Output of
AS8446
Chip Select, Enable Pin of
Three Wire Interface
Analog Measurement Output
(multiplexed)
Wake-up Pin
Test Pin 1 (1)
Test Pin 2 (2)
Data Input of the Three-Wire
Interface
Pinout AS8446
7
8
1
2
3
4
5
6
7
8
9
10
11
12
13
14
CMN
CMP
VSS
28
GND_P
27
26
9
10
11
12
13
14
15
16
17
18
19
20
21
22
AS8446
VMO
Vbat
TP
FAIL
CS
ADC
OUT
Vpump
25
CP2
24
CP1
23
VDDctrl
22
VDD
Iref
RESET
21
20
19
LV DO_T Data Output of the Three-
Wire Interface
LV DIPD
LV DIPU
LV DO
LV DIPU
LV DO
LV AIO
AI
HV AO
Clock of the Three-Wire
Interface
PWM Input (Control of the
Power FET Driver)
Test Pin 3 (2)
Watch Dog Input
Reset Output (controlled by
Watch Dog)
Reference Current Pin
VDD feedback input
VDD supply (5 V generated
by the on chip voltage
regulator)
Charge Pump Capacitor (Vbat
side)
Charge Pump Capacitor
(Vpump side)
Charge Pump Buffer
Capacitor
Power FET Driver Output
Power Ground
Digital/Analog Ground
Wake-Up
n.c.
Tst 1
Tst 2
DATAin
DATAout
WD
18
Tst 3
17
PWM
16
Clk
15
Figure 1
Pinout AS 8446
Pin Description AS8446, Pin Types
S
AI
AO
AIO
DI
DIPU
DIPD
DO
DIO
DO_T
LV
HV
…
…
…
…
…
…
…
…
…
…
power supply
analog in
analog out
analog in/out
digital in
digital in with pull-up
digital in with pull-down
digital out
digital in/out
digital out, tristate
23
24
25
26
27
28
Table 2
CP1
CP2
Vpump
OUT
GND_P
VSS
HV AIO
HV AIO
AO
HV AO
S
S
PIN description of AS 8446
… low voltage
… high voltage
Note (1) Must be connected to VDD
Note (2) Must be left open
Revision 1.8, Date 2005-03-17
Page 4 of 35
Figure 2
CP1 2
CP 0
Data Sheet AS8446
Block Diagram
CP1
C P2
V DDH1
Vpu m p
RESET
R eg is te r
50 kH z
C L K pum p
a ) s ett ing s
b ) c o n trol
Iref
R C O s c il la t o r
D ri v e
V D D H = V bat
10 V
L o w S id e
D A T A in
S E T_0
21
12
3
2
CS
s lee p
S E T _k
slew rate (low)
programming
B it_ 0
S le e p / w a k e
PW M
3
M oto r- a n d
P ow e r F E T
p r o te c tio n
P T o v er1
P T o ve r2
D AT Ao ut
OR
P o ve rc
P Vo ver
P V un d er
prog ra m ma ble :
12 V , 24 V , 4 2 V
Rx
pd
slee p
u p s ys te m
V o lt a g e
M o n it o r in g
FA IL
B i t_n
Self Adjusting Slew Rate Regulation
Interface / Control
CMp
PW M
V re fV
W a k e -u p
V in = V ba t
V b a t_ m o n
GND
programming
Tst 1
VD DH
V
A _ c u r r e n t
= kx * Im otor
V
A _ o v e r c
= k y* I m oto r
A _ c u r r en t
E xte rn a l O ve r
T e m p e r a tu r e
d e tec tio n
V re fT 1
O n ch i p O ve r
T e m p e ra tu r e
d e te c tio n
V re fT 2
CM n
Tst 2
p rogra mm ing
k6 , k 7
A _ o ve r c
PWM
r e fe r en c e
Tst 3
Vref
5 V - r e g u la t o r ( b a n d g a p r e f .)
V r e f/I re f
V re f= 1. 0 V
VDDH
g e n e r a to r
b a nd g a p
V D D c trl
VDD
VSS A
M
VDD
a n d t rim m in g
(o ver cu rr ent,
R m eas )
k5
l ow v o lta ge
h ig h v olt a g e
P ov e r c
H V -IN /
L V -O U T
TP
A _ ove rc
AS 8 44 4
u P ba se d D C M oto r R egu la to r
ADC
Analog
MUX
( a n a lo g )
A _ cu rrent
V ba t_ mo n
a u s t ria
m ic r o
s y s te m s
VSS
VDD
V D D c tr l
CV D D
TP
R N TC
RT1
Rref
VD D
Ire f
G ND _P
p a ck a ge : S O IC 2 8
Rmeas
W a k e-u p
I n te r fa ce
Imotor
2
M o to r c u r r en t a n d s p e e d
m e a s u r e m e n t / o v e r cu r r en t
OUT
Vm o
S h if t
R e g is t e r s
slew rate (high)
programming
Block Diagram of AS8446
C l k_ w d
a c tiv e /d e a c tiv e
C lk
t
R / W
C on tr ol
OR
Revision 1.8, Date 2005-03-17
WD
S e r ia l
PO R
H ig h S id e
D ri v e
V D D H = V b at
C h a rg e p u m p
V DD H
In t e r f a c e
W a tc h d og
POR
VDD
wd
Page 5 of 35
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