Datasheet AS8410 Datasheet (Austria Mikro Systeme International)

AS8410
PWM DC Motor Regulator

Data Sheet (Preliminary)
Rev. 1.0, December 2000

PWM DC Motor Regulator – Data Sheet
AS8410

1 Key Features

The AS8410 builds up a complete PWM DC Motor current regulation loop with an external
n-channel power FET. A full diagnosis of motor failures with stand-alone failure handling
procedures is integrated.
One of the most important features of this ASSP namely in automotive applications is the
slew rate regulated switching of the external power FET. This technology enables two
features of the DC motor regulator, which was up to now impossible to realise at the same
time:

• An excellent EMC behaviour (very low RF emission in the whole frequency

range)

• A high power efficiency > 95 % (fall / rise time < 150 ns)
A short overview of the main features of the AS8410 is given here below:

Main properties:

• Complete PWM DC motor regulator with an external power FET

• Single voltage supply in the range VB = 6 V … 35 V (Vpump

• Analogue motor current regulation loop (two modes: set value as digital duty ratio of a

low frequency (e.g. 10 Hz) or as an analogue voltage in the range Vin = 0 … 5 V)

• High power efficiency of the whole regulator module (> 95 %)

• Low RF emission in the whole frequency range

• Fully protected, analogue / digital failure handling procedures (see below: Security

functions)

= 45 V)

max

• Simple programming possibilities for different classes of DC motors and
different operating modes (set value input, over temperature-handling procedure)

• Applicable directly on the automotive board supply battery (burst and surge)

• Automatic sleep mode controlled by the set value

Security functions:

1. Extensive diagnosis of the DC motor and the power FET,
failures handling procedures and report of the failures:

1.1 Over current detection and protection

1.2 No load detection of the motor

1.3 Open wire detection (motor or power switch)

1.4 Short circuit of the power switch detection

1.5 Blocked motor detection and protection

1.6 Short-circuited motor segments detection and protection

1.7 Protection of the power FET and the ASIC, if the motor works in generator
mode

2. Over- / Under Voltage detection and protection

3. Over Temperature detection and protection in two modes

Rev. 1.0, December 2000 page 2 of 19

PWM DC Motor Regulator – Data Sheet
AS8410

2 General Description

Package and Marking
Package: SOIC16 wide outline

SOIC16 SOIC16 wide outline

Marking (measure in mm)

AS8410 ASSP number min. nom. max.

A 2,46 2,56 2,64

YY Production year A1 0,13 0,22 0,29
WW Production week A2 2,29 2,34 2,39
XXX Assembly-ID B 0,35 0,41 0,48

C 0,23 0,25 0,32
D 10.21 10.34 10.46
E 7,42 7,52 7,59

e 1.27 BSC

H 10.16 10.31 10.41

h 0.25 0.33 0.41
L 0,61 0,81 1,02

α

Table 2.1: Dimensions and marking

0° 5° 8°

Fig. 2.1 Dimensions and marking

Rev. 1.0, December 2000 page 3 of 19

PWM DC Motor Regulator – Data Sheet

src1

src2

AS8410

Maximal Ratings (ASSP out of operation)

Symbol Parameter min max Unit Note

Vbat Supply voltage -0,5 50 V

Vpump Pumped supply -0,5 50 V

VDD Regulated 5V-supply -0,5 7 V

I

IMmax

V

INA

I

or I

Maximal input currents -30 30 mA VIN < V

Analogue input voltage - 0.3 35 V
Input currents at pins SRC1 or

2 mA

SRC2

Θ

Θ

P

STG

LEAD

TOT

Storage Temperature -55 150 °C
Solder Temperature 260 °C
Maximal power dissipation 0.4 W

ESD Electrostatic discharge voltage 1000 V

1

GND = Ground

2

except for Pins SRC1 and SRC2

3

260 °C for 10 s (reflow soldering), 360 °C for 3 s (manual soldering)

4

HBM: R = 1.5 kΩ, C = 100 pF

1

V

2

3

4

IN

> Vbat

IN min

or

Rev. 1.0, December 2000 page 4 of 19

PWM DC Motor Regulator – Data Sheet
AS8410

Operating Conditions

The following conditions are valid in the temperature range ΘRT = -40 °C to +120 °C and the
supply voltage range Vbat = 6.5 V to 35 V.

Symbol Parameter min typ max Unit Note

Vbat Supply voltage 6.5 12 35 V

I

DDA

Current consumption in sleep

400

mode (power down mode)

I

DDB

Current consumption (at Vbat in

10 mA

normal mode 1 or 2)

Vpump Pumped supply voltage 11 Vbat+10 45 V

VDD Regulated 5V-supply 4,7 5,0 5,3 V

I

,

SRC1

I

SRC2

V

V

V
V

I

V

IN

MODE

CMP

CMN

out

out

max. current into the current
inputs SRC1 or SRC2
Voltage at set value input pin IN GND - 0,3 Vbat + 0,5 V
Voltage at the MODE pin GND - 0,3 Vbat + 0,5 V

,

Voltage at the current meas-

GND - 3,5 Vbat + 0,5 V
urement input pins CMp, CMN
Voltage at the output pin OUT GND - 0,3 Vpump V

Max. output current at pin OUT

-300 300 mA

400

(t < 1µs)

V

analog

1

valid in mode 2 only (MODE = low) and Vbat = 12 V

2

without output current at pin OUT

3

the inputs SRC1 and SRC2 must be current limited by the external circuitry (max. 400 µA)

4

max. duration of the current pulse = 1µs

5

valid for the pins OSC, TP, Cint1, Cint2

Analogue input voltage GND - 0,3 VDD + 0,5 V

µA

µA

1

2

3

4

5

Rev. 1.0, December 2000 page 5 of 19

PWM DC Motor Regulator – Data Sheet
AS8410

Pinout and Package Description

Pin Name Typ Description

1 Vpump Output Pumped supply voltage: Vpump = Vbat + 10 V
2 Pump_ctrl Output Connection of the capacitor Cp1 of the charge pump
3 Vbat Power positive supply voltage
4 VDD Output 5V regulator output
5 MODE Input Selection of the operating mode
6 IN Input Set value input
7 OSC Input Connection of the reference current resistor (1 V output)
8 Cint2 Input RC filter of the set value

9 Cint1 Input Connection of the capacitor of the regulation loop
10 TP Input Temperature measurement input
11 CMp Input Motor current measurement input (positive side)
12 CMn Input Motor current measurement input (negative side)
13 SRC1 Input Slew rate regulation input (rising edge)
14 SRC2 Input Slew rate regulation input (falling edge)
15 GND Power Ground
16 OUT Output Power FET control output (Gate drive)

Fig 2.2 Pinning of the SOIC16 package

Rev. 1.0, December 2000 page 6 of 19

PWM DC Motor Regulator – Data Sheet
AS8410

3 Applications

Fig. 3.1 Operating mode 1 (OM1) of the motor regulator (e.g. automotive application)

Fig. 3.2 Operating mode 2 (OM2) of the motor regulator

Rev. 1.0, December 2000 page 7 of 19

PWM DC Motor Regulator – Data Sheet
AS8410

Meaning and Settings of the external devices

Sym-

bol

R

OSC

R

meas

R

int2

C

int2

C

int1

SRC1
SRC2

R

IN

R

MODE

R

TP1

R

TP2

Description Typical value Application Note

Regulation loop settings / slew rate regulation

Resistor of the refer­ence current genera­tion I

ref

100 kΩ

The voltage at the pin OSC is regu­lated to V

= 1 V. The reference cur-

OSC

rent is therefore 10 µA.
This current is used for three functions:

1. The oscillator frequency (I
generates f

OSC

linear function of I

2. Generation of the internal set value
voltage in OM1 together with the
resistor R

int2.

100% set value is build by a volt­age of 2 V at pin Cint2:
V

(100%) = I

Cint2

3. Reference current for the power

FET driver / Slew rate regulation
(linear function between I

driver output current I
Motor current meas­urement resistor

Resistor to convert

Dependent on the
nominal motor
current I

motor_nom

200 kΩ

The voltage drop over the R

be 50 mV for the nominal motor cur-

rent: R

V

Cint2

= 50 mV / I

meas

(100%) = I

ref

the incoming duty
ratio of the set value
in OM1 to the set
value voltage V
Filter capacitor of the
set value conversion
in OM1

Capacitor to set the
regulation loop time
constant and failure
handling time con­stant

Feedback circuitry of
the slew rate regula­tion

Cint2

> 2.2 µF

Dependent on the incoming PWM fre-

quency f

f

IN_PWM

IN_PWM

= 10 Hz à C

100 nF The time constant of the failure han-

dling T

is determined by the max.

fail

current at pin Cint2 (I

… 15 µA) and the min. voltage to start

the PWM generator (1.66 V):

T

Dependent on the
application (motor

= (C

fail

Application Support of Austria Mikro

Systeme AG will be guaranteed

* 1.66 V ) / I

int1

and environment)

Protection Resistors

Protection resistor of

330 Ω

Needed in automotive applications

the pin IN
Protection resistor of

1 kΩ

Needed in automotive applications

the pin MODE

Temperature Sensor

Resistor divider of the
temperature sensor

R

TP1

+ R

< 10 kΩ

TP2

The threshold voltage at the pin TP
must be 0.5 *VDD or (R

= 18 kHz, f

)

ref

* R

ref

int2

OUT

motor_nom

* R

= 2 V

int2

> 2.2 µF

int2

Cint1_max

Cint1_max

ref

OSC

= 2 V

ref

)

meas

= 10 µA

= R

TP1

= 10µA

is a

and

must

)

TP2

Rev. 1.0, December 2000 page 8 of 19

PWM DC Motor Regulator – Data Sheet
AS8410

VTP < 0.5 *VDD à over temp.
VTP > 0.5 *VDD à no over temp.

Charge pump and 5V Regulator

C
C

D1
D2
C

p1
p2

VDD

Charge pump capaci­tors

Diodes of the charge
pump
Filter capacitor of the

100 nF … 200 nF The capacitor value is dependent on

the external power FET to drive

V

> Vbat + 10 V

break

I

> 50 mA

max

(C

gate_source

)

100 nF

5V regulator

C

Vbat

Filter Capacitor of the
Vbat

1000 µF

The capacitor value is dependent on
the motor power.
Typical value: 1000 µF pro 100 W
motor power in automotive applica­tion.

Power Switch and Free wheel diode

Df Free wheel diode
Tr1 Power FET

Dependent on the
max. motor current
and voltage

Austria Mikro Systeme International AG gives all necessary application support to the
user of this PWM DC Motor Regulator device AS8410.

Rev. 1.0, December 2000 page 9 of 19

PWM DC Motor Regulator – Data Sheet
AS8410

4 Functional Description and Electrical

Parameters

The main functions of this PWM-Switch-Regulator are summarised in section 1.3.
The normal regulation loop is build by an analogue difference-integrator, both the input set
value at pin IN and the measured motor current (at pins CMp and CMn) are transformed to the
chip internal control signals. The difference signal is integrated on the capacitor connected to
the pin Cint1 and the voltage at this pin is controlling the PWM generator and closes so the
regulation loop. So the regulation time constant can be determined in width range by the exter­nal capacitor at the pin Cint1.
The AS8410 can be used in two different modes controlled by the pin MODE :

Operating Mode 1 (OM1: V

- The set value must be given at pin IN as the duty ration of a low frequency digital
signal (fIN > 10 Hz).

- The Over Temperature reaction: 100 % duty ratio of the FET-driver output (perma­nent switch on the motor) as long as the temperature is higher than the predefined
threshold value (typical automotive application, the heating source is not the electri­cal system but the combustion engine).

Operating Mode 2 (OM2: V

- The set value must be given at pin IN as analogue voltage in the range

V

= 0 … 5 V

IN

- The Over Temperature reaction: The motor is regulated down to not cross the pre­defined temperature threshold (like a thermostat if the heating source is the electrical
system itself).

MODE

MODE

= high):

= low):

The adaptation of the AS8410 to the DC motor (nominal motor current and power FET) will be
realised by the value of the motor current measurement resistor R

and by the slew rate con-

meas

trolling currents into the pins SRC1 and SRC2 as described in section 3.4.1.
The detection of the different kinds of motor failures is realised by comparing the actual meas-

ured motor working point and the normal motor characteristic. Each motor failure is then treated
by the AS8410 with an adapted failure handling procedure described in section 3.4.2.
A failure report signal is generated and sent to the pin IN by pull down this pin.
Also the over temperature and the over / under voltage failure are treated by the AS8410 itself.

Rev. 1.0, December 2000 page 10 of 19

PWM DC Motor Regulator – Data Sheet
AS8410

Figure 4.1: Simplified Block diagram of the AS8410

Rev. 1.0, December 2000 page 11 of 19

PWM DC Motor Regulator – Data Sheet
AS8410

4.1 Normal Operating Mode (regulation loop)

The regulation loop of the AS8410 consist of the following functional blocks:

1. Analogue / Digital Interface with signal conditioning (set value input / failure signal
output IN, modus input MODE and low pass filter input Cint2)

2. Regulator characteristic generator (high resolution of the set value for set
values < 50 % and lower resolution for set values 50 % … 100 %)

3. Difference generator at the pin Cint1 (V

4. PWM generator (controlled by the voltage V

5. Power FET driver with slew rate regulation controlling the external power FET gate
connected at pin OUT

6. Motor current measurement unit (measuring and converting the voltage over the ex­ternal resistor R

connected at the pins CMp and CMn)

meas

7. Oscillator (20 kHz) and reference current generator (regulated V
with external resistor R

= 100 kΩ )

osc

8. Charge pump with external capacitors at the pins Pump_ctrl and Vpump

9. 5V-regulator with bandgap reference

= (set value) – (motor current value) )

Cint1

and the 20 kHz oscillator)

Cint1

= 1 V at pin OSC

OSC

4.1.1 Analogue / Digital Interface, Signal Conditioning

This interface consists of the three pins MODE, IN and Cint2. The interface sets the operating
mode by the signal MODE, monitors and converts the input set value at the pin IN and drives
the pin IN to the low level in case of a detected failure in operating mode 1.
In operating mode 1 (OM1) the incoming low frequency PWM signal is converted in a dc voltage
by switching a current I

(typical: 200 kΩ / 2.2 µF). V
The monitor of the set value V
sleep / wake function and the input failure detection in operating mode 1, the hysteresis of these
detections is given in Fig. 4.2.

Symbol Meaning Meaning of the level

MODE Operating mode of the AS8410 MODE = high

P00 Detection of the 5 % threshold

value of the set value

P10 Detection of the 10 % threshold

value of the set value

= 10 µA with the incoming duty ratio to the pin Cint2 with R

cint2

must be in the range V

cint2

generates two internal logical signal P00 and P10 to treat the

Cint2

MODE = low
P00 = high
P00 = low
P10 = high
P10 = low

= 0 … 2 V.

cint2

Ü

Operating mode 1 (OM1)

Ü

Operating mode 2 (OM2)

Ü

Set value < 5 %

Ü

Set value > 5 %

Ü

Set value = 5 % ... 17.5 %)

Ü

Set value outside of this range

int2

/ C

int2

Rev. 1.0, December 2000 page 12 of 19

PWM DC Motor Regulator – Data Sheet

MODE_low

MODE_high

AS8410

Fig. 4.2 Monitoring of the set value (generation of the signals P00 and P10)

Symbol Parameter min typ max Unit Note

Operating Mode selection MODE

V

V

f

Duty Duty ratio of the PWM input 0 100 %

V

IN_low

V

IN_high

I

Cint2

V

IN_OM2

I

IN_high

I

IN_failure

Low-level of MODE 4,3 V
High-level of MODE 5,7 Vbat V

Set value input signal IN (OM1)

Frequency of the PWM set value input 10 Hz

IN

Low-level of the PWM input 0 3,35 V
High-level of the PWM input 3,65 Vbat V
Switched current high level at pin Cint2 9,8 10,0 10,4

Set value input signal IN (OM2)

Input voltage range of VIN (0 % … 100 %) 0 5 V

Signal conditioning of the signal at the pin IN

High level current at pin IN (internal pull up) 2.7 3.6 mA
Failure signal current at pin IN (internal pull down) 3.0 10.0 mA

µA

Rev. 1.0, December 2000 page 13 of 19

PWM DC Motor Regulator – Data Sheet

SRC1/SRC2

OUT/ISRC1

OUT/ISRC2

OUT/ISRC1

OUT/ISRC2

AS8410

4.1.2 Regulator Characteristic, PWM Generator

The external set value, incoming at pin IN, is transformed in both modes (OM1 and OM2) to the
internal dc voltage in the range 0 … 2 V corresponding to 0 % … 100 % set value.
A function generator transforms then this set value voltage to a function with two different gradi­ents: a) The input range 0 % … 50 % is transformed to the output range 0 % … 20 %

b) The input range 50 % … 100 % is transformed to the output range

In this way the resolution of the set value input is higher in the first half of the input range (low
motor currents: 0% … 20%) than in the second half one (higher motor currents 20% … 100%).
A special behaviour is implemented for very low input set values in the following way for the
operating mode 1 (OM1) and operating mode 2 (OM2):
a) OM2: For low input set values (< 10%) the system is put in sleep mode

Condition: (P00 or P10) and (/MODE)

b) OM1: For very low input set values (0 < set value < 5%, duty ratio nearly or

equal 0 is taken as input failure: short circuit of the input line to ground),
the internal set value is put to 100 % àsecurity mode: The motor is
permanently switched on and so cooling the heating engine.
For input set values in the range 5% < set value < 10% the system is put in a
special sleep mode.

The difference of the set value output of this block and the internal control value coming from
the motor measurement unit is controlling the PWM generator (voltage at the pin Cint1) and so
generating the duty ratio of the 20 kHz PWM signal what controls the power FET driver.

The time constant of this regulation loop can be chosen in very width ranges by the external
capacitor connected at the pin Cint1.

4.1.3 Power FET driver, Slew rate regulation

The Power FET driver is controlled in two different ways:
First by the digital output of the PWM generator to realise the duty ratio of the motor drive and
so to regulate the motor current in the closed loop.
Second by the analogue motor voltage to regulate the slew rate during the rising and falling
edge of the motor voltage. This control is executed by an external feedback of the motor voltage
to the pins SRC1 (rising edge) and SRC2 (falling edge). The two currents incoming to these
pins are amplified by a factor of about 1000 and drive then the gate of the external power FET.
The supply voltage of this driver is about 10 V higher than the Vbat (n-channel power FET) and
is delivered by the on chip charge pump at pin Vpump.

Symbol Parameter min typ max Unit Note

Vpump Pumped supply voltage 11 Vbat+10 43,00 V

V

I

I

SRC1

I

I

SRC2

OUT

Voltage at the pins SRC1 or SRC2 0.70 0.90 V

or

Input current into the pins SRC1 or SRC2 400
Output current pin OUT -300 300 mA

Current amplification factor (high currents) 900 1100 1600
I
I

Current amplification factor (low currents) 900 1400 1700
I

t

Delay 100 ns

S

µA

1

2
3

4

Rev. 1.0, December 2000 page 14 of 19

PWM DC Motor Regulator – Data Sheet

Cp1

Cp2

CM_diff_nom

CM_diff_over

CM_diff_nom

AS8410

1

This input must be current limited by the external circuitry (max. 400 µA).

2

max. pulse duration = 1µs

3

valid for I

4

valid for I

= 5 mA ... 300 mA and Vbat = 12 V , Vpump = 22 V

OUT

= 1 mA ... 5 mA and VDDA = 12 V , Vpump = 22 V

OUT

(For a fixed output current the tolerance of the current amplification factor is less than 10%.)

4.1.4 Charge pump

The charge pump generates a supply voltage about 10 V higher than the system supply voltage
Vbat (Vpump = Vbat + 10 V) to drive the gate of the external high side power FET switch.
In the case of the min. supply voltage Vbat = 6 V, the pumped voltage Vpump is about 11 V.
The load current of the external capacitors Cp1 and Cp2 is limited to max. 40 mA to prevent RF
emissions by high current peaks.

Symbol Parameter min typ max Unit Note

VPP Pumped voltage difference

9,0 10,0 12,0 V

VPP = (Vpump – Vbat)

I

, I

Currents to the external capacitors 40 mA

DV Ripple of the pumped voltage Vpump 0,50 0,70 V

f

PWM

1

valid for Vbat = (12.. 33) V (for Vbat = 6 V is VPP = 5 V), Vpump = Vbat + VPP

2

valid for I

Frequency (internal oscillator) 18 kHz

= 300 mA ( pulse duration < 1µs and f

Vpump

= 18 kHz ), Cp1 = Cp2 = 400 nF

OSC

1

2

4.1.5 Motor current measurement unit

The motor measurement unit works with an external current measurement resistor in the high
side motor line. The nominal measurement differential voltage (V

CMp

– V

CMn)nom

is fixed to
50 mV (corresponding to 100% of the motor current). So the value of this measurement resistor
is given by R

= 50 mV / I

meas

motor_nom

.
The over current detection is fixed by a motor current 60 % over the nominal motor current
(I

motor_over

= 1.6 * I

motor_nom

). The switch off of the motor in case of an over current (or short circuit

of the motor) is realised in less than 2 µs.

Symbol Parameter min typ max Unit Note

V

CMp/CMn

V

V

FI Relative motor current measurement

1

I

motor_nom

R

meas

2

Over current detection at I

3

FI < 2 % of I

valid for static V

(V

CMp/CMn_min

Common mode voltage at the pins
CMn or CMp
Nominal differential voltage of the
motor current measurement input
(V

– V

CMp

CMn)nom

Threshold voltage of the over current
detection

error

= V

CM_diff_nom

/ R

meas

is the motor current measurement resistor.

= 1,6 * I

– I

motor

CMp/CMn_max

motor_nom

motor_meas

) / I

= Vbat) with t

motor_nom

, FI = (I

or for: Vbat = 12 V , Vpump = 22 V , switching edges of V

CMp/CMn

= -0.7 V and V

motor_over

-1.15 Vbat V
50 mV

1,6 * V

2 %

motor_nom

CMp/CMn

rise/fall

> 200 ns

1

2

3

Rev. 1.0, December 2000 page 15 of 19

PWM DC Motor Regulator – Data Sheet

VDD_OUT

AS8410

4.1.6 Oscillator, Reference Voltage / Current Generator

The oscillator is used to control the PWM generator and the charge pump with a frequency of
typical 18 kHz.
The reference current I
regulator which delivers a stable voltage of 1 V at pin OSC, the R
erates the reference current. This reference current is used for other functions of this chip too
(see section 3).

Symbol Parameter min typ max Unit Note

V

f

OSC

T

rise/fall

I

1

I

ref

Reference voltage at pin OSC

OSC

Oscillator frequency 17,0 18,0 19,0 kHz
Rise or fall time of the clock 100 ns
Reference current 9,6 10,0 10,4

ref

must be generated by the external resistor R

of this oscillator is generated by a temperature compensated voltage

ref

= 100 kΩ at this pin gen-

OSC

0.96 1.00 1.04 V

1

µA

= 100 kΩ at the pin OSC

OSC

4.1.7 5V Regulator (bandgap reference)

The 5V-regulator generates the supply voltage for all internal low voltage blocks and the rough
reference voltage for the 1 V-regulator to generate the reference current I

. This regulated 5 V

ref

supply can also be used externally (e.g. for the temperature sensor at pin TP).
This externally usable 5 V will be switched off in the sleep mode.

Symbol Parameter min typ max Unit Note

Vbat Supply voltage of the regulator 6,5 12 35 V
VDD Regulated voltage 4,7 5,0 5,3 V

I

1

external capacitor to ground C

External load current at pin VDD 3 mA

= 100 nF

VDD

1

4.1.8 Failures Detection, Failure Handling Procedures

Three different kinds of failure detections and protections are implemented:

1. Failure detection of the load circuit (DC motor and power FET)

1.1 Over current detection and protection

1.2 No load detection of the motor and protection

1.3 Open wire detection (motor or power switch)

1.4 Short circuit of the power switch detection

1.5 Blocked motor detection and protection

1.6 Short-circuited motor segments detection and protection

1.7 Protection of the power FET and the ASIC, if the motor works in generator mode

2. Failure detection of the supply voltage Vbat (Over- / Under Voltage)

3. Over Temperature detection and protection in two modes

Rev. 1.0, December 2000 page 16 of 19

PWM DC Motor Regulator – Data Sheet
AS8410

For all detected failures an adequate failure handling procedure is integrated to fully protect the
motor regulator module. This failure procedures works without interaction of the controlling µP
and so the AS8410 can also be used to develop regulator modules without µP. Nevertheless

the most important failures are reported in operating mode 1 (OM1) by pull down the set value
input pin IN with a current source (3 mA … 10 mA).

4.1.8.1 Motor Failures

The principle of the load circuit (motor and power FET) failure detection and handling procedures
is the following:

a) Motor failure detection principle: The motor current at the high side of the motor and the

average value of the motor voltage is permanently measured. In this way the actual
motor working point is monitored and permanently compared with the normal motor
characteristic. This comparison delivers then the different motor or power FET failures.

b) Failure handling procedures: After the detection of any motor or power FET failure, the

control of the motor is taken by internal settings (no longer by the input set value IN) to
protect the whole system.
After a predefined time the AS8410 restarts the control by the input set value again and
monitors the motor and power FET.
This procedure is repeated up the failure disappears (or the controlling µP is executing
a protection reaction by itself).

The main internal setting values and reactions of the different load circuit failures in OM1 are
listed here below:

1. Over current or short circuit of the motor
Handling: a) switch off the motor immediately (delay < 1 µs)

b) report of the failure at the pin IN
c) check the failure condition again after a waiting time
d) reuse the input set value, if the over current condition is over

2. No load of the motor
Handling: a) report of the failure at the pin IN

b) internal setting of the set value to 75 %

c) reuse the input set value, if the no load condition is over

3. Open wire (motor or power FET line)
Handling: a) report of the failure at the pin IN

b) internal setting of the set value to 75 %
c) reuse the input set value, if the open wire condition is over

4. Short-circuited power switch (power FET)

Handling: a) report of the failure at the pin IN

b) internal setting of the set value to 75 %
c) reuse the input set value, if the short-circuit condition is over

5. Mechanically blocked motor

Handling: a) report of the failure at the pin IN

b) pull down the motor
c) check the failure condition again after a waiting time
d) reuse the input set value, if the blocked motor condition is over

Rev. 1.0, December 2000 page 17 of 19

PWM DC Motor Regulator – Data Sheet
AS8410

6. Short-circuited commutator segments (dirt of the lamellas)

Handling: a) internal setting of the set value to 100 % (cleaning of the lamellas)

b) regulation of the motor with adapted characteristic or switch off the
motor if the motor current cross over the over current threshold
c) reuse the input set value, if the short-circuit condition is over

7. Protection function for the power FET and the AS8410 itself, if the motor works as
generator due to its mechanical inertia

Handling: a) The gate potential of the power FET is permanently monitored, if this

potential is to high in the switch off case of the driver, the power FET

gate will be protected

b) If the power FET gate is returned in the normal region (the motor speed

of the off switched motor is low enough), the normal driver function is
reused.

The figure 4.3 is showing an example of the sequence of AS8410 internal events during failures
handling procedure in a reduced time scale.

Fig. 4.3 Example of a failure handling procedure

Rev. 1.0, December 2000 page 18 of 19

PWM DC Motor Regulator – Data Sheet
AS8410

4.1.8.2 Over / Under Voltage Detection and Protection

The over / under voltage detection is used to prevent undefined system status.
Over or under voltage detected:

Handling: a) switch off the motor

b) reuse the input set value, if the supply voltage returns in the
permissible range

Symbol Parameter min typ max Unit Note

Vbat Monitored supply voltage 5 12 50 V

V

bat_min

V

bat_max

Threshold voltage of the under voltage
detection

Threshold voltage of the over voltage
detection

6,2 6,50 6,7 V falling

32 33 34 V rising

4.1.8.3 Over Temperature Detection and Protection

The over temperature detection is realised with an external temperature sensor (e.g. NTC re­sistor) connected to the pin TP and the supply VDD. The threshold value of the temperature
detection is fixed at the voltage level V

Symbol Parameter min typ max Unit Note

VDD 5V supply at pin VDD 4,7 5,00 5,3 V

V

Threshold voltage of the temperature

refT

detection

V

refT_hys

1

Over temperature if VTP < 0.5*VDD

Hysteresis of the threshold voltage 50 mV

No over temperature if VTP > 0.5*VDD
Cross current of the external resistor divider must be > 1 mA

Handling of the over temperature failure:
Operating Mode 1 (V

MODE

= high):

- The Over Temperature reaction: 100 % duty ratio of the FET-driver output (perma­nent switch on the motor) as long as the temperature is higher than the predefined
threshold value (typical automotive application, the heating source is not the electri­cal system but the combustion engine to be cooled).

Operating Mode 2 (V

MODE

= low):

- The Over Temperature reaction: The motor is regulated down to not cross the pre­defined temperature threshold (like a thermostat if the heating source is the electrical
system itself).

= 0.5 *VDD at the pin TP.

refT

0.5*VDD V

1

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Rev. 1.0, December 2000 page 19 of 19