BIDIRECTIONAL SWITCH
MOTOR STOP CONTROLLED BY MOTOR
CURRENT
START UP AND END CURRENT DETEC-
TION
THRESHOLDS
PROGRAMMABLE
WITH EXTERNAL RSHUNT
STOP DELAY TIME FOR START UP AND
END PHASE PROGRAMMABLE WITH EX-
TERNAL RC
OUTPUT SHORT CIRCUIT PROTECTION
OUTPUT CURRENT LIMITING > 8A
THERMAL PROTECTION
ACTIVE DIODE BRIDGE INTERNALLY DIF-
FUSED
MAXIMUM VOLTAGE SUPPLY 50V
TECHNOLOGY MULTIPOWER BCD60II
November 1998
COMMON
19
ACTIVE
BRIDGE
GND
1,10,11,20
LIVE
2
V+
14
POW ER ON
RESET
LOGIC HV
REF.
VOLTAGE
THERMAL
PROTEC T.
CHARGE
CEX.
CONTROL
LOGIC LV
OPEN LOAD
DETECTOR
CHARGE
PUMP
CURRENT
PROTECT.
POWER
DUAL DMOS
COMP.
VREF
S H U N T
5
3
4
6
17
16
RCEX
8
REF. COMP.
CURRENT
BLOCK DIAGRAM
PowerSO20
L9639
FOLDER ACTUATOR
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DESCRIPTION
This device typically drives a direct current motor
servomechanism providing two extreme end posi-
tions and replaces end position switches or sen-
sors.
For more details see the Timing diagram (Fig. 1)
and the Application diagram (Fig. 2)
When the power supply is applied, or its polarity
is inverted the motor is powered up (start point).
The current of the motor reaches the start up
value near to the stall current, always higher than
the threshold value of the device (I
TH
) . A delay
on the detection (T
D
) permits the motor start up
and the consequent decrease of the current.
During the free running phase, the current in the
motor must always be lower the threshold I
TH
.
When the motor reaches the end of the run limit,
the current increases reaching a value that, de-
pending on the application, can be the stall value
or can depend on some torque limiting friction
(end point). Provided that this value is higher the
programmed threshold I
TH
, the motor is stopped
after a time delay T
D
, and the device goes into a
low consumption standby status, ready to restart
the motor for a new cycle if the polarity of the
power supply is inverted (or power is switched off
and on).
In any case, if the current exceeds the higher
threshold I
THCC
, the motor is immediately stopped
because a short circuit is detected. The delay T
D
also permits the motor to overcome some small
obstacle during the free run.
The threshold current for the running phase I
TH
is
obtained by comparing the voltage on an external
sensing resistor (R
SHUNT
) to a threshold voltage
V
TH
.
1) I
TH
= V
TH
/ R
SHUNT
V
TH
is constant in respect to the power supply
voltage because in most applications, the end of
run current is depending only on motor and the
mechanic torque limiting device (friction current).
The threshold current for the short circuit detec-
tion is:
2) I
THCC
= V
THCC
/R
SHUNT
@ V
THCC
= 330mV @
V
bat
= 12V
and depends intentionally on the supply voltage
because of the same dependence of the stall cur-
rent. The time T
D
depends on two external com-
ponents, capacitor C
EX
and resistor R
EX
. TD is
obtained by the following expression :
T
D
= R
EX
R
EX
K
TD
K
TD
is a constant typically of unit value.
The block diagram is shown on the first page.
The change of the polarity between pins COM-
MON and LIVE, needs the active bridge to supply
the internal circuit. The internal supply voltage is
available between pins V+ and GND and a stor-
age and filter capacitor (100nF) must be con-
nected between these pins. The output stage
ELECTRICAL CHARACTERISTICS (Refer to the test circuit, unless otherwise specified.)
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
V
bat
Power supply
8
17
V
I
q
Quiescent current
Stanby
100
200
A
I
ref
Current ref. threshold for start
and end current (note 1)
V
bat
= 8 to 17V
70
100
135
A
I
refcc
Current ref. threshold for short
circuit current det (note 2)
Vbat = 8V
V
bat
= 12V
V
bat
= 17V
240
300
400
300
440
550
400
560
690
A
I
sc1
Current short circuit limit
8
A
T
dsc
Short circuit time delay
I
load
> I
th cc
100
s
R
on
R
on
output power DMOS
I
load
= 1.2A
0.6
1
Ohm
R
ona
R
on
active bridge DMOS
V
bat
= 8V, I
gnd
= 1A
0.7
Ohm
R
load
Open load detector max. load
resistance
200
Ohm
K
td
Delay constant (note 3)
1
Deb
Immunity debouncer switch
V
bat
= pulse
Note 1: I
th
=
R_ref
R
shunt
I
ref
Note 2: I
thcc
=
R_ref
R
shunt
I
refcc
Note 3: T
d
=
In
V
th_high
V
th_low
Rex
Cex
=
Rex
Cex
Ktd
L9639
3/6
consists of two DMOS transistors connected in
series with common drain to act as a switch with
the voltage applied in both direction. A charge
pump takes the gates of the DMOS above the
supply voltage. The motor is controlled by the
control 'logic low voltage' block that receives the
motor status for the comparator. The 'charge C
EX
'
block controls the T
D
delay.
1
2
3
ITH
ITHCC
STALL CURRENT
2.3A
FRICTION
1.2A
VTH_HIGH
VTH_LOW
Figure 1. Functional timing diagram.
LIVE
COMMON
NC
GND
OUT
OUT
NC
V+
GND
NC
GND
SHUNT
SHUNT
SHUNT
GND
RCEX
R_SHUNT
R_REF
M
C+
C_EX
R_EX
NC
NC
NC
VREF
Figure 2. Application schematic diagram.
All the necessary external components are shown in the application diagram. It is important to shunt the
motor with a device that limits the maximum over voltage to 40V. This is necessary when the power sup-
ply circuit is opened on motor power up. In this case the back E.M.F. must be clamped because there is
no other free wheel current path.
L9639
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of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is
granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specification mentioned in this publication are
subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products
are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.
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L9639
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