Variable Speed Fan Motor Driver
Overview
The LB1860 series ICs are drivers for two-phase unipolar drive
DC brushless fan motors. They have functions such as driving,
lock protection, restart and speed control.
Features and Functions
.
Two-speed mode select function requiring less external
component additions: Full speed and Low speed. Or,
thermistor-controlled continuous variable-speed function
according to ambient operation temperatures.
Motor starts rotating at a low speed.
.
Motor lock protection and automatic return circuit built in
.
Output transistors: Output current I
O
= 1.5 A, output circuit
protection Zener diodes (LB1860: M-Vz = 57 V/ LB1861:
M-Vz = 32 V)
Enables low-level noise protection with chip capacitor.
.
Built-in thermal shutdown circuit
.
Built-in rotation detect function
(Drive mode: ``L'', Stop mode: ``H'')
.
The LB1860 series can be operated from either 12 V or 24 V
power supply by changing an external resistor.
(Strong protection against power supply surge)
.
Connectable direct to a Hall element
Package Dimensions
unit: mm
3098B-DIP10S
[LB1860, 1861]
SANYO : DIP10S
unit: mm
3111-MFP14S
[LB1860M, 1861M]
SANYO : MFP14S
Ordering number: EN3519A
Monolithic Digital IC
LB1860,1860M,1861,1861M
SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
73096HA(II)/4060TA,TS No.3519-1/6
Specifications
Absolute Maximum Ratings
at Ta = 25 C, ( ): LB1860M, LB1861M
Parameter
Symbol
Conditions
Ratings
Unit
Maximum input current
I
CC
max
t
%
20 ms
200
mA
Output supply voltage
V
OUT
Internal
V
Output current
I
OUT
1.5
A
RD flow-in current
I
RD
10
mA
RD supply voltage
V
RD
50
V
Allowable power dissipation
Pd1 max
1.1
W
Pd2 max
Mounted on 20
15
1.5 mm glass epoxy board
(0.8)
W
Operating temperature
Topr
30 to +80
C
Storage temperature
Tstg
55 to +125
C
Allowable Operating Ranges
at Ta = 25 C
Parameter
Symbol
Conditions
Ratings
Unit
Input current range
I
CC
6.0 to 50
mA
Common-mode input voltage range
V
ICM
0 to V
IN
1.5
V
Electrical Characteristics
at Ta = 25 C, I
CC
= 10 mA
Parameter
Symbol
Conditions
min
typ
max
Unit
Output limiting voltage
V
OLM
1
LB1860, 1860M: I
O
= 0.1 A
54
57
60
V
LB1861, 1861M: I
O
= 0.1 A
30
32
34
V
Output saturation voltage
V
O sat1
I
O
= 0.5 A
0.95
1.2
V
V
O sat2
I
O
= 1.0 A
1.15
1.5
V
V
O sat3
I
O
= 1.5 A
1.4
2.0
V
Input voltage
V
IN
I
CC
= 7.0 mA
6.4
6.7
7.0
V
Amp input offset voltage
V
OFF
7.0
0
7.0
mV
Amp input bias current
I
BA
250
nA
RD output saturation
voltage
V
RD
(sat)
I
RD
= 5 mA
0.15
0.3
V
C flow-out current
I
C
1
C = GND
2.7
3.9
5.0
A
C discharge current
I
C
2
C = V
IN
0.35
0.50
0.65
A
Comparator input threshold
voltage
V
TH
1
0.77
0.8 V
IN
0.83
V
V
TH
2
0.44
0.47 V
IN
0.50
V
Ct discharge voltage
Vct
0.18
0.2 V
IN
0.22
V
Rt input current
I
RT
V
RT
= GND
440
350
240
A
Rt comparator voltage
V
RT
R
T
= OPEN
0.59
0.62 V
IN
0.65
V
Thermal protection circuit
operating voltage
TSD
Design target
180
C
Thermal protection circuit
hysteresis
TSD
Design target
40
C
Pin Assignments
Top view
Top view
LB1860,1860M,1861,1861M
No.3519-2/6
Block Diagram and Application Circuit
Truth Table
(
): LB1860M, 1861M
IN
+
IN
Ct
Rt1
Rt2
CR
OUT1
OUT2
RD
Mode
H
L
H
L
--
L
H
L
L
Full speed
L
H
H
L
--
L
L
H
L
Full speed
(H)
(L)
--
--
(H)
(L)
(H)
(L)
(L)
(Full speed)
(L)
(H)
--
--
(H)
(L)
(L)
(H)
(L)
(Full speed)
--
--
L
H
L
L
H
H
L
Low speed
--
--
--
--
--
H
H
H
H
Lock protection
Designer's Notes
(1) Variable-speed circuit (Rt and Ct pins) -- Refer to the application circuit diagram
.
The time constant gained by external components C2 and R2 is used to set the length of an `off' operation time period after
phase switching. This means that the variable-speed operations can be performed by changing the `on' operation time of each
phase through the duty control.
.
The sawtooth waveform signals are generated by the C2-R2 time constant. The voltage of this signal (Ct pin voltage) increases
from 1.3 V to 4.0 V (Vct) at each phase switching. That is, during this period, the driver becomes inactive (t
off
), in which
output circuit is turned off.
.
If V
CC
^ 4.0 V, the driver IC remains active (t
on
) until the next phase switching. During this period, output circuit is turned on.
.
If the active drive time of each phase is assumed to `t
o
', the following relation can be established:
t
o
=
t
off
+
t
on
Fixed
Rotation speed
constant
proportional constant
t
off
= 0.69 c C2 c R2 ........................................ 1
Constant
current
circuit
Output timing control
Unit (resistance:
, capacitance: F)
Figure 1
(
): MFP14S
0.47 to 10
LB1860,1860M,1861,1861M
No.3519-3/6
.
From this relation, it can be observed that the `t
o
' and `t
on
' are in proportional relation with each other, and that the `t
on
/t
o
'
equals the `on' time duty. As a result, a certain rotation speed can be fixed despite the fact that rotation speed exclusively
depends on each motor.
.
At the start, the `t
on
' value becomes longer while the `t
off
' value remains unchanged. This means that the `t
off
/t
o
' duty becomes
small enough compared to normal rotation mode. Therefore, the same start torque as that of the full speed rotation can be
obtained because the `on' operation time duty increases. This enables the motor to start at a very low speed.
(2) Supply voltage (V
IN
pin)
.
The LB1860 has the internal parallel regulator which supplies power to the Hall amplifier circuit and the control block.
Therefore, the driver ICs are not affected by power source fluctuations and kickbacks from the motor. They maintain the stable
operations even if noise signals such as surge are generated.
.
Set the resistance R1 between V
CC
and V
IN
so that the I
CC
current of 6 mA to 50 mA can flow onto the V
IN
pin within the
supply voltage range of a fan motor.
.
V
IN
is 6.7 V typ at I
CC
= 7 mA.
.
The current flowing into V
IN
is calculated using the equation shown below.
I
CC
=
V
CC
V
IN
R1
............................ 2
.
Consideration given to surge voltage
.
The maximum allowable current at V
IN
pin is 200 mA. Therefore, the pin is designed to withstand abnormal positive voltage of:
Vsurge
=
V
IN
+ R1
200 mA ............................................ 3
(3) Hall input pin voltage (Pins IN
, IN
+
)
.
Set the voltage levels of the input pin for the Hall element output and the Hall element output voltage to within the range of
0 V to V
IN
1.5 V.
.
The gain between the hall input pin and the output pin is 100 dB or greater. The offset voltage of the hall input amp is
7 mV,
therefore, the hall element output must be set with the offset voltage (
7 mV) considered.
(4) Output transistor (Pins OUT1, OUT2)
.
Output current
I
O
= 1.5 A max
.
Output saturation voltage
V
O
sat = 1.15 V/1.0 A typ
.
Output limiting voltage
V
OLM
= 57 V typ (LB1860, 1860M)
V
OLM
= 32 V typ (LB1861,1861M)
.
Since the LB1860 series have a protect zener diode between collector and base, the kickback voltage induced by the coil is cut
at V
OLM
= 57 V (32 V). When external capacitors are connected between OUT and GND, the capacitance should not exceed
10 F.
(5) Output protection function (C pin)
.
Capacitor pin used in forming an automatic return circuit.
.
If rotation is stopped due to overload, the pin voltage level increases and then forces the output to become inactive. In this case,
after proper load adjustment, the output returns to the `drive' mode from the `stop' mode automatically. By changing the
capacitor value, the lock detect time period can be set.
For C marked with 1 F
Lock detect time
Approximately 2 sec.
Lock protect time (output ON)
Approximately 1 sec.
(output OFF)
Approximately 6 sec.
Rotation
Output ON
Output OFF
Output
ON
Output OFF
Rotation
Lock
Lock release
Automatic Return Circuit C Pin Voltage
LB1860,1860M,1861,1861M
No.3519-4/6
1 When a fan is rotating, the capacitor is charged at 4 A (typ) and discharged through the C with pulses according to the
rotational speed.
2 When a fan is locked, no discharge occurs through the C and the C voltage rises, turning OFF the output at 0.8
V
IN
.
3 When the output is turned OFF, discharge occurs through the C at 0.5 A (typ). If the lock is not released when the C voltage
drops to V
TH
2, the capacitor is charged to V
TH
1 again. (At this moment, the output is turned ON.) These operations 2 and
3 repeated at a cycle of approximately t
on
: t
off
= 1:6 protect a motor.
4 If the lock is released when the C voltage drops to V
TH
2, the output is turned ON, starting rotation.
(6) Rotation detect signal (RD pin)
.
Open collector output (Drive mode: ``L'', Stop mode: ``H'')
(7) Radio noise reducing (Pins B1, B2)
.
Base pin of Darlington connection output transistor
.
If radio noises need to be processed properly, the following actions should be taken:
1 Connect a capacitor of 0.01 to 0.1 F between B1 and B2.
2 Connect a capacitor of 0.001 to 0.01 F between OUT and B.
If output causes oscillation, add a resistor of 200
to 1 k
in series with a capacitor.
(8) Thermal shutdown function
.
Shutdown the driver output in case of coil short-circuiting and abnormal IC heating.
Thermistor-controlled Application Circuit Example
Output Timing Chart
Noise elimination
capacitor
Figure 2
(
): MFP14S
Unit (resistance:
, capacitance: F)
Use of a thermistor enables motor speed to
be sensitive to the operating ambient
temperature.
The Rt pin voltage at Ta = 20 C has
1.42 ms of `t
off
' as calculated in expression
4 with the application constant of Figure 2.
However, the Rt pin voltage at Ta = 40 C
is reduced into less than the Vct (= 1.3 V)
level, which results in a 0 of `t
off
'. This
means the 100% duty.
t = C2 c R2 c 1n
(V
IN
V
Rt
)
V
IN
V
Ct
............. 4
Hall input
Discharge pulse
Ct voltage
Output `off' signal
OUT1 current
OUT2 current
All-phase ON waveform
Control output waveform
Figure 3
LB1860,1860M,1861,1861M
No.3519-5/6
No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace equipment,
nuclear power control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of which may directly or
indirectly cause injury, death or property loss.
Anyone purchasing any products described or contained herein for an above-mentioned use shall:
1
Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors
and all their officers and employees, jointly and severally, against any and all claims and litigation and all damages, cost and
expenses associated with such use:
2
Not impose any responsibility for any fault or negligence which may be cited in any such claim or litigation on SANYO
ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors or any of their officers and employees jointly or severally.
Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for volume
production. SANYO believes information herein is accurate and reliable, but no guarantees are made or implied regarding its use
or any infringements of intellectual property rights or other rights of third parties.
This catalog provides information as of July, 1996. Specifications and information herein are subject to change without notice.
Number
of
rotation
,n-r
p
m
Ambient temperature, Ta - C
Top Speed
LB1860,1860M,1861,1861M
No.3519-6/6
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