EN6088 D

Ordering number : EN6088B
LB1976
Monolithic Digital IC
For Fan Motor
http://onsemi.com
3-phase Brushless Motor Driver
Overview
The LB1976 is a 3-phase brushless motor driver IC suited for use in direct PWM driving of DC fan motors for air
conditioners, water heaters, and other similar equipment. Since a shunt regulator circuit is built in, single power supply
operation sharing the same power supply for the motor is supported.
Features
• Withstand voltage 60V, output current 2.5A
• Direct PWM drive output
• 3 built-in output top-side diodes
• Built-in current limiter
• Built-in FG output circuit
Specifications
Absolute Maximum Ratings at Ta = 25°C
Parameter
Supply voltage
Output current
Symbol
Conditions
VCC max
Ratings
Unit
7
V
VM max
60
V
IO max
2.5
A
10
mA
3
W
Maximum input current
IREG max
VREG pin
Allowable power dissipation
Pd max1
Independent IC
Pd max2
With infinite hear sink
20
W
Operating temperature
Topr
-20 to +100
°C
Storage temperature
Tstg
-55 to +150
°C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating
Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability.
Semiconductor Components Industries, LLC, 2013
May, 2013
D2408 MS / 21003AS (OT) / 52199RM (KI) No.6088-1/10
LB1976
Allowable Operating Ranges at Ta = 25°C
Parameter
Supply voltage range
Symbol
Conditions
Ratings
VCC
Unit
4.5 to 6.7
VM
20 to 56
Input current range
IREG
FG pin applied voltage
VFG
FG pin output current
IFG
VREG pin
1 to 5
0 to VCC
0 to 10
V
V
mA
V
mA
Electrical Characteristics at Ta = 25°C, VCC = 5V, VM = 45V
Parameter
Symbol
Ratings
Conditions
min
Supply current
ICC
typ
10
Unit
max
14
18
mA
Output Block
Output saturation voltage
Output leak current
VOsat1(L)
IO = 1.0A, VO(sink)
1.1
1.4
V
VOsat1(H)
IO = 1.0A, VO(source)
0.9
1.3
V
VOsat1
IO = 1.0A, VO(sink) + VO(source)
2.0
2.6
V
VOsat2(L)
IO = 2.0A, VO(sink)
1.4
1.8
V
VOsat2(H)
IO = 2.0A, VO(source)
1.2
1.7
V
VOsat2
IO = 2.0A, VO(sink) + VO(source)
2.6
3.4
V
IOLeak(L)
100
IOLeak(H)
Upper side diode forward voltage
μA
μA
-100
VFH1
IO = 1.0A
1.2
1.6
V
VFH2
IO = 2.0A
2.1
2.6
V
Hall Amplifier
Input bias current
IHB
-4
μA
-1
Common-mode input voltage range
VICM
1.5
Hall input sensitivity
VHIN
60
VCC-1.5
V
Hysteresis width
ΔVIN(HA)
23
32
39
mV
Input voltage (low to high)
VSLH
6
16
25
mV
Input voltage (high to low)
VSHL
-25
-16
-6
mV
0.5
V
mVp-p
FG Pin (speed pulse output)
Output low-level voltage
VFGL
IFG = 5mA
Pull-up resistor value
RFG
7.5
10
12.5
kΩ
VRF
0.45
0.50
0.55
V
150
180
°C
40
°C
Current Limiter
Limiter
Thermal Shutdown
Thermal shutdown operating
TSD
Design target Value (junction temperature)
ΔTSD
Design target Value (junction temperature)
temperature
Hysteresis width
Low-Voltage Protection
Operating voltage
VLVSD
Non-operating voltage
VLVSD(OFF)
Hysteresis width
ΔVLVSD
3.5
3.8
4.1
V
4.3
4.5
V
0.4
0.5
0.6
V
2.95
3.10
3.25
V
PWM Oscillator
Output high-level voltage
VOH(OSC)
Output low-level voltage
VOL(OSC)
1.38
1.45
1.59
V
Amplitude
VOSC
1.50
1.65
1.71
Vp-p
Oscillator frequency
fOSC
19.6
23.0
27.6
kHz
-110
-94
-83
μA
1.6
2.1
2.6
kΩ
6.6
7.0
7.2
V
Charge current
ICHG
Discharge resistance
RDCHG
C = 2200pF
VREG Pin
Pin voltage
VREG
IREG = 1.5mA
Continued on next page.
No.6088-2/10
LB1976
Continued from preceding page.
Parameter
Symbol
Ratings
Conditions
min
typ
Unit
max
VCTL Pin
Input voltage
Input bias current
VCTL1
Output duty 0%
1.1
1.4
1.7
V
VCTL2
Output duty 100%
3.2
3.5
3.8
V
IB1(CTL)
VCTL = 0V
-82
IB2(CTL)
VCTL = 5V
μA
92
μA
2.46
V
VCTL Amplifier
Reference voltage
VCREF
Output voltage
2.23
2.35
VCOUT1
VCTL = 0V
3.90
4.20
4.40
V
VCOUT2
VCTL = 5V
0.60
0.80
1.10
V
Start/Stop Pin
High-level input voltage range
VIH(S/S)
VCC-1.5
VCC
V
Low-level input voltage range
VIL(S/S)
0
1.5
V
Input open voltage
VIO(S/S)
VCC-0.5
VCC
V
Hysteresis width
ΔVIN(S/S)
High-level input current
IIH(S/S)
V(S/S) = VCC
Low-level input current
IIL(S/S)
V(S/S) = 0V
0.35
0.50
0.65
V
-10
0
+10
μA
-280
-210
μA
Forward/Reverse Pin
High-level input voltage range
VIH(F/R)
VCC-1.5
VCC
Low-level input voltage range
VIL(F/R)
0
1.5
V
V
Input open voltage
VIO(F/R)
VCC-0.5
VCC
V
Hysteresis width
ΔVIN(F/R)
High-level input current
IIH(F/R)
V(F/R) = VCC
Low-level input current
IIL(F/R)
V(F/R) = 0V
0.35
0.50
0.65
V
-10
0
+10
μA
-280
-210
μA
Package Dimensions
unit : mm (typ)
3147C
Pd max -- Ta
15
12.7
11.2
R1.7
0.4
8.4
28
1
14
20.0
4.0
4.0
26.75
(1.81)
1.78
0.6
Allowable power dissipation, Pd max -- W
24
With infinite heat sink
20
16
12
8
4
3
Independent IC
0
-20
0
20
40
60
80
100
120
Ambient temperature, Ta -- °C
1.0
SANYO : DIP28H(500mil)
No.6088-3/10
LB1976
Pin Assignment
VCOUT VCTL OSC
28
27
26
(NC) VCREF IN1−
25
24
23
IN1+
22
IN2− IN2+
21
20
IN3−
IN3+
FG1
19
18
17
10
11
12
FG2 GND1
16
15
LB1976
1
2
VCC VREG
3
5
S/S
F/R
5
6
7
8
9
(NC) OUT1 OUT2 OUT3 (NC)
(NC) GND3 GND2
13
14
RF
VM
Top view
Truth Table
Input
IN1
1
H
2
H
3
H
4
L
5
L
6
L
IN2
L
L
H
H
H
L
Forward/reverse control
IN3
F/R
Source → Sink
L
OUT2 → OUT1
H
OUT1 → OUT2
H
L
L
L
H
H
F/R
L
OUT3 → OUT1
H
OUT1 → OUT3
L
OUT3 → OUT2
H
OUT2 → OUT3
L
OUT1 → OUT2
H
OUT2 → OUT1
L
OUT1 → OUT3
H
OUT3 → OUT1
L
OUT2 → OUT3
H
OUT3 → OUT2
FG output
FG1
FG2
L
L
L
H
L
L
H
H
H
L
H
H
FG output
0V to 1.5V
VCC − 1.5V to VCC
100
FG1
FG2
Duty -- VCTL characteristics
80
Duty -- %
Forward rotation Low
Reverse rotation High
Output
60
40
20
0
VCTL1
Control voltage, VCTL -- V
VCTL2
No.6088-4/10
LB1976
Block Diagram and Peripheral Circuit
VREG
VCC
VCC
S/S
F/R
FG1 FG2
Reg
LVDS
TSD
VM
Hys.Amp
H
VM
IN1
OUT1
H
H
OUT2
Logic
IN2
OUT3
IN3
RF
31kΩ
VCTL
40kΩ
Current
Limiter
VCTL Amp
PWM
OSC
VCTL
0.5V
2.35V
VCREF
VCOUT
OSC
GND1 GND2 GND3
Pin Functions
Pin No.
1
Pin name
VCC
Pin voltage
4.5V to 6.7V
Function
Equivalent circuit
Power supply for blocks other than the
output block.
2
VREG
0.0V to 7.3V
Shunt regulator output pin (7V).
3
S/S
0.0V to VCC
Start/stop control pin.
2
VCC
Low: start
High or Open: stop
20kΩ
Typical threshold voltage for
VCC = 5V:
approx. 2.8V (low to high)
3.8kΩ
3
approx. 2.3V (high to low)
Continued on next page.
No.6088-5/10
LB1976
Continued from preceding page.
Pin No.
4
Pin name
F/R
Pin voltage
0.0V to VCC
Function
Equivalent circuit
Forward/reverse pin.
VCC
Low: forward
High or Open: reverse
20kΩ
Typical threshold voltage for
3.8kΩ
VCC = 5V:
approx. 2.8V (low to high)
4
approx. 2.3V (high to low)
6
OUT1
Output pin 1.
7
OUT2
Output pin 2.
8
OUT3
Output pin 3.
13
RF
0.0V to VCC
VCC
14
Output current detect pin.
6
7
8
Connect resistor Rf between this pin and
ground. Output current is limited to value set
with VRF/Rf. (Current limiter operation)
200Ω
0.5V
13
14
VM
Output block power supply.
11
GND3
Output block ground.
15
GND1
Ground for blocks other than the output
12
GND2
block.
17
FG1
0.0V to VCC
Speed pulse output pin 1 with built-in pull-up
VCC
resistor.
10kΩ
16 17
16
FG2
0.0V to VCC
Speed pulse output pin 2 with built-in pull-up
resistor.
22
23
20
21
IN1+
IN1IN2+
IN2-
19
IN3+
IN3-
26
OSC
18
1.5V to
VCC − 1.5V
Hall input pin.
IN+ > IN- : High input
VCC
IN+ < IN- : Low input
18
20
22
1.0V to VCC
This pin sets the PWM oscillation frequency.
300Ω
300Ω
19
21
23
VCC
Connect a capacitor between this pin and
ground.
2V
94μA
200Ω
26
2.1kΩ
Continued on next page.
No.6088-6/10
LB1976
Continued from preceding page.
Pin No.
27
Pin name
VCTL
Pin voltage
0.0V to 6.7V
Function
Equivalent circuit
Output duty cycle control pin.
31kΩ
• VCTL ≤ VCTL1
VCC
Duty cycle 0%
• VCTL1 < VCTL < VCTL2
Duty cycle is controlled by VCTL
• VCTL ≥ VCTL2
Duty cycle 100%
40kΩ
2.35V
24
VCREF
0.0V to
VCC − 2.0V
VCTL amplifier internal reference voltage pin
(2.35V).
27
VCC
100μA
200Ω
24
23.5kΩ
28
VCOUT
0.7V to
VCC − 0.7V
VCTL amplifier output pin.
28
31kΩ
VCC
200Ω
No.6088-7/10
LB1976
IC Description
1. Direct PWM Drive
The LB1976 employs the direct PWM drive principle. Motor rotation speed is controlled by varying the output duty
cycle according to an analog voltage input (VCTL). This eliminates the need to alter the motor power supply voltage.
Compared to previous ICs using the PAM principle (such as the LB1690), this allows simplification of the power
supply circuitry. The VCTL input can be directly supplied by a microcontroller, motor speed can, therefore, be
controlled directly from the microcontroller.
For PWM, the source-side output transistors are switched on and off so that the ON duty tracks the VCTL input. The
output duty cycle can be controlled over the range of 0% to 100% by the VCTL input.
2. PWM Frequency
The PWM oscillator frequency fPWM [Hz] is set by the capacitance C [pF] connected between the OSC pin and GND.
The following equation applies:
fPWM ≈ 1 / (1.97 × C) × 108
Because output transistor on/off switching is subject to a delay, setting the PWM frequency to a very high value will
cause the delay to become noticeable. The PWM frequency therefore should normally be kept below 40kHz (typ.),
which is achieved with a capacitance C of 1300pF or higher. For reference, the source-side output transistor switching
delay time is about 2μs for ON and about 4μs for OFF.
3. Output Diodes
Because the PWM switching operation is carried out by the source-side output transistors, Schottky barrier diodes must
be connected between the OUT pins and GND (OUT1 to OUT3). Use diodes with an average forward current rating in
the range of 1.0 to 2.0A, in accordance with the motor type and current limiting requirements.
If no Schottky barrier diodes are connected externally, or if Schottky barrier diodes with high forward voltage (VF) are
used, the internal parasitic diode between OUT and GND becomes active. When this happens, the output logic circuit
may malfunction, resulting in feed-through current in the output which can destroy the output transistors. To prevent
this possibility, Schottky barrier diodes must be used and dimensioned properly.
The larger the VF of the externally connected Schottky barrier diodes, or the hotter the IC is, the more likely are the
parasitic diodes between OUT and GND to become active and the more likely is malfunction to occur. The VF of the
Schottky barrier diodes must be determined so that output malfunction does not occur also when the IC becomes hot. If
malfunction occurs, choose a Schottky barrier diode with lower VF.
4. Protection circuits
4-1. Low voltage protection circuit
When the VCC voltage falls below a stipulated level (VLVSD), the low voltage protection circuit cuts off the
source-side output transistors to prevent VCC related malfunction.
4-2. Thermal shutdown circuit (overheat protection circuit)
When the junction temperature rises above a stipulated value (TSD), the thermal shutdown circuit cuts off the
sourceside output transistors to prevent IC damage due to overheating. Design the application heat characteristics so
that the protection circuit will not be triggered under normal circumstances.
4-3. Current limiter
The current limiter cuts off the source-side output transistors when the output current reaches a preset value (limiter
value). This interrupts the source current and thereby limits the output current peak value. By connecting the
resistance Rf between the RF pin and ground, the output current can be detected as a voltage. When the RF pin
voltage reaches 0.5V (typ.), the current limiter is activated. It performs on/off control of the source-side output
transistors, thereby limiting the output current to the value determined by 0.5/Rf.
5. Hall Input Circuit
The Hall input circuit is a differential amplifier with a hysteresis of 32mV (typ.). The operation DC level must be
within the common-mode input voltage range (1.5V to VCC − 1.5V). To prevent noise and other adverse influences,
the input level should be at least 3 times the hysteresis (120 to 16mVp-p). If noise at the Hall input is a problem, a
noise-canceling capacitor (about 0.01μF) should be connected across the Hall input IN+ and IN− pins.
6. FG Output Circuit
The Hall input signal at IN1, IN2, and IN3 is combined and subject to waveform shaping before being output. The
signal at FG1 has the same frequency as the FG1 Hall input, and the signal at FG2 has a frequency that is three times
higher.
No.6088-8/10
LB1976
7. Start/Stop Control Circuit
The start/stop control circuit turns the source-side output transistors OFF (motor stop) when a High signal is input at the
S/S pin or when the pin is Open. When a Low signal is input at the S/S pin, the source-side output transistors are turned
ON, and the normal operation state is established (motor start).
8. Forward/Reverse Switching
The LB1976 is designed under the assumption that forward/reverse switching is not carried out while the motor is
running. If switching is carried out while the motor is running, reverse torque braking occurs, leading to a high current
flow. If the current limiter is triggered, the source-side output transistors are switched off, and the sink-side output
transistors go into the short brake condition. However, because the current limiter of this IC cannot control the current
flowing in the sink-side output transistors, these may be destroyed by the short brake current. Therefore F/R switching
while the motor is running is permissible only if the output current (IO) is limited to a maximum of 2.5A using the
motor coil resistance or other suitable means.
F/R switching should be carried out only while a High signal is input to the S/S pin or the pin is Open (stop condition),
or while the VCTL pin conforms to the following condition: VCTL≤ VCTL1 (duty cycle 0%). In any other condition,
F/R switching will result in feed-through current. The F/R pin should therefore be fixed to Low (forward) or High or
Open (reverse) during use.
9. VCC, VM Power Supplies
When the power supply voltage (VCC, VM) rises very quickly when a power is first applied, a feed-through current
may occur at the output. If the current remains below about 0.2A to 0.3A, it does not pose a problem, but such a
possibility should still be prevented by slowing down the voltage rise at power-on. Especially if the F/R pin is set to
High or Open (reverse), a quick rise in VCC is likely to cause feed-through current. This should be prevented by
ensuring that ΔVCC / Δt = 0.2V/µs or less. Feed-through current can also be prevented by first switching on VCC and
then VM during power-on.
The sequence at power-down should be as follows. Provide a stop input to the S/S pin or a duty ratio 0% input to the
VCTL pin. When the motor has come to a full stop, switch off VM and then VCC. If power is switched off while the
motor is still rotating or a current is flowing in the motor coil (including motor restraint or inertia rotation), a counter
electromotive current or kickback current may flow on the VM side, depending on the motor type and power-off
procedure. If this current cannot be absorbed by the VM power supply or a capacitor, VM voltage may rise and exceed
the absolute maximum VM rating for the IC. Ensure that this does not happen through proper design of the VM power
supply or through use of a capacitor.
Because the LB1976 incorporates a shunt regulator, it can be used on a single power supply. In this case, supply VCC
(6.3V typ.) to the VREG pin via an external NPN transistor and resistor. When not using the regulator, leave the VREG
pin open.
10. Power Supply Stabilizing Capacitors
If the VCC line fluctuates drastically, the low-voltage protection circuit may be activated by mistake, or other
malfunctions may occur. The VCC line must therefore be stabilized by connecting a capacitor of at least several μF
between VCC and GND. Because a large switching current flows in the VM line, wiring inductance and other factors
can lead to VM voltage fluctuations. As the GND line also fluctuates, the VM line must be stabilized by connecting a
capacitor of at least several µF between VM and GND, to prevent exceeding VM max or other problems. Especially
when long wiring runs (VM, VCC, GND) are used, sufficient capacitance should be provided to ensure power supply
stability.
11. VCREF Pin, VCOUT Pin
These pins are always used in the Open condition. If chattering occurs in the PWM switching output, connect a
capacitor (about 0.1μF) between VCREF and ground or between VCOUT and GND.
12. IC Heat Dissipation Fins
A heat sink may be mounted to the heat dissipation fins of this IC, but it may not be connected to GND. The sink should
be electrically open.
No.6088-9/10
LB1976
13. Sample calculation for internal power dissipation (approximate)
The calculation assumes the following parameters:
VCC = 5V
VM = 30V
Source-side output transistor ON duty cycle 80% (PWM control)
Output current IO = 1A (RF pin average current)
(1) ICC power dissipation P1
P1 = VCC × ICC = 5V × 14mA = 0.07W
(2) Output drive current power dissipation P2
P2 = VM × 11mA = 30V × 11mA = 0.33W
(3) Source-side output transistor power dissipation P3
P3 = VO(source) × IO × Duty(on) = 0.9V × 1A × 0.8 = 0.72W
(4) Sink-side output transistor power dissipation P4
P4 = VO(sink) × IO = 1.1V × 1A = 1.10W
(5) Total internal power dissipation P
P = P1 + P2 + P3 + P4 = 2.22W
14. IC temperature Rise Measurement
Because the chip temperature of the IC cannot be measured directly, measurement according to one of the following
procedures should always be carried out.
14-1. Thermocouple measurement
A thermocouple element is mounted to the IC heat dissipation fin. This measurement method is easy to implement,
but it will be subject to measurement errors if the temperature is not stable.
14-2. Measurement using internal diode characteristics of IC
This is the recommended measurement method. It makes use of the parasitic diode incorporated in the IC between
FG1 and GND. Set FG1 to High and measure the voltage VF of the parasitic diode to calculate the temperature.
(Our company data: for IF = −1mA, VF temperature characteristics are about −2mV/°C)
15. NC Pins
Because NC pins are electrically open, they may be used for wiring purpose etc.
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PS No.6088-10/10
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