
Pin
Function
Equivalent circuit diagram
Control and Current Limiting Functions
No. 6109-4/17
LB1987, 1987D, 1987M, 1987H
VLIM = 5 V
CTLREF: OPEN
I OUT
Gm2 = 1.50 A/Vtyp
Gm1 = 0.65 A/Vtyp
VCTL
2.35 Vtyp 3.15 Vtyp
01
2
34
5
I OUT
VCTL = 5 V
CTLREF: OPEN
VLIM
200 mVtyp
01
2
34
5
Control characteristics
Current limiting characteristics
Slope = 0.50 A/V typ
VLIM = 5 V
CTLREF: open
Gm2 = 1.50 A/V typ
Gm1 = 0.65 A/V typ
2.35 V typ 3.15 V typ
200 mV typ
(+) inputs
(–) inputs
Lower side oversaturation
prevention circuit input
block
OUT for
each phase
VCTL = 5 V
CTLREF: open
Pin Functions
U phase Hall element input.
Logic H refers to the state where IN+ > IN–
UIN+
UIN–
A12207
200 Ω
100 μA
200 Ω
A12208
150 μA
VCC
Vs
30
k
Ω
Rf(POWER)
Rf(SENSE)
200 kΩ
200 Ω
10 μA
VCC
V phase Hall element input.
Logic H refers to the state where IN+ > IN–
VIN+
VIN–
W phase Hall element input.
Logic H refers to the state where IN+ > IN–
WIN+
WIN–
U phase output.
V phase output.
(These pins include internal spark killer diodes.)
W phase output.
UOUT
VOUT
WOUT
A12209
200Ω
200μA
VCC
max
LIM
100μA
200Ω
CTL
VCC
5k
Ω
5k
Ω
CTLREF
Speed control.
This circuit implements constant current drive based on current feedback
from the Rf pin.
Gm = 0.58 A/V typ at Rf = 0.5 Ω
CTL
Current limiter function control.
The output current can be modified linearly by the voltage on this pin.
Slope = 0.5 A/V typ at Rf = 0.5 Ω
LIM
CTLREF
(LB1987/D)
Output block power supply.
VS
Rf(POWER)
Rf(SENSE)
Output current detection.
Current feedback is applied to the control block by inserting the resistor Rf
between these pins and ground. Also, both the lower side saturation
prevention circuit and the torque ripple correction circuit operate according to
the voltage on this pin. In particular, since this voltage sets the
oversaturation prevention level, the lower side oversaturation prevention
operation can be degraded if the value of this resistor is set too low.
Note that the PWR pin and the SENSE pin must be connected together.
Continued on next page.