LB1871M 查看數據表（PDF） - SANYO -> Panasonic
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LB1871M Datasheet PDF : 10 Pages
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LB1871, 1871M
External Component Values (reference values)
Crystal (MHz)
C1 (pF) C2 (pF)
R (kΩ)
3 to 4
39
82
0.82
4 to 5
39
82
1.0
5 to 7
39
47
1.5
7 to 10
39
27
2.0
Note: Use a crystal that has a ratio of at least 1:5 between the fundamental f0 impedance and the 3f0 impedance.
Three Phase Logic Truth Table
H1
H2
H3
H
L
H
H
L
L
H
H
L
L
H
L
L
H
H
L
L
H
Columns H1 to H3
H: H+ > H–
L: H+ < H–
Columns OUT1 to OUT3
H: Source
L: Sink
OUT1
L
L
M
H
H
M
OUT2
H
M
L
L
M
H
OUT3
M
H
H
M
L
L
LB1871 Functional Description and External Components
1. Speed control circuit
This IC provides high-precision stable motor control with minimal jitter by adopting a PLL speed control scheme.
This PLL circuit compares the rising edge of the CLK signal with the falling edge of the FG Schmitt output and
outputs that phase error.
When an internal clock is used, the FG servo frequency is determined by the formula shown below. Thus the motor
speed is determined by the number of FG pulses and the crystal oscillator frequency.
fFG(servo) = fOSC/N
fOSC: Crystal oscillator frequency
N: Clock divisor
2. Three-phase full-wave current linear drive
This IC adopts a three-phase full-wave current linear drive to hold motor noise to an absolute minimum. When
switching the output transistor phase, it creates a two-phase excitation state, suppresses kickback, and smooths the
output waveform. This suppresses motor noise. Note that since oscillation may occur with some motors, the
capacitors C12, C13, and C14 (about 0.1 µF) are connected between the OUT pins and ground.
3. Current limiter circuit
The current limiter circuit limits the current (i.e., the peak current) to a level determined by the formula I = 0.58/Rf.
A scheme in which the output stage drive current is limited is adopted for the limiting operation. Therefore, the phase
compensation capacitor C7 (about 0.1 µF) is inserted between FC and ground.
4. Grounding
GND1 (pin 11 in the LB1871, pin 5 in the LB1871M) .........................................Output block ground (sub-ground)
GND2 (pin 28 in the LB1871, pins 1, 2, 17 to 20, 35, and 36 in the LB1871M)..Control circuit ground.
GND1 and GND2 should be connected on the circuit board by the shortest distance that occurs in the pattern. Also,
the Rf resistor R8 ground node and the GND1 and GND2 pattern line should be grounded to a single point on the
connector.
No. 4849-7/10
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