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参数资料
| 型号： | LB1920 |
| 元件分类： | 运动控制电子 |
| 英文描述： | BRUSHLESS DC MOTOR CONTROLLER, 3.1 A, PDIP28 |
| 封装： | HEAT SINK, SDIP-28 |
| 文件页数： | 7/7页 |
| 文件大小： | 205K |
| 代理商： | LB1920 |
LB1920
Νο.4949-7/10
This section describes the LB1920 and the external components used.
1. Speed Control Circuit
This IC uses the combination of a speed discriminator circuit and a PLL circuit for speed control. The speed
discriminator circuit outputs an error signal once every two FG periods using a charge pump scheme. The PLL
circuit outputs a phase error signal once every FG period, also using a charge pump scheme. As compared to earlier
schemes that only used a speed discriminator, the combination of a PLL circuit with a speed discriminator provides
improved speed variation suppression when using a motor with large load variations. Since the following formula
determines the FG servo frequency, the motor speed must be set using the number of FG pulses and the crystal
oscillator frequency.
fFG (servo) = fOSC/8192
fOSC : crystal oscillator frequency
2. Direct PWM Drive
This IC adopts a direct PWM drive scheme to minimize power loss in the output. The output transistors are always
saturated when on and the motor drive power is adjusted by changing the output on duty. Since output switching is
performed by the lower side transistor, the three Schottky diodes D1, D2 and D3 must be inserted between OUT
and VCC. (Note that a through current will flow at the instant the lower side transistor turns on if these diodes do
not have a short reverse recovery time.) Normal rectifying diodes can be used for the diodes between OUT and
ground.
3. Current Control Circuit
The current control circuit applies current control at a current determined by the relation I = 0.5/Rf, i.e. peak current
limitation. The control operation reduces the output on duty and thus suppresses the current. No phase
compensation capacitor is required.
4. Speed Lock Range
The speed lock range is
±6.25% of the fixed speed and the LD pin goes low when the motor is in the lock range.
(This pin is an open collector output.) When the motor speed goes out of the lock range, the LB1920 changes the
motor drive output on duty according to the speed error to control the motor speed to be within the lock range.
5. PWM Frequency
The PWM frequency is determined by the resistor and capacitor (R3 and C6) connected to the CR pin.
When R3 is connected to the 4V fixed voltage supply
f PWM ≈ 1/(1.2×C×R)
When R3 is connected to the 7V fixed voltage supply
f PWM ≈ 1/(0.5×C×R)
R3 should not be any smaller than 30k
. A PWM frequency of about 15kHz is desirable. If the PWM frequency is
too low, the motor will vibrate at the PWM frequency when the motor is restrained causing disturbing audible noise.
Inversely, switching loss increases if the PWM frequency is too high.
6. Ground Leading
GND1 (pin 22) is the ground for circuits other than the output block.
GND2 (pin 11) is the ground for the output block (emitters of the sink transistors).
D4, D5 and D6 are connected to GND2. All other external components are connected to GND1. The GND1 and
GND2 lines are connected to a single ground point at the connector. Since GND2 carries large currents, it should be
kept as short as possible.
7. Output Parasitic Effects
Parasitic effects occur when the output pin voltage falls -0.7V (this value decreases as the temperature increases)
below the GND1 and GND2 voltage. Similarly, the output pin voltage should not be allowed to exceed VCC by
more than 1V. When parasitism occurs, initially speed control is lost intermittently, but if the amount of parasitism
increases the output transistors can be destroyed. Schottky diodes with a small Vf are used for D1, D2 and D3 to
prevent through currents. As a result, the potential difference between the output pins and VCC is not that much of
a problem. Although normal rectifying diodes can be used for D4, D5 and D6, the printed circuit board pattern must
be kept as short as possible (as recommended in item 6) to prevent parasitism from occurring.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LB1920-E | 功能描述:马达/运动/点火控制器和驱动器 RoHS:否 制造商:STMicroelectronics 产品:Stepper Motor Controllers / Drivers 类型:2 Phase Stepper Motor Driver 工作电源电压:8 V to 45 V 电源电流:0.5 mA 工作温度:- 25 C to + 125 C 安装风格:SMD/SMT 封装 / 箱体:HTSSOP-28 封装:Tube |
| LB1920-N-E | 功能描述:马达/运动/点火控制器和驱动器 RoHS:否 制造商:STMicroelectronics 产品:Stepper Motor Controllers / Drivers 类型:2 Phase Stepper Motor Driver 工作电源电压:8 V to 45 V 电源电流:0.5 mA 工作温度:- 25 C to + 125 C 安装风格:SMD/SMT 封装 / 箱体:HTSSOP-28 封装:Tube |
| LB1921 | 制造商:SANYO 制造商全称:Sanyo Semicon Device 功能描述:Three-Phase Brushless Motor Driver for OA Applications |
| LB1922 | 制造商:SANYO 制造商全称:Sanyo Semicon Device 功能描述:Three-Phase Brushless Motor Driver for Office Automation Applications |
| LB1923M | 制造商:SANYO 制造商全称:Sanyo Semicon Device 功能描述:Power Brushless Motor Pre-Driver IC for OA Equipment |
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