Two DC power driver IC and its application

With the rapid development of power electronics, DC motor driver ICs are more and more power, they have high efficiency, output current, less need for external devices, and so on. This article describes the SA60 and LMD18245 the two chips are pin function, features and their respective applications.

SA60 and LMD18245 are the United States launched Apex Inc. and NS-oriented small and medium full-bridge DC power output circuit. They both have a few external components in the case of the motor power driver, control and protection features such as common, but also has its own characteristics. Following their lead, functional characteristics and typical applications for an introduction. .

The main performance parameters of the two chips and Features

SA60's performance parameters and application

SA60 is a PWM type power output of chip circuitry to provide electrical power to the maximum voltage up to 80V, can provide 10A continuous current to the load. The maximum analog input voltage 5V, PWM carrier frequency can go to 250kHz, while the efficiency can be as high as 97%, the chip can also add a compatible TTL-based PWM signal to synchronize the four-quadrant mode amplitude and direction. SA60 are used in small DC motor drive, D class power amplifier, bearing incentives and other occasions.

LMD18245 performance parameters and application

LMD18245 chip can provide the maximum 55V motor power supply voltage, logic voltage of 12V, maximum sustained output current 3A, peak current up to 6A, the minimum input pulse width 2μS, current sensor maximum linearity error ± 9%. As with the SA60, the power output stage with high efficiency. Because the chip integrates four D / A converter and motor current sensor, a fixed cut off time of the chopper amplifier circuit, it is easy LMD18254 complete digital control of motor current to achieve the micro-step stepping motor driver. Therefore, the chip is mainly used for small DC motors in particular stepper motor control and drive on.

Pin and Function

Shape

SA60 and LMD18245 appearance package shown in Figure 1.

Two DC power driver IC and its application

Internal circuit box and the pin functions

SA60 The pin function

Two DC power driver IC and its application

SA60 internal structure of the box shown in Figure 2. Circuit total of 12 pins, which were 10,7 feet and the bridge PWM H Bridge and drive-level power terminal; 9,11 for the power signal output, the output waveform is the relationship between the input signal: 9-pin PWM output signal with the input signal voltage duty cycle increases, 11 feet but the contrary; 1,6 feet for the ground side, the former is the analog ground terminal, which is the power ground terminal; 8,12-side power can be directly connected to can also be grounded through a resistor, as the limited use of influenza, the maximum terminal voltage of ± 2V; 2,4 ends are analog and digital control signal input.

LMD18245 the pin function

LMD18245 block diagram of the internal structure shown in Figure 3. 9 feet is the power supply terminal; 1,15 foot power output of the bridge; 12,5 feet are signal ground and power circuit grounding terminal; 4,6,7,8 is the D / A converter, binary data input, which four feet is the maximum bit binary number; 10 feet is the emergency stop control side, high effective; 11-pin logic input for the direction; 3 feet and a parallel RC network connection can be set to a single steady pulse width: 1 . 1 RC seconds. In addition, the chip also provides amplified output current sensor (13 feet) to compare the signal output (2 feet), and several analog converter reference voltage input (14 feet).

Two DC power driver IC and its application

Chip Application

Although the two chips are switched full-bridge drive circuit, because the internal structure of the different ways of working are not the same, so as a motor control circuit, the circuit works also have their own characteristics. Figure 4 is the SA60 when driving a typical DC motor wiring diagram, in the graph analog chip is connected into the input of the digital inputs (2 feet) and a capacitor connected between the analog to CT, to change its size, can be adjusted PWM carrier frequency changes between 22 ~ 250kHz.

Two DC power driver IC and its application

Although LDM18245 continuous current output of the index less than one-third of SA60, but the way the control has its flexible side, using different ways to achieve electrical connection to control the different ways by different control performance, Figure 5 is driven by bipolar DC output mode instance. One fixed chopper time 1. 1 RC; current sensing resistor RW reference formula:

Two DC power driver IC and its application

Calculation, which UREF is D / A converter reference voltage circuit, D to D / A converter circuit input voltage, IS the best for the motor current settings. And SA60 different, not in LMD18245 chip PWM circuit, want to control the PWM duty cycle of the motor speed and direction, the need for external controller connection method shown in Fig.

Notes on application

In actual use the two chips must pay attention to several matters as follows. First, the power supply terminal and power terminal must be connected to bypass capacitor, or as motor current or for transition to the cause of the peak voltage and inrush current will damage the chip. Specifically, the end of the chip's power supply high-frequency parallel a 1μF ceramic capacitor and a 100μF aluminum electrolytic capacitors, and pay attention to the short connection line as far as possible. Second, when the attention in the cabling and power to the analog to strictly separate, pay attention to the power control signal input line and the distance the signal output line, to avoid feedback, interference.

Summary

Both chips have a power output of the output current, high efficiency circuit design is simple, compact and stable performance. So far more than their scope of application mentioned above several, on the SA60 and its family of products with the SA50, 51 chips, as a Class D audio power output circuit has been applied, such as high power output device power is traditional analog audio power output stage are unmatched.