With an integrated LDO regulator and internal H-Bridge MOS×4 driver, the devices can implement a complete servo circuit with just a few passive components. This feature reduces the PCB size and cost and makes the devices suitable for digital servo applications below 5g.

The HT45RM22/23 features include 2K×15 of Program Memory, 96 bytes of Data RAM, a 2.2V~5.5V operating voltage range and an operating frequency of 4MHz. The devices include an internal high accuracy RC oscillator and a single channel 12-bit analog to digital converter which is used for servo positional detection. Timer control is implemented by a time base function or an 8-bit Timer.

A 16-bit Capture Timer provides the PWM pulse width measurement function for angle control. The integrated 2.3V LDO provides an operating voltage for the MCU and a reference voltage for the servo positioner. The integrated motor driver circuit supports pulse width adjustment and optional complementary or non-complementary output control.

It can drive the motor to forward rotate, backward rotate and brake using easily setup functions. Additionally a 10-bit PWM output with dead time control provides foolproof protection. All these features combine to provide a motor driver that offers safe and flexible control.

With regard to the integrated MOS sink/source current driver, users can select the HT45RM22 (min. 200mA) or the HT45RM23 (min. 400mA) according to their different application requirements.

The LVR function, which can generate a reset when the power supply voltage falls below the minimum level for proper system operation, provides an additional safeguard to ensure stable operating under low power supply voltage conditions.

As is the case with other Holtek 8-bit MCU devices, these devices meet with industrial specifications and have excellent noise immunity characteristics. Protection features such as the watchdog timer and LVR functions enhance the MCU malfunctiona ability.

Holtek also supplies a full suite of hardware and software development tools known as the software HT-IDE3000 and the hardware emulator e-ICE with full trace analysis features as well as many other functions.

The HT45RM22 and HT45RM23 are available in 10-pin MSOP package type. This extremely small package outline makes them especially suitable for digital servo applications where space is at a premium.