ZHCSR80A June 2009 – January 2023 AMC6821-Q1
PRODUCTION DATA
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 说明（续）
- 6 Pin Configuration and Functions
- 7 Specifications
-
8 Detailed Description
- 8.1 Functional Block Diagram
- 8.2 Feature Description
- 8.3 Device Functional Modes
- 8.4 Programming
- 8.5 Register Map
- 9 Application and Implementation
- 10Device and Documentation Support
- 11Mechanical, Packaging, and Orderable Information
8.2.4 PWM Waveform Setting
PWM frequency and duty cycle are programmable. The value of the DCY Register defines the duty cycle: it has 8-bit resolution, 1LSB corresponding to 1/255 (0.392%). Writing 0x00 sets the duty cycle to 0%; writing 0xFF sets the duty cycle to 100%.
PWM frequency has two ranges: the high range is from 1kHz to 40kHz, and the low range is from 10Hz to 94Hz. The PWM-MODE pin status determines which range is selected. When the PWM-MODE pin is tied to ground, the high range is selected. Otherwise, the low range is selected. Bits [PWM2:PWM0] in the Fan Characteristics Register define the frequency; see Table 8-2. The resolution of the PWM waveform period is 0.312μs, corresponding to a 3.2MHz clock. The default value after power-on is 30Hz when the low range is selected, or 25kHz when the high range is selected.
Figure 8-6 PWM Waveform (PWMinv = 1)| PWM2 | PWM1 | PWM0 | PWM FREQUENCY |
|---|---|---|---|
| When the PWM-MODE Pin is Floating or Tied to VDD | |||
| 0 | 0 | 0 | 10Hz |
| 0 | 0 | 1 | 15Hz |
| 0 | 1 | 0 | 23Hz |
| 0 | 1 | 1 | 30Hz (default) |
| 1 | 0 | 0 | 38Hz |
| 1 | 0 | 1 | 47Hz |
| 1 | 1 | 0 | 62Hz |
| 1 | 1 | 1 | 94Hz |
| When the PWM-MODE Pin is Tied to GND | |||
| 0 | 0 | 0 | 1kHz |
| 0 | 0 | 1 | 10kHz |
| 0 | 1 | 0 | 20kHz |
| 0 | 1 | 1 | 25kHz (default) |
| 1 | 0 | 0 | 30kHz |
| 1 | 0 | 1 | 40kHz |
| 1 | 1 | 0 | 40kHz |
| 1 | 1 | 1 | 40kHz |