Description
Features:
- 1X, 2X, 3X Selectable Boost Mode
- 1MHz Boost Converter Operation
- 18Vpp from 3.3Vin / 24Vpp from 5.5Vin
- Automatic Standby and Wake-Up Control
- Only 4 External Caps Required
- Vin = 1.8-5.5V / 4kHz Fin Typical
- Differential or Single-Ended Operation
- Micro-Size Eval Board(12.7×20.4mm)
- 54mm(0.1”) headers on 17.78mm(0.7”) spacing
- Low Power Consumption
- 50uA @ 1X / 720uA @ 2X / 1.7mA @ 3X No Load
- 1uA Sleep
Why?
Sensor Maestros developed the smPWR-PAM8904 breakout board out of a necessity. There were several products that we had developed that utilized Piezo buzzers or some sort of piezo speaker. It is very difficult to get ear-piercing sound out of a piezo without driving them at voltages >10V. The PAM8904 provides a simple and easy to use DC/DC Boost to easily drive piezo buzzer and/or speakers at much louder SPL levels than a typical 3.3V PWM from a MCU.
Firmware/Mobile App for Testing:
You can use the open source smPWM_BLE_nRF52 firmware that works on either a nRF52 or nRF52840 DK to easily test the smPWR-PAM8904. The firmware produces a PWM using PWM0 module and outputs a PWM on LED1 so you can see it visually and also outputs the PWM on P0.28 that you can use to feed into the DIN pin of the smPWM-PAM8904. The firmware application provides a BLE interface that allows adjusting the PWM_DUTY_CYCLE from 0-100% in increments of 1% and provides the ability to change the PWM_FREQUENCY from a range of 200Hz to 12000Hz in increments of 100Hz. The smPWM_BLE-Flutter App is an Open Source Mobile app that interfaces to the smPWM_BLE_nRF52 firmware application and provides sliders to adjust the PWM_DUTY_CYCLE and PWM_FREQUENCY. The Flutter app has an Android APK file for anyone to use/modify. There is currently not an iOS build. If someone has the capability to compile the Flutter app for iOS I would be happy to publish the iOS app in my developer account to make it available for everyone.
smPWM_BLE_nRF52: smPWM_BLE_nRF52 Firmware
smPWM_BLE-Flutter: smPWM_BLE-Flutter
Description:
The PAM8904 1X/2X/3X Boost Piezo Driver IC is a selectable Boost Converter that accepts an input voltage ranging from 1.8-5.5V. The Boost converter can produce up to 13.5Vmax or 27Vpp. This is easy to use Boost Converter that can be operated in Differential or Single-Ended output and is intended to drive Piezo speaker that require much larger voltage ranges to get Maximum Sound Pressure Levels in excess of 100dB. It is ideally suited for a 4kHz PWM/Square Wave.
The 1X/2X/3X mode is selectable via EN1 & EN1 pins which can be configured via the on-board jumper selections. Sensor Maestros will provide two 3pin 2.54mm male headers and 2 Shunts to use for this with the smPWR-PAM8904 breakout board. This Boost Piezo driver is capable of driving up to 15nF loads with the DC/DC Boost switching at 1.0MHz and does not require any inductors. To simplify things the PAM8904 only requires 4 external capacitors to provide a complete piezo driver solution all while providing excellent integrated features such as ‘Automatic Standby’ and ‘Wake-Up Control’. The low cost easy to use PAM8904 comes in 3 package options being a 16pin 3x3mm QFN, 12pin 3×3 QFN and a 12pin 2x2mm QFN. Sensor Maestros utilized the 16pin 3×3 QFN on the smPWR-PAM8904 breakout board as this was the most readily available package in the market place at the time.
PAM8904 Information:
PAM8904 Product Page: PAM8904 Product Page
PAM8904 Datasheet: PAM8904 Datasheet
PWM Firmware Examples:
nRF52 PWM Driver Example: nRF52 PWM Driver Example
