PAM8016

Document number: DS40362 Rev. 2.0

6 of 10

www.diodes.com

June 2018

© Diodes Incorporated

PAM8016

Application Information

Overview

The typical application for applying PAM8016 haptic driver is to utilize the application processor in a touch-enabled or haptic-capable system and

execute haptic effects control to drive PAM8016 with predefined haptic control data. The PAM8016 supports typical analog-control interface with

analog inputs and SD control to operate as instructed by the application processor. A system designer can choose to activate the application

processor by playing low-latency effects (such as an action triggered by a physical button) or predefined analog data patterns through the analog

interface (differential, single-ended, or PWM inputs) to PAM8016. The PAM8016 generates corresponding output voltages for driving the haptic

element accordingly.

The application diagram shown in Figure 1 illustrates the connection between the application processor and PAM8016. For nominal-differential or

for screening out unintended noises to PAM8016 (as shown in the left of Figure 1).

However, if the PWM signals are provided, the low-pass RC filter is suggested to filter out the high-frequency noises induced by PWM driving

signal (as shown in the right of Figure 1). Because typical haptic elements operate in the range of a few hundred hertz (~300Hz or below), it is

while driving the haptic element.

LRA

or

ERM

OUT+

VDD

2.8V to 5.5V

1uF

IN+

IN-

PVDD

OUT-

M

SD

GND

GND

PAM8016

VDD

Vin

SD

LRA

or

ERM

OUT+

VDD

2.8V to 5.5V

1uF

IN+

IN-

PVDD

OUT-

M

SD

GND

GND

Application

Processor

PWM /

GPIO

GPIO

PAM8016

VDD

Figure 1: PAM8016 Simplified Configurations for Typical Single-Ended Analog Inputs or PWM Inputs

Input Capacitors (Ci )

In the typical application an input capacitor, Ci, is required to allow the amplifier to bias the input signal to the proper DC level for optimum

operation. In this case, Ci and the minimum input impedance Ri form a high-pass filter with the corner frequency determined in the follow equation:

It is important to consider the value of Ci as it directly affects the low-frequency performance of the circuit. For example

when Ri is 150kΩ, the

specification calls for a flat bass response down to 150Hz. Equation is reconfigured as followed:

When input resistance variation is considered, the Ci is 7nF, so one would likely choose a value of 10nF. A further consideration for this capacitor

is the leakage path from the input source through the input network (Ci, Ri + Rf) to the load. This leakage current creates a DC offset voltage at

the input to the amplifier that reduces useful headroom, especially in high-gain applications. For this reason, a low-leakage tantalum or ceramic

capacitor is the best choice. When polarized capacitors are used, the positive side of the capacitor should face the amplifier input in most

applications as the DC level is held at VDD/2, which is likely higher than the source DC level. Note that it is important to confirm the capacitor

polarity in the application.

Decoupling Capacitor (CS )

The PAM8016 is a high-performance haptic driver that suggests adequate power-supply decoupling to ensure the output total harmonic distortion

(THD) is as low as possible. Power supply decoupling also prevents the oscillations caused by long lead length between the driver and the haptic

elements.

The optimum decoupling is achieved by using two different types of capacitors that target the different types of noise the power supply leads. For

higher-frequency transients, spikes, or digital hash on the line, a good low-equivalent series

resistance (ESR) ceramic capacitor, typically 1μF,

can be placed as close as possible to the device VDD pin for the best operation. For filtering lower-frequency noise signals, a large ceramic

capacitor of 10

μF or greater placed near the haptic driver is recommended.





C

1

f

2 RiCi









ic

1

Ci

2 R f



