ZHCSGH3A March 2016 – July 2017 TAS5782M
PRODUCTION DATA.
The SPK_MUTE pin can also be used to monitor a system voltage, such as a LCD TV backlight, a battery pack in portable device, by using a voltage divider created with two resistors (see Figure 74).
Figure 75 shows a timing diagram for external undervoltage error protection.
NOTE
The SPK_MUTE input pin voltage range is provided in the Recommended Operating Conditions table. The ratio of external resistors must produce a voltage within the provided input range. Any increase in power supply (such as power supply positive noise or ripple) can pull the SPK_MUTE pin higher than the level specified in the Recommended Operating Conditions table, potentially causing damage to or failure of the device. Therefore, any monitored voltage (including all ripple, power supply variation, resistor divider variation, transient spikes, and others) must be scaled by the resistor divider network to never drive the voltage on the SPK_MUTE pin higher than the maximum level specified in the Recommended Operating Conditions table.
When the divider is set correctly, any DC voltage can be monitored. Figure 74 shows a 12-V example of how the SPK_MUTE is used for external undervoltage error protection.