TS4962M(2005) View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
TS4962M Datasheet PDF : 32 Pages
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TS4962M
Application Information
5.5 Decoupling of the circuit
A power supply capacitor is needed to correctly bypass the TS4962M, referred to as CS.
The TS4962M has a typical switching frequency at 250kHz and output fall and rise time about
5ns. Due to these very fast transients, careful decoupling is mandatory.
A 1µF ceramic capacitor is enough, but it must be located very close to the TS4962M in order
to avoid any extra parasitic inductance created an overly long track wire. These parasitic
inductances introduce, in relation with dI/dt, overvoltage that decreases the global efficiency
and may cause, if this parasitic inductance is too high, a TS4962M breakdown.
In addition, even if a ceramic capacitor has an adequate high frequency ESR value, its current
capability is also important. A 0603 size is a good compromise, particularly when 4Ω load is
used.
Another important parameter is the rated voltage of the capacitor. A 1µF/6.3V capacitor used at
5V, lose about 50% of its value. In fact at 5V power supply voltage, we have a decoupling value
about 0.5µF instead of 1µF. As CS has particular influence on the THD+N in the medium, high
frequency region, this capacitor variation becomes decisive. In addition, less decoupling means
higher overshoot that can be problematic if they reach the power supply AMR value (6V).
5.6 Wake-up Time: tWU
When the standby is released to set the device ON, there is a wait of about 5ms. The TS4962M
has an internal digital delay that mutes the outputs and releases them after this time in order to
avoid any pop noise.
5.7 Shutdown time
When the standby command is set, the time required to put the two output stages into high
impedance and to put the internal circuitry in shutdown mode, is about 5ms. This time is used
to decrease the gain and avoid any pop noise during shutdown.
5.8 Consumption in shutdown mode
Between the shutdown pin and GND there is an internal 300kΩ resistor. This resistor force the
TS4962M to be in shutdown when the shutdown input is leaved floating.
However, this resistor also introduces additional shutdown power consumption if the shutdown
pin voltage is not 0V.
Referring to Table 2: Operating conditions on page 2, with 0.4V shutdown voltage pin for
example, we have 0.4V/300kΩ = 1.3µA in typical (0.4V/273kΩ = 1.46µA in maximum) to add to
the shutdown current specified in the tables in Table 4 on page 4.
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