TS4998IQT STMicroelectronics, TS4998IQT Datasheet - Page 24

• Manufacturer Part Number: TS4998IQT
• Description: IC AMP AUDIO PWR 1W STER 16QFN
• Manufacturer: STMicroelectronics
• Type: Class ABr

Specifications of TS4998IQT

• Output Type: 2-Channel (Stereo)
• Max Output Power X Channels @ Load: 1W x 2 @ 8 Ohm
• Voltage - Supply: 2.7 V ~ 5.5 V
• Features: Depop, Differential Inputs, Standby, Thermal Protection
• Mounting Type: Surface Mount
• Package / Case: 16-QFN
• Operational Class: Class-AB
• Audio Amplifier Output Configuration: 2-Channel Stereo
• Output Power (typ): 1x2@8OhmW
• Audio Amplifier Function: Speaker
• Total Harmonic Distortion: 0.5@8Ohm@700mW%
• Single Supply Voltage (typ): 3/5V
• Dual Supply Voltage (typ): Not RequiredV
• Power Supply Requirement: Single
• Unity Gain Bandwidth Product (typ): 1.5MHz
• Rail/rail I/o Type: No
• Power Supply Rejection Ratio: 80dB
• Single Supply Voltage (min): 2.7V
• Single Supply Voltage (max): 5.5V
• Dual Supply Voltage (min): Not RequiredV
• Dual Supply Voltage (max): Not RequiredV
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 16
• Package Type: QFN EP
• For Use With: 497-8259 - BOARD EVAL BASED ON TS4998
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6842-2

Application information
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The efficiency is the ratio between the output power and the power supply:
Equation 6
The maximum theoretical value is reached when V
The TS4998 is stereo amplifier so it has two power amplifiers. Each amplifier produces heat
due to its power dissipation. Therefore, the maximum die temperature is the sum of each
amplifier’s maximum power dissipation. It is calculated as follows:
●
●
●
In most cases, P
The maximum die temperature allowable for the TS4998 is 150°C. In case of overheating, a
thermal shutdown protection set to 150°C, puts the TS4998 in standby until the temperature
of the die is reduced by about 5°C.
To calculate the maximum ambient temperature T
●
●
●
Example: V
Using the power dissipation formula given in
channel is:
And the power dissipated by both channels is:
T
Equation 7
Therefore, the maximum allowable value for T
If a 4-layer PCB with vias is used, R
value for T
amb
P
P
Total P
the power supply voltage value, V
the load resistor value, R
the package type, R
P
Total P
T
T
is calculated as follows:
amb
amb
diss 1
diss 2
dissmax
= 150 - 85 x 2 x 1.266=42.4°C
= 150 - 45 x 2 x 1.266 = 93°C
amb
= Power dissipation of left channel power amplifier
= Power dissipation of right channel power amplifier
diss
dissmax
CC
= 633mW
in this case is:
=5V, R
=P
diss 1
diss 1
= 2 x P
L
= P
TotalP
=8Ω, R
+ P
THJA
diss 2
dissmax
diss 2
T
amb
diss
L
THJA
, giving:
=
(W)
= 2
= 1266mW
150° C R
QFN16=85°C/W (with 2-layer PCB with vias).
THJA
×
η =
P
CC
diss1
QFN16 = 45°C/W and the maximum allowable
η =
------------------ - =
P
–
P
supply
out
TJHA
π
---- - = 78.5%
Equation
4
=
amb
4 2V
---------------------- P
π R
×
amb
is:
--------------------
πV
peak
4Vcc
TotalP
CC
L
peak
allowable, you need to know:
5, the maximum dissipated power per
= V
dissmax
out
CC
–
, so:
2P
out
(
W
)
TS4998