A5974ADTR STMicroelectronics, A5974ADTR Datasheet - Page 30

• Manufacturer Part Number: A5974ADTR
• Description: IC REG SW STEP-DOWN 2A 8SOIC
• Manufacturer: STMicroelectronics
• Series: -r
• Type: Step-Down (Buck), PWMr

Specifications of A5974ADTR

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.235 V ~ 35 V
• Current - Output: 2A
• Frequency - Switching: 500kHz
• Voltage - Input: 4 V ~ 36 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width) Exposed Pad
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-11423-2

Application information
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continuous output current up to 2 A to the load, however, the maximum power loss of 1.5 W
is reached with an output current of 1.8 A, so the maximum output power is derated if
T
Figure 16
Figure 16. Power losses estimation (V
At T
Figure
As a consequence, the calculation of the internal power losses must be done for each
specific operating condition given by the final application.
In applications where the current to the output is pulsed, the thermal impedance should be
considered instead of the thermal resistance.
The thermal impedance of the system could be much lower than the thermal resistance,
which is a static parameter. As a consequence, the maximum power losses can be higher
than 1.5 W if a pulsed output power is requested from the load:
Therefore, depending on the pulse duration and its frequency, the maximum output current
can be delivered to the load.
The characterization of the thermal impedance is strictly dependent on the layout of the
board. In
of the A5974AD is provided.
AMB
AMB
=80 °C.
16).
=80°C and V
Figure 17
plots the power losses for V
the measurement of the thermal impedance of the demonstration board
IN
=12 V, the device is thermally limited only when V
P
Doc ID 018762 Rev 1
MAX
t ( )
=
IN
=12 V and main output rails.
---------------- -
Z
TH
ΔT
IN
t ( )
= 12 V, f
=
T
------------------------------------- -
J MAX
Z
SW
TH
–
= 500 kHz)
t ( )
T
AMB
OUT
=5 V (see
A5974AD