L5983TR STMicroelectronics, L5983TR Datasheet - Page 15

• Manufacturer Part Number: L5983TR
• Description: IC REG SW 1.5A STEPDOWN 8-VFQFPN
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of L5983TR

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 0.6 ~ 18 V
• Current - Output: 1.5A
• Frequency - Switching: 250kHz ~ 1MHz
• Voltage - Input: 2.9 ~ 18 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-VFQFN, 8-VFQFPN
• Power - Output: 1.5W
• For Use With: 497-6386 - BOARD EVAL FOR L5983
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6860-2; L5983TR

L5983
5
5.1
Application information
Input capacitor selection
The capacitor connected to the input must be able to support the maximum input operating
voltage and the maximum RMS input current required by the device. The input capacitor is
subject to a pulsed current, the RMS value of which is dissipated over its ESR, affecting the
overall system efficiency.
So the input capacitor must have an RMS current rating higher than the maximum RMS
input current and an ESR value compliant with the expected efficiency.
The maximum RMS input current flowing through the capacitor can be calculated as:
Equation 3
where I
Considering η = 1, this function has a maximum at D = 0.5 and it is equal to I
In a specific application the range of possible duty cycles must be considered in order to find
out the maximum RMS input current. The maximum and minimum duty cycles can be
calculated as:
Equation 4
and
Equation 5
where V
the internal PDMOS.
In
Table 6.
Table 6
Manufacturer
o
MURATA
F
is the maximum DC output current, D is the duty cycle, η is the efficiency.
TDK
is the forward voltage on the freewheeling diode and V
some multi layer ceramic capacitors suitable for this device are reported.
Input capacitors
Doc ID 13005 Rev 7
GRM31
GRM55
Series
C3225
I
RMS
D
D
MAX
MIN
=
I
=
O
=
⋅
------------------------------------- -
V
------------------------------------ -
V
INMAX
V
V
INMIN
D
OUT
OUT
–
2 D
-------------- -
+
Cap value (μF)
⋅
+
–
–
η
V
V
V
V
2
F
SW
SW
F
+
D
------ -
η
10
10
10
2
2
SW
Application information
is voltage drop across
Rated voltage (V)
o
/2.
25
25
25
15/43