L7986TA STMicroelectronics, L7986TA Datasheet - Page 17

• Manufacturer Part Number: L7986TA
• Description: 3A step-down switching regulator
• Manufacturer: STMicroelectronics

Specifications of L7986TA

• Low Dropout Operation: 100% duty cycle

L7986TA
Equation 12
Where T
time of the external diode (in CCM, F
fixed Vout, is obtained at maximum T
to calculate minimum duty). So fixing ΔI
minimum inductance value can be calculated:
Equation 13
where F
For example for V
value to have ΔI
The peak current through the inductor is given by:
Equation 14
So if the inductor value decreases, then the peak current (that has to be lower than the
minimum current limit of the device) increases. According to the maximum DC output
current for this product family (3 A), the higher is the inductor value, the higher is the
average output current that can be delivered, without triggering the overcurrent protection.
In the table below some inductor part numbers are listed.
Table 7.
Manufacturer
SUMIDA
Coilcraft
SW
ON
Wurth
is the conduction time of the internal high side switch and T
is the switching frequency, 1/(T
Inductors
L
=30% of I
OUT
=5 V, V
ΔI
O
CDRH6D226/HP
L
CDR10D48MN
is about 18 μH.
IN
=
PD Type M
PD Type L
Doc ID 022098 Rev 1
MSS1038
MSS1048
=24 V, I
Series
V
----------------------------- - T
L
IN
MIN
–
L
OFF
V
SW
=
OUT
O
I
L PK
L
=3 A and F
,
=1/(T
V
--------------------------- -
=20% to 30% of the maximum output current, the
that is at minimum duty cycle (see previous section
OUT
ΔI
⋅
ON
MAX
=
ON
ON
+
+ T
I
O
V
=
Inductor value (μH)
+
+ T
F
OFF
⋅
ΔI
------- -
V
--------------------------- - T
SW
2
1 D
---------------------- -
OUT
OFF
L
–
).
2.2 to 4.7
F
1.5 to 3.3
3.8 to 10
8.2 to 15
6.6 to 12
12 to 22
=250 kHz the minimum inductance
SW
L
)). The maximum current ripple, at
+
MIN
V
F
⋅
OFF
Application informations
Saturation current (A)
OFF
is the conduction
3.84 to 5.34
3.75 to 6.25
3.6 to 5.2
4.1 to 5.7
3.9 to 6.5
4 to 6
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