IFX 80471SK V50 Infineon Technologies, IFX 80471SK V50 Datasheet - Page 25

• Manufacturer Part Number: IFX 80471SK V50
• Manufacturer: Infineon Technologies

Specifications of IFX 80471SK V50

• Packages: PG-DSO-14
• Comment: Vin up to 60V; external MOS; PG-DSO-14
• Vq (max): 5.0 V
• Iq (max): 2,300.0 mA
• Iq (typ): 130.0 µA
• Output: Buck Converter

The inductance value determines together with the input voltage, the output voltage and the switching frequency
the current ripple which occurs during normal operation of the step down converter. This current ripple is important
for the all over ripple at the output of the switching converter.
In this equation f
external source connected to the SYNC pin. When picking finally the inductance of a certain supplier (Epcos,
Coilcraft etc.) the saturation current has to be considered. The saturation current value of the desired inductance
has to be higher than the maximum peak current which can appear in the actual application.
7.8.2
The peak current which the buck converter is able to provide is determined by the peak current limit threshold
voltage V
PWM
The equation above takes account for the foldback characteristic of the current limit as shown in the figures ’Output
Voltage versus Load Current’ on page 17/18 by introducing a factor of 2. It must be assured by correct
dimensioning of R
7.8.3
The crossover thresholds PFM to PWM and vice versa strongly depend on the input voltage V
converter inductance L1, the sense resistor value R
7.8.4
The choice of the output capacitor effects straight to the minimum achievable ripple which is seen at the output of
the buck converter. In continuous conduction mode the ripple of the output voltage can be estimated by the
following equation:
Data Sheet
=I
LOAD
+0.5ΔI) the sense resistor is calculated to
LIM
Determining the current limit
Buck output capacitor (C
PFM and PWM thresholds
and the sense resistor R
sw
SENSE
is the actual switching frequency of the device, given either by the internal oscillator or by an
⎛
⎝
2,0 10
that the load current doesn’t reach the foldback part of the characteristic curve.
×
4 –
⋅
-------- - V
VΩ
H
V
⋅
Ripple
OUT
SENSE
⋅
ΔI
=
R
R
OUT
. With a maximum peak current given by the application (I
SENSE
ΔI
SENSE
=
⋅
) selection:
(
------------------------------------------------------
⎛
⎝
V
SENSE
R
⎞
⎠
IN
ESRCOUT
=
f
<
SW
–
------------------------------------ -
2 I ⋅
L1
24
V
⋅
and the turn on and turn off delays of the external PMOS.
OUT
V
<
PEAK PWM
V
IN
⎛
⎝
4,0 10
LIM
+
) V
⋅
⋅
L1
----------------------------------- -
8 f
,
×
⋅
OUT
SW
4 –
1
⋅
⋅
C
-------- - V
VΩ
OUT
H
⋅
⎞
⎠
OUT
⋅
R
SENSE
Application Information
⎞
⎠
Rev. 1.0, 2011-02-07
IN
IFX80471
, the Buck
PEAK,