LED5000PHR STMicroelectronics, LED5000PHR Datasheet - Page 26

• Manufacturer Part Number: LED5000PHR
• Description: Current & Power Monitors & Regulators 3A monolithic Conv 850kHz Synch
• Manufacturer: STMicroelectronics

Specifications of LED5000PHR

• Rohs: yes
• Product: Current Regulators
• Supply Voltage - Max: 48 V
• Supply Voltage - Min: 5.5 V
• Operating Temperature Range: - 40 C to + 150 C
• Mounting Style: SMD/SMT
• Package / Case: HPSO-8
• Accuracy: +/- 3 %
• Input Voltage Range: 5.5 V to 48 V
• Output Current: 23 uA
• Sensing Method: High or Low Side
• Supply Current: 1.7 mA

Application notes - buck conversion
5.10
26/51
Equation 35
Where V
internal PDMOS. Considering the range D
I
●
These are widely used due to their low price and their availability in a wide range of RMS
current ratings.
The only drawback is that, considering ripple current rating requirements, they are physically
larger than other capacitors.
●
If available for the required value and voltage rating, these capacitors usually have a higher
RMS current rating for a given physical dimension (due to very low ESR).
The drawback is the considerably high cost.
●
Small tantalum capacitors with very low ESR are becoming more available. However, they
can occasionally burn if subjected to very high current during charge.
Therefore, it is suggested to avoid this type of capacitor for the input filter of the device as
they could be stressed by an high surge current when connected to the power supply.
Table 8.
In case the selected capacitor is ceramic (so neglecting the ESR contribution), the input
voltage ripple can be calculated as:
Equation 36
Layout considerations
The layout of switching DC-DC converters is very important to minimize noise and
interference. Power-generating portions of the layout are the main cause of noise and so
high switching current loop areas should be kept as small as possible and lead lengths as
short as possible.
High impedance paths (in particular the feedback connections) are susceptible to
interference, so they should be as far as possible from the high current paths. A layout
example is provided in
RMS
Electrolytic capacitors:
Ceramic capacitors:
Tantalum capacitors:
Manufacturer
going through the input capacitor. Capacitors that can be considered are:
Taiyo Yuden
Murata
F
is the free wheeling diode forward voltage and V
List of ceramic capacitors for the LED5000
V
Figure 17
IN PP
GRM42-2 X7R 475K 50
UMK325BJ106MM-T
=
Doc ID 023951 Rev 1
------------------------- -
C
.
Series
IN
D
I
O
MIN
f
SW
=
MIN
------------------------------------- -
V
INMAX
V
1 D --- -
to D
OUT
–
+
MAX
–
Capacitor value (µ)
V
V
F
SW
D
, it is possible to determine the max
+
D
--- -
4.7
10
SW
1 D
the voltage drop across the
–
Rated voltage (V)
50
50
LED5000