LED5000PHR STMicroelectronics, LED5000PHR Datasheet - Page 16

• 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
5.4
16/51
LED small signal model
Once the system reaches the working condition the LEDs composing the row are biased
and their equivalent circuit can be considered as a resistor for frequencies << 1 MHz.
The LED manufacturer typically provides the equivalent dynamic resistance of the LED
biased at different DC current. This parameter is required to study the behavior of the
system in the small signal analysis.
For instance, the equivalent dynamic resistance of Luxeon III Star from Lumiled measured
with different biasing current levels is reported below:
In case the LED datasheet does not provide the equivalent resistor value, it can be easily
derived as the tangent to the diode I-V characteristic in the present working point (see
Figure 8
Figure 8.
Figure 9
The equivalent loading resistor in the LEDs working point is:
Equation 12
).
shows the equivalent circuit of the LED constant current generator.
Equivalent series resistor
0.1
[A]
1
r
Doc ID 023951 Rev 1
LED
R
LOAD
1
=
1.3
0.9
n
LED
working point
2
r
LED
I
I
LED
LED
+
3
=
=
R
SENSE
350mA
700mA
4
[V]
LED5000
AM13492v1