LED5000PHR STMicroelectronics, LED5000PHR Datasheet - Page 23

• 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

LED5000
5.9
5.9.1
5.9.2
VIN
VIN
the external power components and the compensation network are selected, a direct
measurement to determine T
achieved dimming performance.
Component selection
Sensing resistor
In closed loop operation the LED5000 feedback pin voltage is 200 mV, so the sensing
resistor calculation is expressed as:
Equation 26
Since the main loop (see
average current is regulated into the LEDs. The integration period is at minimum 5*T
since the system bandwidth can be dimensioned up to f
A system loop based on a peak current mode architecture features consistent advantages in
comparison with simpler closed loop regulation schemes like the hysteretic or the constant
ON/OFF control.
The system performs the output current regulation over a period which is at least five times
longer than the switching frequency. The output current regulation neglects the ripple
current contribution and its reliance on external parameters like input voltage and output
voltage variations (line transient and LED forward voltage spread). This performance can
not be achieved with simpler regulation loops like hysteretic control.
For the same reason, the switching frequency is constant over the application conditions,
that helps to tune the EMI filtering and to guarantee the maximum LED current ripple
specification in the application range. This performance cannot be achieved using constant
ON/OFF time architectures.
Inductor and output capacitor selection
The output capacitor filters the inductor current ripple that, given the application condition,
depends on the inductor value. As a consequence the LED current ripple, that is the main
specification for a switching current source, depends on the inductor and output capacitor
selection.
Figure 16. Equivalent circuit
D D
DCR
DCR
L L
Chapter 5.1
COUT
COUT
ESR
ESR
RISE
Doc ID 023951 Rev 1
, T
FALL
) regulates the sensing resistor voltage drop, the
Dled1
Dled1
Dledn
Dledn
Rs
Rs
R
S
(see
=
200 mV
-------------------- -
Equation 24
I
LED
VIN
VIN
Application notes - buck conversion
SW
) is necessary to certify the
/5 at maximum.
D D
DCR
DCR
L L
COUT
COUT
ESR
ESR
AM13500v1
SW
23/51
Rd1
Rd1
Rdn
Rdn
Rs
Rs