LED5000PHR STMicroelectronics, LED5000PHR Datasheet - Page 42

• 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 - alternative topologies
42/51
Figure 31
topology. The input voltage ranges from 12 to 36 V and it can drive a string composed of 11
LEDs with 0.7 A DC (V
Figure 31. LED current source based on floating boost topology
The network D1, R1, R
be neglected during the normal operation since the FB biasing current is negligible (tens of
nA, see
D1. In case the load is disconnected or in case of open LED:
Equation 72
R1 must be dimensioned to limit the D1 rated power so it is an inexpensive small signal
Zener diode.
The circuitry Q1, R3, R4, R5 implements a level shifter to convert the dimming signal
voltage levels (referred to GND) to the device rails, since the LED5000 local ground is
floating. The LED5000 local GND level is:
Equation 73
where VLGND represent the local GND value.
Figure 25
yellow the SW (high level is V
(see
DIM
GND
VIN
Figure 69
TP4
100K
TP1
TP5
R3
Table 5: Electrical characteristics
shows the circuit schematic for an LED current source based on the floating boost
shows the dimming operation: the light blue trace represents the DIM pin, the
BC807-16
R4
10K
) and the purple is the output voltage.
Q1
L1 33uH
FW_LED
S
47K
T1
R5
implements an inexpensive overvoltage protection. R1 effect can
2
IN
Doc ID 023951 Rev 1
= 3.74 V so V
C1
100nF
, low level is V
2
1
V
U1
OUT
DIM
BOOT
I
VIN
ZENER_DIODE
SW
V
7
8
LGND
STPS3L60U
SMB FLAT
=
D2
V
) but it limits the current flowing in the Zener diode
FB
LED5000
=
COMP
GND
OUT
+
INH
V
EP
6
FB
IN
V
IN
=
-V
ZENER_DIODE
=41 V).
5
4
3
EP
–
OUT
-------------------- -
R
V
S
V
OUT
+
FB
), the green trace the inductor current
R
1
R2
10K
C4
2.2nF
D1
R1
C2
15pF
10K
BZX384-C47
RS1
0.28R
C3
2.2uF
50V
C5
100nF
TP2
C6
NM
TP3
LED5000
AM13515v1
VLED+
VLED-