HVLED805TR STMicroelectronics, HVLED805TR Datasheet - Page 20

• Manufacturer Part Number: HVLED805TR
• Description: IC LED DRVR ACDC OFFLINE 16NSOIC
• Manufacturer: STMicroelectronics
• Type: General Purposer

Specifications of HVLED805TR

• Constant Current: Yes
• Constant Voltage: Yes
• Topology: AC DC Offline Switcher, PWM
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: General Purpose
• Voltage - Supply: 11.5 V ~ 23 V
• Mounting Type: Surface Mount
• Package / Case: *
• Internal Switch(s): Yes
• Efficiency: *
• Operating Supply Voltage: 11.5 V to 23 V
• Maximum Supply Current: 1.4 mA
• Maximum Power Dissipation: 0.9 W
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Frequency: -
• Operating Temperature: -
• Current - Output / Channel: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 497-10810-2

Application information
5.6
20/29
Figure 16. Constant current operation: Switching cycle waveforms
Voltage feedforward block
The current control structure uses the voltage V
(7). Actually, the CC comparator will be affected by an internal propagation delay Td, which
will switch off the MOSFET with a peak current than higher the foreseen value.
This current overshoot will be equal to:
Equation 8
Will introduce an error on the calculated CC setpoint, depending on the input voltage.
The HVLED805 implements a Line Feedforward function, which solves the issue by
introducing an input voltage dependent offset on the current sense signal, in order to adjust
the cycle-by-cycle current limitation.
The internal schematic is shown in
Q
I
I
I
C
P
s
Doc ID 18077 Rev 1
Figure 17
Δ I
I
CLED
P
=
T
.
V
=
IN
−
L
C
V
⋅
P
R
T
C
to define the output current, according to
d
I
CLED
t
t
t
t
HVLED805