HVLED805 STMicroelectronics, HVLED805 Datasheet - Page 21

• Manufacturer Part Number: HVLED805
• Description: IC LED DRVR ACDC OFFLINE 16NSOIC
• Manufacturer: STMicroelectronics

Specifications of HVLED805

• Constant Current: Yes
• Constant Voltage: Yes
• Internal Driver: Yes
• Type - Primary: General Purpose
• Mounting Type: Surface Mount
• Topology: AC DC Offline Switcher, PWM
• Number Of Outputs: 1
• Voltage - Supply: 11.5 V ~ 23 V
• Package / Case: 16-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Frequency: -
• Voltage - Output: -
• Operating Temperature: -

HVLED805
Figure 17. Feedforward compensation: internal schematic
During MOSFET’s ON-time the current sourced from DMG pin is mirrored inside the
“ Feedforward Logic ” block in order to provide a feedforward current, I
Such “feedforward current” is proportional to the input voltage according to the formula:
Equation 9
Where m is the primary-to-auxiliary turns ratio.
According to the schematic, the voltage on the non-inverting comparator will be:
Equation 10
The offset introduced by feedforward compensation will be:
Equation 11
As R
Equation 12
FF
Aux
>>R
Rdmg
SENSE
DMG
Rfb
, the previous one can be simplified as:
V
F eedforward
V = R
OFFSET
Doc ID 18077 Rev 1
Logic
(-)
V
SENSE D
=
OFFSET
I
m
FF
.
⋅
V
⋅
R
=
I +I
IN
dmg
m
IF F
=
FF
⋅
V
m
V
R
⋅
⋅
IN
IN
(
(
dmg
⋅
R
R +R
R
Block
⋅
CC
FF
FF
R
dmg
FF
+
R
SENSE
SENSE
+
-
)
CC
)
Application information
FF
RFF
.
LOGIC
PWM
SO URCE
DRAIN
Rsense
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