HVLED805TR STMicroelectronics, HVLED805TR Datasheet - Page 22

• 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
5.7
22/29
This offset is proportional to V
according to the formula:
Equation 13
Finally, the R
Equation 14
In this case the peak drain current does not depend on input voltage anymore.
One more consideration concerns the R
sourced by the DMG pin, I
µA typical).
If I
This feature is especially important when the auxiliary winding is accidentally disconnected
and considerably increases the end-product’s safety and reliability.
Burst-mode operation at no load or very light load
When the voltage at the COMP pin falls 65 mV below a threshold fixed internally at a value,
V
reduced at a lower value to minimize Vcc capacitor discharge.
In this condition the converter operates in burst-mode (one pulse train every T
µs), with minimum energy transfer.
As a result of the energy delivery stop, the output voltage decreases: after 500 µs the
controller switches-on the MOSFET again and the sampled voltage on the DMG pin is
compared with the internal reference. If the voltage on the EA output, as a result of the
comparison, exceeds the V
OFF for another 500 µs period.
In this way the converter will work in burst-mode with a nearly constant peak current defined
by the internal disable level. A load decrease will then cause a frequency reduction, which
can go down even to few hundred hertz, thus minimizing all frequency-related losses and
making it easier to comply with energy saving regulations. This kind of operation, shown in
the timing diagrams of
since the peak current is low
COMPBM
DMG
< I
, the IC is disabled with the MOSFET kept in OFF state and its consumption
DMGON
dmg
, the brownout function is activated and the IC is shut-down.
resistor can be calculated as follows:
Figure 19
DMG
COMPL
IN
Doc ID 18077 Rev 1
, is compared with an internal reference current I
and is used to compensate the current overshoot,
V
R
along with the others previously described, is noise-free
IN
threshold, the device restarts switching, otherwise it stays
dmg
L
⋅
p
T
d
=
⋅
dmg
N
R
N
AUX
SENSE
PRI
value: during MOSFET’s ON-time, the current
⋅
T
=
d
L
⋅
p
m
V
R
⋅
IN
R
SENSE
⋅
R
⋅
FF
R
dmg
FF
START
DMGON
HVLED805
=500
(-50