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PDF IW3612 Data sheet ( Hoja de datos )
| Número de pieza | IW3612 | |
| Descripción | AC/DC Digital Power Controller | |
| Fabricantes | iWatt | |
| Logotipo |  |
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iW3612
AC/DC Digital Power Controller for
Dimmable LED Drivers
1.0 Features
●● Isolated AC/DC offline 100VAC /230VAC LED driver
●● Line frequency ranges from 45Hz to 66Hz
●● Intelligent wall dimmer detection
xx Leading-edge dimmer
xx Trailing-edge dimmer
xx No-dimmer detected
xx Unsupported dimmer
●● Hybrid dimming scheme
●● Wide dimming range from 1% up to 100%
●● Optimized for PF > 0.7
●● No visible flicker
●● Resonant control to achieve high efficiency, 85% without
dimmer
●● Temperature compensated LED current
●● Small size design
xx Small size input bulk capacitor
xx Small size output capacitor
xx Small transformer
●● Primary-side sensing eliminates the need for
opto-isolator feedback and simplifies design
●● Tight LED current regulation ± 5%
●● Fast start-up, typically 10µA start-up current
●● Hot-plug LED module support
●● Multiple protection features:
xx LED open circuit protection
xx Single-fault protection
xx Over-current protection
xx LED short circuit protection
xx Current sense resistor short circuit protection
xx Over-temperature protection
xx Input over-voltage protection
●● Up to 25W output power
2.0 Description
The iW3612 is a high performance AC/DC offline power
supply controller for dimmable LED luminaires, which uses
advanced digital control technology to detect the dimmer
type and phase. The dimmer conduction phase controls
the LED brightness. The LED brightness is modulated by
PWM-dimming. iW3612’s unique digital control technology
eliminates visible flicker.
iW3612 can operate with all dimmer schemes including:
leading-edge dimmer, trailing-edge dimmer, as well as
other dimmer configurations such as R-type, R-C type or
R-L type. When a dimmer is not present, the controller can
automatically detect that there is no dimmer.
iW3612 operates in quasi-resonant mode to provide
high efficiency. The iW3612 provides a number of key
built-in features. The iW3612 uses iWatt’s advanced primary-
side sensing technology to achieve excellent line and load
regulation without secondary feedback circuitry. In addition,
iW3612’s pulse-by-pulse waveform analysis technology
allows accurate LED current regulation. The iW3612
maintains stability over all operating conditions without the
need for loop compensation components. Therefore, the
iW3612 minimizes external component count, simplifies EMI
design and lowers overall bill of materials cost.
3.0 Applications
●● Dimmable LED luminaires
●● Optimized for 3W - 25W output power
●● Capable of higher output power with enhanced external
driver
iW3612
Rev. 1.6
iW3612
Page 1
1 page  
iW3612
AC/DC Digital Power Controller for
Dimmable LED Drivers
6.0 Electrical Characteristics (cont.)
VCC = 12V, -40°C ≤ TA ≤ 85°C, unless otherwise specified (Note 1)
Parameter
Symbol Test Conditions
ISENSE SECTION (Pin 6)
Over-current limit threshold
Isense short protection reference
CC regulation threshold limit (Note 4)
VOCP
VRSNS
VREG-TH
VT SECTION (Pin 4)
Power limit high threshold (Note 4)
(-00, -01)
VP-LIM(HI)
Power limit high threshold (Note 4)
(-03, -05)
VP-LIM(HI)
Power limit low threshold (Note 4)
(-00, -01)
VP-LIM(LO)
Power limit low threshold (Note 4)
(-03, -05)
VP-LIM(LO)
Shutdown threshold (Note 4)
Input leakage current
Pull up current source
VSH-TH
IIN(VT)
IVT
VT = 1.0V
OUTPUT(TR) SECTION (Pin 1)
Output low level ON-resistance
RDS-TR(ON)LO ISINK = 5mA
Min Typ Max Unit
1.83 1.89 1.95
0.16
1.8
V
V
V
0.56 V
1.76 V
0.44 V
0.32 V
0.22 V
1 µA
90 100 110 µA
100 Ω
Notes:
Note 1. Adjust VCC above the start-up threshold before setting at 12V.
Note 2. These parameters are not 100% tested, guaranteed by design and characterization.
Note 3. Operating frequency varies based on the line and load conditions, see Theory of Operation for more details.
Note 4. These parameters refer to digital preset values, and are not 100% tested.
Rev. 1.6
iW3612
Page 5
5 Page 
iW3612
AC/DC Digital Power Controller for
Dimmable LED Drivers
iin(t)
vin(t)
+ ig(t)
vg(t)
–
TS(t)
N:1 id(t) VO
D1
+
CO
IO
VAUX
VAUX
Q1
VAUX
0V
VAUX
=
VO
x
NAUX
NS
Figure 9.8 : Simplified Flyback Converter
In order to tightly regulate the output voltage, the information
about the output voltage and load current needs to be
accurately sensed. In the DCM flyback converter, this
information can be read via the auxiliary winding or the
primary magnetizing inductance (LM). During the Q1 on-time,
tThheelovaodltacguerreancrtoissssuLpMpilsievdg(ftr)o, mastshuemoiuntgputhtefilvteorltcaagpeadcritooprpCeOd.
across Q1 is zero. The current in Q1 ramps up linearly at a
rate of:
dig (t) = vg (t)
dt LM
(9.6)
At the end of on-time, the current has ramped up to:
ig _
peak (t)
=
vg (t) × tON
LM
(9.7)
This current represents a stored energy of:
E=g
LM
2
× ig _ peak (t)2
(9.8)
When Q1 turns off, ig(t) in LM forces a reversal of polarities on
all windings. Ignoring the communication-time caused by the
leakage inductance LK at the instant of turn-off, the primary
current transfers to the secondary at a peak amplitude of:
id =(t )
NP
NS
× ig _
peak
(t)
(9.9)
Assuming the secondary winding is master and the auxiliary
winding is slave.
VAUX
=
-VIN
x
NAUX
NP
Figure 9.9 : Auxiliary Voltage Waveforms
The auxiliary voltage is given by:
=VAUX
N AUX
NS
(VO
+ ∆V )
(9.10)
and reflects the output voltage as shown in Figure 9.9.
The voltage at the load differs from the secondary voltage by
a diode drop and IR losses. The diode drop is a function of
current, as are IR losses. Thus, if the secondary voltage is
always read at a constant secondary current, the difference
between the output voltage and the secondary voltage will
be a fixed ΔV. Furthermore, if the voltage can be read when
the secondary current is small; for example, at the knee of
the auxiliary waveform (see Figure 9.9), then ΔV will also be
small. With the iW3612, ΔV can be ignored.
The real-time waveform analyzer in the iW3612 reads the
auxiliary waveform information cycle by cycle. The part then
generates a feedback voltage VFB. The VFB signal precisely
represents the output voltage and is used to regulate the
output voltage.
9.7 Valley Mode Switching
In order to reduce switching losses in the MOSFET and EMI,
the iW3612 employs valley mode switching during constant
output current operation. In valley mode switching, the
MOSFET switch is turned on at the point where the resonant
voltage across the drain and source of the MOSFET is at its
lowest point (see Figure 9.10). By switching at the lowest
VDS, the switching loss will be minimized.
Rev. 1.6
iW3612
Page 11
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet IW3612.PDF ] | |
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