|
|
PDF IW3620 Data sheet ( Hoja de datos )
| Número de pieza | IW3620 | |
| Descripción | Digital PWM Current-Mode Controller | |
| Fabricantes | iWatt | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de IW3620 (archivo pdf) en la parte inferior de esta página. Total 21 Páginas | ||
|
No Preview Available !
iW3620
Digital PWM Current-Mode Controller for AC/DC LED Driver
1.0 Features
●● Primary-side feedback eliminates opto-isolators and
simplifies design
●● Quasi-resonant operation for highest overall efficiency
●● EZ-EMI ® design to easily meet global EMI standards
●● Up to 130 kHz switching frequency enables small
adapter size
●● Very tight LED constant current regulation
●● No external compensation components required
●● Built-in output constant-current control with primary-side
feedback for LED driver.
●● Low start-up current (10 µA typical)
●● Built-in soft start
●● Built-in short circuit protection and output overvoltage
protection
●● Current sense resistor short protection
●● Overtemperature Protection
●● Open circuit protection
●● Universal input range from 85 Vac to 264 Vac
●● Single-fault protection
●● Small input bulk capacitor
●● Long MTBF
2.0 Description
The iW3620 is a high performance AC/DC offline LED driver
which uses digital control technology to build peak current
mode PWM flyback power supplies. The device operates in
quasi-resonant mode at heavy load to provide high efficiency
along with a number of key built-in protection features while
minimizing the external component count, simplifying EMI
design and lowering the total bill of material cost. The
iW3620 removes the need for secondary feedback circuitry
while achieving excellent line and load regulation. It also
eliminates the need for loop compensation components while
maintaining stability over all operating conditions. Pulse-by-
pulse waveform analysis allows for a loop response that is
much faster than traditional solutions, resulting in improved
dynamic load response. The built-in current limit function
enables optimized transformer design in universal off-line
applications over a wide input voltage range.
3.0 Applications
●● LED lighting
●● High efficiency
L
+
N
VOUT
+
+
Optional
NTC
Thermistor
1 NC
VCC 8
2 VSENSE OUTPUT 7
3 VIN
ISENSE 6
4 SD
GND 5
U1
iW3620
Figure 3.1 : Typical Application Circuit
RTN
Rev. 1.8
iW3620
February 1, 2012
Page 1
1 page  
iW3620
Digital PWM Current-Mode Controller for AC/DC LED Driver
6.0 Electrical Characteristics (cont.)
VCC = 12 V, -40°C ≤ TA ≤ 85°C, unless otherwise specified (Note 1)
Parameter
Symbol Test Conditions
ISENSE SECTION (Pin 6)
Peak limit threshold
VPEAK
Isense short protection reference
CC regulation threshold limit (Note 2)
VRSNS
VREG-TH
SD SECTION (Pin 4)
Shutdown threshold
VSD-TH
TA = 25°C
Shutdown threshold in Startup
(Note 2)
VSD-TH(ST)
Input leakage current
Pull down resistance
Pull up current source
IBVSD
RSD
ISD
VSD = 1.0 V
TA = 25°C
TA = 25°C
Min
1.045
0.127
0.95
7916
96
Typ
1.1
0.15
1.0
1.0
1.2
8333
107
Max
1.155
0.173
1.05
1
8750
118
Unit
V
V
V
V
V
µA
W
µA
Notes:
Note 1. Adjust VCC above the start-up threshold before setting at 12 V.
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.
Rev. 1.8
iW3620
February 1, 2012
Page 5
5 Page 
iW3620
Digital PWM Current-Mode Controller for AC/DC LED Driver
If the ISENSE sense resistor is shorted there is a potential
danger of the over current condition not being detected.
Thus the IC is designed to detect this sense-resistor-short
fault after start-up, and shutdown immediately. The VCC will
be discharged since the IC remains biased. Once VCC drops
below the UVLO threshold, the controller resets itself and
then initiates a new soft-start cycle. The controller continues
attempting start-up, but does not fully start-up until the fault
condition is removed.
9.13 Shutdown
The shutdown (SD) pin in the iW3620 provides protection
against overtemperature (OTP) and additional overvoltage
(OVP) for the power supply.
The iW3620 switches between monitoring overtemperature
fault and overvoltage fault. In order to detect the resistance in
the NTC for an overtemperature fault, the iW3620 connects
a current source to the SD pin and checks the voltage on the
pin. To ensure that the current source is settled before the
voltage is checked both OTP and OVP are detected on the
last cycle, as depicted in Figure 9.6.
OVP
Detection
OTP
Detection
Vgate
9.14 Thermal Design
The iW3620 is typically installed inside a small enclosure,
where space and air volumes are constrained. Under these
circumstances θJA (thermal resistance, junction to ambient)
measurements do not provide useful information for this
type of application.
Instead
we
have
provided
ψ
JB
which
estimates the increase in die junction temperature relative
to the PCB surface temperature. Figure 9.8 shows the PCB
surface temperature is measured at the IC’s GND pin pad.
Thermal Epoxy
Artic Silver
Copper Thermal Pad
Under Package
Exposed
Die Pad
Printed Circuit Board
J ψJB
B
IC Die
PCB Top Copper Trace
GND pin
Printed Circuit Board
Thermal Vias
Connect top thermal pad
to bottom copper
PCB Bottom Copper Trace
Figure 9.8 : Ways to Improve Thermal Resistance
Using ψJB, the junction temperature (TJ) of the IC can be
found using the equation below.
T=J TB + PH ⋅ ψJB (9.9)
Detection Switch
where, TB is the PCB surface temperature and PH is the
power applied to the chip or the product of VCC and ICCQ.
Detection Switch:
When switch is low SD pin is connected to RSD
When switch is high SD pin is connected to a current source ISD
Figure 9.6 : SD Pin Detection Cycles
During an overvoltage monitor cycle the SD pin is connected
to a resistance internal to the chip, RSD, to ground and the
voltage on the SD pin is observed. Figure 9.7 shows how
the SD pin is configured inside the chip.
The iW3620 uses an exposed pad package to reduce the
thermal resistance of the package. Although just by using
an exposed package can provide some thermal resistance
improvement, more significant improvements can be
obtained with simple PCB layout and design. Figure 9.8
demonstrates some recommended techniques to improve
thermal resistance, which are also highlighted below.
Ways to Improve Thermal Resistance
SD pin
iW3620
ISD
VSD-TH
R SD
Detection
Switch
OTP / OVP
Fault Detect
●● Increase PCB area and associated amount of copper
interconnect.
●● Use thermal adhesive to attach the package to a thermal
pad on PCB.
●● Connect PCB thermal pad to additional copper on PCB.
Environment
No Attachment to PCB
Attach Package to PCB with Thermal Adhesive
Use Thermal Adhesive and Thermal Vias
ψJB
70 °C/W
63 °C/W
49 °C/W
Figure 9.7 : Internal Function of SD Pin
Table 9.1 : ImproEvexmpeernimtseinntaψtiJoBnBased on Limited
Rev. 1.8
iW3620
February 1, 2012
Page 11
11 Page | ||
| Páginas | Total 21 Páginas | |
| PDF Descargar | [ Datasheet IW3620.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| IW3620 | Digital PWM Current-Mode Controller | iWatt |
| iW3623 | AC/DC Digital Power Controller | iWatt |
| iW3623 | AC/DC Digital Power Controller |  Dialog Semiconductor |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |