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PDF IW1677 Data sheet ( Hoja de datos )
| Número de pieza | IW1677 | |
| Descripción | Low-Power Off-Line Digital Green-Mode PWM Controller | |
| Fabricantes | Dialog Semiconductor | |
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iW1677
Low-Power Off-Line Digital Green-Mode PWM Controller
1 Description
The iW1677 is a high performance AC/DC power supply controller which uses digital control technology to build
peak current mode PWM flyback power supplies. The device together with an external active device (depletion mode
NFET or NPN BJT) provides a fast start-up without compromising no-load power loss. The device directly drives
a power BJT and operates in quasi-resonant mode 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 iW1677 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 for both one-time and repetitive load transients. The built-in power limit
function enables optimized transformer design in universal off-line applications and allows for a wide input voltage
range.
Dialog’s innovative proprietary technology ensures that power supplies built with the iW1677 can achieve both highest
average efficiency and less than 20mW no-load power consumption, and have fast dynamic load response in a
compact form factor. The active start-up scheme enables shortest possible start-up time without sacrificing no-load
power loss.
2 Features
●● No-load power consumption < 20mW at 230 VAC with
typical application circuit (5 star rating)
●● Fast dynamic load response for both one-time and
repetitive load transients
●● Very tight constant voltage and constant current
regulation over entire operating range
●● PrimAccurateTM primary-side feedback eliminates
opto-isolators and simplifies design
●● Low EMI design enhances manufacturability
●● Intrinsically low common mode noise
●● Optimized 72kHz maximum PWM switching frequency
achieves best size and efficiency
●● Active start-up scheme enables fastest possible start-
up
●● Adaptive multi-mode PWM/PFM control improves
efficiency
●● Quasi-resonant operation for highest overall efficiency
●● Direct drive of low-cost BJT switch
●● Dynamic base current control
●● No external loop compensation components required
●● Complies with EPA 2.0 energy-efficiency
specifications with ample margin
●● Built-in soft start
●● Built-in short circuit protection and output overvoltage
protection
●● Built-in current sense resistor short circuit protection
●● No audible noise over entire operating range
3 Applications
●● Compact low power AC/DC adapter/chargers for cell
phones, PDAs, digital still cameras
●● Linear AC/DC replacement
Datasheet
www.dialog-semiconductor.com
Rev. 2.0
1 of 16
3-June-2016
© 2016 Dialog Semiconductor
1 page  
iW1677
Low-Power Off-Line Digital Green-Mode PWM Controller
6 Electrical Characteristics
VCC = 12V, -40°C ≤ TA ≤ 85°C, unless otherwise specified
Parameter
Symbol
Test Conditions
Min Typ Max Unit
VSENSE SECTION (Pin 2)
Input leakage current
Nominal voltage threshold
Output OVP threshold -00 (Note 1)
Output OVP threshold -01 (Note 1)
Output OVP threshold -03 (Note 1)
Output OVP threshol -05 (Note 1)
ISENSE SECTION (Pin 4)
Overcurrent threshold
ISENSE regulation upper limit (Note 3)
ISENSE regulation lower limit (Note 3)
Input leakage current
IBVS
VSENSE(NOM)
VSENSE(MAX)
VSENSE(MAX)
VSENSE(MAX)
VSENSE(MAX)
VSENSE = 2V
TA=25°C, negative edge
TA=25°C, negative edge
TA=25°C, negative edge, Load = 100 %
TA=25°C, negative edge, Load = 100 %
TA=25°C, negative edge, Load = 100 %
1.518
1.742
1.830
1.873
1.786
1.533
1.834
1.926
1.972
1.880
1
1.548
1.926
2.022
2.071
1.974
μA
V
V
V
V
V
VOCP
VIPK(HIGH)
VIPK(LOW)
ILK
ISENSE = 1.0 V
1.11 1.15 1.19 V
0.97 1.00 1.03 V
0.22 0.23 0.24 V
1 μA
OUTPUT SECTION (Pin 6)
Output low level ON-resistance
Switching frequency (Note 2)
VCC SECTION (Pin 1)
Maximum operating voltage (Note 1)
Start-up threshold
Undervoltage lockout threshold
Start-up current
Quiescent current
No-load operating current (Note 1 & 4)
Zener breakdown voltage
ASU SECTION (Pin 3)
RDS(ON)LO
fSW
VCC(MAX)
VCC(ST)
VCC(UVL)
IIN(ST)
ICCQ
ICC_NL
VZB
ISINK = 5mA
> 50% load
VCC rising
VCC falling
VCC = 10V
VCC = 14V, without driver switching
No-load operation in DDPWM mode
Zener current = 5mA
TA=25°C
1 3W
72 kHz
16 V
10.0 11.0 12.0 V
3.8 4.0 4.2 V
1.0 1.7 3.0 μA
2.7 4.0 mA
0.32 0.46 0.62 mA
18.5 19.5 20.5 V
Maximum operating voltage (Note 1)
Resistance between VCC and ASU
VASU(MAX)
RVcc_ASU
16 V
600 830 1100 kΩ
Notes:
Note 1. These parameters are not 100% tested. They are guaranteed by design and characterization.
Note 2. Operating frequency varies based on the load conditions, see Section 9.6 for more details.
Note 3. These parameters are not 100% tested, guaranteed by design and characterization. Refer to Section 9.0 for operation details.
Note 4. See Sections 9.6 and 9.7 for details.
Datasheet
www.dialog-semiconductor.com
Rev. 2.0
5 of 16
3-June-2016
© 2016 Dialog Semiconductor
5 Page 
iW1677
Low-Power Off-Line Digital Green-Mode PWM Controller
The real-time waveform analyzer in the iW1677 reads this information cycle by cycle. The part then generates a
feedback voltage VFB. The VFB signal precisely represents the output voltage under most conditions and is used to
regulate the output voltage.
9.4 Constant Voltage Operation
After soft-start has been completed, the digital control block measures the output conditions. It determines output
power levels and adjusts the control system according to a light load or heavy load. If this is in the normal range, the
device operates in the Constant Voltage (CV) mode, and changes the pulse width (TON) and off time (TOFF) in order to
meet the output voltage regulation requirements.
If no voltage is detected on VSENSE it is assumed that the auxiliary winding of the transformer is either open or shorted
and the iW1677 shuts down.
9.5 Constant Current Operation
The constant current (CC mode) is useful in battery charging applications. During this mode of operation the iW1677
will regulate the output current at a constant level regardless of the output voltage, while avoiding continuous
conduction mode.
To achieve this regulation the iW1677 senses the load current indirectly through the primary current. The primary
current is detected by the ISENSE pin through a resistor from the BJT emitter to ground.
VNOM
CV mode
Output Current
IOUT(CC)
Figure 9.4 : Power Envelope
9.6 Multi-Mode PWM/PFM Control and Quasi-Resonant Switching
The iW1677 uses a proprietary adaptive multi-mode PWM /PFM control to dramatically improve the light-load
efficiency and thus the overall average efficiency.
During the constant voltage (CV) operation, the iW1677 normally operates in a pulse-width-modulation (PWM) mode
during heavy load conditions. In the PWM mode, the switching frequency keeps around constant. As the output load
IOUT is reduced, the on-time tON is decreased, and the controller adaptively transitions to a pulse-frequency-modulation
(PFM) mode. During the PFM mode, the BJT is turned on for a set duration under a given instantaneous rectified AC
input voltage, but its off time is modulated by the load current. With a decreasing load current, the off time increases
and thus the switching frequency decreases.
When the switching frequency approaches to human ear audio band, the iW1677 transitions to a second level of PWM
mode, namely Deep PWM mode (DPWM). During the DPWM mode, the switching frequency keeps around 25 kHz in
order to avoid audible noise. As the load current is further reduced, the iW1677 transitions to a second level of PFM
Datasheet
Rev. 2.0
3-June-2016
www.dialog-semiconductor.com
11 of 16
© 2016 Dialog Semiconductor
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet IW1677.PDF ] | |
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