Dialog IW1700 Zero power no-load off-line digital pwm controller Datasheet

iW1700
Zero Power No-Load Off-Line Digital PWM Controller
1.0 Features
2.0 Description
●● Zero power consumption at no-load with lowest system
cost (< 5 mW at 230 Vac with typical application circuit)
●● Intelligent low power management achieves ultra-low
operating current at no-load
●● Adaptive load transient detection and fast response
●● Very tight constant voltage and constant current
regulation over entire operating range
●● Primary-side feedback eliminates opto-isolators and
simplifies design
●● EZ-EMI ® design enhances manufacturability
●● Intrinsically low common mode noise
●● Optimized 72 kHz 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
●● No external 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
The iW1700 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 meanwhile
achieving ultra-low no-load power consumption. 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 iW1700 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 transient. The built-in
power limit function enables optimized transformer design
in universal off-line applications and allows for a wide input
voltage range.
iWatt’s innovative proprietary technology ensures that power
supplies built with the iW1700 can achieve both highest
average efficiency and zero no-load power consumption,
and have fast load transient response in a compact form
factor. The active start-up scheme enables shortest possible
start-up time without sacrificing no-load power loss.
3.0 Applications
●● Built-in current sense resistor short circuit protection
●● Compact AC/DC adapter/chargers for cell phones,
PDAs, digital still cameras
●● No audible noise over entire operating range
●● Linear AC/DC replacement
L
+
+
VOUT
GND
N
U1
iW1700
1
VCC
2
VSENSE
3
ASU
OUTPUT
6
GND
5
ISENSE
4
Figure 3.1: iW1700 Typical Application Circuit
(Achieving < 5 mW No-load Power Consumption. Using Depletion Mode NFET as Active Start-up Device)
Rev. 1.2
iW1700
February 13, 2012
Page 1
iW1700
Zero Power No-Load Off-Line Digital PWM Controller
L
+
+
VOUT
GND
N
U1
iW1700
1
VCC
2
VSENSE
3
ASU
OUTPUT
6
GND
5
ISENSE
4
Figure 3.2: iW1700 Typical Application Circuit
(Alternative Circuit Using NPN BJT as the Active Start-up Device)
4.0 Pinout Description
iW1700
1
VCC
2
VSENSE
3
ASU
OUTPUT
6
GND
5
ISENSE
4
Figure 4.1: 6 Lead SOT-23 Package
Pin #
Name
Type
1
VCC
Power Input
2
VSENSE
3
ASU
4
ISENSE
5
GND
Ground
Ground.
6
OUTPUT
Output
Base drive for BJT.
Rev. 1.2
Pin Description
Power supply for control logic.
Analog Input Auxiliary voltage sense (used for primary regulation).
Output
Control signal for active start-up device (BJT or Depletion NFET).
Analog Input Primary current sense. Used for cycle-by-cycle peak current control and limit.
iW1700
February 13, 2012
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iW1700
Zero Power No-Load Off-Line Digital PWM Controller
5.0 Absolute Maximum Ratings
Absolute maximum ratings are the parameter values or ranges which can cause permanent damage if exceeded. For
maximum safe operating conditions, refer to Electrical Characteristics in Section 6.0.
Parameter
Symbol
Value
Units
DC supply voltage range (pin 1, ICC = 20mA max)
VCC
-0.3 to 18.0
V
Continuous DC supply current at VCC pin (VCC = 15 V)
ICC
20
mA
ASU output (pin 3)
-0.3 to 18.0
V
Output (pin 6)
-0.3 to 4.0
V
VSENSE input (pin 2, IVsense ≤ 10 mA)
-0.7 to 4.0
V
ISENSE input (pin 4)
-0.3 to 4.0
V
TJ MAX
150
°C
Storage temperature
TSTG
–65 to 150
°C
Lead temperature during IR reflow for ≤ 15 seconds
TLEAD
260
°C
θJA
190
°C/W
ESD rating per JEDEC JESD22-A114
2,000
V
Latch-up test per JEDEC 78
±100
mA
Maximum junction temperature
Thermal resistance junction-to-ambient
6.0 Electrical Characteristics
VCC = 12 V, -40°C ≤ TA ≤ +85°C, unless otherwise specified.
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
1
μA
1.548
V
VSENSE SECTION (Pin 2)
Input leakage current
IBVS
VSENSE = 2 V
Nominal voltage threshold
VSENSE(NOM)
TA=25°C, negative edge
Output OVP threshold -00 (Note 1)
VSENSE(MAX)
Output OVP threshold -01 (Note 1)
VSENSE(MAX)
Output OVP threshold -03 (Note 1)
VSENSE(MAX)
Output OVP threshold -05 (Note 1)
VSENSE(MAX)
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 %
Rev. 1.2
iW1700
February 13, 2012
1.518
1.533
1.834
V
1.926
V
1.972
V
1.880
V
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iW1700
Zero Power No-Load Off-Line Digital PWM Controller
6.0 Electrical Characteristics
VCC = 12 V, -40°C ≤ TA ≤ +85°C, unless otherwise specified.
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
1.11
1.15
1.19
V
ISENSE SECTION (Pin 4)
Overcurrent threshold
VOCP
ISENSE regulation upper limit (Note 1)
VIPK(HIGH)
1.0
V
ISENSE regulation lower limit (Note 1)
VIPK(LOW)
0.23
V
Input leakage current
ILK
ISENSE = 1.0 V
1
μA
3
W
OUTPUT SECTION (Pin 6)
Output low level ON-resistance
RDS(ON)LO
ISINK = 5 mA
1
Switching frequency (Note 2)
fSW
> 50% load
72
kHz
VCC SECTION (Pin 1)
Maximum operating voltage (Note 1)
VCC(MAX)
Start-up threshold
VCC(ST)
VCC rising
10.0
Undervoltage lockout threshold
VCC(UVL)
VCC falling
Start-up current
IIN(ST)
VCC = 10 V
Quiescent current
ICCQ
No IB current
Zener breakdown voltage
VZB
Zener current = 5 mA
TA=25°C
16
V
11.0
12.0
V
3.8
4.0
4.2
V
1.0
1.7
3.0
μA
2.7
4.0
mA
19.5
20.5
V
16
V
18.5
ASU SECTION (Pin 3)
Maximum operating voltage (Note 1)
VASU(MAX)
Resistance between VCC and ASU
RVcc_ASU
830
kΩ
Notes:
Note 1. These parameters are not 100% tested, guaranteed by design and characterization.
Note 2. Operating frequency varies based on the load conditions, see Section 9.6 for more details.
Rev. 1.2
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February 13, 2012
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iW1700
Zero Power No-Load Off-Line Digital PWM Controller
7.0 Typical Performance Characteristics
12.0
VCC Start-up Threshold (V)
4.08
VCC UVLO (V)
4.04
4.00
3.96
3.92
3.88
-50
-25
0
25
50
75
100
Ambient Temperature (ºC)
125
10.8
10.4
-25
0
25
50
75
100
Ambient Temperature (ºC)
125
150
Figure 7.2 : Start-Up Threshold vs. Temperature
80
2.010
Internal Reference Voltage (V)
fsw @ Load > 50% (kHz)
11.2
10.0
-50
150
Figure 7.1 : VCC UVLO vs. Temperature
76
72
68
64
60
-50
-25
0
25
50
75
100
Ambient Temperature (ºC)
125
150
Figure 7.3 : Switching Frequency vs. Temperature1
VCC Supply Start-up Current (µA)
11.6
2.006
2.002
1.998
1.994
1.990
-50
-25
0
25
50
75
100
Ambient Temperature (ºC)
125
150
Figure 7.4 : Internal Reference vs. Temperature
2.5
2.0
1.5
1.0
0.5
0.0
0.0
3.0
6.0
VCC (V)
9.0
12.0
Figure 7.5 : VCC vs. VCC Supply Start-up Current
Notes:
Note 1. Operating frequency varies based on the load conditions, see Section 9.6 for more details.
Rev. 1.2
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February 13, 2012
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iW1700
Zero Power No-Load Off-Line Digital PWM Controller
8.0 Functional Block Diagram
1 VCC
Start-up
3 ASU
ENABLE
ENABLE
VSENSE 2
Signal
Conditioning
VFB
Digital
Logic
Control
BJT
Base
Drive
OCP
GND
5
VSENSE(NOM)
= 1.533 V
DAC
6 Output
1.15 V
IPK
4 ISENSE
VIPK
Figure 8.1: iW1700 Functional Block Diagram
9.0 Theory of Operation
The iW1700 is a digital controller which uses a new,
proprietary primary-side control technology to eliminate the
opto-isolated feedback and secondary regulation circuits
required in traditional designs. This results in a low-cost
solution for low power AC/DC adapters. The core PWM
processor uses fixed-frequency Discontinuous Conduction
Mode (DCM) operation at higher power levels and switches
to variable frequency operation at light loads to maximize
efficiency. Furthermore, iWatt’s digital control technology
enables fast dynamic response, tight output regulation, and
full featured circuit protection with primary-side control.
Referring to the block diagram in Figure 8.1, the digital logic
control block generates the switching on-time and off-time
information based on the output voltage and current feedback
signal and provides commands to dynamically control the
external BJT base current. The system loop is automatically
compensated internally by a digital error amplifier. Adequate
system phase margin and gain margin are guaranteed by
design and no external analog components are required for
loop compensation. The iW1700 uses an advanced digital
control algorithm to reduce system design time and increase
reliability.
Rev. 1.2
Furthermore, accurate secondary constant-current operation
is achieved without the need for any secondary-side sense
and control circuits.
The iW1700 uses adaptive multi-mode PWM/PFM control
to dynamically change the BJT switching frequency for
efficiency, EMI, and power consumption optimization. In
addition, it achieves unique BJT quasi-resonant switching to
further improve efficiency and reduce EMI. Built-in singlepoint fault protection features include overvoltage protection
(OVP), output short circuit protection (SCP), over current
protection (OCP), and ISENSE fault detection. In particular,
it ensures that power supplies built with the iW1700 can
achieve zero power consumption at no load, and meanwhile
have adaptive load transient detection and fast response.
iWatt’s digital control scheme is specifically designed to
address the challenges and trade-offs of power conversion
design. This innovative technology is ideal for balancing new
regulatory requirements for green mode operation with more
practical design considerations such as lowest possible cost,
smallest size and high performance output control.
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iW1700
Zero Power No-Load Off-Line Digital PWM Controller
9.1 Pin Detail
Pin 1 – VCC
Power supply for the controller during normal operation. The
controller will start up when VCC reaches 11.0 V (typical) and
will shut-down when the VCC voltage is 4.0 V (typical). A
decoupling capacitor of 0.1 μF or so should be connected
between the VCC pin and GND.
Pin 2 – VSENSE
While the ENABLE signal initiates the soft-start process, it
also pulls down the ASU pin voltage at the same time, which
turns off the depletion NFET or the BJT, thus minimizing the
no-load standby power consumption. For the active startup scheme in Figure 3.2, the start-up resistors connected
between the base of the BJT and DC input still conduct
current after start-up is finished. They need to be large
enough to minimize no-load power consumption. The large
start-up resistors require that the BJT have ample gain to
obtain a sufficient charge current for a fast start-up.
Start-up
Sequencing
Sense signal input from auxiliary winding. This provides the
secondary voltage feedback used for output regulation.
VCC(ST)
Pin 3 – ASU
Control signal for active startup device. This signal is pulled
low after start-up is finished to cut off the active device.
VCC
Pin 4 – ISENSE
Primary current sense. Used for cycle-by-cycle peak current
control and limit.
ENABLE
ASU
Pin 5 – GND
Ground.
Figure 9.1: Start-up Sequencing Diagram
Pin 6 – OUTPUT
9.3 Understanding Primary Feedback
Base drive for the external power BJT switch.
Figure 9.2 illustrates a simplified flyback converter. When the
switch Q1 conducts during tON(t), the current ig(t) is directly
drawn from rectified sinusoid vg(t). The energy Eg(t) is stored
in the magnetizing inductance LM. The rectifying diode D1
is reverse biased and the load current IO is supplied by the
secondary capacitor CO. When Q1 turns off, D1 conducts
and the stored energy Eg(t) is delivered to the output.
9.2 Active Start-up and Soft-start
Refer to Figure 3.1 and Figure 3.2 for active start-up circuits
using external depletion NFET and BJT respectively. Prior to
start-up, the depletion NFET or the BJT is turned on, allowing
the start-up current to charge the VCC bypass capacitor. When
the VCC bypass capacitor is charged to a voltage higher than
the start-up threshold VCC(ST), the ENABLE signal becomes
active and the iW1700 commences soft start function. During
this start-up process an adaptive soft-start control algorithm
is applied, where the initial output pulses will be small and
gradually get larger until the full pulse width is achieved. The
peak current is limited cycle by cycle by the IPEAK comparator.
If at any time the VCC voltage drops below undervoltage
lockout (UVLO) threshold VCC(UVL) then the iW1700 goes to
shutdown. At this time ENABLE signal becomes low and the
VCC capacitor begins to charge up again towards the start-up
threshold to initiate a new soft-start process.
Rev. 1.2
iin(t)
+
ig(t)
id(t)
N:1
D1
vin(t)
vg(t)
VO
+
CO
IO
VAUX
–
TS(t)
Q1
Figure 9.2: Simplified Flyback Converter
In order to tightly regulate the output voltage, the
information about the output voltage and load current need
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February 13, 2012
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iW1700
Zero Power No-Load Off-Line Digital PWM Controller
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, the load current is supplied from the output filter
capacitor CO. The voltage across LM is vg(t), assuming the
voltage dropped across Q1 is zero. The current in Q1 ramps
up linearly at a rate of:
dig ( t )
dt
=
vg ( t )
LM
(9.1)
At the end of on-time, the current has ramped up to:
ig _ peak ( t ) =
vg ( t ) × tON
LM
(9.2)
This current represents a stored energy of:
E
=
g
(9.3)
NP
× ig _ peak ( t )
NS
(9.4)
Assuming the secondary winding is master, and the auxiliary
winding is slave,
1 VAUX = VO x
VAUX
NAUX
NS
(9.5)
and reflects the output voltage as shown in Figure 9.3.
The voltage at the load differs from the secondary voltage by
a diode drop and 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, ΔV will also be small. With
the iW1700, ΔV can be ignored.
The real-time waveform analyzer in the iW1700 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.
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 iW1700 shuts down.
9.5 Constant Current Operation
The constant current (CC) mode is useful in battery charging
applications. During this mode of operation the iW1700 will
regulate the output current at a constant level regardless of
the output voltage, while avoiding continuous conduction
mode.
To achieve this regulation the iW1700 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.
0V
2 VAUX = -VIN x
N AUX
(VO + ∆V )
NS
9.4 Constant Voltage Operation
LM
2
× ig _ peak ( t )
2
When Q1 turns off at tO, 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
tO, the primary current transfers to the secondary at a peak
amplitude of:
id =
(t )
VAUX
=
NAUX
NP
Figure 9.3: Auxiliary Voltage Waveforms
The auxiliary voltage is given by:
Rev. 1.2
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iW1700
Zero Power No-Load Off-Line Digital PWM Controller
CV mode
CC mode
Output Voltage
VNOM
Output Current
IOUT(CC)
Figure 9.4: Power Envelope
9.6 Multi-Mode PWM/PFM Control and
Quasi-Resonant Switching
The iW1700 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 iW1700
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-frequencymodulation (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 iW1700 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 iW1700 transitions to a second level
of PFM mode, namely Deep PFM mode (DPFM), which
can reduce the switching frequency to a very low level.
Although the switching frequency drops across the audible
frequency range during the DPFM mode, the output current
in the power converter has reduced to an insignificant level
in the DPWM mode before transitioning to the DPFM mode.
Therefore, the power converter practically produces no
audible noise, while achieving high efficiency across varying
load conditions.
Rev. 1.2
The iW1700 also incorporates a unique proprietary quasiresonant switching scheme that achieves valley-mode turn
on for every PWM/PFM switching cycle, during all PFM and
PWM modes and in both CV and CC operations. This unique
feature greatly reduces the switching loss and dv/dt across
the entire operating range of the power supply. Due to the
nature of quasi-resonant switching, the actual switching
frequency can vary slightly cycle by cycle, providing the
additional benefit of reducing EMI. Together these innovative
digital control architecture and algorithms enable the iW1700
to achieve highest overall efficiency and lowest EMI, without
causing audible noise over entire operating range.
9.7 Zero Power No-Load Operation
At the no-load condition, the iW1700 is operating in the DPFM
mode, where the switching frequency can drop as low as
275 Hz and still maintain tight closed-loop control of output
voltage. The distinctive DPFM operation allows the use of
a relatively large pre-load resistor which helps reduce the
no-load power consumption. In the meanwhile, the iW1700
implements an intelligent low-power management technique
that achieves ultra-low chip operating current at the noload, typically less than 400 µA. One important feature of
the iW1700 is that it directly drives a low-cost BJT switch.
Unlike a power MOSFET, the BJT is a current-driven device
that does not require a high driving voltage. As a result, the
UVLO threshold of the iW1700 is designed to be as low as
4.0 V (typical). The power supply system design can fully
utilize this low UVLO feature to have a low VCC voltage at
the no-load operation in order to minimize the no-load
power. In addition, the active start-up scheme with depletion
NFET eliminates the startup resistor power consumption
after the ENABLE signal becomes active. All together these
features ensure with the lowest system cost power supplies
built with the iW1700 can achieve less than 5 mW no-load
power consumption at 230 Vac input and maintain very tight
constant voltage and constant current regulation over the
entire operating range including the no-load operation.
While achieving ultra-low no-load power consumption, the
iW1700 implements innovative proprietary digital control
technology to intelligently detect load transient events, and
ensure adaptive fast response.
9.8 Variable Frequency Operation Mode
At each of the switching cycles, the falling edge of VSENSE
will be checked. If the falling edge of VSENSE is not detected,
the off-time will be extended until the falling edge of VSENSE
is detected. The maximum allowed transformer reset time is
110 μs. When the transformer reset time reaches 110 μs,
the iW1700 shuts off.
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Zero Power No-Load Off-Line Digital PWM Controller
The iW1700 incorporates an internal Digital Error Amplifier
with no requirement for external loop compensation. For a
typical power supply design, the loop stability is guaranteed
to provide at least 45 degrees of phase margin and -20 dB
of gain margin.
9.10 Voltage Protection Features
The secondary maximum output DC voltage is limited by the
iW1700. When the VSENSE signal exceeds the output OVP
threshold at point 1 indicated in Figure 9.3 the iW1700 shuts
down.
The iW1700 protects against input line undervoltage
by setting a maximum TON time. Since output power is
proportional to the squared VINTON product, then for a given
output power, as VIN decreases the TON will increase. Thus
by knowing when the maximum TON time occurs the iW1700
detects that the minimum VIN is reached, and shuts down.
The maximum tON limit is set to 13.8 μs. Also, the iW1700
monitors the voltage on the VCC pin and when the voltage
on this pin is below UVLO threshold the IC shuts down
immediately.
below the UVLO threshold, the controller resets itself and
then initiates a new soft-start cycle. The controller continues
attempting to startup, but does not fully startup until the fault
condition is removed.
9.12 Dynamic Base Current Control
One important feature of the iW1700 is that it directly drives
a BJT switching device with dynamic base current control to
optimize performance. The BJT base current ranges from
10 mA to 31 mA, and is dynamically controlled according to
the power supply load change. The higher the output power,
the higher the base current. Specifically, the base current is
related to VIPK, as shown in Figure 9.5.
35
30
Base Drive Current (mA)
9.9 Internal Loop Compensation
25
20
15
10
When any of these faults are met the IC remains biased
to discharge the VCC supply. Once VCC drops below UVLO
threshold, the controller resets itself and then initiates a new
soft-start cycle. The controller continues attempting start-up
until the fault condition is removed.
5
0
0
0.1
0.2
0.3 0.4
0.5 0.6 0.7 0.8
0.9 1.0 1.1
VIPK (V)
Figure 9.5: Base Drive Current vs. VIPK
9.11 PCL, OCP and SRS Protection
9.13 Cable Drop Compensation
Peak-current limit (PCL), over-current protection (OCP) and
sense-resistor short protection (SRSP) are features built-in
to the iW1700. With the ISENSE pin the iW1700 is able to
monitor the peak primary current. This allows for cycle by
cycle peak current control and limit. When the primary peak
current multiplied by the ISENSE resistor is greater than 1.15 V,
over current (OCP) is detected and the IC will immediately
turn off the base driver until the next cycle. The output driver
will send out a switching pulse in the next cycle, and the
switching pulse will continue if the OCP threshold is not
reached; or, the switching pulse will turn off again if the
OCP threshold is reached. If the OCP occurs for several
consecutive switching cycles, the iW1700 shuts down.
The iW1700 incorporates an innovative method to
compensate for any IR drop in the secondary circuitry
including cable and cable connector. A 2.5 W adapter with
5 V DC output has 3% deviation at 0.5 A load current due
to the drop across a 24 AWG, 1.8 meter DC cable without
cable compensation. The iW1700 compensates for this
voltage drop by providing a voltage offset to the feedback
signal based on the amount of load current detected.
If the ISENSE 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 startup and shut down immediately. The VCC will be
discharged since the IC remains biased. Once VCC drops
Rev. 1.2
The “Cable Comp” specified in the Table in Section 11.0
refers to the voltage increment at PCB end from no-load to
full-load conditions in the CV mode, with the assumption that
the secondary diode voltage drop can be ignored at the point
when the secondary voltage is sensed. Also, the “Cable
Comp” is specified based on the nominal output voltage of
5 V. For different output voltage, the actual voltage increment
needs to be scaled accordingly. To calculate the amount of
cable compensation needed, take the resistance of the cable
and connector and multiply by the maximum output current.
iW1700
February 13, 2012
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iW1700
Zero Power No-Load Off-Line Digital PWM Controller
10.0 Physical Dimensions
6-Lead SOT Package
5
6
4
E
E1
1
2
3
Symbol
D
MIN
MAX
A
-
1.45
A1
0.00
0.15
A2
0.90
1.30
B
0.30
0.50
C
D
0.08
0.22
2.90
BSC
2.80
3.00
e
e1
A1
A2
B
COPLANARITY
0.10
A
SEATING
PLANE
α
Millimeters
E
2.80 BSC
E1
1.60 BSC
e
0.95 BSC
e1
L
C
1.90 BSC
L
0.30
0.60
α
0°
8°
Figure 10.1: Physical dimensions, 6-lead SOT-23 package
Compliant to JEDEC Standard MO-178AB
Controlling dimensions are in millimeters
This package is RoHS compliant and Halide free.
Soldering Temperature Resistance:
[a] Package is IPC/JEDEC Std 020D Moisture Sensitivity Level 1
[b] Package exceeds JEDEC Std No. 22-A111 for Solder Immersion Resistance;
packages can withstand 10 s immersion < 270ºC
Dimension D does not include mold flash, protrusions or gate burrs. Mold flash, protrusions
or gate burrs shall not exceed 0.25 mm per side.
The package top may be smaller than the package bottom. Dimensions D and E1 are
are determined at the outermost extremes of the plastic body exclusive of mold flash, tie bar
burrs and interlead flash, but including any mismatch between top and bottom of the plastic
body.
11.0 Ordering Information
Part Number
Options
Package
Description
iW1700-00
Cable Comp = 0 mV
SOT-23
Tape & Reel1
iW1700-01
Cable Comp = 300 mV
SOT-23
Tape & Reel1
iW1700-03
Cable Comp = 450 mV
SOT-23
Tape & Reel1
iW1700-05
Cable Comp = 150 mV
SOT-23
Tape & Reel1
Note 1: Tape & Reel packing quantity is 3,000 per reel. Minimum ordering quantity is 3,000.
Rev. 1.2
iW1700
February 13, 2012
Page 11
iW1700
Zero Power No-Load Off-Line Digital PWM Controller
About iWatt
iWatt Inc. is a fabless semiconductor company that develops intelligent power management ICs for computer, communication,
and consumer markets. The company’s patented pulseTrain™ technology, the industry’s first truly digital approach to power
system regulation, is revolutionizing power supply design.
Trademark Information
© 2012 iWatt, Inc. All rights reserved. iWatt, EZ-EMI and pulseTrain are trademarks of iWatt, Inc. All other trademarks and
registered trademarks are the property of their respective companies.
Contact Information
Web: https://www.iwatt.com
E-mail: [email protected]
Phone: 408-374-4200
Fax: 408-341-0455
iWatt Inc.
675 Campbell Technology Parkway, Suite 150
Campbell, CA 95008
Disclaimer
iWatt reserves the right to make changes to its products and to discontinue products without notice. The applications
information, schematic diagrams, and other reference information included herein is provided as a design aid only and are
therefore provided as-is. iWatt makes no warranties with respect to this information and disclaims any implied warranties of
merchantability or non-infringement of third-party intellectual property rights.
iWatt cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an iWatt product. No
circuit patent licenses are implied.
Certain applications using semiconductor products may involve potential risks of death, personal injury, or severe property
or environmental damage (“Critical Applications”).
iWatt SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, INTENDED, AUTHORIZED, OR WARRANTED TO
BE SUITABLE FOR USE IN LIFE‑SUPPORT APPLICATIONS, DEVICES OR SYSTEMS, OR OTHER CRITICAL
APPLICATIONS.
Inclusion of iWatt products in critical applications is understood to be fully at the risk of the customer. Questions concerning
potential risk applications should be directed to iWatt, Inc.
iWatt semiconductors are typically used in power supplies in which high voltages are present during operation. High-voltage
safety precautions should be observed in design and operation to minimize the chance of injury.
Rev. 1.2
iW1700
February 13, 2012
Page 12