Document
Not Recommended For New Designs
iW1690
Low-Power Off-line Digital PWM Controller
1.0 Features
• Primary-side feedback eliminates opto-isolators and simplifies design
• Direct drive of BJT switching device
• Multi-mode operation for highest overall efficiency
• Built-in cable drop compensation
• Very tight output voltage regulation
• No external compensation components required
• Complies with CEC/EPA no load power consumption and average efficiency regulations
• Built-in output constant-current control with primary-side feedback
• Low start-up current (10 µA typical)
• Built-in soft start
• Built-in short circuit protection and output overvoltage protection
• Optional AC line under/overvoltage protection
• Fixed switching frequency: 45 kHz, 65 kHz or 75 kHz
• Dynamic base current control
• PFM operation at light load
• Built-in current sense resistor short protection
2.0 Description
The iW1690 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 directly drives a BJT switching device and provides 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 iW1690 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 power limit function enables optimized transformer design in universal off-line applications and allows for a wide input voltage range.
The ultra-low start-up power and operating current at light load ensure that the iW1690 is ideal for applications targeting the newest regulatory standards for average efficiency and standby power.
3.0 Applications
• Low power AC/DC adapter/chargers for cell phones, PDAs, digital still cameras
• Low power AC/DC adapter/chargers to replace RCC implementations
L N
+
+ VOUT GND
1 VSENSE
VCC 8
2 VIN
OUTPUT 7
3 RIN 4 IBC
ISENSE 6
GND 5
U1 iW1690
Figure 2.0.1 iW1690 Typical Application Circuit
Rev. 1.8
iW1690
February 3, 2012
Page 1
Not Recommended For New Designs
iW1690
Low-Power Off-line Digital PWM Controller
4.0 Pinout Description
iW1690
1 VSENSE
VCC 8
2 VIN
OUTPUT 7
3 RIN
ISENSE 6
4 IBC
GND 5
Pin #
1 2 3 4 5 6 7 8
Name
VSENSE VIN RIN IBC GND
ISENSE OUTPUT
VCC
Type Pin Description
Analog Input Auxiliary voltage sense (used for primary regulation and ZVS). Analog Input Rectified AC line voltage sense. Analog Input Sense line input voltage. Analog Input Adjust maximum base current.
Ground Ground. Analog Input Primary current sense. Used for cycle-by-cycle peak current control and limit.
Output Base drive for BJT. Power Input Power supply for control logic and voltage sense for power-on reset circuitry.
Rev. 1.8
iW1690
February 3, 2012
Page 2
Not Recommended For New Designs
iW1690
Low-Power Off-line Digital PWM Controller
5.0 Absolute Maximum Ratings
Absolute maximum ratings are the parameteic values or ranges which can cause permanent damage if exceeded. For maximum safe operating conditions, refer to Electrical Characteristics in Section 6.0.
Parameter
DC supply voltage range (pin 8, ICC = 20mA max) Continuous DC supply current at VCC pin Peak DC supply current at VCC pin Low voltage output (pin 7) VSENSE input (pin 1) VIN input (pin 2) Low voltage analog input (pins 3, 4 and 6)
Power dissipation at TA ≤ 25°C Maximum junction temperature Storage temperature Lead temperature during IR reflow for ≤ 15 seconds Thermal Resistance Junction-to-Ambient ESD rating per JEDEC JESD22-A114 (HBM) Latch-Up test per JEDEC 78
Symbol
VCC ICC
ICCPK
PD TJ MAX TSTG TLEAD
θJA
Value
-0.3 to 18 20 120
-0.3 to 4.0 -0.6 to 4.0 -0.3 to 18.0 -0.3 to 4.0
526 125 –65 to 150 260 160 2,000 ±100
Units
V mA mA V V V V mW °C °C °C °C/W V mA
6.0 Electrical Characteristics
VCC = 12 V, -40°C ≤ TA ≤ 85°C, unless otherwise specified (Note 1)
Parameter
Symbol Test Conditions
VIN SECTION (Pin 2) Start-up voltage low threshold Start-up voltage high threshold Start-up current Shutdown low voltage threshold Shutdown high voltage threshold VSENSE SECTION (Pin 1) Input leakage current Nominal voltage threshold Output OVP threshold
VINST(LO) VINST(HI) IIN(ST) VUVDC VOVDC
TA= 25°C, positive edge TA= 25°C, positive edge VCC = 10 V TA= 25°C, negative edge TA= 25°C, positive edge
IVSENSE VSENSE(NOM) VSENSE(MAX)
VSENSE = 2 V TA=25°C, negative edge TA=25°C, negative edge
Rev. 1.8
iW1690
February 3, 2012
Min
332 1.755
203 1.791
1.522 1.667
Typ
370 1.950
8 225 1.990
1.538 1.700
Max
407 2.145
15 248 2.189
1 1.553 1.734
Unit
mV V µA mV V
μA V V Page 3
Not Recommen.