HFC0511
Fixed-Frequency Flyback Controller with
Ultra-Low, No-Load Power Consumption
DESCRIPTION
FEATURES
The HFC0511 is a fixed-frequency, currentmode
controller
with
internal
slope
compensation
specifically
designed
for
medium-power, offline, flyback, switch-mode
power supplies. The HFC0511 is a highly
efficient green-mode controller. At light loads,
the controller freezes the peak current and
reduces its switching frequency down to 27kHz
to achieve excellent light-load efficiency. At very
light loads, the controller enters burst mode to
achieve very low standby power consumption.
The HFC0511 offers frequency jittering to help
dissipate energy generated by the conducted
noise.
The HFC0511 employs an over-power
compensation function to narrow the difference
of the over-power protection point between the
low line and high line.
The HFC0511 also has an X-cap discharge
function to discharge the X-capacitor when the
input is unplugged. This helps lower the power
at no load.
Full protection features include thermal
shutdown, VCC under-voltage lockout (UVLO),
overload
protection
(OLP),
over-voltage
protection (OVP), and brown-out protection.
The HFC0511 is available in a SOIC8-7A
package.
Fixed-Frequency, Current-Mode Control
with Internal Slope Compensation
Frequency Foldback down to 27kHz at Light
Load
Burst Mode for Low Standby Power
Consumption, Meeting EuP Lot 6
Frequency Jitter to Reduce EMI Signature
X-Cap Discharge Function
Adjustable Over-Power Compensation
Internal High-Voltage Current Source
VCC Under-Voltage Lockout (UVLO) with
Hysteresis
Brown-Out Protection on HV
Overload Protection with Programmable
Delay
Thermal Shutdown (Auto-Restart with
Hysteresis)
Latch-Off for External Over-Voltage
Protection (OVP) and Over-Temperature
Protection (OTP) on TIMER
Latch-Off for VCC Over-Voltage Protection
(OVP)
Short-Circuit Protection (SCP)
Programmable Soft Start (SS)
Available in a SOIC8-7A Package
APPLICATIONS
AC/DC Power for Small and Large
Appliances
AC/DC Adapters for Notebook Computers,
Tablets, and Smart Phones
Offline Battery Chargers
LCD TVs and Monitors
All MPS parts are lead-free, halogen-free, and adhere to the RoHS directive. For
MPS green status, please visit the MPS website under Quality Assurance.
“MPS” and “The Future of Analog IC Technology” are registered trademarks of
Monolithic Power Systems, Inc.
HFC0511 Rev. 1.0
5/3/2017
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1
HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
TYPICAL APPLICATION
T1
Output
*
Input
85~ 265 Vac
*
*
TIMER
FB
CS
GND
1
8
HV
2
VCC
3
6
4
5
DRV
HFC0511
HFC0511 Rev. 1.0
5/3/2017
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HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
ORDERING INFORMATION
Part Number*
HFC0511GS
Package
SOIC8-7A
Top Marking
See Below
* For Tape & Reel, add suffix –Z (e.g. HFC0511GS–Z)
TOP MARKING
HFC0511: First seven digits of the part number
LLLLLLLL: Lot number
MPS: MPS prefix
Y: Year code
WW: Week code
PACKAGE REFERENCE
TOP VIEW
SOIC8-7A
HFC0511 Rev. 1.0
5/3/2017
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HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance (4)
HV ............................................... -0.7V to 700V
VCC, DRV to GND......................... -0.3V to 30V
FB, TIMER, CS to GND ................... -0.3V to 7V
Continuous power dissipation (TA = +25°C) (2)
..................................................................1.3W
Junction temperature ............................... 150°C
Lead temperature .................................... 260°C
Storage temperature ................ -60°C to +150°C
ESD capability human body model (except HV
and DRV) ................................................. 4.0kV
ESD capability human body model (DRV)
................................................................. 3.5kV
ESD capability human body model (HV) ... 1.0kV
ESD capability for machine mode ..............400V
SOIC8-7A.............................. 96 ....... 45 ... °C/W
θJA
θJC
NOTES:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD (MAX) = (TJ
(MAX)-TA)/θJA. Exceeding the maximum allowable power
dissipation produces an excessive die temperature, causing
the regulator to go into thermal shutdown. Internal thermal
shutdown circuitry protects the device from permanent
damage.
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7, 4-layer PCB.
Recommended Operation Conditions (3)
Operating junction temp. (TJ) ... -40°C to +125°C
Operating VCC range ........................ 9V to 24V
HFC0511 Rev. 1.0
5/3/2017
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HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
ELECTRICAL CHARACTERICS
VCC = 18V, TJ = -40°C ~ 125°C, min and max values are guaranteed by characterization, typical
value is tested under 25°C, unless otherwise specified.
Parameter
Start-Up Current Source (HV)
Supply current from HV
Symbol
IHV_400
IHV_120
ILK_400
Leakage current from HV
ILK_200
Break-down voltage
VBR
Conditions
Min
Typ
Max
Unit
VCC = 12V, VHV = 400V
VCC = 12V, VHV = 120V
VCC increases to 18V,
then decreases to 14V,
VHV = 400V
VCC increases to 18V,
then decreases to 14V,
VHV = 200V
TJ = 25°C
1.5
1.5
2.8
2.7
3.9
3.7
mA
1
16
28
μA
1
13
25
μA
700
790
12.5
15.5
18
V
10.5
12
13
V
1.35
3.5
7.3
8.5
5
7
4.9
5.5
Supply Voltage Management (VCC)
VCC increasing level at which the
VCCOFF
current source turns off
VCC decreasing level above which
VCCSS
soft start takes place if HV > HVON
VCC hysteresis for brown-in
VCCOFF detection
VCCSS
VCC decreasing level at which the
VCCON
current source turns on
VCCOFF VCC UVLO hysteresis
VCCON
VCC recharge level when
VCCPRO
protection takes place
VCC decreasing level at which the
VCCLATCH
latch-off phase ends
Internal IC consumption
Internal IC consumption, latch-off
phase
Voltage on the VCC above which
the controller latches off (OVP)
Blanking duration on the OVP
comparator
Brown-Out
HV turn-on threshold voltage
HV turn-off threshold voltage
Brown-out hysteresis
Timer duration for line cycle
dropout
Oscillator
Oscillator frequency
Frequency jittering amplitude,
in percentage of fOSC
Frequency jittering entry level
Frequency jittering modulation
period
HFC0511 Rev. 1.0
5/3/2017
ICC
ICCLATCH
V
9.6
VFB = 2V, CL = 1nF,
VCC = 12V
VCC = VCCOFF - 1V,
TJ = 25°C
V
V
6.2
2.5
VOVP
V
V
0.9
1.8
2.7
mA
520
700
880
μA
24
26.5
28.5
V
TOVP
HVON
V
μs
60
HV
VHV going up, TJ = 25°C
VHV going down,
TJ = 25°C
TJ = 25°C
THV
CTIMER = 47nF
40
fOSC
VFB > 1.85V, TJ = 25°C
125
130
135
kHz
Ajitter
VFB > 1.85V, TJ = 25°C
5
6.5
8.3
%
1.95
V
HVOFF
95
107
119
V
86
97
110
V
6.5
10
13.5
V
ms
VFB_JITTER
Tjitter
CTIMER = 47nF
3.7
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5
HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
ELECTRICAL CHARACTERICS (continued)
VCC = 18V, TJ = -40°C ~ 125°C, min and max values are guaranteed by characterization, typical
value is tested under 25°C, unless otherwise specified.
Parameter
Symbol
Current Sense
Current-limit point
Short-circuit protection point
Current limitation when frequency
folds back
Current limitation when entering
burst
Current limitation when leaving
burst
Leading edge blanking for VILIM
Leading edge blanking for VSCP
Slope of the compensation ramp
Feedback (FB)
Internal pull-up resistor
Internal pull-up voltage
VFB to internal current set point
division ratio
VFB to internal current set point
division ratio
FB decreasing level at which the
controller enters burst mode
FB increasing level at which the
controller leaves burst mode
Overload Protection (OLP)
FB level at which the controller
enters the OLP after a dedicated
time
Time duration before OLP when
FB reaches protection point
Over-Power Compensation
VHV to IOPC ratio
Current out of CS
FB voltage below which
compensation is removed
FB voltage above which
compensation is applied fully
Frequency Foldback
FB voltage threshold below which
frequency foldback starts
Minimum switching frequency
FB voltage threshold below which
frequency foldback ends
HFC0511 Rev. 1.0
5/3/2017
Conditions
VILIM
VSCP
Min
Typ
Max
Unit
0.93
1.3
1
1.47
1.07
1.63
V
V
0.63
0.68
0.73
V
VFOLD
VFB = 1.85V
VIBURL
VFB = 0.7V
0.11
V
VIBURH
VFB = 0.8V
0.15
V
350
270
25
ns
ns
mV/μs
TLEB1
TLEB2
SRAMP
18
RFB
VDD
32
11.5
14
4.3
17
kΩ
V
KFB1
VFB = 2V
2.55
2.8
3.05
--
KFB2
VFB = 3V
2.8
3.1
3.4
--
VBURL
0.63
0.7
0.77
V
VBURH
0.72
0.8
0.88
V
VOLP
TOLP
3.7
CTIMER = 47nF
40
KOPC
IOPC
VHV = 120V, VFB = 2.5V
VHV = 155V, VFB = 2.5V
VHV = 310V, VFB = 2.5V
VHV = 380V, VFB = 2.5V,
TJ = 25°C
VOPC(OFF)
ms
80
109
138
0.55
V
2.2
VFB(FOLD)
VFB(FOLDE)
μA/V
μA
0.45
0
13
85
VOPC(ON)
FOSC(min)
V
1.8
TJ = 25°C
21
27
1.0
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V
V
33
kHz
V
6
HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
ELECTRICAL CHARACTERICS (continued)
VCC = 18V, TJ = -40°C ~ 125°C, min and max values are guaranteed by characterization, typical
value is tested under 25°C, unless otherwise specified.
Parameter
Symbol
Latch-Off Input (Integration in TIMER)
Threshold below which controller
VTIMER(LATCH)
is latched
Blanking duration on latch
TLATCH
detection
DRV Voltage
Driver voltage high level
VHigh
Driver voltage clamp level
VClamp
Driver voltage low level
VLow
Driver voltage rise time
TR
Driver voltage fall time
TF
Driver pull-up resistance
RPull-up
Driver pull-down resistance
RPull-down
Thermal Shutdown
Thermal shutdown threshold (5)
Thermal shutdown hysteresis (5)
Conditions
CL = 1nF, VCC = 12V
CL = 1nF, VCC = 24V
CL = 1nF, VCC = 24V
CL = 1nF, VCC = 16V
CL = 1nF, VCC = 16V
CL = 1nF, VCC = 16V
CL = 1nF, VCC = 16V
Min
Typ
Max
Unit
0.7
1
1.3
V
12
μs
10.3
13.4
16
13
23
8
10
V
V
mV
ns
ns
Ω
Ω
150
25
°C
°C
NOTE:
5) This parameter is guaranteed by design.
HFC0511 Rev. 1.0
5/3/2017
www.MonolithicPower.com
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HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
PIN FUNCTIONS
Pin #
Name
1
TIMER
2
FB
3
CS
4
5
6
8
GND
DRV
VCC
HV
HFC0511 Rev. 1.0
5/3/2017
Description
Timer. TIMER combines soft start, frequency jittering, and timer functions for overload
protection (OLP), brown-out protection, and X-cap discharging. The HFC0511 can be
latched off by pulling TIMER low.
Feedback. Use a pull-down optocoupler to control the output regulation.
Current sense. CS senses the primary-side current for current-mode operation and
provides a mean for over-power compensation adjustment.
IC ground.
Drive signal output.
Power supply.
High-voltage current source. HV includes brown-out and X-cap discharge functions.
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HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
TYPICAL CHARACTERISTICS
HFC0511 Rev. 1.0
5/3/2017
www.MonolithicPower.com
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HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
TYPICAL CHARACTERISTICS (continued)
HFC0511 Rev. 1.0
5/3/2017
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HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
TYPICAL CHARACTERISTICS (continued)
HFC0511 Rev. 1.0
5/3/2017
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HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
TYPICAL PERFORMANCE CHARACTERISICS
VIN = 230VAC, VOUT = 19V, IOUT = 2.35A, unless otherwise noted.
HFC0511 Rev. 1.0
5/3/2017
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HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
TYPICAL PERFORMANCE CHARACTERISICS (continued)
VIN = 230VAC, VOUT = 19V, IOUT = 2.35A, TA = 25°C, unless otherwise noted.
HFC0511 Rev. 1.0
5/3/2017
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HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
BLOCK DIAGRAM
Vcc
Power
Management
Start-Up Unit
HV
Brown-Out
Detection
X-Cap Discharge
Function
HV Sample
OVP
Fault
Management
Timer
OLP
Driving Signal
Management
DRV
Frequency
Foldback
Burst Mode
Control
FB
Peak Current
Compression
Comparator
Slope
Compensation
Over-Power
Compensation
GND
CS
Figure 1: Functional Block Diagram
HFC0511 Rev. 1.0
5/3/2017
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HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
OPERATION
The HFC0511 incorporates all necessary
features for building a reliable switch-mode
power supply. The HFC0511 is a fixedfrequency, current-mode controller with internal
slope compensation. At light loads, the
controller freezes the peak current and reduces
its switching frequency down to 27kHz to
minimize switching losses. When the output
power falls below a given level, the controller
enters burst mode. The HFC0511 also has
excellent EMI performance due to frequency
jittering. The HFC0511’s high level of
integration requires very few external
components.
Fixed Frequency with Jitter
Frequency jitter reduces EMI by spreading the
energy over the jitter frequency range. Figure 2
shows the circuit of the frequency jittering.
FB
VDD
14pF
Figure 3: Frequency Jitter
Frequency Foldback
The HFC0511 implements frequency foldback
at light load to improve overall efficiency.
When the load decreases to a given level (1.0V
< VFB < 1.8V), the controller freezes the peak
current (as measured on CS, typically 0.7V)
while reducing its switching frequency to 27kHz.
This reduces switching loss. If the load
continues to decrease, the peak current
decreases with 27kHz of fixed frequency to
avoid audible noise. Figure 4 shows the
frequency vs. VFB and peak current (VCS) vs.
VFB.
Frequency
10uA
130kHz
1V
Timer
3.2V
20uA
S
2.8V
R
Q
Burst
27kHz
_
Q
Frequency
foldback
A controlled current sourced (fixed at 2.72µA
when VFB = 2V) charges the internal COSC
capacitor. Comparing the capacitor voltage to
the TIMER voltage determines the switching
frequency. Frequency jitter is accomplished by
varying VTIMER between 3.2V and 2.8V (see
Figure 3). Determine Tjitter with Equation (1):
CTIMER (3.2V 2.8V)
10A
0.7V
Fault
1.0V
1.8V
3V
FB
Figure 4: Frequency and Peak Current (VCS) vs.
VFB
Figure 2: Frequency Jitter Circuit
Tjitter 2
Fixed
frequency
Fixed
frequency
0.7/0.8V
HFC0511 Rev. 1.0
5/3/2017
Peak
Current
Frequency
Jittering
(1)
Current-Mode
Operation
with
Slope
Compensation
The feedback voltage (VFB) controls the primary
peak current. When the peak current reaches
the level determined by VFB, DRV turns off. The
controller can also be used in continuous
conduction mode (CCM) with a wide input
voltage range because of its internal slope
compensation (typically 25mV/µs), avoiding
sub-harmonic oscillations above a 50% duty
cycle.
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15
HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
High Voltage Start-Up Current Source with
Brown-Out Detection
At start-up, the internal high-voltage current
1.75V
source from HV supplies the IC. The IC turns
off the current source once VCC reaches
VCCOFF (typically 15.5V) and detects the
voltage on HV. Once the HV voltage exceeds
HVON before VCC drops down to VCCSS
(typically 12V), the controller begins switching.
If the HV voltage does not exceed VHON, the
system treats this as a brown-out and latches
DRV low. When VCC drops to VCCPRO
(typically 5.5V), the high-voltage current source
turns on to recharge VCC. The auxiliary
transformer winding supplies the IC after the
controller starts switching. If VCC falls below
VCCON (typically 8.5V), the switching pulse
stops, and the current source turns on again.
Figure 5 shows the typical VCC under-voltage
lockout (UVLO) waveform.
1V
The auxiliary winding takes over
VCCOFF
VCCSS
VCCON
VCCPRO
ON
ITIMER=10/4 A
TIMER
ITIMER=10A
Current
limit
1V
Ipri
0.25V
Soft start duration
Figure 6: Soft Start
Burst Mode
To minimize power dissipation in no load or
light load, the HFC0511 employs burst-mode
operation. As the load decreases, VFB
decreases. The IC enters burst mode when VFB
drops below the lower threshold (VBURL, typically
0.7V), stopping output switching. Then the
output voltage starts to drop, which causes VFB
to increase again. Once VFB exceeds VBURH
(typically 0.8V), switching resumes. Burst mode
enables and disables MOSFET switching
alternately, thereby reducing no-load or lightload switching losses.
OFF
HVON
Figure 5: VCC Under-Voltage Lockout
The VCC lower threshold UVLO drops from
VCCON to VCCPRO under fault conditions such
as overload protection (OLP), short-circuit
protection (SCP), brown-out, and overtemperature protection (OTP).
Soft Start (SS)
Soft start is externally programmable with a
capacitor on TIMER. As this capacitor charges
from 1V to 1.75V with 1/4 of the normal charge
current, the peak-current limit threshold
increases gradually from 0.25V to 1V while
increasing the switching frequency gradually.
Figure 6 shows the typical soft-start waveform.
The TIMER capacitor determines the start-up
duration as shown in Equation (2):
TSoft start
HFC0511 Rev. 1.0
5/3/2017
CTIMER (1.75V 1V)
10 / 4A
Adjustable Over-Power Compensation
An offset current proportional to the input
voltage is added to the current sense voltage.
By choosing the value of the resistor to be in
series with CS, the amount of compensation
can be adjusted to the application for a more
accurate output power limit at the total input
range. Figure 7 and Figure 8 show the
compensation current relation to FB and the
peak voltage on HV respectively.
IOPC
VHV
VOPC(OFF)
VOPC(ON)
FB
Figure 7: Compensation Current vs. FB and HV
Voltage
(2)
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HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
Short-Circuit Protection (SCP)
The HFC0511 employs short-circuit protection
(SCP) if VCS reaches VSCP (typically 1.47V) after
a reduced leading-edge blanking time (TLEB2).
Once the fault disappears, the power supply
resumes operation.
IOPC
IOPC(380)
IOPC(310)
IOPC(155)
IOPC(120)
120V 155V
310V 380V
VHV
Figure 8: Compensation Current vs. Peak of
Rectified Input Line AC Voltage
Timer-Based Overload Protection (OLP)
In a flyback converter, if the switching
frequency is fixed, the maximum output power
is limited by the peak current. The output
voltage drops below the set value when the
output power exceeds the power limit. This
reduces the current through the optocoupler,
pulling VFB high.
When FB is higher than the OLP voltage (VOLP)
(typically 3.7V), which is considered to be an
error flag, the timer begins counting. If the error
flag is removed during the count, the timer
resets. If the timer count reaches 17, OLP is
triggered. This timer duration avoids triggering
OLP during power supply start-up or short load
transients. Figure 9 shows the OLP function.
Figure 9: Overload Protection
Timer-Based Brown-Out Protection
The brown-out protection block is similar to the
OLP block. When the HV voltage drops below
HVOFF (typically 97V), which is considered to be
an error flag, the timer begins counting. Once
the HV voltage is higher than HVOFF, the timer
resets. When the timer counts to 17, brown-out
protection is triggered and switching stops.
HFC0511 Rev. 1.0
5/3/2017
Thermal Shutdown
To prevent thermal damage, the HFC0511
stops switching when the temperature exceeds
150°C. Once the temperature drops below
125°C, the power supply resumes operation.
During thermal shutdown, the VCC UVLO lower
threshold drops from 8.5V to 5.5V.
VCC Over-Voltage Protection (OVP)
The HFC0511 enters a latched fault condition if
VCC rises above VOVP (typically 26.5V) for 60µs.
The controller remains fully latched until VCC
drops below VCCLATCH (typically 2.5V), such as
when the power supply is unplugged from the
main input and is plugged in again. This
situation usually occurs when the optocoupler
fails, which results in the loss of output voltage
regulation.
TIMER Latch-Off for OVP and OTP
Pulling TIMER below VTIMER(LATCH) (typically 1V)
for 12µs can latch off the IC. This function can
be used for external over-voltage protection
(OVP) and OTP.
X-Cap Discharge Function
X-capacitors are typically positioned across a
power supply’s input terminals to filter
differential mode EMI noise. These components
pose a potential hazard since they can store
unsafe levels of voltage energy after the AC line
is disconnected. Generally, resistors in parallel
with the X-caps provide a discharge path to
meet safety standards, but these discharge
resistors produce a constant loss while the AC
is connected and contribute to no-load and
standby input power consumption.
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17
HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
HV acts as a smart X-cap discharger. When AC
voltage is applied, the internal high-voltage
current source turns off to block HV current,
and the IC monitors the HV voltage. When
removing the AC voltage, the IC turns on the
high-voltage current source after about 32
TIMER cycles to discharge the X-cap energy.
The first discharge duration is 16 cycles. After
the first discharge, the IC turns off the current
source for 16 cycles to detect whether the input
is plugged into the AC line again. If the AC input
remains disconnected, the IC turns on the
current source for 48 cycles to discharge again,
and then turn off for 16 cycles to detect
repeatedly until the voltage on the X-cap drops
to VCC. Once the reconnected AC input is
detected, the high-voltage current source
remains off until VCC drops to VCCPRO (5.3V),
and then restarts the system by recharging
VCC. Figure 10 shows the discharge function
waveforms.
Discharge
Vpeak
Rectified
Line voltage
Clamped Driver
DRV is clamped at VClamp (typically 13.4V) when
VCC exceeds 16V, allowing for the use of any
standard MOSFET.
Leading-Edge Blanking
An internal leading-edge blanking (LEB) unit
containing two LEB times is employed between
the CS and the current comparator input to
prevent premature switching pulse termination
due to parasitic capacitances (see Figure 11).
During the blanking time, the current
comparator is disabled and cannot turn off the
external MOSFET.
VLimit
TLEB1=350ns
TLEB2=270ns for SCP
Detect whether input
re-plug to AC line
t
37%Vpeak
Figure 11: Leading-Edge Blanking
Driving
Signal
16V
VCC
ON
Internal
Current
Source
OFF
32 TIMER 16 TIMER
Cycles
Cycles
48 TIMER 16 TIMER
Cycles
Cycles
Total discharge time
Figure 10: X-Cap Discharger
This approach provides an intelligent discharge
path for the X-cap, eliminating power loss from
the external discharge resistors.
HFC0511 Rev. 1.0
5/3/2017
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18
HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
APPLICATION INFORMATION
VCC Capacitor Selection
Figure 12 shows the start-up circuit. The values
of R1 and C1 determine the system start-up
delay time. A larger R1 or C1 increases the
start-up delay.
A larger inductor leads to a smaller KP, which
can reduce RMS current, but increases
transformer size. An optimal KP value is
between 0.6 and 0.8 for the universal input
range and 0.8 to 1 for a 230VAC input range.
KP=Iripple/Ipeak
Iripple
Ipeak
Input
85~265Vac
Iav
D1
D2
R1
TIMER
FB
CS
GND
1
Figure 13: Typical Primary-Current Waveform
8
HV
The input power (Pin) at the minimum input can
be estimated with Equation (4):
2
HFC0511
3
6
4
5
VCC
Pin
C1
Figure 12: Start-Up Circuit
The VCC duration (from VCCOFF to VCCSS) for
brown-out detection should exceed half of the
input period. Estimate a value for the VCC
capacitor with Equation (3):
CVCC
ICC(noswitch) 0.5 Tinput
VCCOFF VCCSS
(3)
Where ICC(noswitch) is the internal consumption
(close to ICClatch), and Tinput is the period of the
AC input. For most applications, choose a VCC
capacitor value that exceeds 10µF.
A higher R1 value decreases the current of the
internal high-voltage current source, especially
at a low-input condition. Ensure that the
practical supply current from HV is not smaller
than the corresponding internal IC consumption
current, which is the same as ICCLATCH. For the
universal input range, R1 should be smaller
than 80kΩ. 20kΩ is generally recommended.
Primary-Side Inductor Design (Lm)
With internal slope compensation, the HFC0511
can support CCM when the duty cycle exceeds
50%. Set a ratio (KP) of the primary inductor’s
ripple current amplitude vs. the peak current
value to 0 < KP 1, where KP = 1 for
discontinuous conduction mode (DCM). Figure
13 shows the relevant waveforms.
HFC0511 Rev. 1.0
5/3/2017
VO IO
(4)
Where VO is the output voltage, IO is the rated
output current, and is the estimated efficiency,
which is generally between 0.75 and 0.85
depending on the input range and output
application.
For CCM at minimum input, the converter duty
cycle can be calculated with Equation (5):
D
(VO VF ) N
(VO VF ) N Vin(min)
(5)
Where VF is the secondary diode’s forward
voltage, N is the transformer turn ratio, and
Vin(min) is the minimum voltage on the bulk
capacitor.
The MOSFET turn-on time can be calculated
with Equation (6):
Ton D Ts
(6)
Where Ts is the switching period.
The average value of the primary current is
calculated with Equation (7):
Iav
Pin
Vin(min)
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(7)
19
HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
The peak value of the primary current is
calculated with Equation (8):
Ipeak
Iav
Kp
1
D
2
(8)
The ripple value of the primary current is
calculated with Equation (9):
Iripple KP Ipeak
(9)
The valley value of the primary current is
calculated with Equation (10):
Ivalley (1 KP ) Ipeak
Vin(min) Ton
(11)
Iripples
Q
S
-
FB
R
+
CS
(12)
Then calculate the value of the sense resistor
with Equation (13):
Rsense
Current-Sense Resistor
Figure 14 shows the peak-current comparator
logic and the subsequent waveform.
DRV
Vsense 95% Vlimit Vslope Ton
(10)
Lm can be estimated with Equation (11):
Lm
When the sum of the sensing resistor voltage
and the slope compensator reaches Vpeak, the
comparator goes high to reset the RS flip-flop,
and DRV is pulled down to turn off the
MOSFET. The maximum current limit (Vlimit, as
measured by VCS) is 0.95V. The slope
compensator (Vslope) is ~25mV/µs. Given a
certain margin, use 0.95xVlimit as Vpeak at full
load. Then the voltage on the sensing resistor
can be obtained with Equation (12):
Vsense
Ipeak
(13)
Select the current sense resistor with an
appropriate power rating. Then calculate the
sense resistor power loss with Equation (14):
I
I
2
1
Psense peak valley Ipeak Ivalley D Rsense (14)
2
12
2
Low-Pass Filter on CS
A small capacitor connected to the CS with
Rseries forms a low-pass filter for noise filtering
when the MOSFET turns on and off (see Figure
15).
Vlimit
LEB
Slope
compensation
Peak-Current Comparator Circuit
Vpeak
Vslope*Ton
Ipeak*Rsense
Figure 15: Low-Pass Filter on CS
ton
Typical Waveform
Figure 14: Peak-Current Comparator
HFC0511 Rev. 1.0
5/3/2017
The low-pass filter’s RxC constant should not
exceed 1/3 of the leading-edge blanking period
for SCP (TLEB2, typically 270ns), otherwise the
filtered sensed voltage cannot reach the SCP
point (1.45V) to trigger SCP if an output short
circuit occurs.
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20
HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
Over-Power Compensation (OPC)
The
HFC0511
uses
an
over-power
compensation function (OPC) by drawing
current from CS. OPC minimizes the OLP
difference caused by a different input voltage.
The offset current is proportional to the input
peak voltage sensed by HV.
Supposing that the resistor in the current
sensing loop is Rseries, and the input voltage is
220VAC, calculate the compensation voltage on
CS with Equation (15):
Vcomp Rseries Iopc _ 310V
(15)
The compensation criterion is making the FB
voltage under full-load condition similar whether
in high line or low line.
Jitter Period
Frequency jitter is an effective method to
reduce EMI by dissipating energy. The nth order
harmonic noise bandwidth is calculated with
Equation (16):
BTn n (2 f fjitter )
X-Cap Discharge Time
Figure 10 shows the X-cap discharger
waveforms. The maximum discharge time
occurs at a high-line input with no-load
condition. The maximum discharge delay time
is calculated with Equation (17):
Tdelay 32 Tjitter
If BTn exceeds the resolution bandwidth (RBW)
of the spectrum analyzer (200Hz for noise
frequency less than 150kHz, 9kHz for noise
frequency between 150kHz to 30MHz), the
spectrum analyzer receives less noise energy.
The capacitor on TIMER determines the period
of the frequency jitter. A 10µA current source
charges the capacitor. When the TIMER
voltage reaches 3.2V, another 10µA current
source discharges the capacitor to 2.8V. This
charging and discharging cycle repeats.
Equation (2) describes the jitter period in theory.
A smaller fjitter is more effective for EMI
reduction.
However,
the
measurement
bandwidth requires that fjitter be large compared
to the spectrum analyzer RBW for effective EMI
reduction. fjitter should also be less than the
control-loop-gain crossover frequency to avoid
disturbing the output voltage regulation.
Simultaneously
consider
the
practical
application when selecting the TIMER capacitor.
A capacitor that is too large may cause the
start-up to fail at full load because of the long
soft start-up duration shown in Equation (3).
(17)
The X-cap is discharged from a high-voltage
constant current source (IHV_120V, typically
2.5mA) into HV. The current-source discharge
time for the X-cap to drop to 37% of the peak
voltage can be estimated with Equation (18):
Tdischarge
(16)
Where f is the frequency jitter amplitude.
HFC0511 Rev. 1.0
5/3/2017
However, a TIMER capacitor that is too small
causes the TIMER period to become smaller,
so the TIMER count capability is overloaded,
and some logic problems may occur. For most
applications, a fjitter value between 200Hz and
400Hz is recommended.
CX 63% 2 Vac(max)
IHV _120V
(18)
Where CX is the X-cap capacitance, and VAC(max)
is the maximum AC input RMS value.
The first discharging period is 16xTjitter, with a
subsequent period equal to 48xTjitter. Then the
discharge sections times can be calculated
approximately with Equation (19):
n
Tdischarge 16 Tjitter
48 Tjitter
1
(19)
For every discharge section, there is a certain
period (16xTjitter) for detection as shown in
Equation (20):
Tdetect 16 Tjitter （
n 1）
(20)
As a result, the total discharge time is
determined with Equation (21):
Ttotal Tdelay Tdischarge Tdetect
(21)
The total discharge time is relative to Tjitter,
which is dependent on CTIMER. For example, if
CTIMER is 47nF, and Tjitter is 3.7ms, the X-cap
discharge margin is 1s due to the X-cap value
tolerance (10% typically). It is recommended
to select an X-cap less than 3.3μF.
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21
HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
Though the X-cap has been discharged, it may
still retain a high voltage on the bulk capacitor.
For safety, make sure it is released before
debugging the board.
Dmax Vin(min)
Rsense - ma
(1- Dmax ) Lm
=
Vin(min)
Rsense +ma
Lm
Output
Loop
Auxiliary
winding
Loop
Ramp Compensation
When
adopting
peak
current
control,
subharmonic oscillation occurs when D > 0.5 in
CCM. The HFC0511 is equipped with internal
ramp compensation to solve this problem. α is
calculated with Equation (22):
Input Loop
Top
(22)
Where ma = 18mV/µs is the minimum internal
slope value of the compensation ramp,
Vin(min)
Rsense is the slew rate of the primary-side
Lm
sensed
by
the
CS
resistor,
and
Dmax Vin(min)
Rsense is the slew rate of the
(1 Dmax ) Lm
equivalent secondary-side voltage sensed by
the CS resistor respectively. For stable
operation, α must be less than 1.
PCB Layout Guidelines
Efficient PCB layout is critical for stable
operation, good EMI performance, and good
thermal performance. For best results, refer to
Figure 16 and follow the guidelines below.
1) Minimize the power stage loop area
including the input loop (C1 - T1 - Q1 R11/R12/R13 - C1), the auxiliary winding
loop (T1 - D4 - R4 - C3 - T1), and the output
loop (T1 - D6 - C10 - T1).
Bottom
Figure 16: Recommended Layout
Design Example
Table 1 is a design example of the HFC0511 for
power adapter applications.
Table 1: Design Example
VIN
VOUT
IOUT
85 to 265VAC
19V
2.35A
2) Keep the input loop GND and control circuit
separate.
Only connect them at C1.
3) Connect the Q1 heat sink to the primary
GND plane to improve EMI.
4) Place the control circuit capacitors (such as
those for FB, CS, and VCC) close to the IC
to decouple noise.
HFC0511 Rev. 1.0
5/3/2017
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22
HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
TYPICAL APPLICATION CIRCUIT
CY1 2.2nF
R1
R2
150kΩ 150kΩ
F1 250V/2A
1206
C2
2.2nF/630V
1206 1206
R14 51Ω
C9
R15 51Ω
1nF
T1
1
Vout
P
L
LX1
CX1
85~265VAC
0.22µF
N
1206
R4
0Ω
C3 47µF/25V
VCC
C4 0.1µF
1 TIMER
D5
Q2
S8050
C5
0.1µF
2
FB
C6
47nF
C7
470pF
CS
C7
15pF
3
4
GND
R19
10
5
R16
1kΩ
RM8
Lp=660µH
Np:Ns:Np_aux=60:7:11
FB
HV
19V/2.35A
4
U1
BZT52C16
C11
4.7µF
Np_aux
R5 20kΩ/1206
R7
1kΩ
680µF/25V
Ω
1%
D2
SRGC10MH
VCC
C10
D6 150V/20A
MBR20150FCT
N
2
SRGC10MH
D3
SRGC10MH
D1
SRGC10MH
Ns
D4
R3
0Ω
C1
100µF/400V
30mH/1.5A
150µH/1.5A
Np
BD1
DF06S
600V/1A
LX2
U2
PC817B
8
R20
66.5kΩ
1%
R17
1kΩ
FB
HFC0511
CS
GND
VCC
DRV
6
5
R8 20Ω
R18
Q1
SMK0870F
R9
20K
33kΩ
700V/8A
C12
100nF
U3
CJ431
R21
10kΩ
CS
R10
2.2kΩ
1%
R11
1.1Ω
1206
1%
R12
1.1Ω
1206
1%
R13
5.1Ω
1%
1206
1%
Figure 17: Typical Application
HFC0511 Rev. 1.0
5/3/2017
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23
HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
FLOW CHART
Figure 18: Control Flow Chart
HFC0511 Rev. 1.0
5/3/2017
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24
HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
EVOLUTION OF THE SIGNALS IN PRESENCE OF FAULTS
Figure 19: Signal Evolution in the Presence of Faults
HFC0511 Rev. 1.0
5/3/2017
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25
HFC0511 – FIXED-FREQUENCY FLYBACK CONTROLLER W/ ULTRA-LOW NO LOAD POWER CONSUMPTION
PACKAGE INFORMATION
PACKAGE OUTLINE DRAWING FOR SOIC 8-7-2
MF-PO-D-0126,
revision 0.0
SOIC8-7A
0.189(4.80)
0.197(5.00)
8
0.050(1.27)
0.024(0.61)
5
0.063(1.60)
0.150(3.80)
0.157(4.00)
PIN 1 ID
1
0.228(5.80)
0.244(6.20)
0.213(5.40)
4
TOP VIEW
RECOMMENDED LAND PATTERN
0.053(1.35)
0.069(1.75)
SEATING PLANE
0.004(0.10)
0.010(0.25)
0.013(0.33)
0.020(0.51)
0.050(1.27)
BSC
0.0075(0.19)
0.0098(0.25)
SEE DETAIL "A"
SIDE VIEW
FRONT VIEW
0.010(0.25)
x 45o
0.020(0.50)
GAUGE PLANE
0.010(0.25) BSC
0o-8o
0.016(0.41)
0.050(1.27)
DETAIL "A"
NOTE:
1) CONTROL DIMENSION IS IN INCHES. DIMENSION IN
BRACKET IS IN MILLIMETERS.
2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH
,
PROTRUSIONS OR GATE BURRS.
3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH
OR PROTRUSIONS.
4) LEAD COPLANARITY(BOTTOM OF LEADS AFTER FORMING)
SHALL BE 0.004" INCHES MAX.
5) JEDEC REFERENCE IS MS-012.
6) DRAWING IS NOT TO SCALE.
NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications.
Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS
products into any application. MPS will not assume any legal responsibility for any said applications.
HFC0511 Rev. 1.0
5/3/2017
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