AMS AMS2263 Extended burst mode control for improved Datasheet

AMS 2263
Excellent EMI performance is achieved with
GENERAL DESCRIPTION
frequency shuffling technique together with soft
AMS2263 is a highly integrated current mode PWM
switching control at the totem pole gate drive
control IC optimized for high performance, low
output.
standby power and cost effective offline flyback
Tone energy at below 20KHZ is minimized in the
converter applications in sub 30W range.
design and audio noise is eliminated during
PWM switching frequency at normal operation is
operation. AMS2263 is offered in SOT23-6, SOP-8
externally programmable and trimmed to tight
and DIP-8 packages.
range. At no load or light load condition, the IC
operates in extended ‘burst mode’ to minimize
FEATURES
switching loss. Lower standby power and higher
‹
conversion efficiency is thus achieved.
Efficiency and Minimum Standby Power
Design.
VDD low startup current and low operating
current contribute to a reliable power on startup
design with AMS2263. A large value resistor could
‹
Audio Noise Free Operation
‹
External Programmable
standby power.
internal
slope
compensation
‹
Internal Synchronized Slope Compensation
‹
Low VDD Startup Current and Low Operating
improves
Current (1.4mA)
system large signal stability and reduces the
‹
possible sub-harmonic oscillation at high PWM
Leading Edge Blanking on Current Sense
Input
duty cycle output. Leading-edge blanking on
‹
current sense(CS) input removes the signal glitch
Good
Protection
Coverage
With
Auto
Self-Recovery
due to snubber circuit diode reverse recovery and
‹
thus greatly reduces the external component
VDD Over Voltage Clamp and Under Voltage
Lockout with Hysteresis (UVLO)
count and system cost in the design.
AMS2263 offers complete protection coverage with
‹
Gate Output Maximum Voltage Clamp (18V)
‹
Line Input Compensated Cycle-by-Cycle
including
Over-current Threshold Setting For Constant
Cycle-by-Cycle current limiting (OCP), over load
Output Power Limiting Over Universal Input
protection (OLP), VDD over voltage clamp and
Voltage Range.
automatic
self-recovery
feature
PWM Switching
Frequency
thus be used in the startup circuit to minimize the
The
Extended Burst Mode Control For Improved
under voltage lockout (UVLO).
‹
The Gate-drive
Overload Protection (OLP)
output is clamped to maximum 18V to protect the
power MOSFET.
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AMS 2263
APPLICATIONS
Offline AC/DC flyback converter for
„
Battery Charger
„
Power Adaptor
„
Set-Top Box Power Supplies
„
Open-frame SMPS
BLOCK DIAGRAM
TYPICAL APPLICATION
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AMS 2263
GENERAL INFORMATION
Pin Configuration
Package Dissipation Rating
The AMS2263 is offered in SOT23-6, DIP8
and SOP8 packages, shown as below.
Package
RθJA (°C/W)
DIP8
90
SOP8
150
SOT23-6
200
Absolute Maximum Ratings
Parameter
Value
VDD DC Supply Voltage
30 V
VDD Zener Clamp
VDD_Clamp+0.1V
VoltageNote
VDD DC Clamp Current
10 mA
VFB Input Voltage
-0.3 to 7V
VSENSE Input Voltage to
-0.3 to 7V
Sense Pin
VRI Input Voltage to RI Pin
-0.3 to 7V
Min/Max Operating
-20 to 150 oC
Junction Temperature TJ
-55 to 160 oC
Min/Max Storage
Temperature Tstg
Note: VDD_Clamp has a nominal value of 34V.
Stresses beyond those listed under “absolute
maximum ratings” may cause permanent damage
to the device. These are stress ratings only,
Ordering Information
Part Number
functional operation
Description
of the device at these or
any other conditions beyond those
indicated
AMS2263MP
SOT23-6,Pb-free
under “recommended operating conditions” is not
AMS2263AP
DIP8, Pb-free
implied. Exposure to absolute maximum-rated
AMS2263CP
SOP8, Pb-free
conditions for extended periods may affect device
reliability.
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AMS 2263
TERMINAL ASSIGNMENTS
Pin Name
I/O
Description
GND
P
Ground
FB
I
Feedback input pin. The PWM duty cycle is determined by voltage level into this pin
and SENSE pin input.
RI
I
Internal Oscillator frequency setting pin. A resistor connected between RI and GND
sets the PWM frequency.
SENSE
I
Current sense input pin. Connected to MOSFET current sensing resistor node.
VDD
P
Chip DC power supply pin.
GATE
O
Totem-pole gate drive output for the power MOSFET.
RECOMMENDED OPERATING CONDITION
Symbol
Parameter
Min
Unit
- Max
VDD
VDD Supply Voltage
10 to 30
V
RI
RI Resistor Value
100
Kohm
TA
Operating Ambient Temperature
-20 to 85
o
C
ELECTRICAL CHARACTERISTICS
(TA = 25OC if not otherwise noted)
Symbol
Parameter
Test Conditions
Min
Typ
Max
3
20
Unit
Supply Voltage (VDD)
I_VDD_Startup
VDD Start up
VDD =12.5V, RI=100K
Current
Measure Leakage
uA
current into VDD
I_VDD_Ops
Operation Current
1.4
VDD=16V,
mA
RI=100Kohm, VFB=3V
UVLO(ON)
VDD Under Voltage Lockout Enter
7.5
8.5
9.5
V
UVLO(OFF)
VDD Under Voltage Lockout Exit
13.5
14.5
15.5
V
(Recovery)
VDD_Clamp
VDD Zener Clamp Voltage
IVDD = 5 mA
34
V
ΔVFB /ΔVcs
2.0
V/V
4.8
V
1
mA
Feedback Input Section(FB Pin)
AVCS
PWM Input Gain
VFB_Open
VFB Open Loop Voltage
IFB_Short
FB pin short circuit current
Short FB pin to GND
and measure current
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AMS 2263
VTH_0D
VTH_PL
Zero Duty Cycle FB Threshold
VDD = 16V,
Voltage
RI=100Kohm
Power Limiting
0.75
V
FB Threshold
3.7
V
TD_PL
Power limiting Debounce Time
47
mSec
ZFB_IN
Input Impedance
6
Kohm
DC_MAX
Maximum Duty Cycle
75
%
330
ns
40
Kohm
120
nSec
Voltage
VDD=18V,RI=100Kohm,
FB=3V, CS=0
Current Sense Input(Sense Pin)
T_blanking
Leading edge blanking time
RI = 100 Kohm
ZSENSE_IN
Input Impedance
TD_OC
OCP Control Delay
GATE with 1nF to GND
VTH_OC
Over Current Threshold Voltage at
FB=3.3V, RI=100 Kohm
0.70
0.75
0.80
V
60
65
70
KHZ
zero Duty Cycle
Oscillator
FOSC
Normal Oscillation Frequency
RI = 100 Kohm
∆f_Temp
Frequency Temperature Stability
VDD = 16V,
5
%
5
%
o
RI=100Kohm, TA -20 C
to 85 oC
∆f_VDD
Frequency Voltage Stability
VDD = 12-25V,
RI=100Kohm
RI_range
Operating RI Range
V_RI_open
RI open load voltage
Fosc_BM
Burst Mode Base Frequency
50
VDD = 16V,
100
150
Kohm
2
V
22
KHZ
RI = 100Kohm
Gate Drive Output
VOL
Output Low Level
VDD = 16V, Io = -20 mA
VOH
Output High Level
VDD = 16V, Io = 20 mA
V_Clamp
Output Clamp Voltage Level
T_r
Output Rising Time
T_f
Output Falling Time
0.8
10
V
V
18
V
VDD = 16V, CL = 1nf
200
nSec
VDD = 16V, CL = 1nf
70
nSec
Frequency Shuffling
∆f_OSC
Frequency Modulation range
RI=100K
-3
3
%
/Base frequency
f_shuffling
Shuffling Frequency
RI=100K
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64
HZ
AMS 2263
CHARACTERIZATION PLOTS
VDD = 16V, RI = 100 Kohm, TA = 25oC condition applies if not otherwise noted.
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AMS 2263
OPERATION DESCRIPTION
The AMS2263 is a highly integrated PWM
loss on the snubber circuit. The magnitude of
controller
flyback
power loss is in proportion to the number of
converter applications in sub 30W power range.
switching events within a fixed period of time.
The extended burst mode control greatly reduces
Reducing switching events leads to the reduction
the standby power consumption and helps the
on the power loss and thus conserves the energy.
design easily meet the international power
AMS2263
conservation requirements.
according to the loading condition. At from no
•
IC
optimized
for
offline
self
adjusts
the
switching
mode
load to light/medium load condition, the FB input
Startup Current and Start up Control
Startup current of AMS2263 is designed to be very
drops below burst mode threshold level.
low so that VDD could be charged up above
enters Burst Mode control. The Gate drive output
UVLO threshold level and device starts up quickly.
switches only when VDD voltage drops below a
A large value startup resistor can therefore be
preset level and FB input is active to output an on
used to minimize the power loss yet provides
state. Otherwise the gate drive remains at off
reliable startup in application.
For AC/DC
state tominimize the switching loss and reduces
adaptor with universal input range design, a 2 MΩ,
the standby power consumption to the greatest
1/8 W startup resistor could be used together with
extend.
a VDD capacitor to provide a fast startup and low
the audio noise at any loading conditions.
•
power dissipation solution.
•
Device
The frequency control also eliminates
Oscillator Operation
A resistor connected between RI and GND sets
Operating Current
The Operating current of AMS2263 is low at 1.4mA.
the constant current source to charge/discharge
Good efficiency is achieved with AMS2263 low
the internal cap and thus the PWM oscillator
operating current together with extended burst
frequency is determined.
mode control features.
between RI and switching frequency follows the
•
below equation within the specified RI in Kohm
Frequency shuffling for EMI improvement
The
frequency
Shuffling/jittering
is
range at nominal loading operational condition.
(switching
frequency
modulation)
implemented
AMS2263.
The oscillation frequency is modulated
The relationship
in
with a random source so that the tone energy is
•
spread out. The spread spectrum minimizes the
Blanking
conduction band EMI and therefore reduces
Cycle-by-Cycle current limiting is offered in
system design challenge.
AMS2263 current mode PWM control. The switch
•
Current Sensing and Leading Edge
current is detected by a sense resistor into the
Extended Burst Mode Operation
At zero load or light load condition, majority of the
sense pin. An internal leading edge blanking
power dissipation in a switching mode power
circuit chops off the sense voltage spike at initial
supply is from switching loss on the MOSFET
MOSFET on state due to Snubber diode reverse
transistor, the core loss of the transformer and the
recovery so that the external RC filtering on
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AMS 2263
sense input is no longer required. The current
is added for MOSFET gate protection at higher
limit comparator is disabled and thus cannot turn
than expected VDD input.
off the external MOSFET during the blanking
•
period. PWM duty cycle is determined by the
Good power supply system reliability is achieved
current sense input voltage and the FB input
with
voltage.
Cycle-by-Cycle current limiting (OCP), Over Load
•Internal Synchronized Slope Compensation
Protection Controls
its
rich
protection
Protection (OLP) and over
features
including
voltage clamp, Under
Built-in slope compensation circuit adds voltage
Voltage Lockout on VDD (UVLO).
ramp onto the current sense input voltage for
The OCP threshold tracks PWM Duty cycles and
PWM generation. This greatly improves the close
is line voltage compensated to achieve constant
loop
output power limit over the universal input voltage
stability
at
CCM
and
prevents
the
sub-harmonic oscillation and thus reduces the
range with recommended reference design.
output ripple voltage.
At overload condition when FB input voltage
•
exceeds power limit threshold value for more than
Gate Drive
AMS2263 Gate is connected to an external
TD_PL, control circuit reacts to shut down the
MOSFET gate for power switch control. Too weak
output power MOSFET. Device restarts when
the
VDD voltage drops below UVLO limit.
gate
drive
strength
results
in
higher
conduction and switch loss of MOSFET while too
VDD is supplied by transformer auxiliary winding
strong gate drive output compromises the EMI.
output. It is clamped when VDD is higher than
A good tradeoff is achieved through the built-in
threshold value. The power MOSFET is shut
totem pole gate design with right output strength
down when VDD drops below UVLO limit and
and dead time control. The low idle loss and good
device enters power on start-up sequence
EMI system design is easier to achieve with this
thereafter.
dedicated control scheme. An internal 18V clamp
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PACKAGE MECHANICAL DATA
SOT-23-6 PACKAGE OUTLINE DIMENSIONS
Symbol
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
1.050
1.250
0.041
0.049
A1
0.000
0.100
0.000
0.004
A2
1.050
1.150
0.041
0.045
b
0.300
0.400
0.012
0.016
c
0.100
0.200
0.004
0.008
D
2.820
3.020
0.111
0.119
E
1.500
1.700
0.059
0.067
E1
2.650
2.950
0.104
0.116
e
e1
0.950TYP
1.800
L
0.037TYP
2.000
0.700REF
0.071
0.079
0.028REF
L1
0.300
0.600
0.012
0.024
θ
00
80
00
80
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AMS 2263
SOP8 PACKAGE OUTLINE DIMENSIONS
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AMS 2263
DIP8 PACKAGE OUTLINE DIMENSIONS
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AMS 2263
Disclaimer:
•
AMS reserves the right to make changes to the information herein for the improvement of the design and performance
without further notice! Customers should obtain the latest relevant information before placing orders and should verify
that such information is complete and current.
•
All semiconductor products malfunction or fail with some probability under special conditions. When using AMS products
in system design or complete machine manufacturing, it is the responsibility of the buyer to comply with the safety
standards strictly and take essential measures to avoid situations in which a malfunction or failure of such AMS products
could cause loss of body injury or damage to property.
•
AMS will supply the best possible product for customers!
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