PCN20110806

Product Change Notices
PCN No.: 20110806
Date: 8/19/2011
This is to inform you that AME5290 datasheet has been changed from Rev. A.01 to
Rev. B.01. This notification is for your information and concurrence.
If you require data or samples to qualify this change, please contact AME, Inc.
within 30 days of receipt of this notification.
If we do not receive any response from you within 30 calendar days from the
date of this notification, we will consider that you have accepted this PCN.
If you have any questions concerning this change, please contact:
PCN Originator:
Name: Bill Chou
Email: [email protected]
Expected 1st Device Shipment Date: N/A
Earliest Year/Work Week of Changed Product: N/A
Description of Change : Modify absolute maximum ratings
From:
To:
Reason for Change: To comply AME5290 part real product performance.
QPM018B-B
AME
AME5290
3A, 1MHz Sync Buck Converter
n General Description
The AME5290 is a synchronous buck converter with
internal power MOSFETs. It achieves 3A continuous output current with a fixed frequency of 1MHz with excellent
load and line regulation. The device operates from an
input voltage of 3V to 5.5V and provides an output voltage from 0.8V to VIN, making the AME5290 ideal for onboard post regulation applications.
Internal soft-start minimizes the inrush supply current
at startup. The circuit protection includes cycle-by-cycle
current limiting, output short circuit frequency protection
and thermal shutdown these protect functions improve
design reliability.
This device is available in SOP-8/PP package with exposed pad for low thermal resistance.
n Features
l Input Voltage Operate from 3V to 5.5V
l 3A Output Current
l 100mΩ Internal Power MOSFET Switch
l Stable with Low ESR Output Ceramic
Capacitors
l Up to 95% Efficiency
l Thermal Shutdown
l Output Adjustable from 0.8V to V IN
l Short Circuit Frequency Protection
l Over Temperature Protection
l Available in SOP-8/PP Package
l Green Products Meet RoHS Standards
n Applications
l TV
l Distributed Power Systems
l Pre-Regulator for Linear Regulators
Rev.B.01
1
AME
AME5290
3A, 1MHz Sync Buck Converter
n Typical Operating Circuit
L
2.2µH
VIN
5V
SW
VIN
CFB * (option)
RIN
10Ω
CIN
10µF
AME5290
VCC
FB
R1
50KΩ
CVCC
0.1µF
EN
ON
VOUT
3.3V
OFF
REF
GND
PGND
COUT
22µF
R2
16KΩ
Cref
0.1µF
R1 

VOUT = 0.8V × 1 +

 R2 
n Functional Block Diagram
VCC
IN
250K
EN
Enable
Current
Sense
UVLO
4.5A
Current
Limit
OSC
SLOPE
REF
Softstart
11.5K
LOGIC
+
0.8V
VREF
EA
+
-
Driver
SW
PWM
GND
OTP
FB
PGND
0.9V
2
IRCMP
OVP
Rev.B.01
AME
AME5290
3A, 1MHz Sync Buck Converter
n Pin Configuration
SOP-8/PP
Top View
8
7
6
5
AME5290-AZAxxx
1. VCC
2. REF
3. GND
AME5290
4. FB
5. EN
6. PGND
1
2
3
4
7. SW
8. IN
* Die Attach:
Conductive Epoxy
Note:
Connect exposed pad (heat sink on the back) to GND.
n Pin Description
Pin Number Pin Name
Rev.B.01
Pin Description
1
VCC
Supply Voltage. Bypass with 0.1µF capacitor to ground and 10Ω resistor to
VIN .
2
REF
Reference Bypass. Bypass with 0.1µF capacitor to ground.
3
GND
Ground. Connect the exposed pad to GND.
4
FB
Feedback Input. FB senses the output voltage to regulate that voltage. Drive
FB with a resistive voltage divider from the output voltage. The feedback
reference voltage is 0.8V.
5
EN
Enable. Internal pull high with a resistor. Pull EN below 0.4V to shut down the
regulator.
6
PGND
7
SW
8
IN
Power Ground. Internally connected to GND. Keep power ground and signal
ground planes separate.
Power Switching Output. SW is the switching node that supplies power to the
output. Connect the output LC filter from SW to the output load.
Power-Supply Voltage. Input voltage range from 3V to 5.5V. Bypass with a
10µF (min.) ceramic capacitor to ground and a 10Ω resistor to VCC.
3
AME
AME5290
3A, 1MHz Sync Buck Converter
n Ordering Information
AME5290 - x x x xxx
Output Voltage
Number of Pins
Package Type
Pin Configuration
Pin Configuration
A
(SOP-8/PP)
4
1. VCC
2. REF
3. GND
4. FB
5. EN
6. PGND
7. SW
8. IN
Package
Type
Z: SOP/PP
Number of
Pins
A: 8
Output Voltage
ADJ: Adjustable
Rev.B.01
AME
AME5290
3A, 1MHz Sync Buck Converter
n Available Options
Part Number
Marking*
Output Voltage
Package
Operating Ambient
Temperature Range
AME5290-AZAADJ
A5290
AMyMXX
ADJ
SOP-8/PP
-40oC to +85oC
Note:
1. The first 2 places represent product code. It is assigned by AME such as AM.
2. y is year code and is the last number of a year. Such as the year code of 2008 is 8.
3. A bar on top of first letter represents Green Part such as A5290.
4. The last 3 places MXX represent Marking Code. It contains M as date code in "month", XX as LN code and
that is for AME internal use only. Please refer to date code rule section for detail information.
5. Please consult AME sales office or authorized Rep./Distributor for the availability of output voltage and package
type.
n Absolute Maximum Ratings
Parameter
Maximum
Unit
-0.3V to +6V
V
Switch Voltage
-1V to +6V
V
EN, FB to GND
-0.3V to (VCC + 0.3V)
V
PGND to GND
-0.3V to +0.3V
V
VIN, VCC, REF to GND
B*
ESD Classification
Caution: Stress above the listed in absolute maximum ratings may cause permanent damage to the device.
* HBM B: 2000V ~ 3999V
n Recommended Operating Conditions
Parameter
Symbol
Rating
Ambient Temperature Range
TA
-40 to +85
Junction Temperature Range
TJ
-40 to +125
Storage Temperature Range
TSTG
-65 to +150
Rev.B.01
Unit
o
C
5
AME
AME5290
3A, 1MHz Sync Buck Converter
n Thermal Information
Parameter
Package
Die Attach
Thermal Resistance*
(Junction to Case)
Symbol Maximum
θJC
Unit
19
o
Thermal Resistance
(Junction to Ambient)
SOP-8/PP
Conductive Epoxy
Internal Power Dissipation
Maximum Junction Temperature
θJA
84
PD
1450
C/W
mW
150
o
Solder Iron (10Sec)**
C
350
* Measure θJC on center of molding compound if IC has no tab.
** MIL-STD-202G 210F
6
Rev.B.01
AME
AME5290
3A, 1MHz Sync Buck Converter
n Electrical Specifications
VIN=5V, TA = 25OC unless otherwise noted.
Parameter
Input Voltage Range
Symbol
ISHDN
VREF
EN Voltage High
EN Voltage Low
Output Voltage Range
Shutdown (EN=0V)
VOUT
Max
Units
5.5
V
µA
450
VIN =5V
20
35
µA
When SW starts switching
2
V
IREF =0, VIN =3V to 5V
0.8
V
2
Logic High
VEN
Typ
3
No switching (EN=VCC)
VCC Undervoltage Lockout
Threshold
REF Voltage
Min
VIN
Supply Current
Shutdown Current
Test Condition
V
0.4
Logic Low
When using external feedback
resistors to drive FB
0.8
VIN
V
Output Voltage Line Regulation
VIN =3V to 5V
0.08
%/V
Output Voltage Load Regulation
0A<ILOAD <3A
0.12
%/A
Feedback Voltage
(Error Amp Only)
VFB
VIN =3V to 5V
0.784
FB Input Bias Current
0.8
-0.1
High-side Switch On Resistance
RDSON,HI
VIN =5V
100
Low-side Switch On Resistance
RDSON,LOW
VIN =5V
80
High-side Switch Current Limit
Duty cycle=100%,
V IN =3V to 5V
Low-side Switch Current Limit
Switch Leakage Current
ISWLK
VIN =5V
High-side
3.4
0.816
V
0.1
µA
mΩ
4.5
A
Low-side
-1.3
VSW =5V
SW=GND
10
-10
µA
Current Limit Oscillation
Frequency
fOSC,CL
VIN =3V to 5V
1
MHz
Short Current Oscillation
Frequency
fOSC,SCR
VFB=0V
120
KHz
SW Maximum Duty Cycle
DSW,MAX
VSW =high-Z, VIN =3V to 5V
SW Minimum Duty Cycle
t SWON,MIN
VIN =3V to 5V
Rev.B.01
100
%
15
7
AME
AME5290
3A, 1MHz Sync Buck Converter
n Electrical Specifications ( Contd. )
Symbol
Thermal Shutdown Temperature
OTP
Thermal Shutdown Hysteresis
OTH
20
t ON,MIN
150
Minimum On Time
8
Test Condition
Parameter
When SW starts/stops
switching
Min
TJ rising
Typ
160
Max
Units
o
C
ns
Rev.B.01
AME
AME5290
n Detailed Description
The AME5290 high-efficiency switching regulator is a
small, simple, DC-to-DC step-down converters capable
of delivering up to 3A of output current. The devices operate in pulse-width modulation (PWM) at a fixed frequency
of 1MHz from a 3V to 5.5V input voltage and provide an
output voltage from 0.8V to VIN, making the AME5290
ideal for on-board post-regulation applications. The high
switching frequency allows for the use of smaller external components, and internal synchronous rectifiers improve efficiency and do not use the typical Schottky freewheeling diode. Using the on-resistance of the internal
high-side MOSFET to sense switching currents eliminates current-sense resistors, further improving efficiency
and cost.
The AME5290 step-down converters use a PWM current- mode control scheme. An open-loop comparator
(Modulator) compares the amplified voltage-feedback signal against the sum of the amplified current-sense signal
and the slope compensation ramp. At each rising edge
of the internal clock, the internal high-side MOSFET turns
on until the PWM comparator trips. During this on-time,
current ramps up through the inductor, sourcing current
to the output and storing energy in the inductor. The
current-mode feedback system regulates the peak inductor current as a function of the output voltage error signal.
Since the average inductor current is nearly the same as
the peak inductor current (<30% ripple current ). The
circuit acts as a switch-mode transconductance amplifier. To preserve inner-loop stability and eliminate inductor stair-casing, a slope-compensation ramp is summed
into the main PWM comparator. During the second half
of the cycle, the internal high-side P-channel MOSFET
turns off, and the internal low-side N-channel MOSFET
turns on. The inductor releases the stored energy as its
current ramps down while still providing current to the
output. The output capacitor stores charge when the inductor current exceeds the load current, and discharges
when the inductor current is lower, smoothing the voltage
across the load.
Rev.B.01
3A, 1MHz Sync Buck Converter
Current Limit
The internal high-side MOSFET has a current limit of
4.5A (typ.). If the current flowing out of SW exceeds this
limit, the high-side MOSFET turns off and the synchronous rectifier turns on. This lowers the duty cycle and
causes the output voltage to droop until the current limit
is no longer exceeded. A synchronous rectifier current
limit of -1.3A (typ.) protects the device from current flowing into SW. If the negative current limit is exceeded, the
synchronous rectifier turns off, forcing the inductor current to flow through the high-side MOSFET body diode,
back to the input, until the beginning of the next cycle or
until the inductor current drops to zero. The AME5290
uses a pulse-skip mode to prevent overheating during
short-circuit output conditions. The device enters pulseskip mode when the FB voltage drops below 300mV, limiting the current to 4.5A (typ.) and reducing power dissipation. Normal operation resumes upon removal of the
short-circuit condition.
Over Voltage Protection
The AME5290 monitors a resistor divided feedback voltage to detect over voltage. When the feedback voltage
becomes higher than the target voltage for 12% (typ.),
the OVP comparator output goes high and the circuit
latches as the high-side MOSFET turned OFF and lowside MOSFET turned ON cycle by cycle.
Soft-Start
The AME5290 employ soft-start circuitry to reduce supply inrush current during startup conditions.
Thermal-Overload Protection
Thermal-overload protection limits total power dissipation in the device. When the junction temperature exceeds TJ = +160oC, a thermal sensor forces the device
into shutdown, allowing the die to cool. The thermal sensor turns the device on again after the junction temperature cools by 20oC, resulting in a pulsed output during
continuous overload conditions.
9
AME
AME5290
Undervoltage Lockout
If VCC drops below 1.8V, the UVLO circuit inhibits
switching. Once VCC rises above 2V, the UVLO clears,
and the soft-start sequence activates.
Shutdown Mode
The EN pin has a internal pull high resistor connect to
VCC. To shut down the AME5290, use an NPN bipolar
junction transistor or a MOSFET to pull EN to GND.
Shutdown mode causes the internal MOSFETs to stop
switching, forces SW to a high-impedance state, and
shorts REF to GND. Release EN to exit shutdown and
initiate the soft-start sequence.
VCC Decoupling
Due to the high switching frequency and tight output
tolearance, decouple VCC with a 0.1µF capacitor connected from VCC to GND, and a 10Ω resistor connected
from VCC to VIN. Place the capacitor as close to VCC
as possible.
3A, 1MHz Sync Buck Converter
n Application Information
Inductor Selection
Use a 2µH inductor with a minimum 3A-rated DC current for most application. For best efficiency, use an inductor with a DC resistance of less than 20mΩ and a
saturation current grater than 4A(min). For most designs,
derive a reasonable inductor value(LINIT) from the following equation: L INIT = VOUT * (VIN - V OUT) / (VIN * LIR * IOUT(MAX)
* fSW)
where fSW is the switching frequency (1MHz typ) of the
oscillator. Keep the inductor current ripple percentage
LIR between 20% and 40% of the maximum load current
for the best compromise of cost, size, and performance.
Calculate the maximum inductor current as:
IL(MAX) = (1+LIR / 2) * IOUT(MAX)
Check the final values of the inductor with the output ripple
voltage requirement. The output ripple voltage is given
by:
VRIPPLE = VOUT * (VIN - VOUT) * ESR / (VIN * LFINAL * fSW )
Where ESR is the equivalent series resistance of the
output capacitor.
Capacitor Selection
The input filter capacitor reduces peak currents drawn
from the power source and reduces noise and voltage
ripple on the input caused by the circuit's switching. The
input capacitor must meet the ripple current
requirement(IRMS) imposed by the switching currents defined by the following equation:
IRMS = (1 / VIN) * (IOUT2 * VOUT * (VIN - VOUT))1/2
For duty ratios less than 0.5, the input capacitor RMS
current is higher than the calculated current. Therefore,
use a +20% margin when calculating the RMS current at
lower duty cycles. Use ceramic capacitors for their low
ESR, equivalent series inductance (ESL), and lower cost.
Choose a capacitor that exhibits less than 10oC temperature rise at the maximum operating RMS current for optimum long-term reliability. After determining the input
capacitor, check the input ripple voltage due to capacitor
discharge when the high-side MOSFET turns on. Calculate the input ripple voltage as follows:
VIN_RIPPLE = (IOUT * VOUT) / (fSW * VIN * CIN)
10
Rev.B.01
AME
AME5290
Keep the input ripple voltage less than 3% of the input
voltage. The key selection parameters for the output capacitor are capacitance, ESR, ESL, and the voltage rating requirements. These affect the overall stability, output ripple voltage, and transient response of the DC-toDC converter. The output ripple occurs due to variations
in the charge stored in the output capacitor, the voltage
drop due to the capacitor's ESR, and the voltage drop
due to the capacitor's ESL. Calculate the output voltage
ripple due to the output capacitance, ESR, and ESL as:
3A, 1MHz Sync Buck Converter
Efficiency Considerations
where the output ripple due to output capacitance, ESR,
and ESL is:
Although all dissipative elements in the circuit produce
losses, one major source usually account for most of the
losses in AME5290 circuits: I2R losses. The I2R loss
dominates the efficiency loss at medium to high load
currents. The I2R losses are calculated from the resistances of the internal switches, RSW, and external inductor RL. In continuous mode, the average output current
flowing through inductor L is "chopped" between the main
switch and the synchronous switch. Thus the series resistance looking into the SW pin is a function of both top
and bottom MOSFET RDS(ON) and the duty cycle (D) as
follows:
VRIPPLE(C) = IP-P / (8 x COUT x fSW)
RSW = (RDS(ON)TOP)(D) + (RDS(ON)BOTTOM )(1-D)
VRIPPLE(ESR) = IP-P x ESR
The RDS(ON) for both the top and bottom MOSFETs can
be obtained from Electrical Characteristics table. Thus,
to obtained I2R losses, simply add RSW to RL and multiply the result by the square of the average output current. Other losses including CIN and COUT ESR dissipative losses and inductor core losses generally account
for less than 2% total additional loss.
VRIPPLE = VRIPPLE(C) + VRIPPLE(ESR) + VRIPPLE(ESL)
VRIPPLE(ESL) = (IP-P / tON) x ESL or (IP-P / tOFF) x ESL
whichever is greater and IP-P the peak-to-peak inductor
current is:
IP-P = [ (V IN-V OUT) / fSW x L)] x VOUT / VIN
Use these equations for initial capacitor selection, but
determine final values by testing a prototype or evaluation circuit. As a rule, a smaller ripple current results in
less output voltage ripple. Since the inductor ripple current is a factor of the inductor value, the output voltage
ripple decreases with larger inductance. Use ceramic
capacitors for their low ESR and ESL at the switching
frequency of the converter. The low ESL of ceramic capacitors makes ripple voltages negligible. Load transient
response depends on the selected output capacitor.
During a load transient, the output instantly changes by
ESR * ILOAD . Before the controller can respond, the output deviates further, depending on the inductor and output capacitor values. After a short time, the controller
responds by regulating the output voltage back to its nominal state. The controller response time depends on the
closed-loop bandwidth. A higher bandwidth yields a faster
response time, thus preventing the output from deviating
further from its regulating value.
Thermal Considerations
In most application the AME5290 does not dissipate
much heat due to its high efficiency. But, in applications
where the AME5290 is running at high ambient temperature with low supply voltage and high duty cycles, such
as in dropout, the heat dissipated may exceed the maximum junction temperature of the part. If the junction
temperature reaches approximately 150oC, both power
switches will be turned off and the SW node will become
high impedance.
Thermal performance can be improved with one of the
following options:
l Increase the copper areas connected to
GND, SW, and VIN
l Provide thermal vias next to GND and VIN, to
the ground plane and power plane on the
Output Voltage Programming
The output voltage is set by resistive divider according to
the following formula: VOUT = 0.8 x (1+R1/R2)
Please keep R2 not larger than 25KΩ and select R1 using the formula.
Rev.B.01
back side of PC board, with openings in the
solder mask next to the vias to provide
better thermal conduction.
l Provide forced-air cooling to further reduce
case temperature
11
AME
AME5290
3A, 1MHz Sync Buck Converter
PC Board Layout Considerations
Careful PC board layout is critical to achieve clean and
stable operation. The switching power stage requires
particular attention. Follow these guidelines for good PC
board layout:
l Place decoupling capacitors as close to the
IC as possible. Keep power ground
plane(connected to PGND) and signal
ground plane(connected to GND) separate
l Connect input and output capacitors to the
power ground plane; connect all other
capacitors to the signal ground plane
Note:
Connect exposed pad (heat sink on the back) to GND.
12
Rev.B.01
AME
AME5290
3A, 1MHz Sync Buck Converter
n Characterization Curve
Efficiency vs. Output Current
Load Step
100
90
Efficiency(%)
80
VOUT=3.3V
70
1
VOUT=2.5V
60
50
40
30
20
VIN = 5.0V
10
0
1
10
100
1000
2
10000
200µS / div
Output Current(mA)
VIN=5V
VOUT=3.3V
IOUT=5mA~3A
O
TA = 25 C
1) VOUT= 200mV/div (AC)
2) IOUT = 1A/div
Output Voltage Ripple (Full Load)
Start-Up
1
1
2
2
3
3
4
4
1mS / div
400nS / div
1) VIN= 500mV/div
2) VOUT= 10mV/div
3) IL = 2A/div
4) IOUT = 2A/div
Rev.B.01
1) EN= 2V/div
2) VOUT= 2V/div
3) IIN = 2A/div
4) IOUT = 2A/div
13
AME
AME5290
3A, 1MHz Sync Buck Converter
n Characterization Curve ( Contd. )
VFB vs. Temperature
Frequency vs. Temperature
0.83
1200
VIN = 5.0V
VOUT = 3.3V
0.82
1100
Frequency(KHz)
0.81
VFB(V)
0.80
0.79
0.78
0.77
1000
900
800
0.76
0.75
-50
-25
0
+25
+50
+75
+100
700
-50
+125
0
+75
+100
Frequency vs. Output Current
+125
1200
VOUT = 3.3 V
VIN = 5.0V
VOUT = 3.3V
1100
Frequency(KHz)
1000
900
1000
900
800
800
700
4.00
700
4.25
4.50
4.75
5.00
5.25
5.50
0
500
1000
VIN(V)
550
550
Quiescent Current(µA)
600
500
450
400
350
4. 25
4.50
4.75
VIN(V)
2000
2500
3000
Quiescent Current (No Switching) vs.
Temperature
600
300
4.00
1500
IO(mA)
Quiescent Current (No Switching) vs.
Input Voltage
Quiescent Current(µA)
+50
Frequency vs. Supply Voltage
1100
14
+25
Temperature(°C)
1200
Frequency(KHz)
-25
Temperature(°C)
5.00
5. 25
5.50
500
450
400
350
300
-50
-25
0
+25
+50
+75
+100
+125
Temperature(°C)
Rev.B.01
AME
AME5290
3A, 1MHz Sync Buck Converter
n Date Code Rule
Month Code
1: January 7: July
2: February 8: August
3: March
9: September
4: April
A: October
5: May
B: November
6: June
C: December
n Tape and Reel Dimension
SOP-8/PP
P
PIN 1
W
AME
AME
Carrier Tape, Number of Components Per Reel and Reel Size
Rev.B.01
Package
Carrier Width (W)
Pitch (P)
Part Per Full Reel
Reel Size
SOP-8/PP
12.0±0.1 mm
4.0±0.1 mm
2500pcs
330±1 mm
15
AME
AME5290
3A, 1MHz Sync Buck Converter
n Package Dimension
SOP-8/PP
TOP VIEW
SIDE VIEW
D1
θ
E1
E2
E
L1
C
SYMBOLS
MILLIMETERS
INCHES
MIN
MAX
MIN
MAX
A
1.350
1.750
0.053
0.069
A1
0.000
0.150
0.000
0.006
A2
1.350
1.600
0.053
0.063
C
0.100
0.250
0.004
0.010
E
3.750
4.150
0.148
0.163
E1
5.700
6.300
0.224
0.248
L1
0.300
1.270
0.012
0.050
b
0.310
0.510
0.012
0.020
D
4.720
5.120
0.186
0.202
PIN 1
D
e
A1
FRONT VIEW
16
A
A2
b
1.270 BSC
e
o
0.050 BSC
o
o
8o
θ
E2
2.150
2.513
0.085
0.099
D1
2.150
3.402
0.085
0.134
0
8
0
Rev.B.01
www.ame.com.tw
E-Mail: [email protected]
Life Support Policy:
These products of AME, Inc. are not authorized for use as critical components in life-support
devices or systems, without the express written approval of the president
of AME, Inc.
AME, Inc. reserves the right to make changes in the circuitry and specifications of its devices and
advises its customers to obtain the latest version of relevant information.
 AME, Inc. , August 2011
Document: HU003-DS5290-B.01
Corporate Headquarter
AME, Inc.
2F, 302 Rui-Guang Road, Nei-Hu District
Taipei 114, Taiwan.
Tel: 886 2 2627-8687
Fax: 886 2 2659-2989