AIMTRON AT1366BX-GRE

AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
Features
• High efficiency (95%) possible
• No Schottky Diode Required
• 800mA Output Current at 5V input 3.3V output
• Oscillation frequency 1.0MHz
• Built-in ON/OFF Function
• Built-in Short Circuit Protection
• Low Dropout Operation: 100% Duty Cycle
• Stand-by current max. 1µA
• Input voltage: 2.5V ~5.5V
Applications
• Power Supply for portable devices
General Description
The AT1366B provides complete control for a
DC/DC converter optimized for high-performance
microprocessor applications. It is operated on
current mode architecture for excellent line and
load transient response. 1MHz operation frequency
is allowing the use of small surface mount inductor
and capacitor. The internal synchronous switch
increases efficiency and eliminates the need for an
external Schottky diode. The AT1366 is a family
of low-noise synchronous step-down DC/DC
converters that is ideally suited for systems
powered from a 1-cell Li-ion battery or from a
3-cell to 4-cell NiCd, NiMH, or alkaline battery. It
can also be used to USB-Based power system.
Block Diagram
Aimtron reserves the right without notice to change this circuitry and specifications.
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
1/18/2006 REV:1.2
Email:service@aimtron.com.tw
1
AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
Pin Configuration
Ordering Information
Part number
AT1366BX
AT1366BX_GRE
Package
SOT-25
SOT-25,Green
Marking
: Date Code
: Date Code with one bottom line
▲▲▲▲▲
▲▲▲▲▲
*For more marking information, contact our sales representative directly
Pin Description
Symbol
Pin No.
RUN
GND
SW
VIN
FB
1
2
3
4
5
Descript
ON/OFF Control
Power ground
Switch Node Connection to Inductor
Power Supply
Output Feedback
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
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1/18/2006 REV:1.2
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2
AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
Absolute Maximum Ratings
Parameter
Condition
Power Supply Voltage
Input Pin Voltage
—
RUN,FB
SW
—
P-Channel Switch Source Current
(DC)
N-Channel Switch Sink Current
(DC)
Peak SW Sink and Source Current
Thermal Resistance from Junction
to Ambient θJA
Operating temperature TA
Storage temperature
ESD Susceptibility *2
Unit
Rated Value
Min.
Max.
-0.3
+6.0
-0.3
VIN
-0.3 VIN+0.3
1000
—
-
1000
—
SOT-25
-
1.5
200
—
—
HBM
MM
-35
-55
+85
+150
2
200
V
V
V
mA
mA
0
A
C/W
0
C
C
KV
V
0
1. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the
device. These are stress ratings only, and functional operation of the device at these or any other
conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure
to absolute maximum rating conditions for extended periods may affect device reliability.
2. Device are ESD sensitive. Handling precaution recommended. The Human Body model is a 100pF
capacitor discharged through a 1.5KΩ resistor into each pin.
Recommended Operating Conditions
(Ta=+250C)
Parameter
Power supply voltage
Operating temperature*
Operating junction temperature
Symbol
VIN
TA
TJ
Values
Min.
2.5
-20
-
Typ.
-+25
-
Unit
Max.
5.5
+85
+150
V
°C
°C
*Using X5R or X7R input capacitors.
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
1/18/2006 REV:1.2
Email:service@aimtron.com.tw
3
AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
Electrical Characteristics
(VIN = 3.6V,Ta =+25℃ , unless otherwise noted. )
Parameter
Symbol
Input Supply Range
VIN
Quiescent Current*
IS
Current in standby mode
IST
Feedback Voltage
VFB
Feedback Voltage
line-regulation
VFB-Line
Feedback current
IFB
Peak Inductor Current*
IPK
Maximum Output
Current*
IO
RDS(ON) of P-Channel
MOSFET
RDS(ON) of N-Channel
MOSFET
FB=0.6V, Iload=0A
Active Mode
RUN=0V, VIN=5.5V
Ta =-20℃ to +85℃
VCC=2.5V to 5.5V
Ta =-20℃ to +85℃
Feedback Variation
with Temperature
Oscillator Frequency
Condition
VIN=5V,VOUT=3.3V
Values
Unit
Min.
Typ.
Max.
2.5
--
5.5
V
--
300
--
µA
--
0.5
1
µA
0.588
0.600
0.612
V
--
0.1
0.5
%
--
0.5
1.0
%
--
--
±200
nA
1.10
1.25
1.50
A
-
-
800
mA
fosc1
VIN=5V±5%, VOUT=3.3V,
L=4.7µH
FB=0.6V
0.8
1.0
1.2
MHz
fosc2
FB=0V
--
200
--
KHz
ISW=600mA
--
0.4
0.5
Ω
ISW=-600mA
--
0.35
0.45
Ω
RUN=0V,SW=0V or 5V,VIN=5V
--
±0.1
±1
µA
RPFET
RNFET
SW Leakage Current
ILSW
RUN Threshold
VRUN
0.3
1.0
1.5
V
RUN leakage Current
IRUN
--
±0.1
±1
µA
* I PK = I O +
(V − VOUT ) × t ON
∆I
= I O + IN
2
2× L
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
1/18/2006 REV:1.2
Email:service@aimtron.com.tw
4
AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
Typical characteristics : (refer to Figure 2)
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
1/18/2006 REV:1.2
Email:service@aimtron.com.tw
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AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
Typical characteristics :
Start-Up from Shutdown(VIN=3.6V)
CH1:RUN
CH2:VOUT
CH4:IL
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
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1/18/2006 REV:1.2
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6
AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
Typical characteristics (Continuted)
VIN=5V,VOUT=3.3V CH2:VOUT CH4:IOUT
ILOAD=0mA to 600mA
ILOAD= 200mA to 600mA
ILOAD= 50mA to 600mA
ILOAD= 50mA to 800mA
ILOAD= 100mA to 600mA
ILOAD= 200mA to 800mA
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
1/18/2006 REV:1.2
Email:service@aimtron.com.tw
7
AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
Typical Application Circuit
L1:ABC SH40284R7YSB
Figure 1
L1:ABC SH40284R7YSB
Figure 2
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
1/18/2006 REV:1.2
Email:service@aimtron.com.tw
8
AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
Application Information
Short Circuit Protection Function
The AT1366B has short circuit protection(see the Electrical Characteristics frequency
item). When the output is shorted to ground, the frequency of the oscillator is reduced
to about 200KHz. This frequency foldback ensures that the inductor current has more
time to decay. It will prevent the inductor current and internal P-MOSFET current
runaway to damage the device. The frequency will return to the normal values when
the short circuit condition is removed and the feedback voltage reaches 0.6V.
Capacitor Selection
In continuous mode, the source current of the top MOSFET is square wave of duty
cycle. The Primary function of the input capacitor is to provide a low impedance loop
for the edges of pulsed current drawn by the AT1366B. A load step at the output can
induce ringing at the input VIN. This ringing can couple to the output and be mistaken
as loop instability. The oscillation can be improved by add the capacitance of the input
capacitor. A typical value is 4.7~22µF ceramic (X5R or X7R), POSCAP or Aluminum
Polymer. These capacitors will provide good high frequency bypassing and their low
ESR will reduce resistive losses for higher efficiency. The input capacitor RMS
current varies with the input voltage and the output voltage. The equation for the
maximum RMS current in the input capacitor is:
I RMS = I OMAX
VO
V
(1 − O )
VIN
VIN
The output capacitor depends on the suitable ripple voltage. Low ripple voltage
corresponds to lower effective series resistance (ESR). The output ripple voltage is
determined by:
∆VOUT ≅ ∆I L ( ESR +
1
)
8 fC OUT
The output capacitor RMS ripple current is given by:
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
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1/18/2006 REV:1.2
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AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
I RMS =
1 VOUT × (VIN − VOUT )
L × f × VIN
2 3
When choosing the input and output ceramic capacitors, choose the X5R or X7R
dielectric formulations. These dielectrics have the best temperature and voltage
characteristics of all the ceramics for a given value and size.
Inductor Selection
The inductor is chosen based on the desired ripple current. Large value inductors
lower ripple current and small value inductors result in higher ripple current. Always
consider the losses associated with the DCR and its effect on the total converter
efficiency when selecting an inductor. The inductor is selected to limit the ripple
current to some predetermined value, typically 20~40% of the full load current at the
maximum input voltage. The formula of inductance value is as below:
∆I L = 0.2 ~ 0.4 × I OUT ( MAX )
L=
VOUT
f × ∆I L
⎛ VOUT
⎜⎜1 −
VIN
⎝
⎞
⎟⎟
⎠
Adjustable Output Voltage
The AT1366B appears a 0.6V reference voltage at FB pin. The output voltage is set by
a resistive divider which is according to the following formula:
VOUT = 0.6V × (1 +
R2
)
R1
*R1=150KΩ for stability consideration.
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
1/18/2006 REV:1.2
Email:service@aimtron.com.tw
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AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
The Dissipation
The power loss is given by:
PLOSS = I O2 × RDS (ON ) − P × D + I O2 × R DS ( ON ) − N × (1 − D) + V IN × I O × (t r + t f ) × f s + I s × VIN
TJ ( MAX ) = T A + θ JA × PLOSS
3.3
4.7
Inductors Surface Mount
Manufacturer/Part No.
Sumida CDRH4D28-3R3
Sumida CDRH5D18-4R7
Mitsumi C3-K1.8L-3R3
Mitsumi C4-K1.8L-3R3
ABC SH40283R3YSB
ABC SH40284R7YSB
Capacitance(µF)
22
47
10
4.7
Capacitors Surface Mount
Manufacturer/Part No.
TDK C3216X5R0J226M
TDK C3225X5R0J46M
GRM42-6X5R 106K6.3
TAIYO JMK212BJ475MG
Inductance(µH)
3.3
4.7
3.3
Manufacturer Website
www.sumida.com
www.mitsumi.co.jp
www.atec-group.com
Manufacturer Website
www.tdk.com
www.tdk.com
www.murata.com
www.t-yuden.com
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
1/18/2006 REV:1.2
Email:service@aimtron.com.tw
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AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
PC Board Layout
1. The most critical aspect of the layout is the placement of the input capacitor C1. It
must be placed as close as possible to the AT1366B to reduce the input ripple
voltage.
2. Power loops on the input and output of the converter should be laid out with the
shortest and widest traces possible. The longer and narrower the trace, the higher
resistance and inductance it will have. The length of traces in series with the
capacitors increases its ESR and ESL and reduces their effectiveness at high
frequency.
3. The FB pin should connect to feedback resistors directly. And the route should be
away from the noise source, such as inductor of SW line.
4. Grounding all components at the same point may effectively reduce the occurrence
of loop.
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
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AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
Package Outline :SOT-25
SYMBOL
A
A1
A2
b
C
D
E
E1
L
e
e1
r
INCHES
MIN
0.035
0.000
0.035
0.010
0.003
0.110
0.102
0.059
0.014
MAX
0.057
0.006
0.051
0.020
0.008
0.122
0.118
0.069
0.022
0.037ref
0.075ref
00
100
MILLIMETERS
MIN
MAX
0.90
1.45
0.00
0.15
0.90
1.30
0.25
0.50
0.08
0.20
2.80
3.10
2.60
3.00
1.50
1.75
0.35
0.55
0.95ref
1.90ref
00
100
NOTES
-
-
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
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1/18/2006 REV:1.2
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AT1366B
Preliminary Product Information
1MHz,800mA Synchronous Buck Converter
Reflow Profiles
Profile Feature
Sn-Pb Eutectic Assembly
Large Body
Small Body
Pkg. thickness
Pkg. thickness
<2.5mm or Pkg.
≥2.5mm or Pkg.
3
volume ≥350mm3 volume <350mm
Average ramp-up rate
(TL to TP)
Preheat
-Temperature Min(Tsmin)
-Temperature Max (Tsmax)
-Time (min to max)(ts)
Tsmax to TL
-Ramp-up Rate
Time maintained above:
-Temperature (TL)
-Time (tL)
Peak Temperature(TP)
Time within 5°C of actual Peak
Temperature (tP)
Ramp-down Rate
Time
25°C
to
Peak
Temperature
3°C/second max.
Pb-Free Assembly
Large Body
Small Body
Pkg. thickness
Pkg. thickness
≥2.5mm or Pkg.
≥2.5mm or Pkg.
volume ≥350mm3 volume ≥350mm3
3°C/second max.
100°C
150°C
60-120 seconds
150°C
200°C
60-180 seconds
3°C/second max.
183°C
60-150 seconds
217°C
60-150 seconds
225+0/-5°C
10-30 seconds
240+0/-5°C
10-30 seconds
6°C/second max.
6 minutes max.
245+0/-5°C
10-30 seconds
250+0/-5°C
20-40 seconds
3°C/second max.
8 minutes max.
*All temperatures refer to topside of the package, measured on the package body surface.
7F, No.9, PARK AVENUE II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.
Tel: 886-3-563-0878
Fax: 886-3-563-0879
WWW: http://www.aimtron.com.tw
1/18/2006 REV:1.2
Email:service@aimtron.com.tw
14