Aimtron AT1362AN Synchronous buck converter with power good detector & ldo Datasheet

AT1362A/B
Preliminary Product Information
Synchronous Buck Converter
With Power Good Detector & LDO
Features
General Description
• Operation Voltage 2.5V~6.0V
• Oscillation frequency 1MHz
• Output Current Maximum 400mA(DC-DC
Converter)
• Built-In 400mA/LDO
• Power Good Indicator with Time Delay
Adjustable
• Built-In Current Limit
• Built-In UVLO
• Built-In Thermal ShutDown
The AT1362A/B provides complete control for
a
DC/DC
converter
optimized
for
high-performance microprocessor applications. It
consists of a synchronous step-down DC/DC
converter and a high-speed LDO regulator
connected in series with the DC/DC converter
output. A power good detector and LDO ON/OFF
control is also built-in(metal option). DC/DC
converter 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 AT1362A/B is a family of low-noise
synchronous step-down DC/DC converters that is
ideally suited for systems powered form 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.
Applications
• Power Supply for Slim Type devices
Block Diagram
VBG
VBG
VREG
UVLO
VCC
Vref
AGND
+
Current
Sense
+
R
SLOPE
5
Q
S
SW
OSC
Shoot
Throught
BPC
Vref
+
-
VCC
DELAY
Auto
Discharge
PGND
0.7
R2
R1
OUT1
1uA
*OUT1=2.5V/1.8V
Metal Option
PG
Current
Limit
UVLO
OUT2
R3
-
-
+
+
+
R4
CTL
0.7V
Vref
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
5/30/2006
REV:1.0
Email: [email protected]
1
AT1362A/B
Preliminary Product Information
Synchronous Buck Converter
With Power Good Detector & LDO
Pin Assignment
1
10
2
9
AT1362
3
8
4
7
5
6
AT1362A
AT1362B
DC/DC
2.5V
LDO
3.3V
DC/DC
1.8V
LDO
3.3V
DFN10 (TOP VIEW)
Ordering Information
Part Number
1362 N
:
A:1362AN
Package
DFN10,Green
Marking
B:1362BN
: Date Code
*For more marking information, contact our sales representative directly.
Pin Description
Symbol
Pin No.
1
2
3
4
5
6
7
PG
OUT1
VCC
SW
PGND
VBG
AGND
8
DELAY
9
10
Bottom
OUT2
BPC
GND
Descript
Power Good Indicator Output(Ative Hi)
DC/DC Output (2.5V or 1.8V)
Power Supply
DC/DC Inductor Node
Power Ground
Reference Output Voltage
Analog Ground
The capacitor connection terminal for LDO control and PG
delay time setup
LDO Output (3.3V)
LDO Input By-pass Capacitor Node
Analog Ground
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
5/30/2006
REV:1.0
Email: [email protected]
2
AT1362A/B
Preliminary Product Information
Synchronous Buck Converter
With Power Good Detector & LDO
Absolute Maximum Ratings*1
Parameter
Rated Value
Min.
Max.
Symbol
Power Supply Voltage
Input Pin Voltage
Unit
VCC
-0.3
+6.5
V
OUT1, OUT2
-0.3
VCC
V
SW, PG
-0.3
VCC+0.3
V
—
-
0.5
A
—
-
0.5
A
—
-
0.75
A
DFN10
-
35.25
0
DFN10
-
3
0
—
-20
+85
0
0
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
Thermal Resistance from Junction
to Case θJC
Operating temperature TA
Storage temperature
ESD Susceptibility*2
C/W
C/W
C
—
-20
+150
C
HBM
-
2
KV
MM
-
200
V
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
Symbol
Min.
Values
Typ.
Max.
Unit
Power supply voltage
VIN
2.5
--
6.0
V
Operating temperature*
TOP
-20
+25
+85
°C
Operating junction temperature
TJ
-
-
+150
°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
5/30/2006
REV:1.0
Email: [email protected]
3
AT1362A/B
Preliminary Product Information
Synchronous Buck Converter
With Power Good Detector & LDO
Electrical Characteristics
(VCC = 3.6V,Ta =+25℃ , unless otherwise noted. )
Parameter
Symbol
Condition
Values
Unit
Min. Typ. Max.
DC/DC CONVERTER
VCC UVLO
UVLO Hysteresis width
Input Supply Range
Quiescent Current
Output1 Voltage Accuracy
Output1 Voltage
line-regulation
Output1 Variation
with Temperature
Feedback current
Current Limit
Maximum Output Current
VUV
-
2.4
-
V
VUVHY
-
100
-
mV
VCC
2.5
-
6.0
V
-
500
-
µA
-2
-
+2
%
VOUT1-Line VCC=3.5V to 6.0V
-
0.1
0.5
%
Ta =-20℃ to +85℃
-
0.5
1.0
%
-
6
-
uA
0.6
0.7
0.8
A
400
-
-
mA
0.8
1.0
1.2
MHz
IS
VCC=3V→2V Sweep
Active Mode
VOUT1
IOUT1
ICL1
IO
VIN=5V, VOUT1=2.5V/1.8V
VIN=5V, VOUT1=2.5V/1.8V,
L=4.7uH
fosc1
Vout1=2.5V/1.8V
fosc2
Vout1=0V
-
200
--
KHz
RPFET
ILX= 300mA
-
0.3
0.4
Ω
RNFET
ILX= -300mA
-
0.25
0.35
Ω
-
±0.1
±1
µA
-
-
0.4
V
-
80
-
mV
-
-
1
uA
-
80
-
mV
0.8
1.0
1.2
uA
VOUT2
-2
-
+2
%
Current Limit
ICL2
450
-
-
mA
Dropout Voltage
VDV
IOUT2=400mA
-
400
600
mV
Load Regulation
∆VOUT2
IOUT2=1mA→ 100mA
-
15
50
mV
Line Regulation
LR
IOUT2=100mA, VOUT1=3.6V→6.0V
-
0.05
0.25
%
IOUT2=100mA, f=1kHz
-
60
-
dB
-
6
-
uA
Oscillator Frequency
RDS(ON) of P-Channel
MOSFET
RDS(ON) of N-Channel
MOSFET
SW Leakage Current
ISWL
CONTROL BLOCK
PG on voltage
PG Hysteresis width
VPGON
IPG=1mA
VPGTHYS
PG pin leak current
IPGTLK VPG=5.0V
LDO control on Hysteresis
VLDTHYS
width
DELAY Pin Charge Current IDELAY
LDO
Output2 Voltage Accuracy
Ripple Rejection Rate
PSRR
OUT2 Leakage Current
IOUT2LK
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
5/30/2006
REV:1.0
Email: [email protected]
4
AT1362A/B
Preliminary Product Information
Synchronous Buck Converter
With Power Good Detector & LDO
Typical characteristics
Efficiency VS. Output1 Current
100
95
95
90
90
85
85
Efficiency(%)
Efficiency(%)
Efficiency VS. Output1 Current
100
80
75
70
Vin=5V
Vout1=1.8V
65
L=3.3uH
70
Vout1=1.8V
L=4.7uH
Vin=5.0V
Vin=4.2V
60
L=4.7uH
55
75
65
L=2.2uH
60
80
Vin=3.8V
55
L=6.8uH
50
Vin=3.6V
50
10
100
Output1 Current(mA)
1000
10
100
Output1 Current(mA)
CH1:Vin, CH2:Vout1
CH1:DELAY, CH2:Vout1
CH3:Vout2, CH4:PG
CH3:Vout2, CH4:PG
CH1:Vout1, CH2:Vout2, CH4:Iout1
CH1:Vout1, CH2:Vout2, CH4:Iout2
Iout1=100mA~300mA, Iout2=200mA
Iout1=200mA, Iout2=100mA~300mA
1000
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
5/30/2006
REV:1.0
Email: [email protected]
5
AT1362A/B
Preliminary Product Information
Synchronous Buck Converter
With Power Good Detector & LDO
Typical Application Circuits
5V
UVLO
2.5V
1.8V
90%
0.7V
0.7V
VDELY
3.3V
90%
PG
t1
t2
Timing of Power-On Sequencing
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
5/30/2006
REV:1.0
Email: [email protected]
6
AT1362A/B
Preliminary Product Information
Synchronous Buck Converter
With Power Good Detector & LDO
Typical Application Circuits ( Continued )
VBG
VIN
5.0V
VCC
10nF
10uF
AGND
4.7uH
DELAY
VOUT1
2.5V/400mA
SW
10nF
10uF
BPC
AT1362A
PGND
0.1uF
OUT1
To DSP
PG
OUT2
100K
VOUT2
3.3V/400mA
2.2uF
Figure 1
VIN
5.0V
VCC
VBG
10nF
10uF
AGND
4.7uH
VOUT1
1.8V/400mA
SW
DELAY
10uF
10nF
BPC
AT1362B
0.1uF
PGND
OUT1
To DSP
OUT2
PG
VOUT2
3.3V/400mA
2.2uF
100K
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
5/30/2006
REV:1.0
Email: [email protected]
7
AT1362A/B
Preliminary Product Information
Synchronous Buck Converter
With Power Good Detector & LDO
Application Information
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 AT1362A/B. 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 10µF 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:
I RMS =
1 VOUT × (VIN − VOUT )
L × f × VIN
2 3
VBG Capacitor
A VBG pin is provided to decouple the bandgap reference voltage. An external
capacitor connected form VBG to GND reduces noise present on the internal
reference voltage, which in turn significantly reduces output noise and also improves
PSRR. Larger capacitor values may be used to further improve PSRR, but result in a
longer time period (slower turn on) to settle output voltage when power is initially
applied.
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
5/30/2006
REV:1.0
Email: [email protected]
8
AT1362A/B
Preliminary Product Information
Synchronous Buck Converter
With Power Good Detector & LDO
LDO
For general purposes, use a 2.2uF capacitor on the LDO output. Larger capacitor
values and lower ESR provide better supply noise rejection and transient response. A
higher value input capacitor may be necessary if large, fast transients are anticipated .
Ceramic capacitors have the lowest ESR, and will offer the best AC performance.
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  VOUT
1 −
f × ∆I L 
VIN
I PK = I O +



(V − VOUT ) × t ON
∆I L
= I O + IN
2
2× L
Power Good Indicator with Adjustable Time Delay
When OUT1 pin is above 2.25V or 1.62V (typ.) and with a delay time (t1) the OUT2
is start to regulation. The PG pin terminal is an open drain output of N-MOS. Connect
a resistor from PG pin to VCC or OUT2 to create a logic signal. If OUT2 pin is less
than 2.97V (typ.) this pin is pulled to ground. When OUT2 pin is above 2.97V (typ.)
and with a delay time (t2) this pin is open. PG pin is forced low when in UVLO. The
formula of adjustable delay time is as below:
0.7V
delay − time = t1 = t 2 = C ×
I DELAY
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
5/30/2006
REV:1.0
Email: [email protected]
9
AT1362A/B
Preliminary Product Information
Synchronous Buck Converter
With Power Good Detector & LDO
The Dissipation
The power loss is given by:
2
2
PLOSS ( DC − DC ) = I OUT
1 × R DS ( ON ) − P × D + I OUT 1 × R DS ( ON ) − N × (1 − D ) + V IN × I OUT 1 × (t r + t f ) × f s + I s × V IN
PLOSS ( LDO ) = I OUT 2 × (VIN − VOUT 2 )
TJ ( MAX ) = T A + θ JA × ( PLOSS ( DC − DC ) + PLOSS ( LDO ) )
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
2.2
4.7
Capacitors Surface Mount
Manufacturer/Part No.
TDK C3216X5R0J226M
TDK C3225X5R0J46M
GRM42-6X5R 106K6.3
TAIYO LMK212BJ225MD
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
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
5/30/2006
REV:1.0
Email: [email protected]
10
AT1362A/B
Preliminary Product Information
Synchronous Buck Converter
With Power Good Detector & LDO
PC Board Layout
1. The most critical aspect of the layout is the placement of the input capacitor C2. It
must be placed as close as possible to the AT1362A/B 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 OUT1 pin should connect to C1 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
WWW: http://www.aimtron.com.tw
5/30/2006
REV:1.0
Email: [email protected]
11
AT1362A/B
Preliminary Product Information
Synchronous Buck Converter
With Power Good Detector & LDO
Package Outline : DFN10
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
5/30/2006
REV:1.0
Email: [email protected]
12
AT1362A/B
Preliminary Product Information
Synchronous Buck Converter
With Power Good Detector & LDO
Reflow Condition (IR/Convection or VPR Reflow)
Classification Reflow Profiles
Profile Feature
Average ramp-up rate
(TL to TP)
Sn-Pb Eutectic Assembly
3°C/second max.
Pb-Free Assembly
3°C/second max.
100°C
150°C
60-120 seconds
150°C
200°C
60-180 seconds
183°C
60-150 seconds
217°C
60-150 seconds
See table 1
10-30 seconds
See table 2
10 seconds max.
6°C/second max.
6 minutes max.
6°C/second max.
8 minutes max.
Preheat
-Temperature Min(Tsmin)
-Temperature Max (Tsmax)
-Time (min to max)(ts)
Time maintained above:
-Temperature (TL)
-Time (tL)
Peak/Classification Temperature(TP)
Time within 5°C of actual
Temperature (tP)
Ramp-down Rate
Time 25°C to Peak Temperature
Peak
*All temperatures refer to topside of the package, measured on the package body surface.
Classification Reflow Profiles(Cont.)
Table 1. SnPb Entectic Process –Package Peak Reflow Temperatures
Package Thickness
<2.5mm
≥2.5mm
3
3
Volume mm <350
240+0/-5℃
225+0/-5℃
Volume mm ≥350
225+0/-5℃
225+0/-5℃
Table 2. Pb-free Process –Package Classification Reflow Temperatures
Package Thickness
<1.6mm
1.6mm - 2.5mm
≥2.5mm
3
Volume mm <350
260+0℃
260+0℃
250+0℃
3
Volume mm 350-2000
260+0℃
250+0℃
245+0℃
3
Volume mm >2000
260+0℃
245+0℃
245+0℃
*Tolerance: The device manufacturer/supplier shall assure process compatibility up to and
including the stated classification temperature (this means Peak reflow temperature +0˚С. For
example 260˚С+0˚С) at the rated MSL level.
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
5/30/2006
REV:1.0
Email: [email protected]
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