Datasheet

A S1 3 2 2
L o w Vo lt a g e, M i c ro p o w e r, D C- DC St ep - U p C o n v e r te r s
1 General Description
2 Key Features
The AS1322A and the AS1322B are synchronous, fixed frequency,
very high-efficiency DC-DC boost converters capable of supplying
3.3V at 150mA from a single AA-supply. Compact size and minimum
external parts requirements make these devices perfect for modern
portable devices.
95% Efficiency
High-speed switching frequency (1.2MHz) and internally
compensated PWM current mode design provide highly-reliable DCDC conversion, especially when driving white LEDs.
Delivers 220mA @ 5.0V (from Two AA Cells)
The converters are available as the standard products listed in Table
1.
Low Start-Up Voltage: 0.85V
Single-Cell Operation
Delivers 160mA @ 3.3V (from Single AA Cell)
Delivers 570mA @ 3.3V (from Two AA Cells)
High-Speed Fixed-Frequency: 1.2MHz
Table 1. Standard Products
Internal PMOS Synchronous Rectifier
Model
Light Load Switching
AS1322A
Automatic Powersave Operation
AS1322B
Continuous Switching
Automatic Powersave Operation (AS1322A)
Continuous Switching at Light Loads (AS1322B)
Anti-Ringing Control Minimizes EMI
The devices contain two internal MOSFET switches: one NMOS
switch and one PMOS synchronous rectifier.
Logic Controlled Shutdown (< 1µA)
Anti-ringing control circuitry reduces EMI by damping the inductor in
discontinuous mode, and the devices exhibit extremely low
quiescent current (< 1µA) in shutdown.
Output Range: 2.5 to 5.0V
6-pin TSOT-23 Package
In shutdown mode the battery is connected to the output and VOUT
is held at approximately VIN - 0.6V.
The AS1322 is available in a 6-pin TSOT-23 package.
3 Applications
Figure 1. Typical Application Diagram – Single Cell to 3.3V
Synchronous Boost Converter
The AS1322 is ideal for low-power applications where ultra-small
size is critical as in medical diagnostic equipment, hand-held
instruments, pagers, digital cameras, remote wireless transmitters,
MP3 players, LCD bias supplies, cordless phones, GPS receivers,
and PC cards.
L1
4.7µH
1
SW
6
AA Battery
5
VOUT
VIN
C1
10µF
On
Off
AS1322
4
C2
10µF
3
SHDNN
FB
2
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R1
1.02MΩ
1%
VOUT
3.3V
160mA
GND
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R2
604kΩ
1%
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AS1322
Datasheet - P i n A s s i g n m e n t s
4 Pin Assignments
Figure 2. Pin Assignments (Top View)
SW 1
GND 2
6 VIN
AS1322
FB 3
5
VOUT
4 SHDNN
4.1 Pin Descriptions
Table 2. Pin Descriptions
Pin Number
Pin Name
1
SW
2
GND
3
FB
4
SHDNN
5
VOUT
6
VIN
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Description
Switch Pin. Connect an inductor between this pin and VIN. Keep the PCB trace lengths as
short and wide as is practical to reduce EMI and voltage overshoot. If the inductor current
falls to zero, or pin SHDNN is low, an internal 100Ω anti-ringing switch is connected from this
pin to VIN to minimize EMI.
Note: An optional Schottky diode can be connected between this pin and VOUT.
Signal and Power Ground. Provide a short, direct PCB path between this pin and the
negative side of the output capacitor(s).
Feedback Pin. Feedback input to the gm error amplifier. Connect a resistor divider tap to this
pin. The output voltage can be adjusted from 2.5 to 5V by: VOUT = 1.23V[1 + (R1/R2)]
Shutdown Pin. Logic controlled shutdown input.
1 = Normal operation, 1.2MHz typical operating frequency.
0 = Shutdown; quiescent current <1µA. If SHDNN is undefined, pin SW may ring.
Note: In a typical application, SHDNN should be connected to VIN through a 1MΩ pull-up
resistor.
Output Voltage Sense Input and Drain of the Internal PMOS Synchronous Rectifier.
Bias is derived from VOUT when VOUT exceeds VIN. PCB trace length from VOUT to the
output filter capacitor(s) should be as short and wide as is practical. VOUT is held at
approximately VIN - 0.6V during shutdown.
Input Voltage. The AS1322 gets its start-up bias from VIN unless VOUT exceeds VIN, in
which case the bias is derived from VOUT. Thus, once started, operation is completely
independent from VIN. Operation is only limited by the output power level and the internal
series resistance of the supply.
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AS1322
Datasheet - A b s o l u t e M a x i m u m R a t i n g s
5 Absolute Maximum Ratings
Stresses beyond those listed in Table 3 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 Section 6 Electrical Characteristics on page 4 is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Table 3. Absolute Maximum Ratings
Parameter
Min
Max
Units
VIN to GND
-0.3
7
V
SHDNN, SW to GND
-0.3
7
V
FB to GND
-0.3
5
V
VOUT
-0.3
7
V
Operating Temperature Range
-40
+85
ºC
Storage Temperature Range
-65
+125
ºC
Package Body Temperature
Moisture Sensitive Level
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+260
1
ºC
Notes
The reflow peak soldering temperature (body
temperature) specified is in accordance with IPC/
JEDEC J-STD-020 “Moisture/Reflow Sensitivity
Classification for Non-Hermetic Solid State
Surface Mount Devices”.
The lead finish for Pb-free leaded packages is
matte tin (100% Sn).
Represents an unlimited floor life time
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AS1322
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
6 Electrical Characteristics
TAMB = -40 to +85ºC, VIN = +1.2V, VOUT = +3.3V, VSHDNN = +1.2V (unless otherwise specified). Typ values @ TAMB = +25ºC.
Table 4. Electrical Characteristics
Symbol
Parameter
Conditions
Min
Minimum Start-Up Voltage
ILOAD = 1mA
Minimum Operating Voltage
SHDNN = VIN
Output Voltage Adjust Range
TAMB = 25ºC
2.5
VFB
Feedback Voltage
TAMB = TMIN to TMAX
1.192
IFB
Feedback Input Current
VFB = 1.25V
IQPWS
Quiescent Current
(Powersave Operation)
VFB = 1.4V , AS1322A only
30
50
µA
IQSHDNN
Quiescent Current (Shutdown)
VSHDNN = 0V
0.01
1
µA
1
2
Typ
Max
Units
0.85
1
V
0.65
0.85
V
5
V
1.268
V
1.23
1
3
3
nA
IQ
Quiescent Current (Active)
VFB = 1.4V , AS1322B only
150
300
µA
INMOSSWL
NMOS Switch Leakage
VSW = 5V
0.1
5
µA
IPMOSSWL
PMOS Switch Leakage
VSW = 0V
0.1
5
µA
RONNMOS
NMOS Switch On Resistance
VOUT = 3.3V
0.35
0.8
VOUT = 5V
0.20
0.7
RONPMOS
PMOS Switch On Resistance
VOUT = 3.3V
0.45
0.8
VOUT = 5V
0.30
0.7
INMOS
NMOS Current Limit
VIN = 2.5V
850
mA
IPS
Powersave Operation Current
Threshold
AS1322A only
3
mA
Max Duty Cycle
VFB = 1V, TAMB = TMIN to TMAX
80
87
%
TAMB = 25ºC
0.95
1.2
1.5
TAMB = TMIN to TMAX
0.85
1.2
1.5
fSW
Switching Frequency
VSHDNNH
SHDNN Input High
VSHDNNL
SHDNN Input Low
ISHDNN
SHDNN Input Current
2
1
VSHDNN = 5.0V
Ω
Ω
MHz
V
0.01
0.35
V
1
µA
1. Minimum VIN operation after start-up is only limited by the battery’s ability to provide the necessary power as it enters a deeply discharged state.
2. Specification is guaranteed by design and not 100% production tested.
3. IQPWS is measured at VOUT. Multiply this value by VOUT/VIN to get the equivalent input (battery) current.
Note: All limits are guaranteed. The parameters with min and max values are guaranteed with production tests or SQC (Statistical Quality
Control) methods.
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AS1322
Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
7 Typical Operating Characteristics
Figure 3. Powersave mode threshold vs. VIN,
VOUT = 3.0V
Figure 4. Efficiency vs. Output Current,
VOUT = 3.3V
100
90
25
Efficiency (%) .
Output Current (mA)
.
30
20
15
10
5
VIN = 2.4V
80
VIN = 1.5V
70
VIN = 1.0V
60
50
40
30
0
0.5 0.75
1
1.25 1.5 1.75
2
1
2.25 2.5
10
3.36
3.5
3.34
3
3.32
3.3
3.28
3.26
2.5
2
1.5
1
0.5
0
-25
0
25
50
75
100
0
0.5
1
Temperature (°C)
1.5
900
1.4
.
1000
800
1.3
Output Current (mA)
Startup Voltage (V) .
2
2.5
3
3.5
Figure 8. Output Current vs. Battery Voltage;
VOUT = 3.3V, 3% Tolerance
1.6
700
1.2
1.1
1
5V
3.3V
0.8
1.5
Battery Voltage (V)
Figure 7. Startup Voltage vs. Output Current;
0.9
1000
Figure 6. Output Voltage vs. Battery Voltage;
VOUT = 3.3V, IOUT = 10mA
Output Voltage (V) .
Output Voltage (V) .
Figure 5. Output Voltage vs. Temperature;
VOUT = 3.3V, IOUT = 10mA
3.24
-50
100
Output Current (mA)
Battery Voltage (V)
0.7
600
500
400
300
200
100
0.6
0
0.1
1
10
100
0.5
Output Current (mA)
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1
1.5
2
2.5
3
Battery Voltage (V)
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AS1322
Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
Figure 9. Output Current vs. Battery Voltage;
VOUT = 5.0V, 3% ToleranceVOUT = 3.3V, TAMB = 25ºC
Figure 10. No Load Battery Current vs. VBATT
900
1000
Battery Current (µA) .
.
800
Output Current (mA)
700
600
500
400
300
200
100
100
0
10
0.5
1
1.5
2
2.5
3
3.5
4
1.2 1.4 1.6 1.8
Battery Voltage (V)
2
2.2 2.4 2.6 2.8
Figure 12. SW Pin Fixed Frequency Continuous Current
VIN = 1.3V, VOUT = 3.3V, L = 10µH, C = 10µF, IOUT = 100mA
1V/Div
100ns/Div
100ns/Div
40mA
60mA
100mV/Div
VOUT(AC)
1mA
100mA
100mV/Div
Figure 14. Fixed Frequency vs. Powersave Operation
VIN = 1.3V, VOUT = 3.3V, L = 10µH, C = 10µF
IOUT
Figure 13. VOUT Transient Response.
VIN = 1.3V, VOUT = 3.3V, L = 10µH, C = 10µF
VOUT(AC)
0V
VSW
0V
VSW
1V/Div
Figure 11. SW Pin Antiringing Operation
VIN = 1.3V, VOUT = 3.3V, L = 10µH, C = 10µF, IOUT = 5mA
IOUT
3
Battery Voltage (V)
100µs/Div
10ms/Div
Parts used for measurements: 10µH (MOS6020-103ML) Inductor, 10µF (GRM31CR70J106KA01L) CIN and COUT
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AS1322
Datasheet - D e t a i l e d D e s c r i p t i o n
8 Detailed Description
The AS1322/AS1322B can operate from a single-cell input voltage (VIN) below 1V, and feature fixed frequency (1.2MHz) and current mode
PWM control for exceptional line- and load-regulation. With low RDS(ON) and gate charge internal NMOS and PMOS switches, the devices
maintain high-efficiency from light to heavy loads.
Modern portable devices frequently spend extended time in low-power or standby modes, switching to high power-drain only when certain
functions are enabled. The AS1322A and the AS1322B are ideal for portable devices since they maintain high-power conversion efficiency over
a wide output power range, thus increasing battery life in these types of devices.
In addition to high-efficiency at moderate and heavy loads, the AS1322A includes an automatic powersave mode that improves efficiency of the
power converter at light loads. The powersave mode is initiated if the output load current falls below a factory programmed threshold (see Figure
3 on page 5).
Note: The AS1322B does not support powersave mode and provides continuous operation at light loads, eliminating low-frequency VOUT
ripple at the expense of light load efficiency.
Figure 15. AS1322 - Block Diagram
L1
4.7µH
1.5V
Single Cell
6
VIN
Start Up
OSC
CIN
1µF
1
SW
2.3V
–
A
B
VOUT
Good
A/B
MUX
PWM
Control
1.2MHz
Ramp
Generator
VOUT
CFF*
Current
Sense
Σ
Slope
Compensator
+
0.45Ω
0.35Ω
Sync Drive
Control
AS1322
+
PWM –
Comp
–
4
SHDNN
Shutdown
Control
Powersave
Shutdown
Powersave
Operation
Control
RC
80kΩ
CC
150pF
3.3V
Output
5
3
–
gm Error
Amp
+
R1
1.02MΩ
1%
COUT
4.7µF
FB
CP2
2.5pF
R2
640kΩ 1%
1.23V
Ref
2
GND
* Optional
8.1 Low-Voltage Start-Up
The AS1322 requires VIN of only 0.85V (typ) or higher to start up. The low-voltage start-up circuitry controls the internal NMOS switch up to a
maximum peak inductor current of 850mA (typ), with 1.5ms (approx.) off-time during start-up, allowing the devices to start up into an output load.
With a VOUT > 2.3V, the start-up circuitry is disabled and normal fixed-frequency PWM operation is initiated. In this mode, the AS1322 operates
independent of VIN, allowing extended operating time as the battery can drop to several tenths of a volt without affecting output regulation. The
limiting factor for the application is the ability of the battery to supply sufficient energy to the output.
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AS1322
Datasheet - D e t a i l e d D e s c r i p t i o n
8.2 Low-Noise Fixed-Frequency Operation
8.2.1
Oscillator
The AS1322 switching frequency is internally fixed at 1.2MHz allowing the use of very small external components.
8.2.2
Error Amplifier
The integrated error amplifier is an internally compensated trans-conductance (gm) type (current output). The internal 1.23V reference voltage is
compared to the voltage at pin FB to generate an error signal at the output of the error amplifier. A voltage divider from VOUT to GND programs
the output voltage from 2.5 to 5V via pin FB as:
VOUT = 1.23V(1 + (R1/R2))
8.2.3
(EQ 1)
Current Sensing
A signal representing the internal NMOS-switch current is summed with the slope compensator. The summed signal is compared to the error
amplifier output to provide a peak current control command for the PWM. Peak switch current is limited to approximately 850mA independent of
VIN or VOUT.
8.2.4
Zero Current Comparator
The zero current comparator monitors the inductor current to the output and shuts off the PMOS synchronous rectifier once this current drops to
20mA (approx.). This prevents the inductor current from reversing polarity and results in improved converter efficiency at light loads.
8.2.5
Anti-Ringing Control
Anti-ringing control circuitry prevents high-frequency ringing on pin SW as the inductor current approaches zero. This is accomplished by
damping the resonant circuit formed by the inductor and the capacitance on pin SW (CSW).
8.3 Powersave Operation (AS1322A)
In light load conditions, the integrated powersave feature removes power from all circuitry not required to monitor VOUT. When VOUT has
dropped approximately 1% from nominal, the AS1322A powers up and begins normal PWM operation.
COUT (see Figure 15 on page 7) recharges, causing the AS1322A to re-enter powersave mode as long as the output load remains below the
powersave threshold. The frequency of this intermittent PWM is proportional to load current; i.e., as the load current drops further below the
powersave threshold, the AS1322A turns on less frequently. When the load current increases above the powersave threshold, the AS1322A will
resume continuous, seamless PWM operation.
Notes:
1. An optional capacitor (CFF) between pins VOUT and FB in some applications can reduce VOUTp-p ripple and input quiescent current
during powersave mode. Typical values for CFF range from 15 to 220pF.
2. In powersave mode the AS1322A draws only 30µA from the output capacitor(s), greatly improving converter efficiency.
8.4 Shutdown
When pin SHDNN is low the AS1322 is switched off and <1µA current is drawn from battery; when pin SHDNN is high the device is switched on.
If SHDNN is driven from a logic-level output, the logic high-level (on) should be referenced to VOUT to avoid intermittently switching the device
on.
Note: If pin SHDNN is not used, it should be connected directly to pin OUT. VOUT is held at approximately VIN - 0.6V during shutdown.
In shutdown the battery input is connected to the output through the inductor and the internal synchronous rectifier P-FET. Due to the body diode
of the internal synchronous rectifier PFET, VOUT is held at approximately VIN - 0.6V during shutdown. This allows the input battery to provide
backup power for devices such as an idle microcontroller, memory, or real-time-clock, without the usual diode forward drop. In this way a
separate backup battery is not needed.
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AS1322
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
9 Application Information
The AS1322 is perfectly suited for LED matrix displays, bar-graph displays, instrument-panel meters, dot matrix displays, set-top boxes, white
goods, professional audio equipment, medical equipment, industrial controllers to name a few applications.
Along with Figure 1 on page 1, Figures 16-19 depict a few of the many applications for which the AS1322 converters are perfectly suited.
Figure 16. Single AA Cell to 3.3V Synchronous Boost Converter with Load Disconnect in Shutdown
L1
4.7µH
D1
1
SW
5
6
AA
Battery
VIN
C1
4.7µF
AS1322
On
Off
4
VOUT
3.3V, 160mA
VOUT
C2
4.7µF
R3
510kΩ
R1
1.02MΩ
1%
3
SHDNN
FB
2
R2
604kΩ
1%
GND
Q1
R3
510kΩ
Figure 17. Single Lithium Cell to 5V, 250mA
2Ω
Optional
Snubber
100nF
L1
4.7µH
D1
1
SW
5
6
Lithium
Battery
VIN
C1
4.7µF
On
Off
AS1322
R1
1.02MΩ 1%
C3
100pF
3
4
SHDNN
FB
2
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VOUT
C2
4.7µF
GND
Revision 1.10
R2
332kΩ 1%
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AS1322
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
Figure 18. Single AA Cell to ±3V Synchronous Boost Converter
C3
1µF
L1
4.7µH
1
SW
AA
Battery
C1
4.7µF
VOUT1
3V, 90mA
5
6
VOUT
VIN
On
Off
4
C2
4.7µF
R1
1.02MΩ
1%
AS1322
3
D1
FB
SHDNN
2
D2
C4
10µF
R2
750kΩ
1%
GND
VOUT2
-3V, 10mA
Figure 19. Single AA Cell to 2.5V Synchronous Boost Converter
L1
4.7µH
D1
1
SW
5
6
AA
Battery
C1
10µF
On
Off
R1
1.02MΩ
1%
AS1322
C2
10µF
3
4
FB
SHDNN
2
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VOUT
2.5V, 230mA
VOUT
VIN
GND
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R2
1.02MΩ
1%
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AS1322
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
9.1 Output Voltage Ripple
The AS1322 is designed to work at high efficiency. In order to reduce the output ripple the following improvements are recommended:
Use a higher output capacitor, up to 44µF and a higher input capacitor (22µF).
Use smaller values for the resistor divider. R1 should be about 300kΩ. To avoid a high leakage current from pin VOUT through the resistor
divider to GND, R1 should not be less than 100kΩ.
To reduce the output ripple it’s also possible to speed up the feedback loop. To achieve this, place a 22pF (C4 in Figure 20) capacitor in
parallel to R1. Via C4 the fast transients are shorted to the FB pin and the feedback loop is even faster. A 1MΩ resistor for R1 slows down
the FB loop.
Due to noise and to their non linear behavior, the use of potentiometers is not recommended.
Figure 20. AS1322 - Typical Application for lower Output Voltage Ripple
L1
4.7µH
1
2xAA Battery
SW
VOUT
VIN
C1
22µF
C4
22pF
AS1322
On
Off
VOUT = 2.8V
5
6
R1
250kΩ
C2
22µF
C3
22µF
3
4
FB
SHDNN
2
GND
R2
196kΩ
Note: For correct measurements of the output ripple connect the oscilloscope probe as close as possible to the positive plate of the COUT
and connect the GND of the oscilloscope probe to the negative plate of the COUT. This will reduce the inductive coupling and will
deliver a more accurate measurement result.
The output ripple is getting higher as VIN is getting closer to VOUT. Figure 21 shows that the above mentioned improvements reduce the output
voltage ripple. If VIN is higher than VOUT the AS1322 stops switching and VIN is connected to VOUT via the inductor and the internal P-FET.
Figure 21. Output Voltage Ripple vs. Input Voltage; VOUT = 2.8V, IOUT = 0.8mA
Output Voltage Ripple (mVpp)
125
Cout = 44µF
Cout = 66µF
100
Cout = 44µF + C4 = 22pF
75
50
25
0
0.5
1
1.5
2
2.5
3
3.5
Input Voltage (V)
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AS1322
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
9.2 External Component Selection
9.2.1
Inductor Selection
The fast switching frequency (1.2MHz) of the AS1322 allows for the use of small surface mount or chip inductor for the external inductor (see
Figure 15 on page 7).
The required minimum values for the external inductor are:
3.3µH for applications ≤ 3.6V
4.7µH for applications > 3.6V
Larger inductor values allow greater output current capability by reducing the inductor ripple current. Increasing the inductance above 10µH will
increase size while providing negligible improvement in output current capability.
The approximate output current capability of the AS1322 versus inductor value is given in:
V IN ⋅ D
I OUT ( MAX ) = η ⋅  I P – ------------------ ⋅ ( 1 – D )

f ⋅ L ⋅ 2
(EQ 2)
Where:
η is the estimated efficiency;
IP is the peak current limit value (0.6A);
VIN is the input voltage;
D is the steady-state duty ratio = (VOUT - VIN)/VOUT;
f is the switching frequency (1.2MHz typ);
L is the inductor value.
The inductor current ripple is typically set for 20 to 40% of the maximum inductor current (IP). High-frequency ferrite core inductor materials
reduce frequency dependent power losses compared to less expensive powdered iron types, which result in improved converter efficiency.
2
The inductor should have low ESR to reduce the I R power losses, and must be able to handle the peak inductor current without saturating.
Molded chokes and some chip inductors normally do not have enough core to support the peak inductor currents of the AS1322 (850mA typ). To
minimize radiated noise, use a toroid, pot core, or shielded bobbin inductor.
Table 5. Recommended Inductors
Part Number
L
DCR
Current Rating
Dimensions (L/W/T)
MOS6020-103ML
10µH
93mΩ
1A
6.8x6.0x2.4mm
MOS6020-472ML
4.7µH
50mΩ
1.5A
6.8x6.0x2.4mm
MOS6020-332ML
3.3µH
46mΩ
1.8A
6.8x6.0x2.4mm
CDRH4D18-100
10µH
200mΩ
0.61A
6.9x5.0x2.0mm
CDRH4D18-6R8
6.8µH
200mΩ
0.76A
6.9x5.0x2.0mm
CR43-6R8
6.8µH
131.2mΩ
0.95A
4.8x4.3x3.5mm
CDRH4D18-4R7
4.7µH
162mΩ
0.84A
6.9x5.0x2.0mm
www.ams.com/DC-DC_Step-Up/AS1322
Revision 1.10
Manufacturer
Coilcraft
www.coilcraft.com
Sumida
www.sumida.com
12 - 18
AS1322
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
Figure 22. Efficiency Comparison of Different Inductors, VIN = 1.5V, VOUT = 3.3V
92
90
85
90
80
88
Efficiency (%)
Efficiency (%)
75
70
65
60
10uH - Coi l cr af t (M OS6020-103M L)
55
10uH - Sumi da(CDRH4D18-100)
84
82
10uH - Coi l cr af t (M OS6020-103M L)
80
6. 8uH - Sumi da(CDRH4D18-6R8)
50
86
6. 8uH - Sumi da(CR43-6R8)
10uH - Sumi da(CDRH4D18-100)
6. 8uH - Sumi da(CDRH4D18-6R8)
6. 8uH - Sumi da(CR43-6R8)
4. 7uH - Coi l cr af t(M OS6020-472M L)
45
78
4. 7 uH - Sumi da(CDRH4D18-4R7)
4. 7uH - Coi l cr af t (M OS6020-472M L)
4. 7 uH - Sumi da(CDRH4D18-4R7)
3. 3 uH - Coi l c r af t (M OS6020-332M L)
3. 3 uH - Coi l cr af t (M OS6020-332M L)
40
0.1
1
10
10
Output Current (mA)
9.2.2
Ser i es 8
76
Output Current (mA)
100
Output Capacitor Selection
Low ESR capacitors should be used to minimize VOUT ripple. Multi-layer ceramic capacitors are recommended since they have extremely low
ESR and are available in small footprints. A 2.2 to 10µF output capacitor is sufficient for most applications. Larger values up to 22µF may be
used to obtain extremely low output voltage ripple and improve transient response.
An additional phase lead capacitor may be required with output capacitors larger than 10µF to maintain acceptable phase margin. X5R and X7R
dielectric materials are recommended due to their ability to maintain capacitance over wide voltage and temperature ranges.
Table 6. Recommended Output Capacitor
Part Number
C
TC Code
Rated Voltage
Dimensions (L/W/T)
JMK212BJ226MG-T
22µF ±20%
X5R
6.3V
2x1.3x1.3mm
Manufacturer
Taiyo Yuden
www.t-yuden.com
Input Capacitor Selection. Low ESR input capacitors reduce input switching noise and reduce the peak current drawn from the battery.
Ceramic capacitors are recommended for input decoupling and should be located as close to the device as is practical. A 4.7µF input capacitor
is sufficient for most applications. Larger values may be used without limitations.
Table 7. Recommended Input Capacitor
Part Number
C
TC Code
Rated Voltage
Dimensions (L/W/T)
GRM31CR70J106KA01L
10µF ±10%
X7R
6.3V
3.2x1.6x1.6mm
Manufacturer
Murata
www.murata.com
Diode Selection. A Schottky diode should be used to carry the output current for the time it takes the PMOS synchronous rectifier to switch
on. For VOUT < 4.5V a Schottky diode is optional, although using one will increase device efficiency by 2 to 3%.
Note: Do not use ordinary rectifier diodes, since the slow recovery times will compromise efficiency.
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Revision 1.10
13 - 18
AS1322
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
9.3 PCB Layout Guidelines
The high-speed operation of the AS1322 requires proper layout for optimum performance. Figure 23 shows the recommended component
layout.
A large ground pin copper area will help to lower the device temperature.
A multi-layer board with a separate ground plane is recommended.
Traces carrying large currents should be direct.
Trace area at pin FB should be as small as is practical.
The lead-length to the battery should be as short as is practical.
Figure 23. Recommended Single-Layer Component Placement
Optional
VIN 6
1 SW
AS1322
VIN
R2
2 GND
VOUT
5
CIN
SHDNN
3
FB
R1
SHDNN 4
COUT
VOUT
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Revision 1.10
14 - 18
AS1322
Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s
10 Package Drawings and Markings
The device is available in a 6-pin TSOT-23 package.
Figure 24. 6-pin TSOT-23 Package
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Revision 1.10
15 - 18
AS1322
Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s
Figure 25. 6-pin TSOT-23 Marking
Pin1
Top
ZZZZ
Bottom
XXXX
Pin1
Package Code:
ZZZZ - Marketingcode
XXXX - encoded Datecode
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Revision 1.10
16 - 18
AS1322
Datasheet
11 Ordering Information
The device is available as the standard products listed in Table 8.
Table 8. Ordering Information
Ordering Code
Marking
Description
Delivery Form
Package
AS1322A-BTTT
ASKQ
Low Voltage, Micropower, DC-DC Step-Up Converter with
Automatic Powersave Operation
Tape and Reel
6-pin TSOT-23
AS1322B-BTTT
ASKZ
Low Voltage, Micropower, DC-DC Step-Up Converter with
Continuous Switching
Tape and Reel
6-pin TSOT-23
Note: All products are RoHS compliant.
Buy our products or get free samples online at ICdirect: http://www.ams.com/ICdirect
Technical Support is found at http://www.ams.com/Technical-Support
For further information and requests, please contact us mailto:[email protected]
or find your local distributor at http://www.ams.com/distributor
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Revision 1.10
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AS1322
Datasheet - O r d e r i n g I n f o r m a t i o n
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to designing this product into a system, it is necessary to check with ams AG for current information. This product is intended for use in normal
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Revision 1.10
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