AS1329
Low Voltage, Micropower, DC-DC Step-Up Converters
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 1 - 21
Datasheet
1 General Description
The AS1329A, AS1329B and the AS1329C are synchronous, fixed
frequency, very high-efficiency DC-DC boost converters capable of
supplying 3.3V at 160mA from a single AA-supply . Compact size and
minimum e xternal pa rts requirem ents make t hese devic es perfect f or
modern portable devices.
High-speed switching frequency (1.2MHz) and internally
compensated PWM current mode design provide highly-reliable DC-
DC conversion, especially when driving white LEDs. The converters
are available as the standard products listed in Table 1.
The devices contain two internal MOSFET switches: one NMOS
switch and one PMOS synchronous rectifier. Anti-ringing control
circuitry reduces EMI by damping the inductor in discontinuous
mode, and the devices exhibit extremely low quiescent current (<
1µA) in shutdown.
In shutdown mode the battery is connected directly to the output
enabling the supply of real-time-clocks. The AS1329 is available in a
6-pin TSOT-23 package and 6-bump WL-CSP.
Figure 1. Typical Application Diagram – Single Cell to 3.3V
Synchronous Boost Converter
2 Key Features
! Low Start-Up Voltage: 0.85V
! Output Range: 2.5V to 5.0V
! Single-Cell Operation
! Operating with coils down to 2.2µH
! Delivers 160mA @ 3.3V (from Single AA Cell)
! Delivers 220mA @ 5.0V (from Two AA Cells)
! Delivers 570mA @ 3.3V (from Two AA Cells)
! 95% Efficiency
! High-Speed Fixed-Frequency: 1.2MHz
! Internal PMOS Synchronous Rectifier
! Automatic Powersave Operation (AS1329A&B)
! Continuous Switching at Light Loads (AS1329C)
! Logic Controlled Shutdown (< 1µA)
! 6-pin TSOT-23 Package and 6-bump WL-CSP
3 Applications
The AS1329 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.
Table 1. Standard Products
Model Light Load Switching
AS1329A Medium Load
Automatic Powersave Operation
AS1329B Light Load Automatic Powersave Operation
AS1329C Continuous Switchi ng
AA Battery
AS1329
C2
10µF
R2
604kΩ
1%
R1
1.02MΩ
1%
On
Off
L1
4.7µH
C1
10µF
GND
2
SW
1
VOUT
3.3V
160mA
4
SHDNN
3
FB
6
VIN
5
VOUT
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 2 - 21
AS1329
Datasheet - Pin Assignments
4 Pin Assignments
Figure 2. Pin Assignments (Top View)
4.1 Pin Descriptions
Table 2. Pin Descript ions
Pin Number Pin Name Description
1SW
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.
2GND Signal and Power Ground. Provide a short, direct PCB path between this pin and the
negative side of the output capacitor(s).
3FB 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)]
4SHDNN
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.
5VOUT Output Voltage Sense Input and Drain of the Internal PMOS Synchronous Rectifier.
Bias is derived from VOUT when VOUT exc eeds VIN. PCB trace length from VOUT to the
output filter capacitor(s) should be as short and wide as is practical.
6VIN
Input Voltage. The AS1329 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.
1
SW
AS1329
2
GND
3
FB
6VIN
5VOUT
4SHDNN
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 3 - 21
AS1329
Datashee t - A b s o l u t e M a x i mu 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 Notes
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 +260 ºC
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).
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 4 - 21
AS1329
Datasheet - Electrical Characteristics
6 Electrical Characteristics
T
AMB
= -40°C to +85ºC,
VIN
= +1.2V, V
OUT
= +3.3V,
VSHDNN
= +1.2V (unless otherwise specified). Typ values @ T
AMB
= +25ºC.
Note: All limits are guaranteed. The parameters with min and max values are guaranteed with production tests or SQC (Statistical Quality
Control) methods.
Table 4. Electrical Characteristics
Symbol Parameter Conditions Min Typ Max Units
Minimum Start-Up Voltage ILOAD = 1mA 0.85 1 V
Minimum Operating Voltage SHDNN = VIN 1
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 dis-
charged state.
0.65 0.85 V
Maximum Operating Voltage SHDNN = VIN 1 5V
Output Voltage Adjust Range TAMB = 25ºC 2.5 5 V
VFB Feedback Voltage TAMB = TMIN to TMAX 1.192 1.23 1.268 V
IFB Feedback Input Current VFB = 1.25V 2
2. Specification is guaranteed by design and not 100% production tested.
1 nA
IQPWS Quiescent Current
(Powers ave Operation) VFB = 1.4V 3, AS1329A onl y
3. IQPWS is measured at VOUT. Multiply this value by VOUT/VIN to get the equivalent input (battery) current.
30 50 µA
ISHDNN Shutdown Current VSHDNN = 0V 0.01 1 µA
IQQuiescent Current (Active) VFB = 1.4V 3, AS1329B&C 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 Ω
VOUT = 5V 4
4. Specification is guaranteed by design and not 100% production tested.
0.20 0.7
RONPMOS PMOS Switch On Resistance VOUT = 3.3V 0.45 0.8 Ω
VOUT = 5V 4 0.30 0.7
INMOS NMOS Current Limit VIN = 2.5V 850 mA
IPS Powersave Operation Current
Threshold AS1329A only 23 mA
AS1329B only 20.3 mA
Max Duty Cycle VFB = 1V, TAMB = TMIN to TMAX 80 87 %
fSW Switching Frequency TAMB = 25ºC 0.95 1.2 1.5 MHz
TAMB = TMIN to TMAX 0.85 1.2 1.5
VSHDNNH SHDNN Input High 1 V
VSHDNNL SHDNN Input Low 0.35 V
ISHDNN SHDNN Input Current VSHDNN = 5.0V 0.01 1 µA
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 5 - 21
AS1329
Datasheet - Typical Operating Characteristics
7 Typical Operating Characteristics
All measurements are performed with AS1329A, VOUT = 3.3V, TAMB = +25ºC, unless otherwise specified.
Parts used for measurements: L= 10µH (MOS6020-103ML), CIN and COUT = 10µF (GRM31CR70J106KA01L)
Figure 3. VOUT vs. Battery Voltage; IOUT = 10mA Figure 4. VOUT vs. Temperature; IOUT = 10mA
0
0.5
1
1.5
2
2.5
3
3.5
00.511.522.533.5
Batt er y Volt age ( V)
Output Voltage ( V ) .
3.24
3.26
3.28
3.3
3.32
3.34
3.36
-50-25 0 25 50 75100
Temperature ( °C)
Output Voltage ( V ) .
Figure 5. Startup Voltage vs. Output Current Figure 6. Powersave threshold vs. Input Voltage
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
0.1 1 10 100
Output Current (mA )
S tartup Voltage ( V ) .
Vout = 3.3V
Vout = 5.0V
0
20
40
60
80
100
120
1 1.25 1.5 1.75 2 2.25 2.5
B attery Voltage ( V)
O ut put Current (mA) .
AS1329A
AS1329B
Figure 7. IOUT vs. VBATT; VOUT = 3.3V, 3% Tolerance Figure 8. IOUT vs. VBATT; VOUT = 5.0V, 3% Tolerance
0
100
200
300
400
500
600
700
800
900
1000
0.5 1 1.5 2 2.5 3
Batt er y Volt age ( V)
O utput Curr ent (m A ) .
0
100
200
300
400
500
600
700
800
900
0.511.522.533.54
Battery Voltage (V )
O utput Curr ent (m A ) .
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 6 - 21
AS1329
Datasheet - Typical Operating Characteristics
Figure 9. No Load Battery Current vs. Battery Voltage; Figure 10. Efficiency vs. Battery Voltage; AS1329A
10
100
1000
1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3
Battery Voltage (V )
Batt er y Cur r ent (µA ) .
20
30
40
50
60
70
80
90
100
0.7 1.2 1.7 2.2 2.7 3.2
B attery Voltage ( V)
Ef ficiency (%) .
Iload = 80µA
Iload = 800µA
Iload = 11m A
Figure 11. Efficiency vs. Output Current of AS1329A Figure 12. Efficiency vs. Output Current of AS1329B
20
30
40
50
60
70
80
90
100
0.1 1 10 100 1000
Output Current (mA )
Ef ficiency (%) .
Vin = 1.0V
Vin = 1.5V
Vin = 2.2V
Vin = 2.4V 20
30
40
50
60
70
80
90
100
0.1 1 10 100 1000
Output Current (mA)
Ef ficiency (%) .
Vin = 1.0V
Vin = 1.5V
Vin = 2.2V
Vin = 2.4V
Figure 13. Efficiency vs. Output Current of AS1329C Figure 14. Efficiency vs. IOUT Comparison; VIN = 2.0V
20
30
40
50
60
70
80
90
100
0.1 1 10 100 1000
Output Current (mA )
Ef ficiency (%) .
Vin = 1.0V
Vin = 1.5V
Vin = 2.2V 20
30
40
50
60
70
80
90
100
1 10 100
Output Current (mA )
Ef ficiency (%) .
AS1329A
AS1329B
AS1329C
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 7 - 21
AS1329
Datasheet - Typical Operating Characteristics
Figure 15. SW Pin Antiringing Operation; VIN = 1.3V, L = 10µH,
C = 10µF, IOUT = 5mA Figure 16. SW Pin Fixed Frequency Continuous Current; VIN =
1.3V, L=10µH, C=10µF, IOUT = 100mA
100ns/Div
0V 1V/Div
VSW
100ns/Div
VSW
0V 1V/Div
Figure 17. VOUT Transient Response; VIN = 1.3V,
L = 10µH, C = 10µF Figure 18. Fixed Frequency vs. Powersave Operation; VIN = 1.3V,
L = 10µH, C = 10µF
100µs/Div
VOUT(AC)
IOUT
40mA 100mA 100mV/Div
10ms/Div
VOUT(AC)
1mA 60mA 100mV/Div
IOUT
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 8 - 21
AS1329
Datasheet - Detailed Description
8 Detailed Description
The AS1329 can operate from a single-cell input voltage (VIN) below 1V, and features 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 device maintains 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 AS1329A, AS1329B and AS1329C 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 AS1329A as well as the AS1329B 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 6 on page 5).
Note: The AS1329C does not support powersave mode and provides continuous operation at all loads, eliminating low-frequency VOUT rip-
ple at the expense of light load efficiency.
Figure 19. AS1329 - Bl ock Diagram
8.1 Low-Voltage Start-Up
The AS1329 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 AS1329 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.
AS1329
+
–
Start Up
OSC
PWM
Control
A/B
MUX
Slope
Compensator
1.2MHz
Ramp
Generator
+
–
Powersave
Operation
Control
–
Shutdown
Control
PWM
Comp
Σ
+
–
1.23V
Ref
Sync Drive
Control
A
BVOUT
Good
2.3V
gm Error
Amp
Shutdown
Powersave
0.35Ω0.45Ω
R2
640kΩ 1%
R1
1.02MΩ
1%
CFF*
COUT
4.7µF
3.3V
Output
CIN
1µF
1.5V
Single Cell
* Optional
Current
Sense
RC
80kΩCP2
2.5pFCC
150pF
GND
2
SW
1
4
SHDNN
3
FB
6
VIN 5
VOUT
L1
4.7µH
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AS1329
Datasheet - Detailed Description
8.2 Low-Noise Fixed-Frequency Operation
8.2.1 Oscillator
The AS1329 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)) (EQ 1)
8.2.3 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 curren t d r ops t o
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 (AS1329A, AS1329B)
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 AS1329A & B powers up and begins normal PWM operation.
COUT (see Figure 19 on page 8) recharges, causing the AS1329A and AS1329B 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 AS1329A and AS1329B turns on less frequently. When the load current increases above the
powersave threshold, the AS1329A and AS1329B will resume continuous, seamless PWM operation.
While the AS1329A switches to automatic powersave mode already at medium loads, the AS1329B will do so only at very light loads.
The AS1329C is a continuous switching device, hence the output voltage ripple is very low and no additional frequencies are produced which
may cause interference.
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 AS1329A and AS1329B draws only 30µA from the output capacitor(s), greatly improving converter efficiency.
8.4 Shutdown
When pin SHDNN is low the AS1329 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.
In shutdown the battery input is connected to the output through the inductor and the internal synchronous rectifier P-FET. 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.
In cases where there is residual voltage during shutdown, some small amount of energy will be transferred from pin OUT to pin BATT
immediately after shutdown, resulting in a momentary spike of the voltage at pin BATT. The ratio of CIN and COUT partly determine the size and
duration of this spike, as does the current-sink ability of the input device.
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 10 - 21
AS1329
Datasheet - Application In formation
9 Application Information
The AS1329 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 20-23 depict a few of the many applications for which the AS1329 converters are perfectly suited.
Figure 20. Single AA Cell to 3.3V Synchronous Boost Converter with Load Disconnect in Shutdown
Figure 21. Single Lithium Cell to 5V, 250mA
AS1329 C2
4.7µF
R2
604kΩ
1%
On
Off
Q1
L1
4.7µH
AA
Battery C1
4.7µF
R3
510kΩ
R3
510kΩ
VOUT
3.3V, 160mA
D1
R1
1.02MΩ
1%
GND
2
SW
1
4
SHDNN
3
FB
6
VIN
5
VOUT
AS1329 C2
4.7µF
R2
332kΩ 1%
R1
1.02MΩ 1%
On
Off
L1
4.7µH
Lithium
Battery C1
4.7µF
D1
C3
100pF
100nF
2Ω
Optional
Snubber
GND
2
SW
1
4
SHDNN
3
FB
6
VIN
5
VOUT
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 11 - 21
AS1329
Datasheet - Application In formation
Figure 22. Single AA Cell to ±3V Synchronous Boost Converter
Figure 23. Single AA Cell to 2.5V Synchronous Boost Converter
AS1329
R2
750kΩ
1%
R1
1.02MΩ
1%
On
Off
L1
4.7µH
AA
Battery C1
4.7µF
C3
1µF
D1
VOUT2
-3V, 10mA
VOUT1
3V, 90mA
C2
4.7µF
C4
10µF
D2
GND
2
SW
1
4
SHDNN
3
FB
6
VIN
5
VOUT
AS1329 C2
10µF
R2
1.02MΩ
1%
R1
1.02MΩ
1%
On
Off
L1
4.7µH
AA
Battery C1
10µF
VOUT
2.5V, 230mA
D1
GND
2
SW
1
4
SHDNN
3
FB
6
VIN
5
VOUT
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 12 - 21
AS1329
Datasheet - Application In formation
9.1 Output Voltage Ripple
The AS1329 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 24) 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 24. AS1329 - Typical Application for lower Output Voltage Ripple
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 m ore accurate measurement resul t.
The output ripple is getting higher as VIN is getting closer to VOUT. Figure 25 shows that the above mentioned improvements reduce the output
voltage ripple. If VIN is higher than VOUT the AS1329 stops switch ing and VIN is connected to VOUT via the inductor and the internal P-FET.
Figure 25. Output Voltage Ripple vs. Input Voltage; VOUT = 2.8V, IOUT = 0.8mA
AS1329 C2
22µF
R2
196kΩ
R1
250kΩ
On
Off
L1
4.7µH
2xAA Battery
C1
22µF
VOUT = 2.8V
GND
2
SW
1
4
SHDNN
3
FB
5
VOUT C3
22µF
C4
22pF
6
VIN
0
25
50
75
100
125
0.5 1 1.5 2 2.5 3 3.5
Input Volt age ( V)
Output V oltage Ripple ( m V pp)
Cout = 44µF
Cout = 66µF
Cout = 44µF + C4 = 22pF
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 13 - 21
AS1329
Datasheet - Application In formation
9.2 Smallest External Components
The AS1329 is also able to work with smallest Capacitors and Inductors (see Figure 26).
Figure 26. AS1329 - Typical Application for Smallest External Components
Figure 27. Efficiency vs. Output Current with Smallest External Components
Table 5. Recommended Smallest Components
Part Number Value Code Rating Size Manufacturer
C1 GRM188R61A225KE34 2.2µF X5R 10V 0603 Murata
www.murata.com
C2 GRM188R60J475KE19 4.7µF X5R 6.3V 0603
L1 LQM31PN2R2M00 2.2µH 238mΩ0.9A 1206
AS1329 C2
4.7µF
R2
kΩ
R1
kΩ
On
Off
L1
2.2µH
2xAA Battery
C1
2.2µF
VOUT = 5V
GND
2
SW
1
4
SHDNN
3
FB
5
VOUT
6
VIN
20
30
40
50
60
70
80
90
100
1 10 100 1000
Output Current (mA)
Ef ficiency (%) .
Vin = 3.3V
Vin = 3.5V
Vin = 3.8V
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 14 - 21
AS1329
Datasheet - Application In formation
9.3 External Component Selection
9.3.1 Inductor Selection
The fast switching frequency (1.2MHz) of the AS1329 allows for the use of small surface mount or chip inductor for the external inductor (see
Figure 19 on page 8).
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 AS1329 versus inductor value is given in:
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.
The inductor should have low ESR to reduce the I²R 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 AS1329 (850mA typ). To
minimize radiated noise, use a toroid, pot core, or shielded bobbin inductor.
Table 6. Recommended Inductors
Part Number LDCR Current Rating Dimensions (L/W/T) Manufacturer
MOS6020-103ML 10µH 93mΩ1A 6.8x6.0x2.4mm Coilcraft
www.coilcraft.com
MOS6020-472ML 4.7µH 50mΩ1.5A 6.8x6.0x2.4mm
MOS6020-332ML 3.3µH 46mΩ1.8A 6.8x6.0x2.4mm
CDRH4D18-100 10µH 200mΩ0.61A 6.9x5.0x2.0mm Sumida
www.sumida.com
CDRH4D18-6R8 6.8µH 200mΩ0.76A 6.9x5.0x2.0mm
CR43-6R8 6.8µH 131.2mΩ0.95A 4.8x4.3x3.5mm
CDRH4D18-4R7 4.7µH 162mΩ0.84A 6.9x5.0x2.0mm
(EQ 2)
IOUT MAX()ηIPVIN D⋅
fL2⋅⋅
------------------
–
⎝⎠
⎛⎞
1D–()⋅⋅=
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 15 - 21
AS1329
Datasheet - Application In formation
Figure 28. Efficiency Comparison of Different Inductors, VIN = 1.5V, VOUT = 3.3V
9.3.2 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.
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.
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 .
Table 7. Recommended Output Capacitor
Part Number CTC Code Rated Voltage Dimensions (L/W/T) Manufacturer
JMK212BJ226MG-T 22µF ±20% X5R 6.3V 2x1.3x1.3mm Taiyo Yuden
www.t-yuden.com
Table 8. Recommended Input Capacitor
Part Numb er CTC Code Rated Voltage Dimensions (L/W/T) Manufacturer
GRM31CR70J106KA01L 10µF ±10% X7R 6.3V 3.2x1.6x1.6mm Murata
www.murata.com
10010
76
78
80
82
84
86
88
90
92
Output Current (mA)
Ef ficiency (%)
10uH - Coilcr af t (MOS6020-103ML)
10uH - S um ida(CDRH4D18-100)
6.8u H - Sum ida( CDRH4D1 8 -6R8 )
6.8uH - S umida(CR43-6R8)
4.7uH - Coilcr af t(MOS6020-472ML)
4.7 uH - S um ida(CDRH4D18-4R7)
3.3 uH - Coilcr af t(MOS6020-332ML)
40
45
50
55
60
65
70
75
80
85
90
0.1 1 10
Output Current (mA)
Efficiency (%)
10uH - Coilcr af t (MOS 6020-103ML)
10u H - Sum ida (CDRH4D1 8-1 00)
6.8uH - Sumida(CDRH4D1 8-6 R8)
6.8uH - S um ida(CR43-6R8)
4.7uH - Coilcr af t(MOS 6020-472ML)
4.7 uH - Sum ida(CDRH4 D18- 4R7)
3.3 uH - Coilcraf t(MOS6020-332ML)
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 16 - 21
AS1329
Datasheet - Application In formation
9.4 PCB Layout Guidelines
The high-speed operation of the AS1329 requires proper layout for optimum performance. Figure 29 shows the recom men ded 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.
! T races carrying large currents should be direct.
! T race 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 29. Recommended Single-Layer Component Placement
1AS1329
2
3
6
5
4
Optional
SHDNN
VIN
FB
VOUT
GND
SW
VOUT
VIN
SHDNN
R2
R1COUT
CIN
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 18 - 21
AS1329
Datasheet - Package Drawings and Markings
Notes:
1. Dimensioning and tolerancing conform to ASME Y14.5M - 1994.
2. Dimensions are in millimeters.
3. Dimension D does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, and gate burrs shall not exceed 0.15mm
per end. Dimension E1 does not include interlead flash or protrusion. Interlead flash or protrusion shall not exceed 0.15mm per side.
Dimensions D and E1 are determined at datum H.
4. The package top can be smaller than the package bottom. Dimensions D and E1 are determined at the outermost extremes of the
plastic body exclusive of mold flash, tie bar burrs, gate burrs, and interlead flash, but include any mistmatches between the top of the
package body and the bottom. D and E1 are determined at datum H.
5. Datums A and B are to be determined at datum H.
6. These dimensions apply to the flat section of the lead between 0.08 and 0.15mm from the lead tip.
7. Dimension b does not include dambar protrusion. Allowable dambar protrusion shall be 0.08mm total in excess of the b dimension at
the maximum material condition. The dambar cannot be located on the lower radius of the foot. Minimum space between the
protrusion and an adjacent lead shall not be less than 0.77mm.
Tolerances of Form and Position
aaa 0.15 1,2
bbb 0.25 1,2
ccc 0.10 1,2
ddd 0.20 1,2
Symbol Min Typ Max Notes
A1.00
A1 0.01 0.05 0.10
A2 0.84 0.87 0.90
b 0.30 0.45 6,7
b1 0.31 0.35 0.39 6,7
c 0.12 0.15 0.20 6
c1 0.08 0.13 0.16 6
D 2.90BSC 3,4
E 2.80BSC 3,4
E1 1.60BSC 3,4
Symbol Min Typ Max Notes
e 0.95BSC
e1 1.90BSC
L 0.30 0.40 0.50
L1 0.60REF
L2 0.25BSC
N6
R0.10
R1 0.10 0.25
θ0º 4º 8º
θ14º 10º 12º
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 20 - 21
AS1329
Datasheet - Ordering Information
11 Ordering Information
The device is available as the standard products listed in Table 9.
Note: All products are RoHS compliant.
Buy our products or get free samples online at ICdirect: http://www.austriamicrosystems.com/ICdirect
Technical Support is found at http://www.austriamicrosystems.com/Technical-Support
For further information and requests, please contact us mailto:sales@austriamicrosystems.com
or find your local distributor at http://www.austriamicrosystems.com/distributor
Design the AS1329 online at http://www.austriamicrosystems.com/analogbench
analogbench is a powerful design and simulation support tool that operates in on-line and off-line mode to evaluate performance and
generate application-specific bill-of-materials for austriamicrosystems' power management devices.
Table 9. Ordering Information
Ordering Code Marking Description Delivery Form Package
AS1329A-BTTT ASPA Low Voltage, Micropower , DC-DC Step-Up Converter with
Automatic Powersave Operation beginning at Medium
Loads Tape and Reel 6-p in TSOT-23
AS1329B-BTTT ASPB Low V oltage, Micropower , DC-DC Step-Up Converter with
Automatic Powersave Operation beginning at Light Loads Tape and Reel 6-pin TSOT-23
AS1329C-BTTT ASPC Low V oltage, Micropower , DC-DC Step-Up Converter with
Continuous Switching Tape and Reel 6-pin TSOT-23
AS1329A-BWLT tbd Low Voltage, Micropower , DC-DC Step-Up Converter with
Continuous Switching Tape and Reel 6-bump WL-CSP
www.austriamicrosystems.com/DC-DC_Step-Up/AS1329 Revision 1.11 21 - 21
AS1329
Datasheet
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All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of
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the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at
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specifically not recommended without additional processing by austriamicrosystems AG for each application. For shipments of less than 100
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