AMSCO AS1326A

AS1326
D a ta S he e t
H i g h C u r r e n t , 0 . 8 A D C - D C St e p - U p C o n v e r t e r s
1 General Description
2 Key Features
The AS1326A/AS1326B are high-efficiency, high current, DC-DC step-up converters specifically designed for
battery-powered wireless applications. Low quiescent
supply current (65µA), high operating frequency (1MHz),
and minimal external component requirements make
these devices perfect for small hand-held applications.
Table 1. Standard Products
Model
Input Signal Activation
AS1326A
Logic-Low On
AS1326B
Logic-High On
Both devices use synchronous-rectified pulse-width
modulation (PWM) boost technology to generate 2.5 to
5.0V outputs from a wide range of inputs, such as 1 to 3
alkaline/NiCd/NiMH cells or a single lithium-ion (Li+)
cell. Automatic powersave operation significantly
improves efficiency at light-loads.
Continuous switching mode is available for applications
requiring constant-frequency operation at all load currents. PWM operation can also be synchronized to an
external clock to protect sensitive frequency bands in
communications equipment.
!
Up to 800mA Output
!
Constant-Frequency (1MHz) Operation
!
Up to 96% Efficiency
!
Input Range: 0.7 to 5.0V
!
Fixed Output: 3.3V
!
Adjustable Output: 2.5 to 5.0V
!
PWM Synchronous-Rectified Technology
!
Logic-Controlled Shutdown: 0.1µA
!
Synchronizable Switching Frequency
(0.5 to 1.2MHz)
!
Adjustable Current Limit
!
Adjustable Soft-Start
!
10-pin TDFN (3.0mm x 3.0mm) Package
3 Applications
Analog soft-start and adjustable current limit permit optimization of rush in current and external component size.
The devices are ideal for digital cordless phones. mobile
phones, wireless handsets, hand-held instruments,
PDAs, two-way pagers, and any battery-operated equipment.
The AS1326A/AS1326B are available in a 10-pin TDFN
(3.0mm x 3.0mm) package.
Figure 1. Block Diagram
5
OUT
+
AS1326A
only
AS1326
IC Power
2.15V
AS1326B
only
Undervoltage
Lockout
9
–
On
Q
Startup
Osc
10
ON
10
ONN
2
REF
3
D
POUT
Controller
8
On
Rdy
1.25V Reference
Ref GND
En
Osc
1MHz Osc
CLK/SEL Mode
En
Osc
LX
Mode
7
PGND
GND
6
FB
CLK/SEL
4
ISET
FB
1
ISET
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Revision 1.02
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AS1326
Data Sheet - P i n o u t
4 Pinout
Pin Assignments
Figure 2. Pin Assignments (Top View)
ISET 1
10 ONN/ON
REF 2
9 POUT
GND 3
AS1326A/
AS1326B
FB 4
OUT 5
8 LX
7 PGND
11
6 CLK/SEL
Pin Descriptions
Table 2. Pin Descriptions
Pin Number
Pin Name
1
ISET
2
REF
3
GND
4
FB
5
OUT
6
CLK/SEL
7
8
9
PGND
LX
POUT
ONN
10
ON
11
NC
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Description
N-Channel Current-Limit Control. For maximum current limit, connect to pin REF.
To reduce current, supply a voltage between pin REF and GND using a resistive
voltage-divider. If soft-start is desired, connect a capacitor from this pin to GND.
1.250V Internal Reference Bypass. Connect a 10nF ceramic bypass capacitor to
GND. Up to 50µA of external load current is allowed.
Ground. Connect this pin to PGND using a short trace. The exposed pad can be
used for this routing.
DC-DC Converter Feedback Input. To set fixed output voltage of +3.3V, connect
this pin to GND. For adjustable output of 2.5 to 5.0V, connect to a resistor-divider
network from pin OUT to GND. The set point for this pin is 1.24V.
IC Power, Supplied from the Output. Bypass this pin to GND with a 330nF
ceramic capacitor, and connect to POUT with a 10Ω series resistor (see Figure 19
on page 11).
Clock Input for the DC-DC Converter. This pin is also used to program the
operational mode as follows:
0 = Normal operation – the AS1326A operates at a fixed frequency, and switches
into automatic powersave operation if the load is minimized.
1 = Forced-PWM mode – the AS1326A operates in low-noise, constant-frequency
mode at all loads.
Clocked = Forced-PWM mode with the internal oscillator synchronized to this pin in
500 to 1200kHz range.
N-Channel Power MOSFET Switch Source
Inductor Connection
Power Output. P-channel synchronous rectifier source.
Enable Low (AS1326A only). Must be connected to GND for normal operation.
0 = The AS1326A is on.
1 = The AS1326A is off.
Enable High (AS1326B only). Must be connected to OUT for normal operation.
0 = The AS1326B is off.
1 = The AS1326B is on.
Exposed Pad. This pad is not connected internally. It can be used for ground
connection between GND and PGND.
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AS1326
Data Sheet - 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 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
ON, ONN, OUT, CLK/SEL to GND
-0.3
7
V
PGND to GND
-0.3
+0.3
V
REF, FB, ISET, POUT to GND
-0.3
VOUT +
0.3
V
LX to PGND
-0.3
VPOUT +
0.3
V
POUT to OUT
-0.3
+0.3
V
33
ºC/W
Thermal Resistance ΘJA
Operating Temperature Range
-40
+85
ºC
Storage Temperature Range
-65
+150
ºC
+150
ºC
Junction Temperature
Package Body Temperature
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+260
ºC
Revision 1.02
Comments
on PCB
The reflow peak soldering temperature (body
temperature) specified is in accordance with
IPC/JEDEC J-STD-020C “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).
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AS1326
Data Sheet - 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
CLK/SEL = FB = PGND = GND, ISET = REF, OUT = POUT, VOUT = 3.6V, TAMB = -40 to +85ºC. Typical values are at
TAMB = +25ºC. Unless otherwise specified.
Table 4. Electrical Characteristics
Symbol
Parameter
Condition
Min
Typ
Max
Unit
0.7
5.0
V
0.9
1.1
V
DC-DC Converter
1
VIN
Input Voltage Range
VMINSU
Minimum Startup Voltage
2
ILOAD < 1mA, TAMB = +25ºC
Temperature Coefficient of
Startup Voltage
-1.6
mV/°C
fSU
Frequency in Startup Mode
VOUT = 1.5V
125
500
1000
kHz
fSW
Internal Oscillator Frequency
CLK/SEL = OUT
0.8
1
1.2
MHz
Oscillator Maximum
3
Duty Cycle
80
86
90
%
fSWEXT
External Clock
Frequency Range
0.5
1.2
MHz
VOUT
Output Voltage
3.3
3.38
V
VFB
FB Regulation Voltage
1.240
1.270
V
IFB
FB Input Leakage Current
VFB = 1.35V, TAMB = +25ºC
0.01
100
nA
Load Regulation
CLK/SEL = OUT, no load to full load,
0 < ILX < 1.0A
3.17
Adjustable output, CLK/SEL = OUT,
includes load regulation for 0 < ILX < 0.55A 1.215
Output Voltage
Adjust Range
VOUTADJ
ISHDN
VFB < 0.1V, CLK/SEL = OUT, includes load
regulation for 0 < ILX < 0.55A
-100
-1
2.5
%
5.0
V
Output Voltage
4
Lockout Threshold
Rising edge
2.00
2.15
2.30
V
ISET Input Leakage Current
VISET = 1.25V, TAMB = +25ºC
-50
0.01
50
nA
Supply Current in Shutdown
VON = 0V, VONN = 3.6V
0.1
5
µA
CLK/SEL = GND
65
100
µA
CLK/SEL = OUT
2
POUT Leakage Current
VLX = 0, VOUT = 5.5V, TAMB = +25ºC
0.1
10
µA
LX Leakage Current
VLX = VOUT = 5.5V, in shutdown,
TAMB = +25ºC
0.1
10
µA
N-channel
0.2
0.35
P-channel
0.25
0.45
1.25
1.6
1.95
A
1.230
1.250
1.270
V
5
No-Load Supply Current
5
No-Load Supply Current ,
Forced PWM Mode
mA
DC-DC Switches
RON
Switch On-Resistance
INMOS
N-Channel Current Limit
Ω
References
VREF
Reference Output Voltage
IREF = 0
Reference Load Regulation
-1µA < IREF < +50µA
5
15
mV
Reference Supply Rejection
2.5V < VOUT < 5V
0.2
6
mV
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AS1326
Data Sheet - 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
Table 4. Electrical Characteristics (Continued)
Symbol
Parameter
Condition
CLK/SEL Input Low Level
2.5V ≤ VOUT ≤ 5.0V
CLK/SEL Input High Level
2.5V ≤ VOUT ≤ 5.0V
Min
Typ
Max
Unit
0.2 x
VOUT
V
Logic Inputs
ON, ONN Input Low Level
ON, ONN Input High Level
Input Leakage Current
6
6
0.8 x
VOUT
V
1.1V ≤ VOUT ≤ 1.8V
0.2
1.8V ≤ VOUT ≤ 5.0V
0.4
1.1V ≤ VOUT ≤ 1.8V
VOUT 0.2
1.8V ≤ VOUT ≤ 5.0V
1.6
CLK/SEL, ON, ONN, TAMB = +25ºC
V
V
0.1
1
µA
Minimum CLK/SEL
Pulse Width
200
ns
Maximum CLK/SEL
Rise/Fall Time
100
ns
1. Operating voltage; since the regulator is bootstrapped to the output, once started, the AS1326 operates down to
0.7V input. If CLK/SEL = GND then VIN ≤ VOUT. If CLK/SEL = VOUT then VIN ≤ 0.75xVOUT.
2. Startup is tested with the circuit shown in Figure 25 on page 14.
3. Defines maximum step-up ratio.
4. The regulator is in startup mode until this voltage is reached. Caution: Do not apply full load current until the
device output > 2.3V.
5. Supply current into pin OUT. This current correlates directly to the actual battery-supply current, but is reduced
in value according to the step-up ratio and efficiency.
6. ON and ONN have a hysteresis of typically 0.15V.
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AS1326
Data Sheet - 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
Circuit of Figure 19, VIN = 2.4V, VOUT = 3.3V, TA = +25°C, unless otherwise noted.
Figure 3. Efficiency vs. Output Current, VOUT = 3.3V
100
Figure 4. Efficiency vs. Output Current, VOUT = 5.0V
100
VIN = 2.4V
Powersave Mode
90
Efficiency (%) .
Efficiency (%) .
VIN = 1.2V
80
70
VIN = 0.9V
60
Powersave Mode
90 VIN = 3.6V
80
50
40
30
VIN = 3.0V
70
60 VIN = 2.4V
50
40
30
20
20
Continuous Mode
10
Continuous Mode
10
0
0
0.1
1
10
100
0.1
1000
1
10
100
1000
Output Current (mA)
Output Current (mA)
Figure 5. Maximum Output Current vs. Input Voltage;
Figure 6. No-Load Current vs. Input Voltage;
500
900
Input Current (µA) .
Output Current (mA)
.
800
700
VOUT = 3.3V
600
500
VOUT = 5V
400
300
400
300
VOUT = 5V
200
100
VOUT = 3.3V
200
0
100
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
4
Input Voltage (V)
Input Voltage (V)
Figure 7. Internal Oscillator Frequency vs. Temp;
Figure 8. Total Shutdown Current vs. Input Voltage
1.2
10
.
1.1
Shutdown Current (µA)
Frequency (MHz) .
1.15
1.05
1
0.95
0.9
0.85
1
0.1
0.8
0.75
-40
0.01
-15
10
35
60
85
0 0.5 1 1.5 2
Temperature (°C)
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2.5 3 3.5 4 4.5 5
Input Voltage (V)
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AS1326
Data Sheet - 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. Startup Voltage vs. Output Current
Figure 10. Peak Inductor Current vs. VISET
2.5
Peak Inductor Current (A)
Startup Voltage (V) .
.
1.6
2
1.5
+25°C
1
+85°C
1.4
1.2
1
0.8
0.6
0.4
0.2
-40°C
0.5
0
1
10
100
1000
0
0.2
0.4
0.6
1.2
1.4
5V/Div
200mA/Div
LX pin
500ns/Div
50mV/Div
50mV/Div
Output
Ripple
Inductor
Current
200mA/Div
LX pin
Inductor
Current
1
Figure 12. Heavy-Load Switching Waveform
IOUT = 500mA
5V/Div
Figure 11. Light-Load Switching Waveform
IOUT = 10mA, CLK/SEL = OUT
Output
Ripple
0.8
VISET (V)
Output Current (mA)
500ns/Div
Figure 13. Line-Transient Response. VIN =2.4 to 1.4V,
IOUT = 200mA
Figure 14. Noise Spectrum
CLK/SEL = OUT
4
.
3
RMS )
2.5
Noise (mV
VOUT
50mV/Div
Vin
1V/Div
3.5
2
1.5
1
0.5
0
0.2
500ns/Div
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1
10
20
Frequency (MHz)
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AS1326
Data Sheet - 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
IOUT
100ms/Div
100ms/Div
5V/Div
200mA/Div
2V/Div
ONN
Inductor
Current
VOUT
5V/Div
500mA/Div
Figure 18. Turn-On Waveform
Soft Start, RSS = 220kΩ ,CSS = 100nF
2V/Div
Inductor
Current
ONN
Figure 17. Turn-On Waveform
No Soft Start
VOUT
50mV/Div
50mV/Div
VOUT
0mA
VOUT
IOUT
0mA
100mA/Div
Figure 16. Load Transient Response
Continuous Switching, CLK/SEL = OUT
100mA/Div
Figure 15. Load Transient Response;
Automatic Powersave Mode, CLK/SEL = GND
2ms/Div
2ms/Div
Parts used for measurments: 3.3µH (Coilcraft MOS6020-332ML) Inductor, 33µF (Panasonic EEFCD0K330R) CIN,
100µF (Panasonic EEFUD0J101R) COUT
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AS1326
Data Sheet - D e t a i l e d D e s c r i p t i o n
8 Detailed Description
The AS1326A/AS1326B are high-efficiency, low-noise DC-DC boost converters suitable as power supplies for portable
devices. Both devices feature integrated boost switching regulator, N-channel power MOSFET, P-channel synchronous rectifier, precision reference, and shutdown control circuitry (see Figure 1 on page 1).
The AS1326A/AS1326B are able to boost a 1- to 3-cell battery voltage input to a fixed 3.3V output, or adjustable output
between 2.5 and 5.0V (an external Schottky diode is required for output voltages greater than 4V).
Table 5. Typical Output Voltages and Currents
# of NiCd/NiMh Cells
Input Voltage (V)
Output Voltage (V)
Output Current (mA)
1
1.2
3.3
335
2.4
3.3
800
2.4
5.0
450
3.6
5.0
800
2
3
The devices are guaranteed to startup with an input voltage as low as 1.1V and remain operational down to an input of
as little as 0.7V, and are optimized for use in mobile phones and other RF applications which have low noise and low
quiescent current (extended battery life) requirements.
The integrated shutdown circuitry reduces device quiescent current down to 0.1µA.
Step-Up Converter
During boost operation, the internal N-channel MOSFET switch turns on for the first part of each cycle, allowing current
to ramp up in the inductor and store energy in a magnetic field. During the second part of each cycle, the MOSFET
turns off and inductor current flows through the synchronous rectifier to the output filter capacitor and the load. As the
energy stored in the inductor is depleted, the current ramps down and the synchronous rectifier turns off.
At light loads, the device operates at fixed-frequency or only as needed to maintain regulation, depending on the setting of pin CLK/SEL (see Table 6).
Operational Modes
The AS1326A/AS1326B are capable of operating in 3 different modes (see Table 6) as controlled by pin CLK/SEL (see
page 2).
Table 6. Operational Modes
CLK/SEL Setting
Operational Mode
Description
0
Normal
High-efficiency at all loads; Fixed-frequency (1MHz) at heavy and
medium loads.
1
Forced PWM
Fixed-frequency (1MHz), low-noise at all loads. VIN ≤ 0.75xVOUT
External 500kHz to
1.2MHz clock
Synchronized PWM
Fixed-frequency, low-noise at all loads. VIN ≤ 0.75xVOUT
Normal Operation
When CLK/SEL is pulled low, the devices are in normal operating mode. In normal mode the devices operate in PWM
when driving medium-to-heavy loads, and automatically switches to automatic powersave mode if the load requires
less power. The use of automatic powersave mode will boost the efficiency futhermore at light-load conditions.
Forced-PWM Operation
Pulling CLK/SEL high, selects the low-noise PWM-only mode. During forced-PWM operation, the devices switch at a
constant frequency (1MHz) and modulates the MOSFET switch pulse width to control the power transferred per cycle
to regulate the output voltage. Switching harmonics generated by fixed-frequency operation are consistent and can be
filtered. See the Noise Spectrum plot in the Typical Operating Characteristics (see Figure 14 on page 7).
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AS1326
Data Sheet - D e t a i l e d D e s c r i p t i o n
Synchronized-PWM Operation
In PWM mode the AS1326A/AS1326B can be synchronized with an external clock (500kHz to 1.2MHz) by applying an
external clock signal to pin CLK/SEL. This synchronization will minimize interference in wireless applications since the
operating frequency can be set to a preferred value. The synchronous rectifier is active during synchronized-PWM
operation.
Synchronous Rectifier
The AS1326A/AS1326B feature an integrated, P-channel synchronous rectifier for enhanced efficiency operation. Synchronous rectification provides 5% improved efficiency over similar non-synchronous boost regulators.
In PWM mode, the synchronous rectifier is turned on during the second half of each switching cycle. In low-power
mode, an internal comparator turns on the synchronous rectifier when the voltage at LX exceeds the boost regulator
output.
Note: While operating with output voltages greater than 4V, an external 0.5A Schottky diode must be connected in
parallel with the P-channel synchronous rectifier.
Low-Voltage Startup Oscillator
The AS1326A/AS1326B contain a CMOS, low-voltage startup oscillator for a 1.1V guaranteed minimum startup input
voltage. At startup, the low-voltage oscillator switches on the N-channel MOSFET until the output voltage reaches
2.15V. With output voltages > 2.15V, the boost-converter feedback and control circuitry are acitvated.
When the AS1326A/AS1326B is in regulation, it can operate down to 0.7V input since internal power for the device is
bootstrapped from the output through pin OUT.
Caution: Do not apply full load until the output > 2.3V.
Shutdown
The AS1326A/AS1326B feature an integrated shutdown mode that reduces quiescent current to 0.1µA. During shutdown mode (ONN = 1 on AS1326A, ON = 0 on AS1326B), the internal reference and feedback/control circuitry are disabled.
Note: During shutdown, the output voltage is one diode drop below the input voltage.
Reference
The AS1326A/AS1326B contain an internal reference (1.250V ±1%). A 10nF ceramic bypass capacitor must be connected between pins REF and GND. REF can source up to 50µA of external load current.
Note: The bypass capacitor must be placed within 5mm (0.2”) of pin REF.
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AS1326
Data Sheet - 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
Figure 19. Typical AS1326A Application Circuit
3.3µH
VIN = 2.4V
33µF
8
LX
10
+
ONN
6
9
CLK/SEL
1
POUT
AS1326A
ISET
2
100µF
+
5
REF
4
10nF
10Ω
VOUT = 3.3V
800mA
OUT
330nF
FB
3
GND
7
PGND
Setting the Output Voltages
For a fixed 3.3V output, connect pin FB to GND. To set adjustable output voltages between 2.5 and 5.0V, connect a
resistor voltage-divider to pin FB from pin OUT to GND (Figure 20).
Figure 20. Application Circuit using External Feedback Resistors
3.3µH
VIN = 2.4V
33µF
8
LX
10
+
ONN
6
9
VOUT
POUT
CLK/SEL
1
10Ω
AS1326A
ISET
2
100µF
+
5
OUT
REF
R1
10nF
330nF
4
FB
3
R2
GND
7
PGND
For the circuit shown in Figure 20, the input bias current into FB is <20nA, permitting large-value resistor-divider networks while maintaining accuracy. Place the resistor-divider network as close to the device as possible. Use a ≤ 270kΩ
resistor for R2, then calculate R1 as:
V OUT
R 1 = R 2 ⋅ ⎛ -------------- – 1⎞
⎝ V FB
⎠
(EQ 1)
Where:
VFB (the boost-regulator feedback set point) is 1.24V.
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AS1326
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
Setting the Switch Current Limit
The ISET pin is used to adjust the inductor current limit and to implement the soft-start feature.
With pin ISET connected to pin REF, the inductor current limit is set to 1.6A. With ISET connected to a resistor-divider
network from pin REF to GND, the current limit is calculated as:
V ISET
I LIMIT = 1.6A ⋅ ⎛⎝ ----------------⎞⎠
1.25V
(EQ 2)
Soft Start
The soft-start feature can be implemented by placing a resistor between pin ISET and pin REF (see Figure 21) and a
capacitor between pin ISET and GND.
Figure 21. Circuit for Soft-Start with Maximum Switch Current Limit
2
REF
10nF
AS1326A/
AS1326B
RSS
≥220kΩ
1
ISET
ILIMIT = 1.6A
tSS = Rss x CSS
CSS
At power-up, ISET is 0V and the LX current is zero. As the capacitor voltage rises, the current increases and the output
voltage rises. The soft-start time constant is:
tSS = RSS x CSS
(EQ 3)
Where:
RSS ≥ 220kΩ.
Note: Placing a capacitor across the lower resistor of the current-limiting resistor-divider network enables both the
current-limit and soft-start (see Figure 22).
Figure 22. Application Circuit for Soft-Start with Reduced Switch Current Limit
2
REF
10nF
AS1326A/
AS1326B
RSS
≥220kΩ
1
ISET
RSS2
CSS
ILIMIT = 1.6A
(
Rss2
Rss1 + Rss2
)
tSS = (Rss1 || Rss2) CSS
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Revision 1.02
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AS1326
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
Inductor Selection
The AS1326A/AS1326B high switching-frequency allows the use of a small 3.3µH surface-mount inductor. The inductor should generally have a saturation current rating exceeding the N-channel switch current limit; however, it is
acceptable to bias the inductor current into saturation by as much as 20% if a slight reduction in efficiency is acceptable.
Lower current-rated inductors may be used if ISET is used to reduce the peak inductor current (see Setting the Switch
Current Limit on page 12). For high efficiency, select an inductor with a high-frequency ferrite core material to reduce
core losses. To minimize radiated noise, use a toroid or shielded inductor. Connect the inductor from the battery to the
pin LX as close to the device as possible.
Table 7. Recommended Inductors
Part Number
L
DCR
Current Rating Dimensions (L/W/T)
MOS6020-332
3.3µH
46mΩ
1.8A
6.8x6.0x2.4mm
LPS4018-332
3.3µH
80mΩ
2.0A
4x4x1.8mm
DO1608C-272
2.7µH
80mΩ
2.1A
6.6x4.45x2.92mm
CDRH5D18NP-4R1N
4.1µH
57mΩ
1.95A
6x6x2mm
Figure 23. Efficiency vs. IOUT; VIN = 2V, VOUT = 3.3V
94
Efficiency (%) .
Efficiency (%) .
92
88
86
84
82
80
MOS6020-332
DO1608C-272
CDRH5D18NP-4R1N
LPS4018-332
78
76
0.1
1
10
100
1000
Sumida
www.sumida.com
Figure 24. Efficiency vs. IOUT; VIN = 3V, VOUT = 5V
96
90
Manufacturer
Coilcraft
www.coilcraft.com
96
94
92
90
88
86
84
82
80
78
76
74
72
70
MOS6020-332
DO1608C-272
CDRH5D18NP-4R1N
LPS4018-332
0.1
1
10
100
1000
Output Current (mA)
Output Current (mA)
External Schottky Diode
For output voltages greater than 4V, an external Schottky diode must be connected between pin LX and POUT, in parallel with the integrated synchronous rectifier (see Figure 25). The diode should be rated for 0.5A. An external diode is
also recommended for applications that must start with input voltages at or below 1.8V. The Schottky diode carries current during startup and after the synchronous rectifier turns off; thus, its current rating only needs to be 500mA.
Note: Connect the diode as close to the IC as possible.
For circuits that do not require startup with inputs below 1.8V and have an output of 4V or less, the external
diode is not needed.
Caution: Do not use ordinary rectifier diodes as their slow switching speeds and long reverse-recovery times render
them unacceptable.
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Revision 1.02
13 - 18
AS1326
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
Input and Output Filter Capacitors
Choose input and output filter capacitors that will service the input and output peak currents with acceptable voltage
ripple. Choose input capacitors with voltage ratings greater than the maximum input voltage, and output capacitors
with voltage ratings greater than the output voltage.
Table 8. Recommended Input Capacitor
Part Number
C
ESR
Rated Voltage
Dimensions (L/W/T)
TPSC336K010R0150
33µF ±10%
150mΩ
10V
6x3.2x2.6mm
T495V336K010ATE100
33µF ±10%
100mΩ
10V
A700V226M006ATE028
22µF ±20%
28mΩ
6.3V
7.3x4.3x2mm
7.3x4.3x2mm
EEFCD0K330R
33µF ±20%
18mΩ
8V
7.3x4.3x1.8mm
Manufacturer
AVX Corp
www.avxcorp.com
Kemet
www.kemet.com
Panasonic
www.panasonic.com
Table 9. Recommended Output Capacitor
Part Number
C
ESR
TPSD107K010R0050
100µF
±10%
Rated Voltage Dimensions (L/W/T)
50mΩ
10V
7.3x4.3x2.9mm
T495D107M010ATE050
100µF
±20%
50mΩ
10V
7.3x4.3x2.8mm
A700V826M006ATE018
82µF ±20%
18mΩ
6.3V
7.3x4.3x2mm
EEFUD0J101R
100µF
±20%
15mΩ
6.3V
7.3x4.3x2.8mm
Manufacturer
AVX Corp
www.avxcorp.com
Kemet
www.kemet.com
Panasonic
www.panasonic.com
Figure 25. Application Circuits using External Schottky Diode for Output Voltages Greater than 4V, or for LowVoltage Startup Assistance
MBR0520L
VOUT = 3.3V
3.3µH
VIN = 0.7V
to VOUT
33µF
100µF
8
+
LX
10
+
ONN
6
9
CLK/SEL
1
ISET
2
10nF
POUT
AS1326B
10Ω
5
REF
4
OUT
330nF
FB
3
GND
7
PGND
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Revision 1.02
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AS1326
Data Sheet - A p p l i c a t i o n I n f o r m a t i o n
The input filter capacitor reduces peak currents drawn from the input source and also reduces input switching noise.
The input voltage source impedance determines the required value of the input capacitor. When operating directly from
one or two NiMh cells placed close to the AS1326A/AS1326B, use a single 33µF low-ESR input filter capacitor.
Note: With higher impedance batteries, such as alkaline and Li+, a higher value input capacitor may improve efficiency.
The output filter capacitor reduces output ripple voltage and provides the load with transient peak currents when necessary. For the output, a 100µF, low-equivalent series-resistance (ESR) capacitor is recommended for most applications.
Low-ESR tantalum capacitors offer a good trade-off between price and performance. Do not exceed the ripple current
ratings of tantalum capacitors.
Note: Aluminum electrolytic capacitors should not be used as their high ESR typically results in higher output ripple
voltage.
Additional External Components
Two ceramic bypass capacitors are required for proper device operation (see Figure 20 on page 11):
!
Bypass pin REF to GND with a 10nF ceramic capacitor.
!
Bypass pin OUT to GND with a 330nF ceramic capacitor.
A 10Ω resistor is required between pin OUT and pin POUT (see Figure 25 on page 14).
Note: External components should be placed as close to its respective pins as possible, within 5mm (0.2”).
Layout Considerations
High switching-frequencies and large peak currents of the AS1326A/AS1326B make PC board layout a critical part of
design. Poor design may cause excessive EMI and ground bounce, both of which can cause instability or regulation
errors by corrupting the voltage and current feedback signals.
!
Power components such as the inductor, converter IC, filter capacitors, and output diode should be placed as close
together as possible, and their traces should be kept short, direct, and wide.
!
Keep the voltage feedback network very close to the device, within 5mm (0.2”) of the pin.
!
Do as many vias as possible on the exposed pad (for thermal performance) to the ground plane
!
Keep noisy traces, such as those from the pin LX, away from the voltage feedback network and guarded from
them using grounded copper traces.
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Revision 1.02
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AS1326
Data Sheet - 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 devices are available in a 10-pin TDFN (3.0mm x 3.0mm) package.
Figure 26. 10-pin TDFN (3.0mm x 3.0mm) Package
D2
A
D
D2/2
DETAIL B
B
aaa C 2x
E
E2
E2/2
NX L
P IN 1 INDEX AREA
(D/2 xE /2)
4
NX K
P IN 1 IN DEX AREA
(D /2 xE /2)
aaa
4
C
7
2x
TOP VIEW
e
N N-1
NX b
e
(ND-1) X e
6
5
C A B
bbb
C
ddd
BTM VIEW
Terminal Tip
A3
5
C
A
ccc C
S EATIN G
P LA NE
7
NX
0.08 C
A1
SIDE VIEW
Datum A or B
ODD TERMINAL SIDE
Symbol
A
A1
A3
L1
L2
aaa
bbb
ccc
ddd
eee
ggg
Min
0.70
0.00
Typ
0.75
0.02
0.20 REF
0.03
Max
0.80
0.05
0.15
0.13
0.15
0.10
0.10
0.05
0.08
0.10
Notes
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
Symbol
D BSC
E BSC
D2
E2
L
θ
K
b
e
N
ND
Min
2.20
1.40
0.30
0º
0.20
0.18
Typ
3.00
3.00
0.40
0.25
0.50
10
5
Max
2.70
1.75
0.50
14º
0.30
Notes
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2
1, 2, 5
1, 2
1, 2, 5
Notes:
1. Dimensioning and tolerancing conform to ASME Y14.5 M-1994.
2. All dimensions are in millimeters; angles in degrees.
3. N is the total number of terminals.
4. The terminal #1 identifier and terminal numbering convention shall conform to JEDEC 95-1, SPP-012. Details of terminal #1 identifier are optional, but must be located within the zone indicated. The terminal #1 identifier may be either
a mold or marked feature.
5. Dimension b applies to metallized terminal and is measured between 0.15mm and 0.30mm from the terminal tip.
6. ND refers to the maximum number of terminals on side D.
7. Figure 26 is shown for illustration only.
8. Unilateral coplanarity zone applies to the exposed heat sink slug as well as the terminals
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Revision 1.02
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AS1326
Data Sheet - O r d e r i n g I n f o r m a t i o n
11 Ordering Information
The devices are available as the standard products shown in Table 10.
Table 10. Ordering Information
Model
Marking
Description
Delivery Form
Package
AS1326A-BTDT
ASLG
Active-Low, High-Current, 0.8A
DC-DC Step-Up Converter
Tape & Reel
10-pin TDFN
(3.0mm x 3.0mm)
AS1326A-BTDR
ASLG
Active-Low, High-Current 0.8A
DC-DC Step-Up Converter
Tray
10-pin TDFN
(3.0mm x 3.0mm)
AS1326B-BTDT
ASLH
Active-High, High-Current 0.8A
DC-DC Step-Up Converter
Tape & Reel
10-pin TDFN
(3.0mm x 3.0mm)
AS1326B-BTDR
ASLH
Active-High, High-Current 0.8A
DC-DC Step-Up Converter
Tray
10-pin TDFN
(3.0mm x 3.0mm)
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Revision 1.02
17 - 18
AS1326
Data Sheet
Copyrights
Copyright © 1997-2007, austriamicrosystems AG, Schloss Premstaetten, 8141 Unterpremstaetten, Austria-Europe.
Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner.
All products and companies mentioned are trademarks or registered trademarks of their respective companies.
Disclaimer
Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing
in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding
the information set forth herein or regarding the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior
to designing this product into a system, it is necessary to check with austriamicrosystems AG for current information.
This product is intended for use in normal commercial applications. Applications requiring extended temperature
range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or lifesustaining equipment are specifically not recommended without additional processing by austriamicrosystems AG for
each application. For shipments of less than 100 parts the manufacturing flow might show deviations from the standard
production flow, such as test flow or test location.
The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However,
austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not limited to
personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or
consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of
austriamicrosystems AG rendering of technical or other services.
Contact Information
Headquarters
austriamicrosystems AG
A-8141 Schloss Premstaetten, Austria
Tel: +43 (0) 3136 500 0
Fax: +43 (0) 3136 525 01
For Sales Offices, Distributors and Representatives, please visit:
http://www.austriamicrosystems.com/contact
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Revision 1.02
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