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PDF AS1341 Data sheet ( Hoja de datos )
| Número de pieza | AS1341 | |
| Descripción | Step-Down Converter | |
| Fabricantes | austriamicrosystems AG | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de AS1341 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
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AS1341
Data Sheet
20V, 600mA, 100% Duty Cycle, Step-Down Converter
1 Generalwww.datasheet4u.com Description
The AS1341 is a high-efficiency step-down converter
with adjustable output voltages from 1.25V to VIN using
supply voltages of up to 20V.
An integrated current-limited 0.4Ω MOSFET delivers
load currents up to 600mA.
The AS1341 also includes a 100% duty cycle LDO
mode with a low dropout of only 250mV for high effi-
ciency if input voltages is in the range of the output volt-
age.
The AS1341 has a low quiescent current (12µA) to
improve light-load efficiency and minimize battery use,
and draws only 0.8µA in shutdown mode.
High switching frequencies (up to 200kHz) allow the use
of small surface-mount inductors and output capacitors.
The device is available in a TDFN-8 3x3mm pin pack-
age.
2 Key Features
! Output Voltages: Fixed 5V or Adjustable
! Input Voltage Range: 4.5 to 20V
! Output Current: Up to 600mA
! 1.25V Lowest Output Voltage
! Efficiency: up to 96%
! Quiescent Supply Current: 12µA
! Power-OK Output
! Internal 0.4Ω P-Channel MOSFET
! Shutdown Current: 0.8µA
! 100% Maximum Duty Cycle for Low Dropout
! Current-Limited Architecture
! Thermal Shutdown
! TDFN-8 3x3mm Package
Figure 1. Typical Application
3 Applications
The device is ideal for notebook computers, distributed
power systems, keep-alive supplies, and any other bat-
tery-operated, portable device.
4.5 to 20V
CIN
5
IN
7
SHDNN
6
ILIMIT
2
GND
AS1341
4
LX
D1
8
OUT
3
POK
1
FB
L1
5V
+
COUT
RPULL
Indicates High-Power Trace
FB 1
8 OUT
GND 2
POK 3
LX 4
AS1341
7 SHDNN
6 ILIMIT
9 5 IN
www.austriamicrosystems.com
Revision 1.00
1 - 16
1 page  
AS1341
Data Sheet - Typical Operating Characteristics
7 Typical Operating Characteristics
www.datashFeeigt4uur.eco3m. Efficiency vs. IOUT; VOUT = 5V, Circuit 1
100 ILIMIT = high
95
90
85
80
VIN = 6V
VIN = 12V
VIN = 20V
75
70
65
60
55
50
0.1
1 10 100
Output Current (mA)
1000
Figure 5. Efficiency vs. IOUT; VOUT = 3.3V, Circuit 1
100
ILIMIT = high
95
90
VIN = 4.5V
85
80
75
70 VIN = 12V
VIN = 20V
65
60
55
50
0.1
1 10 100
Output Current (mA)
1000
Figure 4. Efficiency vs. IOUT; VOUT = 5V, Circuit 3
100
ILIMIT = low
95
90
VIN = 6V
VIN = 12V
85 VIN = 20V
80
75
70
65
60
55
50
0.1
1 10 100
Output Current (mA)
1000
Figure 6. Efficiency vs. IOUT; VOUT = 3.3V, Circuit 3
100
ILIMIT = low
95
VIN = 4.5V
90
VIN = 12V
85
80 VIN = 20V
75
70
65
60
55
50
0.1
1 10 100
Output Current (mA)
1000
Figure 7. Efficiency vs. IOUT; VOUT = 5V, VIN = 12V
95
ILIMIT = high
90
Figure 8. Efficiency vs. IOUT; VOUT = 5V, VIN = 12V
95
ILIMIT = low
90
85 85
80 80
75 75
70
65
0.1
1 10 100
Output Current (mA)
22uH
10uH
4.1uH
1000
70
65
0.1
1 10 100
Output Current (mA)
10uH
39uH
22uH
1000
www.austriamicrosystems.com
Revision 1.00
5 - 16
5 Page 
AS1341
Data Sheet - Application Information
The trade-off for improved efficiency is a higher output ripple and slower transient response. On the other hand, low-
value inductors respond faster to transients, improve output ripple, offer smaller physical size, and minimize cost. If the
inductor value is too small, the peak inductor current exceeds the current limit due to current-sense comparator propa-
gation delay, potentially exceeding the inductor’s current rating. Calculate the minimum inductance value as follows:
www.datasheet4u.com
Where:
tONMIN = 1µs
LMIN = ((VINMAX - VOUTPUT) x tONMIN/ILXPEAK
(EQ 3)
The inductor saturation current rating must be greater than the peak switch current limit, plus the overshoot due to the
250ns current-sense comparator propagation delay. Saturation occurs when the magnetic flux density of the inductor
reaches the maximum level the core can support and the inductance starts to fall. Choose an inductor with a saturation
rating greater than IPEAK in the following equation:
IPEAK = (ILXPEAK + (VIN - VOUTPUT) x 250ns)/L
(EQ 4)
Inductor series resistance affects both efficiency and dropout voltage (see Dropout Voltage on page 9). High series
resistance limits the maximum current available at lower input voltages, and increases the dropout voltage. For opti-
mum performance, select an inductor with the lowest possible DC resistance that fits in the allotted dimensions.
Table 5. Recommended Inductors
Part Number
MSS6132-103ML
LPS4018-472ML
MSS6132-393ML
LPS4018-223ML
CDRH6D28NP-150
CDRH5D18NP-4R1
CDRH6D28NP-470
CDRH5D18NP-220
LQH66SN-100M03
LQH55DN-150M03
LQH66SN-470M03
LQH55DN-470M03
L
10µH
4.7µH
39µH
22µH
15µH
4.1µH
47µH
22µH
10µH
15µH
47µH
47µH
DCR
85mΩ
125mΩ
345mΩ
360mΩ
62mΩ
57mΩ
176mΩ
215mΩ
36mΩ
150mΩ
170mΩ
400mΩ
Current Rating
1.4A
1.8A
0.8A
0.7A
1.4A
1.95A
0.8A
0.8A
1.6A
1.4A
0.8A
0.8A
Circuit
1, 4, 5
2, 5
3, 5
4, 5
1, 5
2, 5
3, 5
4, 5
1, 5
1, 5
3, 5
3, 5
Manufacturer
Coilcraft
www.coilcraft.com
Sumida
www.sumida.com
Murata
www.murata.com
Maximum Output Current
The AS1341 output current determines the regulator’s switching frequency. When the converter approaches continu-
ous mode, the output voltage falls out of regulation. For the typical application, the maximum output current is approxi-
mately:
ILOADMAX = 1/2 x ILXPEAKMIN
(EQ 5)
For low-input voltages, the maximum on-time may be reached and the load current is limited by:
ILOAD = (1/2 x (VIN - VOUT) x 10µs)/L
(EQ 6)
www.austriamicrosystems.com
Revision 1.00
11 - 16
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet AS1341.PDF ] | |
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