AS1332_07 [AMSCO]
650mA, Step-Down DC-DC Converter for RF Power Amplifiers; 650毫安，降压型DC -DC转换器，用于射频功率放大器
| 型号： | AS1332_07 |
| 厂家： | 
AMS(艾迈斯) |
| 描述： | 650mA, Step-Down DC-DC Converter for RF Power Amplifiers |
| 文件： | 总20页 (文件大小：2151K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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Datasheet
AS1332
650mA, Step-Down DC-DC Converter for RF Power Amplifiers
1 General Description
2 Key Features
ꢀ
ꢀ
ꢀ
PWM Switching Frequency: 2MHz
The AS1332 is a step-down DC-DC converter designed
to power radiofrequency (RF) power amplifiers (PAs)
from a single Li-Ion battery. The device also achieves
high-performance in mobile phones and similar RF PA
applications.
Single Lithium-Ion Cell Operation (2.7V to 5.5V)
Dynamic Programmable Output Voltage (1.3V to
3.16V)
ꢀ
ꢀ
Maximum load capability of 650mA
The AS1332 steps down an input voltage of 2.7V to 5.5V
to output voltages ranging from 1.3V to 3.16V. Using a
VCON analog input, the output voltage is set for
High Efficiency (96% Typ at 3.6VIN, 3.16VOUat
400mA) from internal synchronous rectificatio
controlling power levels and efficiency of the RF PA.
ꢀ
ꢀ
ꢀ
ꢀ
Current Overload Protection
Thermal Overload Protection
Soft Start
The RF interferences are minimized due to the fixed-
frequency PWM operation. The battery consumption is
reduced to 0.01µA (typ.) during shutdown.
8-pin WL-CSP
Because of the high switching frequencies (2 MHz) tiny
surface-mount components can be used. Additional to
the small size the amount is also small. Only three
external components are required, an inductor and two
ceramic capacitors.
3 Applications
he AS1332 is an ial solution for cellular phones,
hand-held radios, RF Pcards, and battery powered RF
devices.
The AS1332 is available in a 8-pin WL-CSP.
Figure 1. AS1332 - Typical Application Cicut
VIN
2.7V to 5.5V
VDD
VIN
10 µF
VOUT
3.3 µH
1.3V to 3.16V
SW
FB
N
VOUT = 2.5 x VCON
AS1332
4.7 µF
VCON
0.52V to 1.27V
VCON
PGND
AGND
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AS1332
Datasheet - Pin Assignments
4 Pin Assignments
Figure 2. Pin Configuration
Top View
Bottom View
SW
SW
A2
A2
PVIN
VDD
A1
B1
A3
B3
PGND
AGND
PGND
AGND
A3
B3
A1
B1
PVIN
VDD
EN
C1
C2
C3
FB
FB
C3
C2
C1
EN
VCON
VCON
Pin Descriptions
Table 1. Pin Descriptions
Pin Name
Pin Number
Description
A1
+2.7V to + 5.5V PoweSupply Voltage. Inut to the internal PFET switch.
PVIN
+2.7V to + .5V Analog Supply Input. ypass this pin to GND with a ≥10µF
capacitor.
ActiveHigEnable Input. t thdgital input high for normal operation. For
shudown, set low.
B1
C1
VDD
EN
C2
C3
B3
A3
Voltage Control Analog Inut. VCON controls VOUT.
VCON
FB
dback Pin. Connect the output at the output filter capacitor.
nalog and Conound. Connect this pin with low resistance to PGND.
Power Ground. Conect this pin with low resistance to AGND.
AGND
PGND
Switch PinSwith node connection to the internal PFET switch and NFET
synhronous rectifier. Limit specification of the AS1332.
SW
A2
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AS1332
Datasheet - Absolute Maximum Ratings
5 Absolute Maximum Ratings
Stresses beyond those listed in Table 2 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 2. Absolute Maximum Ratings
Parameter
VDD, PVIN to AGND
PGND to AGND
EN, FB, VCON
Min
-0.3
-0.3
Max
+7
Units
V
Comments
+0.3
V
AGND - 0.3 VDD + 0.3
PGND - 0.3 PVIN + 0.3
V
7V max
SW
V
PVIN to VDD
-0.3
-40
+0.3
+85
V
Operating Temperature Range
ºC
ºC
C
Junction Temperature (TJ-MAX
)
+150
+150
Storage Temperature Range
-65
Maximum Lead Temperature
(soldering, 10sec)
+260
ºC
ESD Rating
Human Body Model
Operating Ratings
2
kV
HM MIL-Std. 883E 3015.7 methods
Input Voltage Range
27
40
5.5
650
Recommended Load Current
mA
ºC
Junction Temperature (TJ) Range
+125
In applications where high power
dissipation and/or poor package thermal
resistance is present, the maximum
ambient temperature may have to be
derated.
Maximum ambient temperature (TA-MAX
is dependent on the maximum operating
junction temperature (TJ-MAX-OP
125ºC), the maximum power dissipation
of the device in the application (PD-MAX),
and the junction-to ambient thermal
resistance of the part/package in the
application (θJA), as given by the
following
)
=
Ambient Temperature (TA) Range
40
+85
ºC
equation: TA-MAX = TJ-MAX-OP – (θJA
×
PD-MAX).
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AS1332
Datasheet - Electrical Characteristics
6 Electrical Characteristics
TA = TJ = -40ºC to +85ºC; PVIN = VDD = EN = 3.6V, unless otherwise noted
. Typ values are at TA = 25ºC.
Table 3. Electrical Characteristics
Symbol
VFB,MIN
VFB
Parameter
Conditions
VCON = 0.4V
Min
1.21
2.693
3.03
Typ
1.30
2.75
3.17
Max
1.39
Units
Feedback Voltage at Minimum
Setting
V
V
V
Feedback Voltage
VCON = 1.1V
VCON = 1.4V
2.807
3.29
Feedback Voltage at Maximum
Setting
VFB,MAX
1
Shutdown Supply Current
DC Bias Current into VDD
EN = SW = VCON = 0V
0.01
1
2
µA
ISHDN
VCON = 1V, FB = 0V,
No Switching
2
1.4
mA
IQ
DC-DC Switches
Current limit is built-in, fixed,
and not adjutable
ILIM,PFET Switch Peak Current Limit
935
100
140
1200
mA
I
I
I
I
SW = 200mATA = 25°C
200
230
415
485
RDSON(P) Pin-Pin Resistance for PFET
mΩ
SW = A
SW = -20mA; TA = +25°C
SW = -200mA
300
Pin-Pin Resistance for NFET
RDSON(N)
mΩ
Control Inputs
VIH,EN
Logic High Input Threshold
VIL,EN
Logic Low Input Threshold
1.2
V
V
0.5
7
IPIN,ENABLE Pin Pull Down Curren
VCON Threshold
5
µA
VCOpt down
VCON,min
0.484
1.208
0.52
0.556
1.312
V
Commanding VFB,MIN
VCON Threshold
Commanding VFB,MAX
VON swept up
TA = +25°C
VCON,max
1.27
V
VCON Input Resistance3
ZCON
100
-10
kΩ
ICON
Control Pin Leakage Curre
VCON to VOUT Gain
10
µA
0.556V ≤ VCON ≤ 1.208V
Gain
Oscillator
FOSC
2.5
2
V/V
Internal OsillatoFrequency
1.8
2.2
MHz
1. Shutdown curreincldes leakage current of PFET.
2. IQ specified here iwhen the part is operating at 100% duty cycle.
3. Derived by nput eakage test.
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AS1332
Datasheet - Electrical Characteristics
System Characteristics
TA = 25ºC; PVIN = VDD = EN = 3.6V, unless otherwise noted
.
The following parameters are verfied by characterisation
and are not production tested
.
Table 4. System Characteristics
Unit
s
Symbol
Parameter
Conditions
Min Typ Max
Control Inputs
VIN = 4.2V, COUT = 4.7µF,
Time for VOUT to rise from
1.3V to 3.16V
20
20
30
L = 3.3µH, RLOAD = 5Ω
TRESP
µs
VIN = 4.2V, COUT = 4.7µF,
Time for VOUT to fall from
3.16V to 1.3V
30
20
+3
L = 3.3µH, RLOAD = 10Ω
CCON
VCON Input Capacitance
VCON = 1V, Test frequency = 100 kHz
pF
%
Linearity in Control
Range 0.556V to 1.208V
VIN = 3.6V,
Monotonic in nature
Linearity
-3
Turn-On Time
(time for output to reach 3.16V from
enable low to high transition)
EN = Low to High, VIN = 4.2V,
VOUT = 3.16V, COUT = 4.7µF, IOUT ≤ 1mA
T_ON
210 750 µs
Performance Parameters
VIN = 3.6UT = 1.3V, IOUT = 0mA
VIN = 3.6V, VOUT = 3.16V, IOUT = 400mA
VIN = 3V to 4.5V, VOUT = 1.V,
87
Efficiency
(L = 3.3µH, DCR ≤ 100mΩ)
η
%
96
VOUT-
ripple
mVp
Ripple voltage, PWM mode1
10
-p
I
OUT = 10mA to 400m
N = 600mV perbance, over Vin range
3V to 5.5V; TE = ALL = 10µs,
mVp
k
Line transient response
Line_tr
50
VOUT = 1.3VIOUT = 100mA
VIN = 36/4.5V, VOUT = 1.3V, transients
up to , TRISE = TFALL = 10µs
mVp
Load transient response
VIN = 3.6V, VOUT = 1.3V,
Load_tr
PSRR
50
40
k
ne wave perturbation frequency = 10kHz,
apliude = 100mVp-p
dB
IOUT = 100mA
1. Ripple voltage should measured at COUT elctrode on good layout PC board and under condition using sug-
gested inductors and capacitors.
Note: All limits are guaranteed. he prameters with min and max values are guaranteed with production tests or
SQC (Statistical QualitControl) methods.
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AS1332
Datasheet - Typical Operating Characteristics
7 Typical Operating Characteristics
Circuit in Figure 31 on page 12, PVIN = VDD = EN = 3.6V, L = 3.3µH (LPS4018-332ML_), CIN = 10µF
(GRM21BR61C106KA01), COUT = 4.7µF (GRM32ER71H475KA88) unless otherwise noted;
Figure 3. IQ vs. VIN; VCON = 2V, FB = 0V, no switching
Figure 4. ISHDN vs. Temperature; VCON = 0V, EN = 0V
1.4
0.25
Vi n=2.7V
Vi n=3.6V
- 45°C
+ 25°C
1.2
Vi n=4.2V
+ 95°C
0.2
Vi n=5.5V
1
0.8
0.6
0.4
0.2
0.15
0.1
0.05
0
2.5
3
3.5
4
4.5
5
5.5
-40
-15
10
35
60
85
SupplyVoltage (V)
Temperature (°C)
Figure 5. Switching Frequency Variation vs. Temp.
ure 6. VOUT vs. VIN; VOUT = 1.3V
4
1.39
3
2
1.36
1.33
.3
1
0
-1
1.27
Vin=2.
-2
Vin=3.6V
Vin=4.2V
Iout=50mA
1.24
-3
Iout=300mA
Iout=650mA
in=5.5V
-4
1.21
-40
-15
10
35
0
85
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Temperatur(°C)
SupplyVoltage (V)
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AS1332
Datasheet - Typical Operating Characteristics
Figure 7. VOUT vs. Temp; VIN = 3.6V, VOUT = 1.3V
Figure 8. VOUT vs. Temp; VIN = 3.6V, VOUT = 3.16V
1.35
3.2
Iout=50mA
Iout=50mA
1.34
3.19
Iout=300mA
Iout=300mA
Iout=650mA
Iout=650mA
1.33
3.18
1.32
1.31
1.3
3.17
3.16
3.15
3.14
3.13
3.12
3.11
3.1
1.29
1.28
1.27
1.26
1.25
-40
-15
10
35
60
85
-40
-15
10
35
0
85
Temperature (°C)
Temperature (°C)
Figure 9. Switch Peak Current Limit vs. Temp.
Figur10. VON vs. VOUT; VN = 4.2V, RLOAD = 8Ω
1.2
3.5
3
2.5
2
1.15
1.1
1.05
1
1.5
- 45°C
Vin=2.7V
Vin=3.6
Vin=5.
+ 25°C
+ 90°C
1
-40
-15
10
35
0
85
0
0.5
1
1.5
2
VCON Voltage (V)
Temperature (°C)
Figure 11. Efficiency vs. VOUT; VI= 3V
Figure 12. Efficiency vs. IOUT; VOUT = 1.3V
100
100
Vi n=2.7V
Vi n=3.25V
Vi n=3.6V
Vi n=4.2V
Vi n=5.5V
95
90
85
80
75
70
95
90
85
80
75
70
Rload=5Ohm
Rload=10Ohm
Rload=15Ohm
1
1.5
2
2.5
3
3.5
0
100 200 300 400 500 600 700 800
Output Current (mA)
Output Voltage (V)
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AS1332
Datasheet - Typical Operating Characteristics
Figure 13. Efficiency vs. IOUT; VOUT = 3.09V
100
95
90
85
80
Vin=2.7V
Vin=3.25V
Vin=3.6V
Vin=4.2V
Vin=5.5V
75
70
0
100 200 300 400 500 600 700 800
Output Current (mA)
Figure 14. Load Transient Response; VIN = 3.6V,
VOUT = 1.3V
Figur15. Srtup; VIN = 3.6V, VOUT = 1.3V,
IUT<1mA, RLOAD = 4.kΩ
10µs/Div
50µs/Div
Figure 16. Startup; VIN = 4.2V, VOT = .16V,
Figure 17. Shutdown Response; VIN = 4.2V, VOUT =
IOUT<1mA, RLOAD = 4.7kΩ
3.16V, COUT = 4.7µF, RLOAD = 10Ω
50µs/Div
50µs/Div
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AS1332
Datasheet - Typical Operating Characteristics
Figure 18. VCON Voltage Response; VIN = 4.2V,
Figure 19. VCON and Load Transient; VIN = 4.2V,
VCON = 0V to 1.4V, RLOAD = 10Ω
VCON = 0V to 1.4V, 15Ω/8Ω, same time
50µs/Div
50µs/Div
Figure 20. Timed Current Limit Response; VIN = 3.6V,
Figur21. Otput Voltage Ripple; VIN = 3.6V,
VOUT = 1.3V, IOUT = 20mA
VOUT = 1.3V, RLOAD = 10Ω
5µs/Div
200ns/Div
Figure 22. VOUT Ripple in Skip Mde; IN = 3.547V,
Figure 23. RDSON (P-Chanel) vs. Temperature;
ISW = 200mA
VOUT = 3.16V, RLOA= 5Ω
350
300
250
200
150
100
Vin=2.7V
50
Vin=3.6V
Vin=5.5V
0
-40
-15
10
35
60
85
500ns/Div
Temperature (°C)
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AS1332
Datasheet - Typical Operating Characteristics
Figure 24. RDSON (N-Chanel) vs. Temp.; ISW=-200mA
Figure 25. EN High Threshold vs. VIN
350
1.2
300
250
200
150
1.1
1
0.9
0.8
0.7
100
Vin=2.7V
- 45°C
+25°C
50
Vin=3.6V
Vin=5.5V
+90
0
-40
-15
10
35
60
85
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Temperature (°C)
SupplyVoltage (V)
Figure 26. VCON Threshold min vs. VIN
Figur27. VON Threshold max vs. VIN
0.52
1.27
0.518
0.516
0.514
0.512
0.51
1.268
1.266
1.264
1.262
1.
0.508
0.506
0.504
0.502
0.5
1.28
.256
1.254
1.252
1.25
- 45°C
+25°C
-45°C
+25°C
+90°
+90°C
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
SupplyVoltage (V)
SupplyVoltage (V)
Figure 28. VFB min vs. VIN; VCON 0.4, RLOAD = 10Ω
Figure 29. VFB max vs. VIN; VCON = 0.4V, RLOAD=10Ω
1.39
3.2
1.36
1.33
1.3
3.18
3.16
3.14
.27
- 45°C
3.12
- 45°C
1.24
+ 25°C
+ 90°C
+ 25°C
+ 90°C
1.21
3.1
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
3
3.5
4
4.5
5
5.5
SupplyVoltage (V)
SupplyVoltage (V)
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AS1332
Datasheet - Detailed Description
8 Detailed Description
For driving RF power amplifiers in portable devices and battery powered RF devices the AS1332 is a very suitable DC-
DC converter. The AS1332 features current overload protection, thermal overload shutdown and soft start. Besides
these features the device also displays the following characteristics:
ꢀ
ꢀ
ꢀ
Current-mode buck architecture with synchronous rectification for high efficiency.
Operation at maximum efficiency over a wide range of power levels from a single Li-Ion battery cell.
The maximum load capability of 650mA is provided in PWM mode, wherein the maximum load range may vary
depending on input voltage, output voltage and the selected inductor.
ꢀ
ꢀ
Efficiency is of around 96% for a 400mA load with 3.16V output and 3.6V input.
For longer battery life, the output voltage can be dynamically programmable from 1.3V (typ) to 3.16V (typ) by
adjusting the voltage on the control pin without the need for external feedback resistors.
Figure 30. AS1332 Block Diagram
VDD
PVIN
Oscillator
Current
Sense
FB
Moe
ontrol
Logic
SW
Clamp
Logic and
Soft Start
VCON
Main Contol
Shutdown
Corol
EN
AS1332
AGND
PGND
AS1332 is faricated using a 8-pin WL-CSP, which requires special design considerations for implementation. Its fine
bumppitch reqirecareful board design and precision assembly equipment. This package offers the smallest possible
size, for ce-critical applications such as cell phones, where board area is an important design consideration. The
se of thexernal components is reduced by using a high switching frequency (2MHz). For implementation only three
extrnal power components are required (see Figure 1 on page 1). The 8-pin WL-CSP package is appropriate for
opaqucase applications, where its edges are not subject to high intensity ambient red or infrared light. Also the
system controller should set EN low during power-up and other low supply voltage conditions. See Shutdown Mode on
page 13.
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AS1332
Datasheet - Detailed Description
Figure 31. Typical Operating System Circuit
VIN
2.7V to 5.5V
C1
PVIN
VDD
L1
VOUT
10 µF
3.3 µH
1.3V to 3.16V
SW
FB
VOUT = 2.5 x VCON
AS1332
DAC
System
Controller
C2
4.7 µF
ON/OFF
AGND
PGND
Operating the AS1332
AS1332’s control block turns on the internal PFET (P-chanMOSFET) switch dung the first part of each switching
cycle, thus allowing current to flow from the input through the inductor to the outut filter capacitor and load. The
inductor limits the current to a ramp with a slope of around (VIN - VOUT) / L, bstoring energy in a magnetic field.
During the second part of each cycle, the controller turnthe PFET switff, blocking current flow from the input, and
then turns the NFET (N-channel MOSFET) sncronous rectifier n. As reult, the inductor’s magnetic field
collapses, generating a voltage that forces curent from ground throgh the synchronous rectifier to the output filter
capacitor and load.
While the stored energy is transferrd k into the circuit and epleted, the inductor current ramps down with a slope
around VOUT / L. The output filter capor stores chargn the inductor current is high, and releases it when low,
smoothing the voltage across the load. The output voltaegulated by modulating the PFET switch on time to
control the average current sent to the load. The efect is identical to sending a duty-cycle modulated rectangular wave
formed by the switch and synchronous rectifier at W ta low-pass filter formed by the inductor and output filter
capacitor.
The output voltage is equal to the average voltge at the SW pin.
While in operation, the output voltage is rlated by switching at a constant frequency and then modulating the
energy per cycle to control power to the lod. Energy per cycle is set by modulating the PFET switch on-time pulse
width to control the peak inductor urret. This is done by comparing the signal from the current-sense amplifier with a
slope compensated error signafrom the voltage-feedback error amplifier. At the beginning of each cycle, the clock
turns on the PFET switch, casing the inductor current to ramp up. When the current sense signal ramps past the error
amplifier signal, the PWM comparator turns off the PFET switch and turns on the NFET synchronous rectifier, ending
the first part of the cyce.
If an increase in loapulls the output down, the error amplifier output increases, which allows the inductor current to
ramp higher bfore the comparator turns off the PFET. This increases the average current sent to the output and
adjusts for the incrase in the load. Before appearing at the PWM comparator, a slope compensation ramp from the
oscillatoubtracted from the error signal for stability of the current feedback loop. The minimum on time of PFET in
PWM me i50ns (typ.)
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AS1332
Datasheet - Detailed Description
Internal Synchronous Rectifier
To reduce the rectifier forward voltage drop and the associated power loss, the AS1332 uses an internal NFET as a
synchronous rectifier. The big advantage of a synchronous rectification is the higher efficiency in a condition where the
output voltage is low compared to the voltage drop across an ordinary rectifier diode. During the inductor current down
slope in the second part of each cycle the synchronous rectifier is turned on. Before the next cycle the synchronous
rectifier is turned off.
There is no need for an external diode because the NFET is conducting through its intrinsic body diode during the
transient intervals before it turns on.
Dynamic Output Voltage Programming
Because of the dynamically adjustable output voltage of the AS1332 there is no need for external feedback resistors
Through changing the voltage at the analog pin VCON, the output voltage is set from VFB,MIN to VFB,MAX. This is a ve
helpful feature because the supply voltage of a PA application can be changed due to the operation mode. For
example, during the data transmission from a handset peak power is needed. In the other states the transmitting ower
can be reduced to ensure a longer battery lifetime.
Shutdown Mode
If EN is set to high (>1.2V) the AS1332 is in normal operation mode. During power-up and wn thpower supply is
less than 2.7V minimum operating voltage, the chip should be tuned fby setting EN low. In sutdown mode the
following blocks of the AS1332 are turned off, PFET switch, NFEsyncronous rectifierreference voltage source,
control and bias circuitry. The AS1332 is designed for comact portable applications, such as mobile phones where the
system controller controls operation mode for maximizing ife and requirents for small package size
outweigh the additional size required for inclusion of UVLO nder Voltage Lock-Ou) circuitry.
Note: Setting the EN digital pin low (<0.5V) places the AS1332 in a 0.01µA typ.) shutdown mode.
Thermal Overload Protection
To prevent the AS1332 from short-term msusand overload conditins the chip includes a thermal overload
protection. To block the normal operation mode the device is turnig the PFET and the NFET off in PWM mode as
soon as the junction temperature exces 150°C. To resume te normal operation the temperature has to drop below
125°C.
Note: Continuing operation in thermal overload conditiomay damage the device and is considered bad practice.
Current Limiting
If in the PWM mode the cycle-by-cycle currenlimit of 1.2A (max.) is reached the current limit feature takes place and
protects the device and the external compents. A timed current limiting mode is working when a load pulls the output
voltage down to approximately 0.375V. In timed current limit mode the inductor current is forced to ramp down to a
safe value. This is achieved by tuning off the internal PFET switch and delaying the start of the next cycle for 3.5us.
The synchronous rectifier is also tuneoff in the timed current limit mode.
The advantage of the timed curret limit mode is to prevent the device of the loss of the current control.
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AS1332
Datasheet - Application Information
9 Application Information
Through setting the voltage on the VCON pin (see Table 5) the output voltage of the AS1332 can be programmed from
1.3V (typ) to 3.16V (typ). This feature eliminates the need for external feedback resistors.
If the voltage on the control pin varies from 0.556V to 1.208V, the output voltage will change according to the equation
stated in Table 5. The output voltage is regulated at VFB,MIN as long as the voltage on the control pin is less than
0.484V. If the voltage on the control pin is higher than 1.312V, the output voltage is regulated at VFB,MAX.
Before the control voltage is fed to the error amplifier inputs, the control voltage is clamped internal in the device.
Table 5. Output Voltage Selection
VCON (V)
VCON ≤ 0.484
VOUT (V)
VFB,MIN
0.556 < VCON < 1.208
VCON ≥ 1.312
VOUT = 2.5 x VCON
VFB,MAX
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AS1332
Datasheet - Application Information
External Component Selection
Inductor Selection
For the external inductor, a 3.3µH inductor is recommend. Minimum inductor size is dependant on the desired effi-
ciency and output current. Inductors with low core losses and small DCR at 2MHz are recommended.
Table 6. Recommended Inductors
Part Number
L
DCR
Current Rating Dimensions (L/W/T)
Manufacturer
Coilcraft
www.coilcraft.com
LPS4018-222ML_
LPS4018-332ML_
LPS4018-472ML_
2.2µH
3.3µH
4.7µH
0.070Ω
0.080Ω
0.125Ω
2.9A
2.4A
1.9A
3.9x3.9x1.7mm
3.9x3.9x1.7mm
3.9x3.9x1.7mm
Capacitor Selection
A 10µF capacitor is recommend for CIN as well as a 4.7µF for COUT. Small-sized X5R or X7R ceamic capacitors are
recommend as they retain capacitance over wide ranges of voltags and temperatures.
Input and Output Capacitor Selection
Low ESR input capacitors reduce input switching noise aeduce the peak current drawn from the battery. Also low
ESR capacitors should be used to minimize VOUT ripple. Myr ceramic captors are recommended since they
have extremely low ESR and are available in small footprint
For input decoupling the ceramic capacitor should be located as close to the evicas practical. A 4.7µF input capaci-
tor is sufficient for most applications. Larger valuemabe used without limitaons.
A 2.2µF to 10µF output ceramic capacitor is sufcient for most applicats. arger values up to 22µF may be used to
obtain extremely low output voltage ripple animpove transient resonse.
Table 7. Recommended Capacitors fe Step-Down Certe
Part Number
C
Voltage
.3V
6.3V
16V
Type
X5R
X5R
X5R
X5R
X5R
Size
0805
0805
0805
0603
0603
Manufacturer
Murata
www.murata.com
GRM21BR60J226ME39
GRM21BR60J106KE01
GRM21BR61C475KA88
GRM188R61C225KE15
GRM188R61A225KE34
22µF
10µF
4.7µF
2.2µF
2.2µF
16V
10V
KEMET
www.kemet.com
C0603C475K8PAC7867
4.7µF
10V
X5R
0603
EN Pin Contro
Drive the EN in ung the system controller to turn the AS1332 ON and OFF. Use a comparator, Schmidt trigger or
logic gate drive the EN pin. Set EN high (>1.2V) for normal operation and low (<0.5V) for a 0.01µA (typ.) shutdown
mode. SEN low to turn off the AS1332 during power-up and under voltage conditions when the power supply is less
hn the 2.7V minimum operating voltage. The part is out of regulation when the input voltage is less than 2.7V.
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AS1332
Datasheet - Application Information
Layout Considerations
The AS1332 converts higher input voltage to lower output voltage with high efficiency. This is achieved with an inductor
based switching topology. During the first half of the switching cycle, the internal PMOS switch turns on, the input
voltage is applied to the inductor, and the current flows from PVDD line to the output capacitor (C2) through the
inductor. During the second half cycle, the PMOS turns off and the internal NMOS turns on. The inductor current
continues to flow via the inductor from the device PGND line to the output capacitor (C2). Referring to Figure 32, the
AS1332 has two major current loops where pulse and ripple current flow. The loop shown in the left hand side is most
important, because pulse current shown in Figure 32 flows in this path. The right hand side is next. The current
waveform in this path is triangular, as shown in Figure 32. Pulse current has many high-frequency components due to
fast di/dt. Triangular ripple current also has wide high-frequency components. Board layout and circuit pattern design
of these two loops are the key factors for reducing noise radiation and stable operation. Other lines, such as from
battery to C1(+) and C2(+) to load, are almost DC current, so it is not necessary to take so much care. Only pattern
width (current capability) and DCR drop considerations are needed.
Figure 32. Current Loop
VIN
2.7V to 5.5V
i
fOSC = 2MHz
i
+
DD
C1
PVIN
1
- 10 µF
3.3 µH
VOUT
SW
F
EN
VOUT = 2.5 x VCON
C2
4.7 µF
+
-
VCON
AGND
VCON
0.52V to 1.27V
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AS1332
Datasheet - Package Drawings and Markings
10 Package Drawings and Markings
The device is available in a 8-pin WL-CSP
Figure 33. Package Drawings
Top through view
Bottoµ view
(Ball side)
5ꢀꢀ
5ꢀꢀ
4ꢀ typ.
24ꢀ typ.
1
1
A
A
4ꢀ 0µ
32ꢀ tp.
1515 2ꢀ0µ
6ꢀꢀ 3ꢀ0µ
Notes:
ccc Coplanarity
All diµensions are in 0µ
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AS1332
Datasheet - Ordering Information
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
AS1332-BWLT
650mA, DC-DC Step-Down for RF Tape and Reel
8-pin WL-CSP
ASQW
Note: All products are RoHS compliant and Pb-free.
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AS1332
Datasheet
Copyrights
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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 f
current information. This product is intended for use in normal commercial applications. Applications requiring
extended temperature range, unusual environmental requirements, or high reliability applications, sucas military,
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