Datasheet
AS1334
6 5 0 m A , U l t r a l o w R i p p l e St e p D o w n D C / D C C o n v e r t e r
1 General Description
The AS1334 is a step-down DC-DC converter designed to power portable applications from a single Li-Ion battery. The device also achieves high-performance in mobile phones and other applications requiring low dropout voltage. The AS1334 operates from an input voltage range of 2.7 to 5.5V while providing output voltages of 1.2, 1.5, 1.8, 2.5, 3.0 and 3.3V. Fixed-frequency PWM operation minimizes RF interference. Shutdown function turns the device off and reduces battery consumption to 0.01µA (typ.). The AS1334 is available in a TDFN(3x3) 8-pin package. A high switching frequency (2 MHz) allows use of tiny surface-mount components. Only three small external surface-mount components, an inductor and two ceramic capacitors are required.
2 Key Features
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Output Voltage Ripple: 2mV PWM Switching Frequency: 2MHz Single Lithium-Ion Cell Operation Output Voltage Range: 1.2V to 3.4V (available in 100mV steps, see Ordering Information on page 16) Fixed Output Voltages: - 1.2V, 1.5V, 1.8V, 2.5V, 3.0V, 3.3V Maximum Load Capability of 650mA 97% High Efficiency, 94% Average Efficiency Current Overload Protection Thermal Overload Protection Power-OK Soft Start Low Dropout Voltage (140 mΩ Typ PFET) TDFN(3x3) 8-pin
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3 Applications
The AS1334 is an ideal solution to supply noise sensitive applications as cellular phones, hand-held radios, RF PC cards, battery powered RF devices, RFID chipsets, A/D Converter, Sensors and OpAmps.
Figure 1. AS1334 - Typical Application Circuit
VIN 10 µF
PVIN
SW
3.3 µH
VOUT
VDD
FB
AS1334
10 µF ON OFF EN POK
PGND
SGND
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AS1334
Datasheet - P i n A s s i g n m e n t s
4 Pin Assignments
Figure 2. Pin Configuration
FB 1 POK 2
8 PGND 7 SW
AS1334
EN 3 VDD 4 SGND 9 6 PVIN 5 SGND
Pin Descriptions
Table 1. Pin Descriptions Pin Name FB POK EN VDD SGND PVIN SW PGND Pin Number Description 1 Feedback Pin. Connect to the output at the output filter capacitor. Power-OK. 0 = VOUT < 90% of VOUTNOM. 2 1 = VOUT > 90% of VOUTNOM. Enable Input. Set this digital input high for normal operation. For shutdown, 3 set low. +2.7V to +5.5V Power Supply Voltage. Analog Supply Input. 4 Analog and Control Ground. 5, 9 6 +2.7V to +5.5V Power Supply Voltage. Input to the internal PFET switch. Switch Pin. Switch node connection to the internal PFET switch and NFET synchronous rectifier. Connect to an inductor with a saturation current rating 7 that exceeds the maximum switch peak current limit specification of the AS1334. Power Ground. 8
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Datasheet - A b s o l u t e M a x i m u m R a t i n g s
5 Absolute Maximum Ratings
Stresses beyond those listed in Table 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 SGND PGND to SGND POK, EN, FB SW PVIN to VDD Operating Temperature Range Junction Temperature (TJ-MAX) Storage Temperature Range Maximum Lead Temperature (Soldering, 10 sec) ESD Rating Human Body Model Operating Ratings Input Voltage Range Recommended Load Current Junction Temperature (TJ) Range -40 2.7 5.5 650 +125 V mA ºC 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 equation: TA-MAX = TJ-MAX-OP – (θJA × PD-MAX). 2 kV HBM MIL-Std. 883E 3015.7 methods -65 Min -0.3 -0.3 Max +7.0 +0.3 Units V V V V V °C ºC ºC ºC 7.0V max Notes
SGND - 0.3 VDD + 0.3 PGND - 0.3 PVIN + 0.3 -0.3 -40 +0.3 +85 +150 +150 +260
Ambient Temperature (TA) Range
-40
+85
ºC
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Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
6 Electrical Characteristics
TA = TJ = -40ºC to +85ºC; PVIN = VDD = EN = 3.6V, unless otherwise noted. Typ. values are at TA=25°C. Table 3. Electrical Characteristics Symbol Parameter Conditions Min 1.176 1.47 VOUT Output Voltage PVIN = 3.6V 1.764 2.45 2.94 3.234 ISHDN IQ RDSON(P) Shutdown supply current DC bias current into VDD Pin-Pin Resistance for PFET EN = SW = 0V
1 2
Typ 1.2 1.5 1.8 2.5 3.0 3.3 0.01 1 140
Max Units 1.224 1.53 1.836 2.55 3.06 3.366 2 1.4 200 230 V V V V V V µA mA mΩ mΩ mA
FB = 0V, No Switching
ISW = 200mA; TA = +25°C ISW = 200mA ISW = -200mA; TA = +25°C ISW = -200mA 935
RDSON(N) ILIM,PFET VOL
Pin-Pin Resistance for NFET Switch peak current limit
300
415 485
1100
1200
POK Output POK Output Low Voltage POK sinking 0.1mA 0.05 0.2 500 87 90 93 V nA %
POK Output High Leakage Current POK = 3.6V POK Threshold Enable Input VIH,EN VIL,EN Logic high input threshold Logic low input threshold 5 1.2 Rising edge, referenced to VOUT(NOM)
V 0.5 10 V µA
IPIN,ENABLE Pin pull down current Oscillator FOSC Internal oscillator frequency 1.8
2
2.2
MHz
1. Shutdown current includes leakage current of PFET. 2. IQ specified here is when the part is operating at 100% duty cycle.
System Characteristics
TA = 25ºC; PVIN = VDD = EN = 3.6V, unless otherwise noted. The following parameters are verified by characterisation and are not production tested. Table 4. System Characteristics Symbol T_ON
η
Parameter Turn on time (from Enable low to high transition) Efficiency (L = 3.3µH, DCR ≤ 100mΩ)
Conditions EN = Low to High, VIN = 4.2V, COUT = 10µF, IOUT ≤ 1mA VIN = 3.6V, IOUT = 400mA VIN = 4.2V, IOUT = 10mA to 400mA
Min Typ Max 210 350 96 5
Units µs % mVp-p
VOUT_ripple Ripple voltage, PWM mode1
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Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
Table 4. System Characteristics Symbol Line_tr Parameter Line transient response Conditions VIN = 600mV perturbance, over Vin range 3.4V to 5.5V; TRISE = TFALL = 10µs, VOUT = 3.0V, IOUT = 100mA VIN = 4.2V, VOUT = 3.0V, transients up to 100mA, TRISE = TFALL = 10µs Min Typ Max 50 Units mVpk
Load_tr
Load transient response
50
mVpk
1. Ripple voltage should measured at COUT electrode on good layout PC board and under condition using suggested inductors and capacitors.
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Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
7 Typical Operating Characteristics
Circuit in Figure 23 on page 11, PVIN = VDD = EN = 3.6V, L = 3.3µH (LPS4018-332ML_), CIN = COUT = 10µF (GRM21BR61C106KA01) unless otherwise noted; Figure 3. Quiescent Current vs. VIN
0.55
Figure 4. Shutdown Current vs. Temperature
0.3
Vi n=3.25V Vi n=3.6V
Quiescent Current (mA)
Shutdown Current (µA)
0.25 0.2 0.15 0.1 0.05 0 -40
Vi n=4.2V Vi n=5.5V
0.5
0.45
0.4
- 45°C + 25°C + 85°C
0.35 2.5 3 3.5 4 4.5 5 5.5
-15
10
35
60
85
Supply Voltage (V) Figure 5. Switching Frequency Variation vs. Temp. Switching Frequency Variation (%)
4 3
Temperature (°C) Figure 6. Output Voltage vs. Supply Voltage
3.06 3.04
Output Voltage (V)
Vi n=3.6V
2 1 0 -1 -2 -3 -4 -40
Vi n=4.2V Vi n=5.5V
3.02 3 2.98 2.96 2.94 3.25
Iout=50mA Iout=300mA Iout=650mA
-15
10
35
60
85
3.75
4.25
4.75
5.25
Temperature (°C)
Supply Voltage (V)
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Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s
Figure 7. Output Voltage vs. Temperature
3.06 3.04
Figure 8. Efficiency vs. Output Current
100 95
Output Voltage (V)
Efficiency (%)
3.02 3 2.98 2.96 2.94 -40
Iout=50mA Iout=300mA Iout=650mA
90 85 80 75 70
Vi n=3.25V Vi n=3.6V Vi n=3.9V Vi n=4.2V Vi n=4.5V Vi n=5.5V
-15
10
35
60
85
0
100
200
300
400
500
600
700
Temperature (°C)
Output Current (mA)
Figure 9. Switch Peak Current Limit vs. Temperature; closed loop
1.2
Figure 10. Load Transient Response; VOUT = 3.0V, VIN = 4.2V
Peak Current Limit (A)
1.15
1.1
IL
Vi n=3.6V Vi n=5.5V
1 -40
-15
10
35
60
85
IOUT
Vi n=2.7V
10µs/Div
Temperature (°C)
Figure 11. Startup; VIN = 3.6V, VOUT = 3.0V, IOUT