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AIC1642
3-Pin One-Cell Step-Up DC/DC Converter
1/2 FEATURES
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1/2
DESCRIPTION
The AIC1642 is a high efficiency step-up DC/DC converter for applications using 1 to 4 battery cells. Only three external components are required to deliver a fixed output voltage of 2.7V, 3.0V, 3.3V, or 5V. The AIC1642 starts up from less than 0.9V input with 1mA load. Pulse Frequency Modulation scheme brings optimized performance for applications with light output loading and low input voltages. The output ripple and noise are lower compared with the circuits operating in PSM mode. The PFM control circuit operating in 100KHz (max.) switching rate results in smaller passive components. The space saving SOT-89 and TO-92 packages make the AIC1642 is an ideal choice of DC/DC converter for space conscious applications, like pagers, electronic cameras, and wireless microphones.
A Guaranteed Start-Up from less than 0.9 V. High Efficiency. Low Quiescent Current. Less Number of External Components needed. Low Ripple and Low Noise. Fixed Output Voltage: 2.7V, 3.0V, 3.3V, and 5V. Space Saving Packages: SOT-89 and TO-92
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APPLICATIONS
Pagers. Cameras. Wireless Microphones. Pocket Organizers. Battery Backup Suppliers. Portable Instruments.
1/2
TYPICAL APPLICATION CIRCUIT
VIN L1 100H D1 GS SS12 AIC1642-27 AIC1642-30 AIC1642-33 AIC1642-50 GND VOUT
+ C2 22F SW
VOUT
+ C1 47F
One Cell Step-Up DC/DC Converter
Analog Integrations Corporation
4F, 9 Industry E. 9th Rd, Science-Based Industrial Park, Hsinchu, Taiwan TEL: 886-3-5772500 FAX: 886-3-5772510 www.analog.com.tw
DS-1642-01 012102
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AIC1642
1/2 ORDERING INFORMATION
AIC1642-XXCXXX PACKING TYPE TR: TAPE & REEL TB: TUBE BG: BAG PACKAGE TYPE X: SOT-89 Z: TO-92 OUTPUT VOLTAGE 27: 2.7V 30: 3.0V 33: 3.3V 50: 5.0V Example: AIC1642-27COTR a 2.7V Version, in MSOP8 Package & Tape & Reel Packing Type
PIN CONFIGURATION
SOT-89 TOP VIEW 1: GND 2: VOUT 3: SW
1 2 3
TO-92 TOP VIEW 1: GND 2: VOUT 3: SW
1 2 3
1/2
ABSOLUATE MAXIMUM RATINGS
Supply Voltage SW pin Voltage ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .12V ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .12V
SW pin Switch Current ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 0.6A Operating Temperature Range ... ... ... ... ... ... ... ... ... ... ... ... ..... ... ... ... ... .... .--40C to 85C Storage Temperature Range ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... -65C to 150 C Lead Temperature (Soldering 10 Sec.) 1/2 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 260C
TEST CIRCUIT
AIC1642 100 2.5V VOUT GND SW FOUT
Oscillator Test Circuit
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AIC1642
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ELECTRICAL CHARACTERISTICS
specified) PARAMETER TEST CONDITIONS
VIN=1.8V, AIC1642-27 Output Voltage VIN=1.8V, AIC1642-30 VIN=2.0V, AIC1642-33 VIN=3.0V, AIC1642-50 Input Voltage Start-Up Voltage Hold-on Voltage No-Load Input Current IOUT=1mA, VIN:02V IOUT=1mA, VIN:20V IOUT=0mA AIC1642-27 AIC1642-30 AIC1642-33 Supply Current AIC1642-50 VIN=VOUT x 0.95
(TA=25C, IOUT=10mA, Unless otherwise
SYMBOL
MIN.
2.633 2.925
TYP.
2.700 3.000 3.300 5.000
MAX.
2.767 3.075 3.382 5.125 8
UNIT
VOUT
3.218 4.875
V
VIN VSTART VHOLD IIN 15 42 50 60 IDD1 90 0.8
V V V A
0.9 0.7
A
Measurement of the IC input current (VOUT pin) VIN=VOUT + 0.5V Supply Current SW Leakage Current Measurement of the IC input current (VOUT pin) VSW =10V, VIN=VOUT + 0.5V AIC1642-27 AIC1642-30 SW Switch-On Resistance AIC1642-33 AIC1642-50 VIN=VSW x 0.95, VSW =0.4V VIN=VOUT x 0.95 Oscillator Duty Cycle Measurement of the SW Pin Waveform VIN=VOUT x 0.95 Max. Oscillator Freq. Efficiency Measurement of the SW Pin Waveform FOSC 80 105 80 130 KHz % DUTY 65 75 85 % RON 2.2 2.1 2.0 1.9 IDD2 8 0.5 A A
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AIC1642
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TYPICAL PERFORMANCE CHARACTERISTICS
Capacitor (C1) : 47 F (Tantalum Type) Diode (D1) : 1N5819 Schottky Type
2.8
85
2.7
80
Output voltage (V)
VIN=2.0V VIN=1.5V
2.5
VIN=1.8V
Efficiency (%)
2.6
75
VIN=2.0V
70
VIN=1.2V
VIN=1.8V VIN=1.5V
2.4
65
VIN=1.2V
2.3
VIN=0.9V
60
VIN=0.9V
2.2 0
55
20 40 60 80 100 120 140 160 180
0
20
40
60
80
100
120
140
160
180
Output Current (mA)
Output current (mA)
Fig. 1 AIC1642-27 Load Regulation (L=100H CD54)
Fig. 2 AIC1642-27 Efficiency (L=100H CD54)
1.0 0.9
2.78 2.76
0.8
Start up
Output Voltage VOUT (V) 2.74 2.72 2.70 2.68 2.66 2.64
0 2 4 6 8 10 12 14 16 18
Input Voltage (V)
0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0
No Load
Hold on
2.62 -40
-20
0
20
40
60
80
100
Fig. 3
Output Current (mA) AIC1642-27 Start-up & Hold-on Voltage (L=100H)
Temperature (C) Fig. 4 AIC1642-27 Output Voltage vs. Temperature
160 140 120 100 80 60 40 20
82 80
Switching Frequency (kHz)
Maximum Duty Cycle (%)
-20 0 20 40 60 80 100
78 76 74 72 70 68 66 -40
-40
-20
0
20
40
60
80
100
Fig. 5
Temperature (C) AIC1642-27 Switching Frequency vs. Temperature
Fig. 6
Temperature (C) AIC1642-27 Maximum Duty Cycle vs. Temperature
4
AIC1642
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TYPICAL PERFORMANCE CHARACTERISTICS
3.2 52 48
(Continued)
SW Turn On Resistance ()
2.8 2.4 2.0 1.6 1.2 0.8 0.4 0.0 -40
Supply Current IDD1 (A)
-20 0 20 40 60 80 100
44 40 36 32 28 24 20 -40
-20
0
20
40
60
80
100
Fig. 7
Temperature (C) AIC1642-27 SW On Resistance vs. Temperature
Fig. 8
Temperature (C) AIC1642-27 Supply Current IDD1 vs. Temperature
3.1 3.0 2.9
85
VIN=2.0V VIN=1.5V VIN=.8V
80
Output voltage VOUT(V)
2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0 0 10 20
75
Efficiency (%)
70 65 60 55
VIN=2.0V VIN=1.8V VIN=1.5V VIN=1.2V VIN=0.9V
0 20 40 60 80 100 120 140 160 180
VIN=1.2V
VIN=0.9
30 40 50 60 70 80 90 100 110 120 130 140
50
Output Current (mA) Fig. 9 AIC1642-30 Load Regulation (L=100H CD54)
Fig. 10
Output Current (mA) AIC1642-30 Efficiency (L=100H CD54)
1.0 0.9 0.8
3.06
Start up
3.04
Output Voltage Vout (V)
Input Voltage (V)
0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0
3.02 3.00 2.98 2.96 2.94 2.92
No Load
Hold on
0
2
4
6
8
10
12
14
16
18
20
Output Current (mA) Fig. 11 AIC1642-30 Start-up & Hold-on Voltage (L=100H)
2.90 -40
-20
0
20
40
60
80
100
Temperature (C) Fig. 12 AIC1642-30 Output Voltage vs. Temperature
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AIC1642
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TYPICAL PERFORMANCE CHARACTERISTICS
160 140 120 100 80 60 40 20 0 -40 82 80
(Continued)
Switching Frequency (kHz)
Maximum Duty Cycle (%)
-20 0 20 40 60 80 100
78 76 74 72 70 68 66 -40
-20
0
20
40
60
80
100
Temperature (C) Fig. 13 AIC1642-30 Switching Frequency vs. Temperature
Temperature (C) Fig. 14 AIC1642-30 Maximum Duty Cycle vs. Temperature
3.2 2.8
52 48
SW Turn On Resistance ()
Supply Current IDD1 (A)
2.4 2.0 1.6 1.2 0.8 0.4 0.0 -40
44 40 36 32 28 24 20 -40 -20 0 20 40 60 80 100
-20
0
20
40
60
80
100
Temperature (C) Fig. 15 AIC1642-30 SW On Resistance vs. Temperature
Temperature (C) Fig. 16 AIC1642-30 Supply Current vs. Temperature
3.4 3.3 3.2
90 85
VIN=2.0V VIN=1.5V VIN=1.2 VIN=1.8
80
Output Voltage (V)
3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.4 2.3 0 25 50
VIN=2.0V
Efficiency (%)
75 70
VIN=1.8V
65 60 55 50
VIN=1.5V VIN=1.2V
VIN=0.9
75 100 125 150 175 200
VIN=0.9V
0 25 50 75 100 125 150 175 200
Output Current (mA) Fig. 17 AIC1642-33 Load Regulation (L=100H CD54)
Output Current (mA) Fig. 18 AIC1642-33 Efficiency (L=100H CD54)
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AIC1642
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TYPICAL PERFORMANCE CHARACTERISTICS
1.1 1.0
(Continued)
3.50 3.45
Output Voltage VOUT (V)
0.9 0.8
Start up
3.40 3.35 3.30 3.25 3.20 3.15 3.10 3.05
Input Voltage (V)
0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 2 4 6 8 10 12 14 16 18 20
No Load
Hold on
3.00
-40
-20
0
20
40
60
80
100
Fig. 19
Output Current (mA) AIC1642-33 Start-up & Hold-on Voltage (L=100H)
Temperature (C) Fig. 20 AIC1642-33 Output Voltage vs. Temperature
150 140
82 80 78 76 74 72 70 68 66 -40
Switching Frequency (KHz)
130 120 110 100 90 80 70 60 50 -40 -20 0 20 40 60 80 100
Maximum Duty Cycle (%)
-20
0
20
40
60
80
100
Temperature (C) Fig. 21 AIC1642-33 Switching Frequency vs. Temperature
Temperature (C) Fig. 22 AIC1642-33 Maximum Duty Cycle vs. Temperature
3.2 2.8
60 56
SW Turn On Resistance ()
Supply Current IDD1 (A)
2.4 2.0 1.6 1.2 0.8 0.4 0.0 -40
52 48 44 40 36 32 28 24 -40
-20
0
20
40
60
80
100
-20
0
20
40
60
80
100
Fig. 23
Temperature (C) AIC1642-33 SW On Resistance vs. Temperature
Temperature (C) Fig. 24 AIC1642-33 Supply Current vs. Temperature
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AIC1642
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TYPICAL PERFORMANCE CHARACTERISTICS
5.5 5.0
(Continued)
90 85
VIN=3.0V
Output Voltage (V)
4.5 4.0 3.5 3.0 2.5 2.0 1.5 0 50 100 150
80
Efficiency (%)
VIN=2.0V
75 70 65 60
VIN=3.0V VIN=2.0V
VIN=1.5V VIN=1.2V VIN=0.9
VIN=1.5V VIN=0.9V VIN=1.2
55 50 45 0 50
200
250
300
350
400
100
150
200
250
300
350
400
Output Current (mA) Fig. 25 AIC1642-50 Load Regulation ( L=100H CD54)
Output Current (mA) Fig. 26 AIC1642-50 Efficiency (L=100H, CD54)
1.8 1.6 1.4
5.3 5.2
Output Voltage Vout (V)
5.1 5.0 4.9 4.8 4.7 4.6 4.5 4.4 -40
No Load
Input Voltage (V)
1.2 1.0 0.8 0.6 0.4 0.2 0.0 0
Start up
Hold on
2
4
6
8
10
12
14
16
18
20
-20
0
20
40
60
80
100
Fig. 27
Output Current (mA) AIC1642-50 Start-up & Hold-on Voltage (L=100H)
Temperature (C) Fig. 28 AIC1642-50 Output Voltage vs. Temperature
150 140
82 80
Maximum Duty Cycle (%)
-20 0 20 40 60 80 100
Switching Frequency (KHz)
130 120 110 100 90 80 70 60 -40
78 76 74 72 70 68 66 64 -40
-20
0
20
40
60
80
100
Temperature (C) Fig. 29 AIC1642-50 Switching Frequency vs. Temperature
Temperature (C) Fig. 30 AIC1642-50 Maximum Duty Cycle vs. Temperature
8
AIC1642
n
TYPICAL PERFORMANCE CHARACTERISTICS
3.2
(Continued)
100 90
SW Turn On Resistance ()
2.8
Supply Current IDD1 (A)
-20 0 20 40 60 80 100
2.4 2.0 1.6 1.2 0.8 0.4 0.0 -40
80 70 60 50 40 30 20 10 -40
-20
0
20
40
60
80
100
Temperature (C) Fig. 31 AIC1642-50 SW On Resistance vs. Temperature
Temperature (C) Fig. 34 AIC1642-50 Supply Current vs. Temperature
1/2
BLOCK DIAGRAM
VOUT 1M
1.25V REF.
SW
+
Enable GND
OSC, 100KHz
1/2
PIN DESCRIPTIONS
PIN1 : GND - Ground. Must be low impedance; sorer directly to ground plane. PIN2 : VOUT - IC supply pin. Connect VOUT to the regulator output. PIN3 : SW - Internal drain of N-MOSFET switch.
9
AIC1642
1/2 APPLICATION INFORMATION
GENERAL DESCRIPTION AIC1642 PFM (pulse frequency modulation) controller ICs combine a switch mode regulator, N-channel power MOSFET, precision voltage reference, and voltage detector in a single monolithic device. They offer extreme low quiescient current, high efficiency, and very low gate threshold voltage to ensure startup with low battery voltage (0.8V typ.). Designed to maximize battery life in portable products, and minimize switching losses by only switching as needed service the load. PFM controllers transfer a discrete amount of energy per cycle and regulate the output voltage by modulating switching frequency with the constant turn-on time. Switching frequency depends on load, input voltage, and inductor value, and it can range up to 100KHz. The SW on-resistance is typically 1.9 to 2.2 to minimize switch losses. When the output voltage drops, the error comparator enables 100kHz oscillator that turns on the MOSFET around 7.5us and 2.5us off time. Turning on the MOSFET allows inductor current to ramp up, storing energy in a magnetic field. When MOSFET turns off that force inductor current through diode to the output capacitor and load. As the stored energy is depleted, the current ramp down until the diode turns off. At this point, inductor may ring due to residual energy and stray capacitance. The output capacitor stores charge when current flowing through the diode is high, and release it when current is low, thereby maintaining a steady voltage across the load. As the load increases, the output capacitor discharges faster and the error comparator initiates cycles sooner, increasing the switching frequency. The maximum duty cycle ensure adequate time for energy transfer to output during the second half each cycle. Depending on circuit, PFM controller can operate in either discontinuous mode or conDiscontinuous Conduction Mode
t VSW TDIS Discharge Co. ID Charge Co. IOUT ISW IIN IPK VEXT
EXT Isw Ico IIN SW + VOUT ID IOUT VIN
tinuous conduction mode. Continuous conduction mode means that the inductor current does not ramp to zero during each cycle.
10
AIC1642
In the continuous mode, the switching frequency is
VEXT
fSW =
IIN IPK
1 (VOUT + VD - VIN ) TON (VOUT + VD - VSW ) x VIN - VSW * [1 + ( )] 2 VOUT + VD - VSW 1 VOUT + VD - VIN TON VOUT + VD - VSW
ISW
where Vsw = switch drop and proportion to output current.
ID IOUT
Inductor Selection To operate as an efficient energy transfer ele-
VSW
ment, the inductor must fulfill three requirements. First, the inductance must be low enough for the inductor to store adequate ent
ergy under the worst case condition of minimum input voltage and switch ON time. Second, the inductance must also be high enough so maximum current rating of AIC1642 and inductor are not exceed at the other worst case condition of maximum input voltage and ON time. Lastly, the
Continuous Conduction Mode
Continuous Conduction Mode
At the boundary between continuous and discontinuous mode, output current (IOB) is determined by
inductor must have sufficiently low DC resistance so excessive power is not lost as heat in the windings. But unfortunately this is inversely related to physical size. Minimum and maximum input voltage, output
VIN 1 VIN IOB = * TON * (1 - x ) * * VOUT 2 L
where Vd is the diode drop,
voltage and output current must be established in advance and then inductor can be selected. In discontinuous mode operation, at the end of the switch ON time, peak current and energy in the inductor build according to
TON x = (RON + RS ) * L
RON= Switch turn on resistance, RS= Inductor DC resistance TON = Switch ON time In the discontinuous mode, the switching frequency (Fsw) is Fsw =
RON + Rs VIN IPK = * TON) * 1 - exp( - L RON + Rs x VIN * (TON ) * 1 - 2 L
2 * (L) * (VOUT + VD - VIN) * (IOUT) VIN 2 x TON 2
VIN TON L
(simple loss equation),
(1 + x )
where x = (RON + RS ) *
TON L
11
AIC1642
1 L x Ipk 2 2
VOUT+ VD - VSW x VIN- VSW x IPK = - * IOUT+ * TON * 1- VIN - VSW 2 2L 2
Valley current (Iv) is
VOUT+ VD - VSW x VIN - VSW x IV = - * IOUT- * TON* 1- 2 2L VIN - VSW 2
EL =
Power required from the inductor per cycle must be equal or greater than
PL/fSW = (VOUT + VD - VIN) * (IOUT) * (
1 ) fsw
In order for the converter to regulate the output. When loading is over IOB, PFM controller operates in continuous mode. Inductor peak current can be derived from
Table 1 Indicates resistance and height for each coil. Power Inductor Type Inductance ( H ) 22 Coilcraft SMT Type (www.coilcraft.com) DO3316 Sumida SMT Type CD54 Hold SMT Type PM54 Hold SMT Type PM75 DS1608 47 100 22 47 47 100 47 100 33 Resistance ( ) 0.10 0.18 0.38 0.08 0.14 0.25 0.50 0.25 0.50 0.11 Rated Current (A) 0.7 0.5 0.3 2.7 1.8 0.7 0.5 0.7 0.5 1.2 5.2 4.5 4.5 5.0 2.9 Height (mm)
Capacitor Selection A poor choice for an output capacitor can result in poor efficiency and high output ripple. Ordinary aluminum electrolytic, while inexpensive may have unacceptably poor ESR and ESL. There are low ESR aluminum capacitors for switch mode DC-DC converters which work much well than general unit. Tantalum capacitors provide still better performance at more expensive. OS-CON capacitors have extremely low ESR in a small size. If capacitance is reduced, output ripple will increase.
Most of the input supply is supplied by the input bypass capacitor, the capacitor voltage rating should be at least 1.25 times greater than a maximum input voltage. Diode Selection Speed, forward drop, and leakage current are the three main considerations in selecting a rectifier diode. Best performance is obtained with Schottky rectifier diode such 1N5819. Motorola makes MBR0530 in surface mount. For lower output power a 1N4148 can be used although efficiency and start-up voltage will suffer substantially.
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AIC1642
VD = Diode drop. Component Power Dissipation Operating in discontinuous mode, power loss in the winding resistance of inductor can be approximate equal to The power dissipated in a switch loss is
PDSW =
2 TON VOUT + VD - VIN * (RON) * * (POUT ) 3 L VOUT
PD L =
2 TON VOUT + VF * (RD ) * * (POUT ) 3 L VOUT
The power dissipated in rectifier diode is
where POUT=VOUT * IOUT; RS=Inductor DC R;
VD PDd = * (POUT ) VOUT
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PHYSICAL DIMENSIONS
l SOT-89 (unit: mm)
D D1 C A
SYMBOL A B C D
MIN 1.40 0.36 0.35 4.40 1.62 2.29
MAX 1.60 0.48 0.44 4.60 1.83 2.60 1.50 (TYP.) 3.00 (TYP.)
H E
D1 E e
L e e1 B
e1 H L 3.94 0.89
4.25 1.20
l
SOT-89 MARKING
Part No. AIC1642-27 AIC1642-30 AIC1642-33 AIC1642-50 Marking AM27 AM30 AM33 AM50
13
AIC1642
l TO-92 (unit: mm)
L C E
SYMBOL A C
MIN 4.32
MAX 5.33 0.38 (TYP.)
A
e1 D
D E e1
4.40 3.17 1.27 (TYP.)
5.20 4.20
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