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AP1602
Step-Up DC/DC Converter Features
-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. -Space Saving Packages: SOT89-5
General Description
The AP1602 is a high efficiency step-up DC/DC converter for applications using 1 to 2 NiMH battery cells. Only three external components are required to deliver a fixed output voltage of 3.3V. The AP1602 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 SOT89-5 packages make the AP1602 an ideal choice of DC/DC converter for space conscious applications, like pagers, electronic cameras, and wireless microphones.
Applications
-Pagers. -Cameras. -Wireless Microphones. -Pocket Organizers. -Battery Backup Suppliers. -Portable Instruments.
Pin Assignments
REF 1 GND 2 SHDN 3 AP1602A 7 LX 4 5 OUT
Pin Descriptions
Pin Name REF OUT LX Pin No. A B 1 5 4 2 3 3 4 5 2 1 Description 1.2V Reference Voltage. Bypass with a 0.1F capacitor. Power Output. OUT provides bootstrap power to the IC. N-Channel and P-Channel Power MOSFET Drain Ground Shutdown Input. Drive high (>80% of VOUT) for operating mode. Drive low (<20% of VOUT) for shutdown mode. Connect to OUT for normal operation. Feedback pin
FB
1 AP1602B
5
LX
GND
GND 2 REF 3
SHDN
7 OUT 4
SOT89-5L
FB
Ordering Information
AP1602 X X X X Version A: A version B: B version Package Y: SOT89-5L Lead Free Packing
Blank : Normal Blank : Tube L : Lead Free Package A : Taping
This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sale of the product.
Rev. 0.1 Apr. 14, 2004 1/7
AP1602
Step-Up DC/DC Converter Block Diagram
SHDN
Minimum Off-Time One-Shot Q TRIG One-Shot
EN
Zero Crossing Amplifier P
OUT
0.1uF + 47uF
+
LX + 22uH F/F Q S R N GND
VIN + 47uF
Maximum On-Time One-Shot TRIG Q One-Shot
+
-
-
Current-Limit Amplifier
+ FB
Absolute Maximum Ratings
Symbol VCC VREF VSW IOUT ISW TST TOT Parameter Supply Voltage (OUT to GND) REF to GND Switch Voltage (LX to GND) Output Current (OUT) Switch Current (LX) Storage Temperature Range Operation Temperature Range Rating -0.3 to 5.5 -0.3 to VOUT+0.3 -0.3 to VOUT+0.3 -0.8 to 0.8 -0.8 to 0.8 -65 to +150 -40 to +80 Unit V V V A A o C o C
+
Error Amplifier REF 0.1uF
Anachip Corp. www.anachip.com.tw 2/7
Rev.0.1 Apr. 14, 2004
AP1602
Step-Up DC/DC Converter Electrical Characteristics
(RL = , TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
Symbol VIN
Parameter Minimum Input Voltage Operating Voltage Start-Up Voltage Start-Up Voltage Tempco Output Voltage Range Steady-State Output Current (Note2) Reference Voltage Output Voltage Reference Voltage Tempco Reference Voltage Load Regulation Reference Voltage Line Regulation Internal NFET, PFET On-Resistance LX Switch Current Limit (NFET) LX Leakage Current Operating Current into OUT Shutdown Current into OUT Efficiency LX Switch On-Time LX Switch Off-Time
SHDN Input Current
Conditions TA = +25C TA = +25C, RL = 3k (Note 1)
Min. 1.1 2
Typ. 0.9 0.9 -2 220 1.2 3.3 0.024 15 0.08 0.3 0.5 0.05 16 0.1 90 4 1
Max. 5.5 1.1 5.5 1.224 3.43 30 2.5 0.6 0.65 1 35 1 7 1.2
Unit V V V mV/C V mA V V mV/C mV mV/V A A A A % s s
IOUT VREF VOUT
TEMPCO
(VOUT = 3.3V) IREF=0
150 1.176 3.17 0.4
VREF_LOAD VREF_LINE RDS(ON) ILIM ILEAK
IREF=0 to 80 A VIN=1.1V to 3.6V ILX=100mA
VLX=0, 5.5V; VOUT=5.5V VOUT=3.3V
SHDN =GND VOUT=3.3V, ILOAD=200mA
tON tOFF
3 0.8
ISHDN VIL VIH
VSHDN =0 or VOUT
0.8
0.07 -
50 0.2 -
nA VOUT
SHDN Input Voltage
Based on VOUT Voltage
Note 1: Start-up voltage operation is guaranteed with the addition of a Schottky MBR0520 external diode between the input and output. Note 2: Steady-state output current indicates that the device maintains output voltage regulation under load.
Typical Application Circuit
1.1V to 3.6V VIN ON 22uH
+
100uF
OFF
SHDN
REF 0.1uF GND
LX OUT
Optional
+
220uF
Fixed Output ( 3.3V )
Anachip Corp. www.anachip.com.tw 3/7
Rev.0.1 Apr. 14, 2004
AP1602
Step-Up DC/DC Converter Typical Performance Characteristics
REFERENCE OUTPUT VOLTAGE v.s. TEMPERATURE
1.21
MAXIMUM OUTPUT CURRENT v.s. INPUT VOLTAGE (VOUT=3.3V)
600 500 400 300 200 100 0 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3
REFERENCE OUTPUT VOLTAGE (V)
1.19 1.18 1.17 1.16 1.15 1.14 -40 -20 0 20 40 60 80 100
TEMPERATURE (C)
MAXIMUM OUTPUT CURRENT (mA)
1.2
INPUT VOLTAGE (V)
START-UP VOLTAGE v.s. LOAD CURRENT
1.8 1.6 1.4
Without Diode With Diode
NO-LOAD BATTERY CURRENT v.s. INPUT BATTERY VOLTAGE
160 140
INPUT BATTERY CURRENT (uA)
START-UP VOLTAGE (V)
120 100 80 60 40 20 0 0.5 1 1.5 2 2.5 3
1.2 1 0.8 0.6 0.4 0.2 0 0.01 0.1 1 10 100
LOAD CURRENT (mA)
INPUT BATTERY VOLTAGE (V)
Anachip Corp. www.anachip.com.tw 4/7
Rev.0.1 Apr. 14, 2004
AP1602
Step-Up DC/DC Converter Typical Performance Characteristics (Continued)
EFFICIENCY vs. LOAD CURRENT
100 90 80 70 60 50 40 30 20 10 0 0.1 1 10 100 1000
VIN=1.2V VIN=2.4V
SHUTDOWN CURRENT (uA)
1 0.8 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1 1
SHUTDOWN CURRENT v.s. SUPPLY VOLTAGE
EFFICIENCY (%)
2
3
4
LOAD CURRENT (mA)
SUPPLY VOLTAGE (V)
SHUTDOWN THRESHOLD VOLTAGE v.s. SUPPLY VOLTAGE
SHUTDOWN THRESHOLD VOLTAGE (V)
1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 1 1.5 2 2.5 3 3.5 4
SUPPLY VOLTAGE (V)
Marking Information
Appendix
XX : Identification code (See Appendix) Y : Year: 0-9 M : Month: A~L X : Blank: Normal L: Lead Free Package
1 XX 2 3 YM X
5
Part Number
Package
AP1602A AP1602B
SOT89-5 SOT89-5
Identification Code EZ ET
7 4
Anachip Corp. www.anachip.com.tw 5/7
Rev.0.1 Apr. 14, 2004
AP1602
Step-Up DC/DC Converter Function Descriptions
General Description AP1602 PFM (pulse frequency modulation) converter IC series combine a switch mode converter, power MOSFET, and precision voltage reference in a single monolithic device. They offer both extreme low quiescent current, high efficiency, and very low gate threshold voltage to ensure start-up with low battery voltage (0.9V typ.). Designed to maximize battery life in portable products, and minimize switching losses by only switching as needed service the load. PFM converters 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 to 1.5 W to minimize switch losses. When the output voltage drops, the error comparator enables 100KHz oscillator that turns on the MOSFET around 7.5us and 2.5ms off time. Turning on the MOSFET allows inductor current to ramp up, storing energy in a magnetic field and 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 converter can operate in either discontinuous mode or continuous conduction mode. Continuous conduction mode means that the inductor current does not ramp to zero during each cycle. 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 as 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. Inductor Selection To operate as an efficient energy transfer element, the inductor must fulfill three requirements. First, the inductance must be low enough for the inductor to store adequate energy 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 AP1602 and inductor are not exceed at the other worst case condition of maximum input voltage and ON time. Lastly, the 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 voltage and output current must be established before and inductor can be selected. Capacitor Selection A poor choice for a output capacitor can result in poor efficiency and high output ripple. Ordinary aluminum electrolyzers, while inexpensive may have unacceptably poor ESR and ESL. There are low ESR aluminum capacitors for switch mode DC-DC converters which work much better than general propose 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.
Anachip Corp. www.anachip.com.tw 6/7
Rev.0.1 Apr. 14, 2004
AP1602
Step-Up DC/DC Converter Package Information
Package Type: SOT89-5L
A C D F
E
B K
J F L I H G
Symbol
Dimensions In Millimeters Min. Nom. Max.
Dimensions In Inches Min. Nom. Max.
A B C D E F G H I J K L
4.40 4.05 1.50 1.30 2.40 0.80
4.50 4.15 1.60 1.40 2.50 3.00 Ref. 1.50 Ref.
4.60 4.25 1.70 1.50 2.60 -
0.173 0.159 0.059 0.051 0.094 0.031
0.177 0.163 0.063 0.055 0.098 0.118 Ref. 0.059 Ref.
0.181 0.167 0.067 0.059 0.102 -
0.40 1.40 0.35
0.46 1.50 0.39 5 Typ.
o
0.52 1.60 0.43
0.016 0.055 0.014
0.018 0.059 0.015 5 Typ.
o
0.020 0.063 0.017
Anachip Corp. www.anachip.com.tw 7/7
Rev.0.1 Apr. 14, 2004

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