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AIC1899
1.0MHz Current-Mode Step-Up DC/DC Converter
FEATURES
Fixed Frequency 1.0MHz Current-Mode PWM Operation. Adjustable Output Voltage up to 24V. 2.5V to 5.5V Input Range. Maximum 0.1A Shutdown Current. Programmable Soft-Start. Tiny Inductor and Capacitors are allowed. Space-Saving TSOT-23-6 and SOT-23-6 Package. The high switching frequency allows the use of small external components. The Soft-Start function is programmable with an external capacitor, which sets the input current ramp rate. The AIC1899 is available in a space-saving TSOT-23-6 and SOT-23-6 package.
DESCRIPTION
The current-mode pulse-width modulation, AIC1899, step up converter is designed for MP3 player. The built-in high voltage N-channel MOSFET allows AIC1899 for step-up applications with up to 24V output voltage, and other low-side switching DC/DC converter.
APPLICATIONS
OLED Driver for MP3 Player White LED Backlight
TYPICAL APPLICATION CIRCUIT
L1 22uH
Vin=3V +
U1 AIC1899 IN LX
D1
SS0540 +
15V/15mA
Cin 33uF/6.3V
SHDN FB SS GND R2 1k
R1
11k
Cout 10uF/25V
Co 0.1uF
CF 1nF
C2 33nF
Fig. 1
Typical Step up Application Circuit
Analog Integrations Corporation
Si-Soft Research Center 3A1, No.1, Li-Hsin Rd. I, Science Park, Hsinchu 300, Taiwan, R.O.C. TEL: 886-3-5772500 FAX: 886-3-5772510 www.analog.com.tw
DS-1899G-01
121208
1
AIC1899
ORDERING INFORMATION
AIC1899XXXX PACKING TYPE TR: TAPE & REEL BG: BAG PACKAGE TYPE G: SOT-23-6 K: TSOT-23-6 P: LEAD FREE COMMERCIAL G: GREEN PACKAGE Example: AIC1899PGTR in Lead Free SOT-23-6 Package & Tape & Reel Packing Type AIC1899PKTR in Lead Free TSOT-23-6 Package & Tape & Reel Packing Type PIN CONFIGURATION SOT-23-6 / TSOT-23-6 FRONT VIEW 6 5 1: LX 2: GND 1899G 3: FB 4: SHDN 5: SS 2 1 6: IN
4
3
Note: Pin1 is determined by orienting the package marking as shown.
TSOT-23-6 Marking
Part No. AIC1899PK Marking 899PK Part No. AIC1899GK Marking 899GK
SOT-23-6 Marking
Part No. AIC1899PG Marking 1899P Part No. AIC1899GG Marking 1899G
ABSOLUTE MAXIMUM RATINGS
IN, SHDN , FB, SS to GND LX to GND LX Pin RMS Current Operating Temperature Range Junction Temperature Storage Temperature Range Lead Temperature (soldering, 10s) Thermal Resistance Junction to Case Thermal Resistance Junction to Ambient (Assume no ambient airflow, no heatsink) Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. -0.3V to +6V -0.3V to +27V 0.14A -40 to 85 C C 125C -65 to 150 C C 260C 130C /W 220C /W
2
AIC1899
ELECTRICAL CHARACTERISTICS
(VIN=V SHDN =3V, FB=GND, SS=Open, TA=25C, unless otherwise specified) (Note 1)
PARAMETER Input Supply Range Output Voltage Adjust Range VIN Undervoltage Lockout Quiescent Current Output Current Shutdown Supply Current ERROR AMPLIFIER Feedback Regulation Set Point FB Input Bias Current Line Regulation OSCILLATOR Frequency Maximum Duty Cycle POWER SWITCH On-Resistance Leakage Current SOFT-START Reset Switch Resistance Charge Current CONTROL INPUT Input Low Voltage Input High Voltage VIL VIH I SHDN V SHDN , VIN = 2.5V to 5.5V V SHDN , VIN = 2.5V to 5.5V V SHDN = 1.8V V SHDN = 0 1.0 25 0.01 50 0.1 0.3 V V A Guaranteed By Design VSS = 1.2V 1.5 4 100 7.0 A RDS(ON) Vin = 5V ILX(OFF) VLX = 24V, TA = +25C VLX = 24V 1.2 0.1 1.6 1 10 A fOSC DC 800 80 1000 82 1700 KHz % VFB IFB VFB = 1.24V 2.6V < VIN < 5.5V 1.205 1.23 21 0.05 1.255 80 0.20 V nA %/V
SYMBOL
CONDITIONS
MIN 2.5
TYP
MAX UNITS 5.5 24 V V V 0.2 5 mA mA 0.5 10 A A
VIN VOUT UVLO VIN rising, 50mV hysteresis IIN Iout VFB = 1.3V, not switching VFB = 1.0V, switching Vin = 3V, Vout = 15V Vin = 3.3V, Vout = 15V V SHDN = 0, TA = +25C V SHDN = 0
2.2 0.1 1 15 17 0.01 0.01
SHDN Input Current
Note 1: Specifications are production tested at TA=25C. Specifications over the -40C to 85C operating temperature range are assured by design, characterization and correlation with Statistical Quality Controls (SQC).
3
AIC1899
TYPICAL PERFORMANCE CHARACTERISTICS
1.15
1.25
Switching Frequency (MHz)
1.05
VIN=3.6V
1.00
Feedback Voltage (V)
1.24
VIN=3.6V
1.23
0.95
1.22
0.90
0.85
1.21
0.80 -40 -20 0 20 40 60 80 100
1.20 -50
-25
0
25
50
75
100
Temperature (C) Fig. 2 Switching Frequency vs. Temperature
Temperature (C) Fig. 3 Feedback Pin Voltage
90 85
VIN=4.2V VIN=3.6V VIN=3.3V VIN=2.7V VIN=2.5V
90 85
Efficiency (%)
Efficiency (%)
VIN=5.0V VIN=4.2V VIN=3.6V VIN=3.3V
80 75 70 65 60 0 15
80 75 70 65 60
VOUT=5.0V L1: 10uH, GTSK-51-100M
30 45 60 75 90
VOUT=15V L1: 22uH, SLF6025-220MR
0 15 30 45 60
Fig. 4
5.50
Output Current (mA) Efficiency vs. Output Current
15.5
Fig. 5
Output Current (mA) Efficiency vs. output current
VIN=3.6V Output Voltage (V)
Output Voltage (V)
5.25
15.0
VIN=3.3V
5.00
14.5
4.75
14.0
4.50 1 10 100
13.5
1
10
100
Output Current (mA) Fig. 6 Load Regulation (L1=10H)
Fig. 7
Output Current (mA) Load Regulation (L1=22H)
4
AIC1899
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
1.10
1.9
TA=25oC
1.05
1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1
FREQUENCY(MHz)
1.00
0.95
RDSON ()
3.0 3.5 4.0 4.5 5.0 5.5
0.90 2.5
1.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY VOLTAGE(V)
Fig. 8 Frequency vs. Supply Voltage
1.4
85
SUPPLY VOLTAGE (V)
Fig. 9 RDS-ON vs. Supply Voltage
FB=1.0V
SUPPLY CURRENT (mA)
SUPPLY CURRENT (A)
1.2
SHDN=1.0V
1.0
80
FB=1.3V
75
SHDN=1.0V
0.8
70
0.6
65 2.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
Fig. 10 Switching Current
Fig. 11
Non-Switching Current
VOUT VLX
VSHDN
VOUT
VLX IL
Fig. 12 Operation Waveform (VIN=3V; VOUT=15V, IOUT=15mA, Test circuit as Fig.1)
Fig. 13 Start-up Waveform (VIN=3V; VOUT=15V, IOUT=15mA, Test circuit as Fig.1)
5
AIC1899
BLOCK DIAGRAM
VIN Control
PWM/PFM
I9
Soft Start
R3 R4
Error Amp + Q1
SS
4A
PWM Comparator
+ Control Logic Driver
SHDN
FB
1
Q2
8
RC
CC 1.0MHz
R1
LX x1 RS GND x20
Oscillator
R2 Slope Compensation Current AMP x 5 + -
PIN DESCRIPTIONS
PIN 1: LX Power Switching Connection. Connect LX to inductor and output rectifier. Keep the distance between the components as close to LX as possible. Ground. Feedback Input. Connect a resistive voltage-divider from the output to FB to set the output voltage.
SHDN with a slew rate of 0.1V/s or greater. Do not leave SHDN unconnected. SHDN draws up to 50A.
PIN 5: SS Soft-Start Input. Connect a soft-start capacitor from SS to GND in order to soft-start the converter. Leave SS open to disable the soft-start function. Internal Bias Voltage Input. Connect IN to the input voltage source. Bypass IN to GND with a capacitor sitting as close to IN as possible.
PIN 2: GND PIN 3: FB -
PIN 6: IN
-
PIN 4: SHDN - Shutdown Input. Drive SHDN low to turn off the converter. To automatically start the converter, connect SHDN to IN. Drive
6
AIC1899
APPLICATION INFORMATION
The AIC1899 operates well with a variety of external components. The components in Figure 1 are suitable for most applications. See the following sections to optimize external components for a particular application.
K=
iL : Ratio of the inductor peak-to-peak IL
AC current to average DC inductor current
The inductance value is then given by:
Inductor Selection
A 22H inductor is recommended for most AIC1899 applications. Although small size and high efficiency are major concerns, the inductor should have low core losses at 1.0MHz and low DCR (copper wire resistance). Inductor selection depends on input voltage, output voltage, maximum current, size, and availability of inductor values. Other factors can include efficiency and ripple voltage. Inductors are specified by their inductance (L), peak current (IL(PK)), and resistance (DCR). The following step-up circuit equations are useful in choosing the inductor values based on the application. They allow the trading of peak current and inductor value while considering component availability and cost. The equation used here assumes a constant K, which is the ratio of the inductor peak-to-peak AC current to average DC inductor current. A good compromise between the size of the inductor versus loss and output ripple is to choose a K of 0.3 to 0.5. The peak inductor current is then given by:
L=
Vi (min) D K f Vo I o (max)
Vi (min) - (V f + Vo ) I i (max) R ds (on ) - (V f + Vo )
2
where:
D = Duty cycle =
V f : Catch diode forward drop f : Switching frequency
Capacitor Selection
The AIC1899 operates with both tantalum and ceramic output capacitors. When using tantalum capacitors, the zero caused by the ESR of the tantalum is used to ensure stability. When using ceramic capacitors, the zero due to the ESR will be at too high a frequency to be useful in stabilizing the control loop. When using ceramic capacitors, increase add the a feedforward margin, capacitor improving to the phase
control-loop stability.
Diode Selection
Schottky diodes, with their low forward voltage drop and fast reverse recovery, are the ideal choices for AIC1899 applications. The forward voltage drop of an Schottky diode represents the conduction losses in the diode, while the diode capacitance (CT or CD) represents the switching losses. For diode selection, both forward voltage drop and diode capacitance need to be considered. Schottky diodes with higher current ratings usually have lower forward voltage drop
i L ( pk )
I o (max) Vo K = 1 + Vi (min) 2
where: IO(max): Maximum output current, (A) Vi(min): Minimum input voltage, (V)
: Conversion efficiency, 0.8
7
AIC1899
and larger diode capacitance, which can cause significant switching losses at the 1.0MHz switching frequency of AIC1899.
Calculate
R1 and R2 using the equation:
R 1 Vo = V - 1 R 2 FB
where
Setting the Output Voltage
The AIC1899 operates with an adjustable output from Vin to 24V. Connect a resistive voltage divider from the output to FB (see Fig.1).
VFB , the step-up regulator feedback set
point, is 1.23V. Connect the resistive-divider as close to the IC as possible.
APPLICATION EXAMPLES
L1 22uH
Vin=3V~4.2V +
U1 AIC1899 IN LX
D1
SS0540 +
15V/15mA
Cin 33uF
SHDN FB SS GND R2 1k
R1
11k
Cout 10uF
Co 0.1uF
CF 1nF
C2 33nF
Fig. 14
1-Cell Li-Ion boost converter for OLED Application
8
AIC1899
PHYSICAL DIMENSIONS (unit: mm)
TSOT-23-6
D
E1
E
SEE VIEW B
b A2
WITH PLATING
A
c
0.25
L
L1
VIEW B
Note : 1. Refer to JEDEC MO-193AA. 2. Dimension "D" does not include mold flash, protrusions or gate burrs. Mold flash, protrusion or gate burrs shall not exceed 6 mil per side. 3. Dimension "E1" does not include inter-lead flash or protrusions. 4. Controlling dimension is millimeter, converted inch dimensions are not necessarily exact.
06.0
8
FER 06.0
03.0
0
1L
L
GAUGE PLANE SEATING PLANE
07.1
CSB 59.0
CSB 09.1
05.1
1E
BASE METAL SECTION A-A
A1
05.0
22.0
00.3
00.3
08.2
06.2
03.0
80.0
1e
D
E
e
b
A
A
e e1
.XAM 01.0 09.0 00.1
SRETEMILLIM .NIM 07.0 0 -
6-32-TOST
1A 2A c
L O B M Y S
A
9
AIC1899
SOT-23-6
D
Note:
Information provided by AIC is believed to be accurate and reliable. However, we cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AIC product; nor for any infringement of patents or other rights of third parties that may result from its use. We reserve the right to change the circuitry and specifications without notice. Life Support Policy: AIC does not authorize any AIC product for use in life support devices and/or systems. Life support devices or systems are devices or systems which, (I) are intended for surgical implant into the body or (ii) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user.
00.3
00.3
06.0
07.1
8
CSB 59.0
CSB 09.1
FER 24.0
08.2
D
.XAM 51.0 05.0 22.0 03.1 54.1
SRETEMILLIM .NIM 06.2 59.0 50.0 09.0 03.0 80.0 03.0 05.1 0
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