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19-2296; Rev 0; 1/02
Low-Voltage, 400mA Step-Down DC-DC Converters in SOT23 MAX1920/MAX1921
General Description
The MAX1920/MAX1921 step-down converters deliver over 400mA to outputs as low as 1.25V. These converters use a unique proprietary current-limited control scheme that achieves over 90% efficiency. These devices maintain extremely low quiescent supply current (50A), and their high 1.2MHz (max) operating frequency permits small, low-cost external components. This combination makes the MAX1920/MAX1921 excellent high-efficiency alternatives to linear regulators in space-constrained applications. Internal synchronous rectification greatly improves efficiency and eliminates the external Schottky diode required in conventional step-down converters. Both devices also include internal digital soft-start to limit input current upon startup and reduce input capacitor requirements. The MAX1920 provides an adjustable output voltage (1.25V to 4.0V). The MAX1921 provides factory-preset output voltages (see the Selector Guide). Both are available in space-saving 6-pin SOT23 packages.
Features
400mA Guaranteed Output Current Internal Synchronous Rectifier for >90% Efficiency Tiny 6-Pin SOT23 Package Up to 1.2MHz Switching Frequency for Small External Components 50A Quiescent Supply Current 0.1A Logic-Controlled Shutdown 2.0V to 5.5V Input Range Fixed 1.5V, 1.8V, 2.5V, 3.0V, and 3.3V Output Voltages (MAX1921) Adjustable Output Voltage (MAX1920) 1.5% Initial Accuracy Soft-Start Limits Startup Current
Ordering Information
PART MAX1920EUT-T* MAX1921EUT_ _-T TEMP RANGE -40C to +85C -40C to +85C PIN-PACKAGE 6 SOT23-6 6 SOT23-6
Applications
Next-Generation Wireless Handsets PDAs, Palmtops, and Handy-Terminals Battery-Powered Equipment CDMA Power Amplifier Supply
Note: The MAX1921 offers five preset output voltage options. See the Selector Guide, and then insert the proper designator into the blanks above to complete the part number. *Future product--contact factory for availability.
Typical Operating Circuit
INPUT 2.0V TO 5.5V IN CIN LX 4.75k 5600pF 4.7F 4.7H OUTPUT 1.5V UP TO 400mA
Pin Configuration
TOP VIEW
IN 1 6 LX
MAX1921
AGND PGND
AGND 2
ON SHDN OFF OUT
MAX1920 MAX1921
5
PGND
SHDN 3
4
OUT (FB)
SOT23-6
( ) ARE FOR MAX1920 ONLY
____________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
Low-Voltage, 400mA Step-Down DC-DC Converters in SOT23 MAX1920/MAX1921
ABSOLUTE MAXIMUM RATINGS
IN, FB, SHDN to AGND............................................. -0.3V to +6V OUT to AGND, LX to PGND ........................... -0.3V to (IN + 0.3V) AGND to PGND....................................................... -0.3V to +0.3V OUT Short Circuit to GND........................................................ 10s Continuous Power Dissipation (TA = +70C) 6-Pin SOT23-6 (derate 8.7mW/C above +70C) ..........695mW Operating Temperature Range .............................-40C to +85C Junction Temperature........................................................ +150C Storage Temperature...........................................-65C to +150C Lead Temperature (soldering 10s).................................... +300C
Stresses beyond those listed under "Absolute Maximum Ratings" 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 the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN = 3.6V, SHDN = IN, TA = 0C to +85C. Typical parameters are at TA = +25C, unless otherwise noted.) (Note 1) PARAMETER Input Voltage Range Startup Voltage UVLO Threshold UVLO Hysteresis Quiescent Supply Current Quiescent Supply Current Dropout Shutdown Supply Current IIN IIN ISHDN No switching, no load SHDN = IN, OUT/FB = 0 SHDN = GND IOUT = 0, TA = +25C IOUT = 0 to 400mA, TA = -40C to +85C IN = SHDN = 2V, IOUT = 0 to 200mA, TA = -40C to +85C OUT BIAS Current Output Voltage Range (MAX1920) FB Feedback Threshold (MAX1920) FB Feedback Hysteresis (MAX1920) FB Bias Current (MAX1920) Load Regulation Line Regulation SHDN Input Voltage High SHDN Input Voltage Low SHDN Leakage Current High-Side Current Limit VIH VIL ISHDN ILIMP SHDN = GND or IN 525 0.001 730 VFB TA = -40C to +85C VHYS IFB FB = 1.5V IOUT = 0 to 400mA VIN = 2.5V to 5.5V 1.6 0.4 1 950 IOUT SHDN = 0 OUT at regulation voltage Figure 4, IN = 4.5V TA= 25C 1.25 1.231 1.220 1.210 5 0.01 0.005 0.2 0.2 1.25 1.25 UVLO VIN rising VIN falling 1.50 1.85 1.65 200 50 220 0.1 -1.5 -3 -3 70 300 4 +1.5 +3 +3 1 8 16 4.0 1.269 1.280 1.280 mV A %/mA %/V V V A mA V A V % SYMBOL VIN I(LX) < 400mA I(LX) < 200mA CONDITIONS MIN 2.5 2.0 TYP MAX 5.5 2.5 2.0 1.95 UNITS V V V mV A A A
Output Voltage Accuracy (MAX1921)
2 ____________________________________________________________________________________________
Low-Voltage, 400mA Step-Down DC-DC Converters in SOT23 MAX1920/MAX1921
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 3.6V, SHDN = IN, TA = 0C to +85C. Typical parameters are at TA = +25C, unless otherwise noted.) (Note 1) PARAMETER Low-Side Current Limit High-Side On-Resistance Rectifier On-Resistance Rectifier Off-Current Threshold LX Leakage Current LX Reverse Leakage Current Minimum On-Time Minimum Off-Time SYMBOL ILIMN RONHS RONSR ILXOFF ILXLEAK ILXLKR tON(MIN) tOFF(MIN) IN = SHDN = 5.5V, LX = 0 to IN IN unconnected, VLX = 5.5V, SHDN = GND 0.28 0.28 ILX = -40mA, VIN = 3V ILX = 40mA, VIN = 3V CONDITIONS MIN 350 TYP 550 0.6 0.5 60 0.1 0.1 0.4 0.4 5 5 0.5 0.5 MAX 800 1.1 0.9 UNITS mA mA A A s s
Note 1: All devices are 100% production tested at TA = +25C. Limits over the operating temperature range are guaranteed by design.
Typical Operating Characteristics
(CIN = 2.2F ceramic, Circuit of Figure 1, components of Table 1, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT (VOUT = 3.3V)
MAX1920 toc01
EFFICIENCY vs. LOAD CURRENT (VOUT = 2.5V)
MAX1920 toc02
EFFICIENCY vs. LOAD CURRENT (VOUT = 1.5V)
90 80
EFFICIENCY (%)
90 80
EFFICIENCY (%)
VIN = 3.6V VIN = 5.0V
90 80
EFFICIENCY (%)
VIN = 2.7V
VIN = 2.5V
70 60 50 40 30 20 10 0 0.1 1
VIN = 4.2V
70 60 50 40 30 20 10 0
VIN = 3.3V
VIN = 5.0V
70 60 50 40 30 20 10 0 VIN = 5.0V
VIN = 3.3V
10
100
1000
0.1
1
10
100
1000
0.1
1
10
100
1000
LOAD CURRENT ( mA)
LOAD CURRENT ( mA)
LOAD CURRENT ( mA)
OUTPUT VOLTAGE ACCURACY vs. LOAD (VOUT = 3.3V)
MAX1920 toc04
OUTPUT VOLTAGE ACCURACY vs. LOAD (VOUT = 2.5V)
MAX1920 toc05
OUTPUT VOLTAGE ACCURACY vs. LOAD (VOUT = 1.5V)
MAX1920 toc06
3.399 3.366
OUTPUT VOLTAGE
2.575 2.550
OUTPUT VOLTAGE
1.545 1.530
OUTPUT VOLTAGE
VIN = 5V
VIN = 5.0V
3.333 3.300 VIN = 4.2V 3.267
VIN = 5.0V
2.525 2.500 VIN = 3V 2.475 2.450 2.425
1.515 1.500 1.485 1.470 1.455
VIN = 3.3V VIN = 2.5V
VIN = 3.6V 3.234 3.201 0 50 100 150 200 250 300 350 400 LOAD (mA)
0
50
100 150 200 250 300 350 400 LOAD (mA)
0
50
100 150 200 250 300 350 400
LOAD (mA)
____________________________________________________________________________________________ 3
MAX1920 toc03
100
100
100
Low-Voltage, 400mA Step-Down DC-DC Converters in SOT23 MAX1920/MAX1921
Typical Operating Characteristics (continued)
(CIN = 2.2F ceramic, Circuit of Figure 1, components of Table 1, unless otherwise noted.)
SWITCHING FREQUENCY vs. LOAD (VOUT = 1.8V)
MAX1920 toc07
SWITCHING FREQUENCY vs. LOAD (VOUT = 1.5V)
MAX1920 toc08
NO-LOAD SUPPLY CURRENT vs. SUPPLY VOLTAGE
90
NO-LOAD SUPPLY CURRENT (A)
MAX1920 toc09
10,000
10,000
100 VOUT = 3.3V
SWITCHING FREQUENCY (kHz)
1000
SWITCHING FREQUENCY (kHz)
80 70 60 50 40 30 20 10 0
1000
100
100
VOUT = 2.5V VOUT = 1.5V
10 VIN = 3.3 1 0.1 1 10 LOAD (mA) 100 1000
10 VIN = 3.3 1 0.1 1 10 LOAD (mA) 100 1000
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
LIGHT-LOAD SWITCHING WAVEFORM
MAX1920 toc10
MEDIUM-LOAD SWITCHING WAVEFORM
MAX1920 toc11
SOFT-START AND SHUTDOWN RESPONSE
MAX1920 toc12
VOUT AC-COUPLED 5mV/div
VOUT AC-COUPLED 5mV/div
VOUT 1V/div
IIN 100mA/div VLX 2V/div
VLX 2V/div
VIN = 3.3V, VOUT = 1.5V, ILOAD = 40mA 1s/div
VIN = 3.3V, VOUT = 1.5V, ILOAD = 250mA 1s/div
VSHDN 5V/div VIN = 3.3V, VOUT = 1.5V, RLOAD = 6 200s/div
MEDIUM-LOAD LINE-TRANSIENT RESPONSE
MAX1920 toc13
LIGHT-LOAD LINE-TRANSIENT RESPONSE
MAX1920 toc14
LOAD-TRANSIENT RESPONSE
MAX1920 toc15
VIN = 3.3V, VOUT = 1.5V, ILOAD = 20mA TO 320mA
VIN AC-COUPLED 200mV/div VIN AC-COUPLED 200mV/div
VIN AC-COUPLED 100mV/div IL 200mA/div
VOUT AC-COUPLED 5mV/div VIN = 3.8V to 4.2V, VOUT = 1.5V, ILOAD = 250mA 4s/div VIN = 3.8V to 4.2V, VOUT = 1.5V, ILOAD = 20mA 4s/div
VOUT AC-COUPLED 5mV/div
ILOAD 100mA/div
4s/div
4 ____________________________________________________________________________________________
Low-Voltage, 400mA Step-Down DC-DC Converters in SOT23 MAX1920/MAX1921
Pin Description
PIN 1 2 3 NAME IN AGND SHDN OUT 4 5 6 FB PGND LX FUNCTION Supply Voltage Input. 2.0V to 5.5V. Bypass IN to GND with a 2.2F ceramic capacitor as close to IN as possible. Analog Ground. Connect to PGND. Active-Low Shutdown Input. Connect SHDN to IN for normal operation. In shutdown, LX becomes high-impedance and quiescent current drops to 0.1A. MAX1921 Voltage Sense Input. OUT is connected to an internal voltage-divider. MAX1920 Voltage Feedback Input. FB regulates to 1.25V nominal. Connect FB to an external resistive voltage-divider between the output voltage and GND. Power Ground. Connect to AGND. Inductor Connection
Detailed Description
The MAX1920/MAX1921 step-down DC-DC converters deliver over 400mA to outputs as low as 1.25V. They use a unique proprietary current-limited control scheme that maintains extremely low quiescent supply current (50A), and their high 1.2MHz (max) operating frequency permits small, low-cost external components.
side switch turns on again or the inductor current approaches zero. The internal synchronous rectifier eliminates the need for an external Schottky diode. This control scheme allows the MAX1920/MAX1921 to provide excellent performance throughout the entire load-current range. When delivering light loads, the high-side switch turns off after the minimum on-time to reduce peak inductor current, resulting in increased efficiency and reduced output voltage ripple. When delivering medium and higher output currents, the MAX1920/MAX1921 extend either the on-time or the offtime, as necessary to maintain regulation, resulting in nearly constant frequency operation with highefficiency and low-output voltage ripple.
Control Scheme
The MAX1920/MAX1921 use a proprietary, currentlimited control scheme to ensure high-efficiency, fast transient response, and physically small external components. This control scheme is simple: when the output voltage is out of regulation, the error comparator begins a switching cycle by turning on the high-side switch. This switch remains on until the minimum ontime of 400ns expires and the output voltage regulates or the current-limit threshold is exceeded. Once off, the high-side switch remains off until the minimum off-time of 400ns expires and the output voltage falls out of regulation. During this period, the low-side synchronous rectifier turns on and remains on until either the high-
Shutdown Mode
Connecting SHDN to GND places the MAX1920/ MAX1921 in shutdown mode and reduces supply current to 0.1A. In shutdown, the control circuitry, internal switching MOSFET, and synchronous rectifier turn off and LX becomes high impedance. Connect SHDN to IN for normal operation.
Soft-Start
INPUT 2.0V TO 5.5V CIN 2 1 6 R1 L OUTPUT UP TO 400mA
IN
LX
COUT CFF
MAX1921
AGND PGND
5
ON OFF
3
SHDN
OUT
4
The MAX1920/MAX1921 have internal soft-start circuitry that limits current draw at startup, reducing transients on the input source. Soft-start is particularly useful for higher impedance input sources, such as Li+ and alkaline cells. Soft-start is implemented by starting with the current limit at 25% of its full current value and gradually increasing it in 25% steps until the full current limit is reached. See Soft-Start and Shutdown Response in the Typical Operating Characteristics.
Figure 1. Typical Output Application Circuit (MAX1921)
____________________________________________________________________________________________ 5
Low-Voltage, 400mA Step-Down DC-DC Converters in SOT23 MAX1920/MAX1921
Design Procedure
The MAX1920/MAX1921 are optimized for small external components and fast transient response. There are several application circuits (Figures 1 through 4) to allow the choice between ceramic or tantalum output capacitor and internally or externally set output voltages. The use of a small ceramic output capacitor is preferred for higher reliability, improved voltagepositioning transient response, reduced output ripple, and the smaller size and greater availability of ceramic versus tantalum capacitors.
Inductor Selection
In order to calculate the smallest inductor, several calculations are needed. First, calculate the maximum duty cycle of the application as:
DutyCycle(MAX) =
VOUT x 100% VIN (MIN)
Voltage Positioning
Figures 1 and 2 are the application circuits that utilize small ceramic output capacitors. For stability, the circuit obtains feedback from the LX node through R1, while load transients are fed-forward through CFF. Because there is no D.C. feedback from the output, the output voltage exhibits load regulation that is equal to the output load current multiplied by the inductor's series resistance. This small amount of load regulation is similar to voltage positioning as used by high-powered microprocessor supplies intended for personal computers. For the MAX1920/MAX1921, voltage positioning eliminates or greatly reduces undershoot and overshoot during load transients (see the Typical Operating Characteristics), which effectively halves the peak-to-peak output voltage excursions compared to traditional step-down converters. For convenience, Table 1 lists the recommended external component values for use with the MAX1921 application circuit of Figure 1 with various input and output voltages.
Second, calculate the critical voltage across the inductor as: if DutyCycle(MAX) < 50%, then VCRITICAL = (VIN(MIN) - VOUT), else VCRITICAL = VOUT Last, calculate the minimum inductor value as:
L(MIN) = 2.5 x 10 -6 x VCRITICAL
Select the next standard value larger than L(MIN). The L(MIN) calculation already includes a margin for inductance tolerance. Although values much larger than L(MIN) work, transient performance, efficiency, and inductor size suffer. A 550mA rated inductor is enough to prevent saturation for output currents up to 400mA. Saturation occurs when the inductor's magnetic flux density reaches the maximum level the core can support and inductance falls. Choose a low DC-resistance inductor to improve efficiency. Tables 2 and 3 list some suggested inductors and suppliers.
Table 2. Suggested Inductors
PART NUMBER Coilcraft LPO1704 L (H) 4.7 6.8 10 4.7 Sumida CDRH3D16 6.8 10 4.7 6.8 4.7 10 4.7 10 4.7 Toko D52LC 6.8 10 RL Isat (A) (ohms max) 0.200 0.320 0.410 0.080 0.095 0.160 0.081 0.108 0.38 0.79 0.230 0.490 0.087 0.105 0.150 1.10 0.90 0.80 0.90 0.73 0.55 0.63 0.57 0.74 0.50 0.84 0.55 1.14 0.95 0.76 3.2 x 3.2 x 2.0 = 20.5mm3 3.6 x 3.6 x 1.2 = 15.6mm3 4.6 x 4.6 x 1.2 = 25.4mm3 5.0 x 5.0 x 2.0 = 50.0mm3 3.8 x 3.8 x 1.8 = 26.0mm3 SIZE 6.6 x 5.5 x 1.0 = 36.3mm3
Table 1. MAX1921 Suggested Components for Figure 1
INPUT SOURCE OUTPUT 3.3V 3.0V 2.5V 5V 3.3V, 1 Li+, 3 x AA 2.5V, 2 x AA
L = 10H, COUT = 10F, R1 = 8.25k, CFF = 3300pF L = 6.8H, COUT = 6.8F, R1 = 5.62k, CFF = 4700pF L = 10H, COUT = 10F, R1 = 8.25k, CFF = 3300pF
Sumida CDRH2D18 Toko D312F Toko D412F
N/A
1.8V 1.5V
L = 4.7H, COUT = 4.7F, R1 = 4.75k, CFF = 5600pF
6 ____________________________________________________________________________________________
Low-Voltage, 400mA Step-Down DC-DC Converters in SOT23 MAX1920/MAX1921
Capacitor Selection
For nearly all applications, the input capacitor, CIN, may be as small as 2.2F ceramic with X5R or X7R dielectric. The input capacitor filters peak currents and noise at the voltage source and, therefore, must meet the input ripple requirements and voltage rating. Calculate the maximum RMS input current as: Tantalum Output Capacitor For tantalum COUT, use the application circuit of Figure 3 or Figure 4. With tantalum COUT, the equivalent series resistance (ESR) of COUT must be large enough for stability. Generally, 25mV of ESR-ripple at the feedback node is sufficient. The simplified calculation is:
IIN (RMS) = IOUT (MAX) x
VOUT (VIN - VOUT ) VIN
The output capacitor, COUT, may be either ceramic or tantalum depending upon the chosen application circuit (see Figures 1 through 4). Table 3 lists some suggested capacitor suppliers. Ceramic Output Capacitor For ceramic COUT, use the application circuit of Figure 1 or Figure 2. Calculate the minimum capacitor value as:
ESRCOUT (MIN) = 8.0 x 10 -2 x VOUT Because tantalum capacitors rarely specify minimum ESR, choose a capacitor with typical ESR that is about twice as much as ESRCOUT(MIN). Although ESRs greater than this work, output ripple becomes larger. For tantalum COUT, calculate the minimum output capacitance as:
COUT (MIN) = 1.25 x L x IOUT (MAX) ESRCOUT (MIN) x VCRITICAL
COUT (MIN) = 2.5 x 10 -6 x VCRITICAL
Select the next standard value larger than COUT(MIN). The COUT(MIN) calculation already includes a margin for capacitor tolerance. Values much larger than COUT(MIN) always improve transient performance and stability, but capacitor size and cost increase.
The 1.25 multiplier is for capacitor tolerance. Select any standard value larger than COUT(MIN).
Feedback and Compensation
The MAX1921 has factory preset output voltages of 1.5V, 1.8V, 2.5V, 3.0V, and 3.3V, while the MAX1920 is externally adjusted by connecting FB to a resistive voltage-divider. When using a ceramic output capacitor, the feedback network must include a compensation feed-forward capacitor, CFF.
INPUT 2.0V TO 5.5V CIN
1
IN
LX
6 R1
L
OUTPUT UP TO 400mA
INPUT 2.0V TO 5.5V 1 IN LX 6 L OUTPUT UP TO 400mA
COUT CFF
CIN
2
MAX1920
AGND PGND
5
COUT 2
MAX1921
AGND PGND
5
ON OFF
3
SHDN
FB
4
ON 3 SHDN OUT 4
R2
OFF
Figure 2. Typical Application Circuit (MAX1920)
Figure 3. MAX1921 Application Circuit Using Tantalum Output Capacitor
____________________________________________________________________________________________ 7
Low-Voltage, 400mA Step-Down DC-DC Converters in SOT23 MAX1920/MAX1921
Table 3. Component Suppliers
SUPPLIER Coilcraft Kemet Murata Sumida Taiyo Yuden Toko USA Japan USA Japan USA Japan PHONE 847-639-6400 408-986-0424 814-237-1431 847-956-0666 81-3-3607-5111 408-573-4150 81-3-3833-5441 847-297-0070 81-3-3727-1161 WEBSITE www.coilcraft.com www.kemet.com www.murata.com www.sumida.com www.T-Yuden.com www.yuden.co.jp www.tokoam.com www.toko.co.jp
MAX1920 Using Ceramic COUT When using the application circuit of Figure 2, the inductor's series resistance causes a small amount of load regulation, as desired for a voltage-positioning load transient response. Choose R1 and R2 such that VOUT is high at no load by about half of this load regulation:
V + RL x IOUT (MAX) 2 R1 = R2 x OUT - 1 VREF
where R2 is chosen in the 50k to 500k range, VREF = 1.25V and RL is the typical series resistance of the inductor. Use 1% or better resistors. Next, calculate the equivalent resistance at the FB node as:
MAX1921 Using Ceramic COUT When using the application circuit of Figure 1, the inductor's series resistance causes a small amount of load regulation, as desired for a voltage-positioning load transient response. Choose R1 such that VOUT is high at no load by about half of this load regulation. The simplified calculation is:
R1 x R2 R1 + R2 Then, calculate CF F for 25mV ripple at FB. The simplified calculation is: Re q = R1 || R2 =
R1 = 5.0 x 104 x RL (MAX) where RL(MAX) is the maximum series resistance of the inductor. Select a standard resistor value that is within 20% of this calculation. Next, calculate CFF for 25mV ripple at the internal feedback node. The simplified calculation is: CFF = 2.5 x 10 -5 R1
where R1 is the standard resistor value that is used. Select a standard capacitor value that is within 20% of the calculated CFF.
CFF = 2.5 x 10 -5 Re q
Select a standard capacitor value that is within 20% of the calculated CFF. MAX1920 Using Tantalum COUT When using the application circuit of Figure 4, choose R1 and R2 such as to obtain the desired VOUT:
V R1 = R2 x OUT - 1 VREF
where R2 is chosen to be less than 50k and VREF = 1.25V. Use 1% or better resistors.
Layout Considerations
High switching frequencies make PC board layout a very important part of design. Good design minimizes excessive EMI on the feedback paths and voltage gradients in the ground plane, both of which can result in instability or regulation errors. Connect the inductor, input filter capacitor, and output filter capacitor as close to the device as possible, and keep their traces short, direct, and wide. Connect their ground pins at a single common node in a star ground configuration. The external voltage-feedback network should be very close to the FB pin, within 0.2in (5mm). Keep noisy traces, such as the LX trace, away from the voltage-feedback network; also keep them separate, using grounded copper. The MAX1920/MAX1921 evaluation kit data sheet includes a proper PC board layout and routing scheme.
INPUT 2.0V TO 5.5V CIN
1
IN
LX
6
L
OUTPUT UP TO 400mA
COUT 2
MAX1920
AGND PGND
5
R1
ON OFF
3
SHDN
FB
4
R2
Figure 4. MAX1920 Application Circuit Using Tantalum Output Capacitor
8 ____________________________________________________________________________________________
Low-Voltage, 400mA Step-Down DC-DC Converters in SOT23 MAX1920/MAX1921
Selector Guide
PART MAX1920EUT* MAX1921EUT33* MAX1921EUT30* MAX1921EUT25* MAX1921EUT18 MAX1921EUT15 VOUT (V) Adjustable 3.3 3.0 2.5 1.8 1.5 TOP MARK ABCO ABCJ ABCK ABCL ABCM ABCN
Chip Information
TRANSISTOR COUNT: 1467
*Future product specification subject to change prior to release. Contact factory for availability.
Package Information
6LSOT.EPS
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _______________________ 9 ____________________________________________________________________________________________ 9 (c) 2002 Maxim Integrated Products Printed USA MAXIM is a registered trademark of Maxim Integrated Products.

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