19-1735; Rev 0; 7/01 1.5µA IQ, Step-Up DC-DC Converters in Thin SOT23-5 The MAX1722/MAX1723/MAX1724 compact, high-efficiency, step-up DC-DC converters are available in tiny, 5pin thin SOT23 packages. They feature an extremely low 1.5µA quiescent supply current to ensure the highest possible light-load efficiency. Optimized for operation from one to two alkaline or nickel-metal-hydride (NiMH) cells, or a single Li+ cell, these devices are ideal for applications where extremely low quiescent current and ultra-small size are critical. Built-in synchronous rectification significantly improves efficiency and reduces size and cost by eliminating the need for an external Schottky diode. All three devices feature a 0.5Ω N-channel power switch. The MAX1722/ MAX1724 also feature proprietary noise-reduction circuitry, which suppresses electromagnetic interference (EMI) caused by the inductor in many step-up applications. The family offers different combinations of fixed or adjustable outputs, shutdown, and EMI reduction (see Selector Guide). Applications Features ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ Up to 90% Efficiency No External Diode or FETs Needed 1.5µA Quiescent Supply Current 0.1µA Logic-Controlled Shutdown ±1% Output Voltage Accuracy Fixed Output Voltage (MAX1724) or Adjustable Output Voltage (MAX1722/MAX1723) Up to 150mA Output Current 0.8V to 5.5V Input Voltage Range 0.91V Guaranteed Startup (MAX1722/MAX1724) Internal EMI Suppression (MAX1722/MAX1724) Thin SOT23-5 Package (1.1mm max Height) Ordering Information TEMP. RANGE PINPACKAGE MAX1722EZK-T -40°C to +85°C 5 SOT23 ADQF -40°C to +85°C -40°C to +85°C -40°C to +85°C 5 SOT23 5 SOT23 5 SOT23 ADQG ADQH ADQI -40°C to +85°C -40°C to +85°C 5 SOT23 5 SOT23 ADQJ ADQK PART Pagers Remote Controls Single-Cell BatteryPowered Devices MAX1723EZK-T MAX1724EZK27-T MAX1724EZK30-T Remote Wireless Transmitters Low-Power Hand-Held Instruments MAX1724EZK33-T MAX1724EZK50-T Personal Medical Devices MP3 Players Personal Digital Assistants (PDA) Digital Still Cameras Typical Operating Circuit TOP MARK Selector Guide PART OUTPUT (V) SHDN LX DAMPING MAX1722EZK Adjustable No Yes MAX1723EZK MAX1724EZK27 MAX1724EZK30 Adjustable Fixed 2.7 Fixed 3.0 Yes Yes Yes No Yes Yes MAX1724EZK33 MAX1724EZK50 Fixed 3.3 Fixed 5.0 Yes Yes Yes Yes Pin Configurations 10µH TOP VIEW IN 0.8V TO 5.5V BATT LX BATT 1 MAX1724 OUT OUT ON OFF SHDN 3.3V AT UP TO 150mA GND 2 5 LX 4 OUT MAX1722 FB 3 GND THIN SOT23-5 Pin Configurations are continued at end of data sheet. ________________________________________________________________ Maxim Integrated Products 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. 1 MAX1722/MAX1723/MAX1724 General Description MAX1722/MAX1723/MAX1724 1.5µA IQ, Step-Up DC-DC Converters in Thin SOT23-5 ABSOLUTE MAXIMUM RATINGS OUT, SHDN, BATT, LX to GND ................................-0.3V to +6V FB to GND ................................................-0.3V to (VOUT + 0.3V) OUT, LX Current.......................................................................1A Continuous Power Dissipation (TA = +70°C) 5-Pin Thin SOT23 (derate 7.1mW/°C above +70°C) ...571mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) ................................ +300°C 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 (VBATT = 1.2V, VOUT = 3.3V (MAX1722/MAX1723), VOUT = VOUT(NOM) (MAX1724), SHDN = OUT, RL = ∞, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL Minimum Input Voltage Operating Input Voltage CONDITIONS VIN TA = +25°C TA = +25°C, RL = 3kΩ Minimum Startup Input Voltage MAX1724EZK27 MAX1724EZK30 Output Voltage VOUT MAX1724EZK33 MAX1724EZK50 Output Voltage Range MIN TYP MAX 0.8 MAX1722/MAX1724 V MAX1722/MAX1724 0.91 5.5 MAX1723 (Note 2) 1.2 5.5 MAX1722/MAX1724 0.83 0.91 MAX1723 (Note 2) 0.87 1.2 2.7 UNITS TA = +25°C 2.673 TA = 0°C to +85°C 2.633 TA = +25°C 2.970 TA = 0°C to +85°C 2.925 TA = +25°C 3.267 TA = 0°C to +85°C 3.218 TA = +25°C 4.950 TA = 0°C to +85°C 4.875 5.125 2 5.5 V V 2.727 2.767 3.0 3.030 3.075 3.3 3.333 V 3.383 5.0 5.050 VOUT MAX1722/MAX1723 Feedback Voltage VFB MAX1722/MAX1723 Feedback Bias Current IFB MAX1722/MAX1723 N-Channel On-Resistance RDS(ON) VOUT forced to 3.3V 0.5 1.0 Ω P-Channel On-Resistance RDS(ON) VOUT forced to 3.3V 1.0 2.0 Ω N-Channel Switch Current Limit ILIM VOUT forced to 3.3V 400 500 600 mA Switch Maximum On-Time tON 3.5 5 6.5 µs 5 20 35 mA µA Synchronous Rectifier ZeroCrossing Current VOUT forced to 3.3V Quiescent Current into OUT (Notes 3, 4) TA = +25°C 1.223 TA = 0°C to +85°C 1.210 1.235 TA = +25°C 1.5 TA = +85°C 2.2 20 1.5 3.6 0.01 0.5 Shutdown Current into OUT MAX1723/MAX1724 (Notes 3, 4) TA = +25°C TA = +85°C 0.1 Quiescent Current into BATT MAX1722/MAX1724 (Note 4) TA = +25°C 0.001 TA = +85°C 0.01 2 1.247 1.260 _______________________________________________________________________________________ 0.5 V V nA µA µA 1.5µA IQ, Step-Up DC-DC Converters in Thin SOT23-5 (VBATT = 1.2V, VOUT = 3.3V (MAX1722/MAX1723), VOUT = VOUT(NOM) (MAX1724), SHDN = OUT, RL = ∞, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL Shutdown Current into BATT SHDN Voltage Threshold MAX1724 (Note 4) VIL MAX1723/MAX1724 VIH MAX1723/MAX1724 MAX1723/MAX1724, V SHDN = 5.5V SHDN Input Bias Current TYP MAX TA = +25°C 0.001 0.5 TA = +85°C 0.01 CONDITIONS MIN 75 400 500 800 TA = +25°C 2 100 TA = +85°C 7 UNITS µA mV nA ELECTRICAL CHARACTERISTICS (VBATT = 1.2V, VOUT = 3.3V (MAX1722/MAX1723), VOUT = VOUT(NOM) (MAX1724), SHDN = OUT, RL = ∞, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX MAX1724EZK27 2.633 2.767 MAX1724EZK30 2.925 3.075 MAX1724EZK33 3.218 3.383 MAX1724EZK50 4.875 5.125 UNITS V Output Voltage VOUT Output Voltage Range VOUT MAX1722/MAX1723 2 5.5 V VFB MAX1722/MAX1723 1.200 1.270 V N-Channel On-Resistance RDS(ON) VOUT forced to 3.3V 1.0 Ω P-Channel On-Resistance RDS(ON) VOUT forced to 3.3V 2.0 Ω N-Channel Switch Current Limit ILIM VOUT forced to 3.3V 400 620 mA Switch Maximum On-Time tON 3.5 6.5 µs 5 35 mA 3.6 µA Feedback Voltage Synchronous Rectifier ZeroCrossing Current VOUT forced to 3.3V Quiescent Current into OUT (Notes 3,4) SHDN Voltage Threshold VIL MAX1723/MAX1724 VIH MAX1723/MAX1724 75 800 mV Note 1: Limits are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by design. Note 2: Guaranteed with the addition of a Schottky MBR0520L external diode between LX and OUT when using the MAX1723 with only one cell, and assumes a 0.3V voltage drop across the Schottky diode (see Figure 3). Note 3: Supply current is measured with an ammeter between the output and OUT pin. This current correlates directly with actual battery supply current, but is reduced in value according to the step-up ratio and efficiency. Note 4: VOUT forced to the following conditions to inhibit switching: VOUT = 1.05 ✕ VOUT(NOM) (MAX1724), VOUT = 3.465V (MAX1722/MAX1723). _______________________________________________________________________________________ 3 MAX1722/MAX1723/MAX1724 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (Figure 3 (MAX1723), Figure 7 (MAX1722), Figure 8 (MAX1724), VBATT = VIN = 1.5V, L = 10µH, CIN = 10µF, COUT = 10µF, TA = +25°C, unless otherwise noted.) EFFICIENCY vs. LOAD CURRENT (VOUT = 5.0V) 70 VIN = 1.0V 60 80 70 60 L = DO1606 0.1 1 10 100 1000 0.01 0.1 MAX1722 toc03 VIN = 1.5V 70 VIN = 1.0V 1 10 100 0.01 1000 0.1 1 10 100 LOAD CURRENT (mA) LOAD CURRENT (mA) MAXIMUM OUTPUT CURRENT vs. INPUT VOLTAGE STARTUP VOLTAGE vs. LOAD CURRENT QUIESCENT CURRENT INTO OUT vs. OUTPUT VOLTAGE VOUT = 5.0V 80 VOUT = 3.3V 2.0 1.8 1.6 1.4 1.2 1.0 40 0.8 0 3 4 5 MAX1722 toc06 1.4 1.2 1.0 0.8 0.6 0.4 0 0.01 0.1 INPUT VOLTAGE (V) 1 10 LOAD CURRENT (mA) STARTUP VOLTAGE vs. TEMPERATURE NO LOAD 1.0 100 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 OUTPUT VOLTAGE (V) SWITCHING WAVEFORMS MAX1722 toc07 1.2 STARTUP VOLTAGE (V) 1.6 MAX1722 toc08 2 0.8 ILX 500mA/div VOUT 50mV/div 0.6 0.4 VLX 2V/div 0.2 0 -40 -15 10 35 TEMPERATURE (°C) 1000 0.2 0.6 1 NO LOAD 1.8 QUIESCENT CURRENT (µA) 120 STARTUP VOLTAGE (V) 160 RESISTIVE LOAD VOUT = 5.0V 2.2 2.0 MAX1722 toc05 2.4 MAX1722 toc04 VOUT = 2.5V 4 L = DO1606 50 LOAD CURRENT (mA) 200 0 VIN = 2.0V 80 L = DO1606 VIN = 1.5V 50 0.01 90 60 VIN = 1.0V VIN = 1.5V 50 100 EFFICIENCY (%) 80 VIN = 2.5V VIN = 2.0V 90 EFFICIENCY (%) VIN = 4.0V MAX1722 toc02 100 MAX1722 toc01 VIN = 2.0V 90 EFFICIENCY (%) VIN = 3.3V EFFICIENCY vs. LOAD CURRENT (VOUT = 2.5V) EFFICIENCY vs. LOAD CURRENT (VOUT = 3.3V) 100 IOUT(MAX) (mA) MAX1722/MAX1723/MAX1724 1.5µA IQ, Step-Up DC-DC Converters in Thin SOT23-5 60 85 1µs/div IOUT = 50mA, VOUT = 5.0V, VIN = 3.3V _______________________________________________________________________________________ 1.5µA IQ, Step-Up DC-DC Converters in Thin SOT23-5 SHUTDOWN RESPONSE 3.3V MAX1722 toc10 MAX1722 toc09 LOAD-TRANSIENT RESPONSE 5V A VOUT 2V/div 0 50mA 2V VSHDN 1V/div B 0 0 A: VOUT, 50mV/div B: IOUT, 20mA/div 1ms/div VIN = 3.3V, VOUT = 5.0V, ROUT = 100Ω 200µs/div SHUTDOWN INPUT THRESHOLD vs. TEMPERATURE MAX1722 toc11 0.8 SHUTDOWN THRESHOLD (mV) 0.7 0.6 RISING EDGE 0.5 0.4 FALLING EDGE 0.3 0.2 0.1 0 -40 -15 10 35 60 85 TEMPERATURE (°C) Pin Description PIN NAME FUNCTION MAX1722 MAX1723 MAX1724 1 — 1 BATT Battery Input and Damping Switch Connection — 1 3 SHDN Shutdown Input. Drive high for normal operation. Drive low for shutdown. 2 2 2 GND Ground 3 3 — FB 4 4 4 OUT 5 5 5 LX Feedback Input to Set Output Voltage. Use a resistor-divider network to adjust the output voltage. See Setting the Output Voltage section. Power Output. OUT also provides bootstrap power to the IC. Internal N-channel MOSFET Switch Drain and P-Channel Synchronous Rectifier Drain _______________________________________________________________________________________ 5 MAX1722/MAX1723/MAX1724 Typical Operating Characteristics (continued) (Figure 3 (MAX1723), Figure 7 (MAX1722), Figure 8 (MAX1724), VBATT = VIN = 1.5V, L = 10µH, CIN = 10µF, COUT = 10µF, TA = +25°C, unless otherwise noted.) MAX1722/MAX1723/MAX1724 1.5µA IQ, Step-Up DC-DC Converters in Thin SOT23-5 OUT MAX1723 ZEROCROSSING DETECTOR STARTUP CIRCUITRY P SHDN CONTROL LOGIC DRIVER LX FB ERROR COMPARATOR 1.235V REFERENCE N CURRENT LIMIT GND Figure 1. MAX1723 Simplified Functional Diagram Detailed Description The MAX1722/MAX1723/MAX1724 compact, high-efficiency, step-up DC-DC converters are guaranteed to start up with voltages as low as 0.91V and operate with an input voltage down to 0.8V. Consuming only 1.5µA of quiescent current, these devices include a built-in synchronous rectifier that reduces cost by eliminating the need for an external diode and improves overall efficiency by minimizing losses in the circuit (see Synchronous Rectification section). The MAX1722/MAX1724 feature a clamp circuit that reduces EMI due to inductor ringing. The MAX1723/MAX1724 feature an active-low shutdown that reduces quiescent supply current to 0.1µA. The MAX1722/MAX1723 have an adjustable output voltage, while the MAX1724 is available with four fixed-output voltage options (see Selector Guide). Figure 1 is the MAX1723 simplified functional diagram and Figure 2 is the MAX1724 simplified functional diagram. PFM Control Scheme A forced discontinuous, current-limited, pulse-frequencymodulation (PFM) control scheme is a key feature of the 6 MAX1722/MAX1723/MAX1724. This scheme provides ultra-low quiescent current and high efficiency over a wide output current range. There is no oscillator; the inductor current is limited by the 0.5A N-channel current limit or by the 5µs switch maximum on-time. Following each on cycle, the inductor current must ramp to zero before another cycle may start. When the error comparator senses that the output has fallen below the regulation threshold, another cycle begins. Synchronous Rectification The internal synchronous rectifier eliminates the need for an external Schottky diode, thus reducing cost and board space. While the inductor discharges, the Pchannel MOSFET turns on and shunts the MOSFET body diode. As a result, the rectifier voltage drop is significantly reduced, improving efficiency without the addition of external components. Low-Voltage Startup Circuit The MAX1722/MAX1723/MAX1724 contain a low-voltage startup circuit to control DC-DC operation until the output voltage exceeds 1.5V (typ). The minimum start- _______________________________________________________________________________________ 1.5µA IQ, Step-Up DC-DC Converters in Thin SOT23-5 MAX1722/MAX1723/MAX1724 DAMPING SWITCH BATT OUT MAX1724 ZEROCROSSING DETECTOR STARTUP CIRCUITRY R2 P SHDN CONTROL LOGIC DRIVER ERROR COMPARATOR LX N R1 CURRENT LIMIT 1.235V REFERENCE GND Figure 2. MAX1724 Simplified Functional Diagram 10µH 1.2V TO VOUT D1 10µF SHDN LX OUT R2 2.37MΩ MAX1723 GND VOUT = 3.6V 10µF lacks a BATT pin; therefore, this circuit is powered through the OUT pin. Adding a Schottky diode in parallel with the P-channel synchronous rectifier allows for startup voltages as low as 1.2V for the MAX1723 (Figure 3). The external Schottky diode is not needed for input voltages greater than 1.8V. Once started, the output maintains the load as the battery voltage decreases below the startup voltage. Shutdown (MAX1723/MAX1724) FB R1 1.24MΩ Figure 3. MAX1723 Single-Cell Operation up voltage is a function of load current (see Typical Operating Characteristics). This circuit is powered from the BATT pin for the MAX1722/MAX1724, guaranteeing startup at input voltages as low as 0.91V. The MAX1723 The MAX1723/MAX1724 enter shutdown when the SHDN pin is driven low. During shutdown, the body diode of the P-channel MOSFET allows current to flow from the battery to the output. VOUT falls to approximately VIN - 0.6V and LX remains high impedance. Shutdown can be pulled as high as 6V, regardless of the voltage at BATT or OUT. For normal operation, connect SHDN to the input. _______________________________________________________________________________________ 7 MAX1722/MAX1723/MAX1724 1.5µA IQ, Step-Up DC-DC Converters in Thin SOT23-5 VOUT VIN OUT MAX1722 MAX1724 PDRV P BATT DAMPING SWITCH TIMING CIRCUIT DAMP LX NDRV N GND Figure 4. Simplified Diagram of Damping Switch 1V/div 1V/div 1µs/div Figure 5. LX Ringing Without Damping Switch (MAX1723) 1µs/div Figure 6. LX Ringing With Damping Switch (MAX1722/MAX1724) Design Procedure BATT/Damping Switch (MAX1722/MAX1724) The MAX1722/MAX1724 include an internal damping switch (Figure 4) to minimize ringing at LX and reduce EMI. When the energy in the inductor is insufficient to supply current to the output, the capacitance and inductance at LX form a resonant circuit that causes ringing. The damping switch supplies a path to quickly dissipate this energy, suppressing the ringing at LX. This does not reduce the output ripple, but does reduce EMI with minimal impact on efficiency. Figures 5 and 6 show the LX node voltage waveform without and with the damping switch, respectively. 8 Setting the Output Voltage (MAX1722/MAX1723) The output voltage can be adjusted from 2V to 5.5V using external resistors R1 and R2 (Figure 7). Since FB leakage is 20nA (max), select feedback resistor R1 in the 100kΩ to 1MΩ range. Calculate R2 as follows: V R2 = R1 OUT − 1 VFB where VFB = 1.235V. _______________________________________________________________________________________ 1.5µA IQ, Step-Up DC-DC Converters in Thin SOT23-5 10µF 10µH OUT MAX1722 L< OUTPUT 2V TO 5.5V LX BATT R2 10µF VBATT t ON(MAX) ILIM where the maximum on-time is typically 5µs, and the current limit (ILIM) is typically 500mA (see Electrical Characteristics table). FB R1 GND For larger inductor values, determine the peak inductor current (IPEAK) by: IPEAK = VBATT t ON(MAX) L Figure 7. Adjustable Output Circuit Inductor Selection The control scheme of the MAX1722/MAX1723/ MAX1724 permits flexibility in choosing an inductor. A 10µH inductor value performs well in most applications. Smaller inductance values typically offer smaller physical size for a given series resistance, allowing the smallest overall circuit dimensions. Circuits using larger inductance values may start up at lower battery voltages, provide higher efficiency, and exhibit less ripple, but they may reduce the maximum output current. This occurs when the inductance is sufficiently large to prevent the maximum current limit (I LIM ) from being reached before the maximum on-time (t ON(MAX) ) expires. Table 1. Suggested Inductors and Suppliers INPUT 0.8V TO VOUT 10µH C1 10µF BATT LX OUT OUTPUT VOUT (NOM) MAX1724 C2 10µF ON OFF SHDN GND Figure 8. MAX1724 Standard Application Circuit The inductor’s incremental saturation current rating should be greater than the peak switching current. However, it is generally acceptable to bias the inductor into saturation by as much as 20%, although this will slightly reduce efficiency. Table 1 lists suggested inductors and suppliers. INDUCTOR PHONE WEBSITE Coilcraft DO1608 Series DO1606 Series 847-639-2361 www.coilcraft.com Murata LQH4C Series 770-436-1300 www.murata.com Maximum Output Current CDRH4D18 Series CR32 Series CMD4D06 Series 847-545-6700 www.sumida.com The maximum output current depends on the peak inductor current, the input voltage, the output voltage, and the overall efficiency (η): CXLD140 Series +81 (06) 6355-5733 www.daidoo.co.jp 3DF Type D412F Type 847-297-0070 www.toko.com MANUFACTURER Sumida Sumitomo/ Daidoo Electronics Toko IOUT(MAX) = V 1 IPEAK BATT η 2 VOUT _______________________________________________________________________________________ 9 MAX1722/MAX1723/MAX1724 INPUT 0.8V TO VOUT For maximum output current, choose the inductor value so that the controller reaches the current-limit before the maximum on-time is triggered: MAX1722/MAX1723/MAX1724 1.5µA IQ, Step-Up DC-DC Converters in Thin SOT23-5 Table 2. Suggested Surface-Mount Capacitors and Manufacturers (C1 and C2) CAPACITOR VALUE DESCRIPTION 1µF to 10µF X7R Ceramic 10µF to 330µF TAJ Tantalum Series TPS Tantalum Series 1µF to 22µF X5R/X7R Ceramic 10µF to 330µF T494 Tantalum Series 68µF to 330µF T520 Tantalum Series Sanyo 33µF to 330µF TPC Polymer Series 408-749-9714 www.secc.co.jp Taiyo Yuden 33µF to 330µF X5R/X7R Ceramic 800-368-2496 www.t-yuden.org 1µF to 10µF X7R Ceramic 847-803-6100 www.tdk.com 10µF to 330µF 594D Tantalum Series 595D Tantalum Series 203-452-5664 www.vishay.com MANUFACTURER AVX Kemet TDK Vishay Sprague For most applications, the peak inductor current equals the current limit. However, for applications using large inductor values or low input voltages, the maximum ontime limits the peak inductor current (see Inductor Selection section). Capacitor Selection Choose input and output capacitors to supply the input and output peak currents with acceptable voltage ripple. The input filter capacitor (CIN) reduces peak currents drawn from the battery and improves efficiency. Low equivalent series resistance (ESR) capacitors are recommended. Ceramic capacitors have the lowest ESR, but low ESR tantalum or polymer capacitors offer a good balance between cost and performance. Output voltage ripple has two components: variations in the charge stored in the output capacitor with each LX pulse, and the voltage drop across the capacitor’s ESR caused by the current into and out of the capacitor: PHONE WEBSITE 843-448-9411 www.avxcorp.com where IPEAK is the peak inductor current (see Inductor Selection section). For ceramic capacitors, the output voltage ripple is typically dominated by VRIPPLE(C). For example, a 10µF ceramic capacitor and a 10µH inductor typically provide 75mV of output ripple when stepping up from 3.3V to 5V at 50mA. Low input-to-output voltage differences (i.e. two cells to 3.3V) require higher output capacitor values. Capacitance and ESR variation of temperature should be considered for best performance in applications with wide operating temperature ranges. Table 2 lists suggested capacitors and suppliers. PC Board Layout Considerations Careful PC board layout is important for minimizing ground bounce and noise. Keep the IC’s GND pin and the ground leads of the input and output capacitors less than 0.2in (5mm) apart using a ground plane. In addition, keep all connections to FB (MAX1722/MAX1723 only) and LX as short as possible. VRIPPLE = VRIPPLE(C) + VRIPPLE(ESR) VRIPPLE(ESR) ≈ IPEAK RESR(COUT) VRIPPLE(C) ≈ 10 1 L (IPEAK2 - IOUT2 ) 2 (VOUT - VBATT )COUT 864-963-6300 www.kemet.com Chip Information TRANSISTOR COUNT: 863 ______________________________________________________________________________________ 1.5µA IQ, Step-Up DC-DC Converters in Thin SOT23-5 TOP VIEW SHDN 1 GND 2 5 LX MAX1723 FB 3 GND 2 4 THIN SOT23-5 BATT 1 OUT SHDN 5 LX 4 OUT MAX1724 3 THIN SOT23-5 THIN SOT23.EPS Package Information ______________________________________________________________________________________ 11 MAX1722/MAX1723/MAX1724 Pin Configurations (continued) MAX1722/MAX1723/MAX1724 1.5µA IQ, Step-Up DC-DC Converters in Thin SOT23-5 Package Information (continued) 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. 12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.