19-1499; Rev 3; 12/08 60mA, SOT23 Inverting Charge Pump with Shutdown The MAX1697 ultra-small, monolithic, CMOS chargepump voltage inverter accepts an input voltage ranging from +1.25V to +5.5V. This device features an ultra-low 12 output resistance, permitting loads of up to 60mA with maximum efficiency. The MAX1697 is available with operating frequencies of 12kHz, 35kHz, 125kHz, or 250kHz, allowing optimization of supply current or external component size. Its small external components and micropower shutdown mode make this device ideal for both battery-powered and board-level voltage conversion applications. Oscillator control circuitry and four power MOSFET switches are included on-chip. Applications include generating a negative supply from a +5V or +3.3V logic supply to power analog circuitry. All versions come in a 6-pin SOT23 package and deliver 60mA. For applications with lower current requirements, the MAX1719/MAX1720/MAX1721 are pin-compatible SOT23 charge pumps that supply up to 25mA. Applications Features 60mA Output Current Low 12 Output Resistance 150A Supply Current (MAX1697R) Requires Only Two 1F Capacitors (MAX1697U) Start-Up Current Limited +1.25V to +5.5V Input Voltage Range Slew-Rate Limited to Reduce EMI Ordering Information PART TEMP RANGE MAX1697_EUT-T -40C to +85C PIN-PACKAGE 6 SOT23 Note 1: The MAX1697 requires special solder temperature profile described in the Absolute Maximum Ratings section. Note 2: The MAX1697 is available with four different operating frequencies. Choose the desired frequency from the table below and insert the suffix in the blank above to complete the part number. TOP MARK PART NO. SUFFIX FREQUENCY (kHz) -T +T #T Small LCD Panels R 12 AABV AABV ACBT GaAsFET Bias Supplies S 35 AABW AABW ACCK T 125 AABX AABX ACCL U 250 AABY AABY ACCM Negative Supply from +5V or +3.3V Logic Supplies Handy-Terminals, PDAs Battery-Operated Equipment Note 3: MAX1697 is available in different package material. Add the following suffix to the part number when ordering: -T = Denotes a package containing lead(Pb). +T = Denotes a lead(Pb)-free/RoHS-compliant package. #T = Denotes an RoHS-compliant device that may include lead(Pb) that is exempt under the RoHS requirements. Pin Configuration Typical Operating Circuit TOP VIEW 1F INPUT 1.5V to 5.5V C1+ C1OUT IN MAX1697U SHDN ON OFF + GND NEGATIVE OUTPUT -1 VIN 60mA 1F OUT 1 IN 2 C1- 3 MAX1697 6 C1+ 5 SHDN 4 GND SOT23 Note 4: Leaded and lead-free top marks are identical. Per Maxim guideline, the pin 1 indicator for leaded package is a `*' and the lead-free package is a `+'. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. 1 MAX1697 General Description MAX1697 60mA, SOT23 Inverting Charge Pump with Shutdown ABSOLUTE MAXIMUM RATINGS IN to GND .................................................................-0.3V to +6V C1+, SHDN to GND .....................................-0.3V to (VIN + 0.3V) C1- to GND..............................................(VOUT - 0.3V) to + 0.3V OUT to GND .............................................................+0.3V to -6V OUT Output Current............................................................90mA OUT Short-Circuit to GND .............................................Indefinite Note 5: Note 6: Continuous Power Dissipation (TA = +70C) 6-Pin SOT23 (derate 14mW/C above +70C) (Note 5)...1.1W Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature ..........................................................(Note 6) Thermal properties are specified with product mounted on the PC board with one square-inch of copper area and still air. This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device can be exposed to during board level solder attach and rework. Maxim recommends the use of the solder profiles recommended in the industry standard specification, JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and Convection reflow processes. Preheating, per this standard, is required. Hand or wave soldering is not recommended. 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 (Circuit of Figure 1, capacitors from Table 2, VIN = +5V, SHDN = IN, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER CONDITIONS MAX1697R/S, RL = 5k Supply Voltage Range MAX1697T/U, RL = 5k Quiescent Supply Current (Note 9) TA = 0C to +85C 1.5 5.5 TA = +25C 1.4 5.5 TA = 0C to +85C 1.5 5.5 MAX1697R 150 MAX1697S 350 650 MAX1697T 950 1700 MAX1697U 1800 3400 TA = +25C 0.002 1 TA = +85C 0.03 Short-Circuit Current Output shorted to ground, TA = +25C Voltage Conversion Efficiency MAX1697S 20 35 50 MAX1697T 70 125 180 MAX1697U 140 250 360 99 99.9 IOUT = 0, TA = +25C TA = +25C OUT to GND Shutdown Resistance SHDN = GND, OUT is internally pulled to GND in shutdown SHDN Bias Current 12 TA = 0C to +85C 2.5V VIN 5.5V 8 0.6 VIN(MIN) VIN 2.5V 0.2 TA = +25C TA = +85C -100 kHz V VIN - 0.2 2.5V VIN 5.5V SHDN = GND or IN A % 25 2.0 VIN(MIN) VIN 2.5V A 17 33 3 V mA 7 IOUT = 60mA SHDN Input Logic Low 170 12 UNITS 300 MAX1697R Output Resistance (Note 7) SHDN Input Logic High MAX 5.5 SHDN = GND TA = +25C TYP 1.25 Shutdown Supply Current Oscillator Frequency 2 TA = +25C MIN TA = +25C 0.05 10 _______________________________________________________________________________________ +100 V nA 60mA, SOT23 Inverting Charge Pump with Shutdown (Circuit of Figure 1, capacitors from Table 2, VIN = +5V, SHDN = IN, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Wake-Up Time from Shutdown CONDITIONS IOUT = 15mA MIN TYP MAX1697R 1200 MAX1697S 600 MAX1697T 100 MAX1697U 70 MAX UNITS s THERMAL SHUTDOWN Trip Temperature Temperature increasing Hysteresis 150 C 15 C ELECTRICAL CHARACTERISTICS (Circuit of Figure 1, capacitors from Table 2, VIN = +5V, SHDN = IN, TA = -40C to +85C, unless otherwise noted.) (Note 8) PARAMETER CONDITIONS MIN MAX MAX1697R/S 1.5 5.5 MAX1697T/U 1.6 5.5 Supply Voltage Range RL = 5k Output Current Continuous, long-term 60 MAX1697R 350 MAX1697S 750 MAX1697T 1800 MAX1697U 3600 Quiescent Current (Note 9) Oscillator Frequency MAX1697R 6 MAX1697S 16 60 MAX1697T 60 200 MAX1697U 120 400 UNITS V mARMS A 21 kHz Output Resistance (Note 7) IOUT = 60mA 33 OUT to GND Shutdown Resistance SHDN = GND, OUT is internally pulled to GND in shutdown 8 SHDN Input Logic High SHDN Input Logic Low 2.5V VIN 5.5V VIN(MIN) VIN 2.5V 2.1 V VIN - 0.2 2.5V VIN 5.5V 0.6 VIN(MIN) VIN 2.5V 0.2 V Note 7: Output resistance is guaranteed with capacitor ESR of 0.3 or less. Note 8: All specifications from -40C to +85C are guaranteed by design, not production tested. Note 9: The MAX1697 may draw high supply current during startup, up to the minimum operating supply voltage. To guarantee proper startup, the input supply must be capable of delivering 90mA more than the maximum load current. _______________________________________________________________________________________ 3 MAX1697 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (Circuit of Figure 1, capacitors from Table 2, VIN = +5V, SHDN = IN, TA = +25C, unless otherwise noted.) MAX1697T MAX1697S MAX1697R OUTPUT VOLTAGE OUTPUT VOLTAGE OUTPUT VOLTAGE vs. OUTPUT CURRENT vs. OUTPUT CURRENT vs. OUTPUT CURRENT -3.0 -3.5 -4.0 -3.0 -3.5 20 30 40 50 60 70 -3.0 -3.5 10 20 30 40 50 60 70 0 80 20 30 40 50 60 70 OUTPUT CURRENT (mA) MAX1697U OUTPUT VOLTAGE vs. OUTPUT CURRENT MAX1697R EFFICIENCY vs. OUTPUT CURRENT MAX1697S EFFICIENCY vs. OUTPUT CURRENT 90 VIN = +3.3V -3.0 -3.5 70 VIN = +3.3V 60 50 VIN = +2V 40 100 90 50 40 30 30 20 10 10 -5.0 0 20 30 40 50 60 70 VIN = +2V 0 0 80 VIN = +3.3V 60 20 VIN = +5V 80 70 -4.5 -4.0 VIN = +5V 80 EFFICIENCY (%) -2.0 VIN = +5V 80 EFFICIENCY (%) -1.5 -2.5 100 MAX1697 TOC04 VIN = +2V -1.0 10 20 30 40 50 60 70 0 80 10 20 30 40 50 60 70 80 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) MAX1697T EFFICIENCY vs. OUTPUT CURRENT MAX1697U EFFICIENCY vs. OUTPUT CURRENT MAX1697R/S/T/U OUTPUT IMPEDANCE vs. INPUT VOLTAGE VIN = +3.3V 60 50 VIN = +2V 40 VIN = +5V 80 EFFICIENCY (%) 70 90 70 VIN = +3.3V 60 50 VIN = +2V 40 30 30 20 20 10 10 10 20 30 40 50 60 OUTPUT CURRENT (mA) 70 80 25 20 15 10 5 0 0 0 MAX1697 TOC09 VIN = +5V 80 30 OUTPUT IMPEDANCE () 90 100 MAX1697 TOC07 100 0 10 OUTPUT CURRENT (mA) 0 10 VIN = +5V OUTPUT CURRENT (mA) -0.5 0 VIN = +3.3V -2.5 -5.0 0 80 -2.0 -4.5 MAX1697 TOC05 10 VIN = +2V -1.5 -4.0 VIN = +5V -5.0 0 MAX1697 TOC03 MAX1697 TOC02 VIN = +3.3V -2.5 -1.0 -4.5 -5.0 OUTPUT VOLTAGE (V) -2.0 -4.0 VIN = +5V -4.5 4 -1.5 MAX1697 TOC06 VIN = +3.3V 0 -0.5 OUTPUT VOLTAGE (V) -2.0 VIN = +2V -1.0 MAX1697 TOC08 OUTPUT VOLTAGE (V) -1.5 -2.5 -0.5 OUTPUT VOLTAGE (V) VIN = +2V -1.0 0 MAX1697 TOC01 0 -0.5 EFFICIENCY (%) MAX1697 60mA, SOT23 Inverting Charge Pump with Shutdown 0 10 20 30 40 50 60 OUTPUT CURRENT (mA) 70 80 1.5 2.0 2.5 3.0 3.5 4.0 INPUT VOLTAGE (V) _______________________________________________________________________________________ 4.5 5.0 5.5 60mA, SOT23 Inverting Charge Pump with Shutdown (Circuit of Figure 1, capacitors from Table 2, VIN = +5V, SHDN = IN, TA = +25C, unless otherwise noted.) MAX1697R/S/T/U SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE MAX1697R MAX1697 TOC11 VIN = +3.3V VIN = +2V 10 VIN = +2V 20 15 VIN = +3.3V 10 VIN = +5V 5 0 2.5 3.0 3.5 4.0 4.5 5.0 0 20 40 60 80 -40 -20 0 20 40 60 TEMPERATURE (C) TEMPERATURE (C) MAX1697S OUTPUT RESISTANCE vs. TEMPERATURE MAX1697T OUTPUT RESISTANCE vs. TEMPERATURE MAX1697U OUTPUT RESISTANCE vs. TEMPERATURE 25 VIN = +2V 20 15 VIN = +3.3V 10 35 VIN = +5V 25 VIN = +2V 20 10 5 0 0 20 40 60 80 VIN = +3.3V 15 5 0 VIN = +1.5V 30 VIN = +5V 40 VIN = +1.5V 35 30 VIN = +2V 25 20 VIN = +3.3V 15 VIN = +5V 10 5 0 -40 -20 0 20 40 60 -40 80 -20 0 20 40 60 TEMPERATURE (C) TEMPERATURE (C) TEMPERATURE (C) PUMP FREQUENCY vs. TEMPERATURE MAX1697R/S OUTPUT NOISE AND RIPPLE MAX1697T/U OUTPUT NOISE AND RIPPLE MAX1697 TOC16 MAX1697U 100 80 MAX1697 TOC18 MAX1697 TOC17 1000 80 45 OUTPUT RESISTANCE () VIN = +1.5V -20 -20 INPUT VOLTAGE (V) 30 -40 0 -40 5.5 OUTPUT RESISTANCE () 2.0 MAX1697 TOC13 1.5 OUTPUT RESISTANCE () 20 VIN = +1.5V 25 5 0 PUMP FREQUENCY (kHz) VIN = +5V 15 30 MAX1697 TOC15 MAX1697S 35 OUTPUT RESISTANCE () MAX1697T 1.0 25 MAX1697 TOC14 SUPPLY CURRENT (mA) 1.5 0.5 30 SUPPLY CURRENT (nA) MAX1697U 2.0 35 MAX1697 TOC10 2.5 MAX1697R OUTPUT RESISTANCE vs. TEMPERATURE MAX1697 TOC12 SUPPLY CURRENT vs. INPUT VOLTAGE MAX1697 Typical Operating Characteristics (continued) VOUT MAX1697R (12kHz) MAX1697T VOUT MAX1697T (125kHz) MAX1697S MAX1697R 10 VOUT MAX1697S (35kHz) VOUT MAX1697U (250kHz) VIN = +1.5V TO +5V 1 -40 -20 0 20 40 TEMPERATURE (C) 60 80 20s/div VIN = +3.3V, IOUT = 5mA, 10mV/div, AC-COUPLED 2s/div VIN = +3.3V, IOUT = 5mA, 10mV/div, AC-COUPLED _______________________________________________________________________________________ 5 Typical Operating Characteristics (continued) (Circuit of Figure 1, capacitors from Table 2, VIN = +5V, SHDN = IN, TA = +25C, unless otherwise noted.) MAX1697R OUTPUT CURRENT vs. CAPACITANCE START-UP FROM SHUTDOWN MAX1697 TOC20 MAX1697 TOC19 0V MAX1697S (35kHz) VOUT, 2V/div 0V MAX1697U (250kHz) VOUT, 2V/div 0V 0V MAX1697R (12kHz) VOUT, 2V/div MAX1697T (125kHz) VOUT, 2V/div SHDN 70 MAX1697 TOC21 START-UP FROM SHUTDOWN VIN = +4.75V, VOUT = -4.0V 60 OUTPUT CURRENT (mA) MAX1697 60mA, SOT23 Inverting Charge Pump with Shutdown SHDN VIN = +3.15V, VOUT = -2.5V 50 40 30 VIN = +1.9V, VOUT = -1.5V 20 10 0 50s/div 400s/div 0 5 10 15 20 25 30 35 40 45 50 CAPACITANCE (F) MAX1697T OUTPUT CURRENT vs. CAPACITANCE 50 40 VIN = +1.9V, VOUT = -1.5V 30 60 OUTPUT CURRENT (mA) VIN = +3.15V, VOUT = -2.5V VIN = +4.75V, VOUT = -4.0V 20 VIN = +3.15V, VOUT = -2.5V 50 40 30 VIN = +1.9V, VOUT = -1.5V 20 0 5 10 15 20 25 30 35 40 45 1 2 3 4 5 6 7 8 9 10 VIN = +1.9V, VOUT = -1.5V 20 0 1 2 4 5 500 350 VIN = +4.75V, VOUT = -4.0V VIN = +3.15V, VOUT = -2.5V VIN = +1.9V, VOUT = -1.5V 450 400 350 300 250 VIN = +4.75V, VOUT = -4.0V 200 VIN = +3.15V, VOUT = -2.5V VIN = +1.9V, VOUT = -1.5V 150 100 100 50 50 0 MAX1697 TOC26 400 3 MAX1697S OUTPUT RIPPLE vs. CAPACITANCE OUTPUT RIPPLE (mV) 450 150 30 0 0 5 10 15 20 25 30 35 40 45 50 CAPACITANCE (F) 6 7 CAPACITANCE (F) MAX1697 TOC25 500 200 40 CAPACITANCE (F) MAX1697R OUTPUT RIPPLE vs. CAPACITANCE 250 VIN = +3.15V, VOUT = -2.5V 50 0 0 CAPACITANCE (F) 300 60 10 0 0 VIN = +4.75V, VOUT = -4.0V 70 10 10 6 80 OUTPUT CURRENT (mA) 60 OUTPUT RIPPLE (mV) OUTPUT CURRENT (mA) 70 70 MAX1697 TOC23 VIN = +4.75V, VOUT = -4.0V MAX1697 TOC22 80 MAX1697U OUTPUT CURRENT vs. CAPACITANCE MAX1697 TOC24 MAX1697S OUTPUT CURRENT vs. CAPACITANCE 0 5 10 15 20 25 30 35 40 45 50 CAPACITANCE (F) _______________________________________________________________________________________ 8 9 10 60mA, SOT23 Inverting Charge Pump with Shutdown MAX1697T OUTPUT RIPPLE vs. CAPACITANCE 400 450 400 OUTPUT RIPPLE (mV) 350 300 250 VIN = +4.75V, VOUT = -4.0V 200 VIN = +3.15V, VOUT = -2.5V 150 VIN = +1.9V, VOUT = -1.5V 100 MAX1697 TOC28 450 OUTPUT RIPPLE (mV) 500 MAX1697 TOC27 500 MAX1697U OUTPUT RIPPLE vs. CAPACITANCE 350 300 250 200 VIN = +4.75V, VOUT = -4.0V 150 VIN = +3.15V, VOUT = -2.5V 100 50 VIN = +1.9V, VOUT = -1.5V 50 0 0 0 1 2 3 4 5 6 7 8 9 10 0 1 2 CAPACITANCE (F) 3 4 5 6 7 8 9 10 CAPACITANCE (F) Pin Description PIN NAME 1 OUT Inverting Charge-Pump Output IN Power-Supply Voltage Input. Input range is 1.5V to 5.5V. 3 C1- Negative Terminal of the Flying Capacitor 4 GND Ground 5 SHDN Shutdown Input. Drive this pin high for normal operation; drive it low for shutdown mode. OUT is actively pulled to ground during shutdown. 6 C1+ 2 C1 FUNCTION Positive Terminal of the Flying Capacitor Detailed Description The MAX1697 capacitive charge pumps invert the voltage applied to their input. For highest performance, use low equivalent series resistance (ESR) capacitors (e.g., ceramic). During the first half-cycle, switches S2 and S4 open, switches S1 and S3 close, and capacitor C1 charges to the voltage at IN (Figure 2). During the second halfcycle, S1 and S3 open, S2 and S4 close, and C1 is level shifted downward by VIN volts. This connects C1 in parallel with the reservoir capacitor C2. If the voltage across INPUT 1.5V to 5.5V 2 6 C1+ 3 C1- IN OUT C3 MAX1697 ON OFF 5 SHDN NEGATIVE OUTPUT -1 VIN 1 RL C2 GND 4 TE: ( Figure 1. Typical Application Circuit C2 is smaller than the voltage across C1, charge flows from C1 to C2 until the voltage across C2 reaches -VIN. The actual voltage at the output is more positive than -VIN, since switches S1-S4 have resistance and the load drains charge from C2. Efficiency Considerations The efficiency of the MAX1697 is dominated by its quiescent supply current (IQ) at low output current and by its output impedance (ROUT) at higher output current; it is given by: I OUT x ROUT 1 - VIN IOUT + IQ IOUT _______________________________________________________________________________________ 7 MAX1697 Typical Operating Characteristics (continued) (Circuit of Figure 1, capacitors from Table 2, VIN = +5V, SHDN = IN, TA = +25C, unless otherwise noted.) MAX1697 60mA, SOT23 Inverting Charge Pump with Shutdown S1 REQUIV S2 V+ IN REQUIV = C1 S3 VOUT 1 fOSC C1 C2 RL C2 S4 VOUT = -(VIN) Figure 3b. Equivalent Circuit Thermal Shutdown Figure 2. Ideal Voltage Inverter fOSC V+ VOUT C2 C1 The MAX1697 has a thermal shutdown mode for additional protection against fault conditions. When the temperature of the die exceeds +150C, the internal clock stops, suspending the device's operation. The MAX1697 resumes operation when the die temperature falls 15C. This prevents the device from rapidly oscillating around the temperature trip point. RL Applications Information Capacitor Selection Figure 3a. Switched-Capacitor Model where the output impedance is roughly approximated by: 1 ROUT + 2RSW + 4ESRC1 + ESRC2 fOSC x C1 ( ) The first term is the effective resistance of an ideal switched-capacitor circuit (Figures 3a and 3b), and RSW is the sum of the charge pump's internal switch resistances (typically 4 to 5 at VIN = +5V). The typical output impedance is more accurately determined from the Typical Operating Characteristics. Current Limit The MAX1697 limits its input current upon start-up to 170mA (typ). This prevents low-current or higher output impedance input supplies (such as alkaline cells) from being overloaded when power is applied or when the device awakes from shutdown. Shutdown The MAX1697 has a logic-controlled shutdown input. Driving SHDN low places the device in a low-power shutdown mode. The charge-pump switching halts, supply current is reduced to 2nA, and OUT is actively pulled to ground through a 3 resistance. Driving SHDN high will restart the charge pump. The switching frequency and capacitor values determine how soon the device will reach 90% of the input voltage. 8 The charge-pump output resistance is a function of the ESR of C1 and C2. To maintain the lowest output resistance, use capacitors with low ESR. (See Table 1 for a list of recommended manufacturers.) Tables 2 and 3 suggest capacitor values for minimizing output resistance or capacitor size. Flying Capacitor (C1) Increasing the flying capacitor's value reduces the output resistance. Above a certain point, increasing C1's capacitance has negligible effect because the output resistance is then dominated by internal switch resistance and capacitor ESR. Output Capacitor (C2) Increasing the output capacitor's value reduces the output ripple voltage. Decreasing its ESR reduces both output resistance and ripple. Lower capacitance values can be used with light loads if higher output ripple can be tolerated. Use the following equation to calculate the peak-to-peak ripple: VRIPPLE = IOUT + 2 x IOUT x ESRC2 2(fOSC )C2 Input Bypass Capacitor (C3) If necessary, bypass the incoming supply to reduce its AC impedance and the impact of the MAX1697's switching noise. A bypass capacitor with a value equal to that of C1 is recommended. _______________________________________________________________________________________ 60mA, SOT23 Inverting Charge Pump with Shutdown Combined Doubler/Inverter In the circuit of Figure 6, capacitors C1 and C2 form the inverter, while C3 and C4 form the doubler. C1 and C3 are the pump capacitors; C2 and C4 are the reservoir capacitors. Because both the inverter and doubler use part of the charge-pump circuit, loading either output causes both outputs to decline toward GND. Make sure the sum of the currents drawn from the two outputs does not exceed 60mA. Cascading Devices Two devices can be cascaded to produce an even larger negative voltage (Figure 4). The unloaded output voltage is normally -2 VIN, but this is reduced slightly by the output resistance of the first device multiplied by the quiescent current of the second. When cascading more than two devices, the output resistance rises dramatically. For applications requiring larger negative voltages, see the MAX865 and MAX868 data sheets. The maximum load current and startup current of the nth cascaded circuit must not exceed the maximum output current capability of the (n-1)th circuit to ensure proper startup. Heavy Load Connected to a Positive Supply Under heavy loads, where a higher supply is sourcing current into OUT, the OUT supply must not be pulled above ground. Applications that sink heavy current into OUT require a Schottky diode (1N5817) between GND and OUT, with the anode connected to OUT (Figure 7). Layout and Grounding Paralleling Devices Good layout is important, primarily for good noise performance. To ensure good layout, mount all components as close together as possible, keep traces short to minimize parasitic inductance and capacitance, and use a ground plane. Paralleling multiple MAX1697s reduces the output resistance. Each device requires its own pump capacitor (C1), but the reservoir capacitor (C2) serves all devices (Figure 5). Increase C2's value by a factor of n, where n Table 1. Low-ESR Capacitor Manufacturers PRODUCTION METHOD MANUFACTURER SERIES PHONE FAX Surface-Mount Tantalum Surface-Mount Ceramic AVX TPS series 803-946-0690 803-626-3123 Matsuo 267 series 714-969-2491 714-960-6492 Sprague 593D, 595D series 603-224-1961 603-224-1430 AVX X7R 803-946-0690 803-626-3123 Matsuo X7R 714-969-2491 714-960-6492 Table 2. Capacitor Selection to Minimize Output Resistance Table 3. Capacitor Selection to Minimize Capacitor Size PART FREQUENCY (kHz) CAPACITOR (F) TYPICAL ROUT () PART FREQUENCY (kHz) CAPACITOR (F) TYPICAL ROUT () MAX1697R 12 22 12 MAX1697R 12 10 17 MAX1697S 35 6.8 12 MAX1697S 35 3.3 17 MAX1697T 125 2.2 12 MAX1697T 125 1 17 MAX1697U 250 1 12 MAX1697U 250 0.47 17 _______________________________________________________________________________________ 9 MAX1697 is the number of parallel devices. Figure 5 shows the equation for calculating output resistance. Voltage Inverter The most common application for these devices is a charge-pump voltage inverter (Figure 1). This application requires only two external components--capacitors C1 and C2--plus a bypass capacitor, if necessary. Refer to the Capacitor Selection section for suggested capacitor types. MAX1697 60mA, SOT23 Inverting Charge Pump with Shutdown SHDN ... +VIN 2 3 C1 4 3 3 MAX1697 4 C1 6 1 C1 MAX1697 ... SHDN VOUT C1 3 C1 1 6 5 SHDN C4 VOUT = (2VIN) (VFD1) - (VFD2) Figure 6. Combined Doubler and Inverter GND 2 MAX1697 VOUT = -VIN C2 ... 2 4 1 C3 Figure 4. Cascading MAX1697s to Increase Output Voltage 3 6 D2 VOUT = -nVIN +VIN MAX1697 C2 5 C2 4 D1, D2 = 1N4148 2 D1 1 6 5 +VIN 5 2 ... 1 VOUT 5 VOUT = -VIN V+ MAX1697 MAX1697 4 6 4 RL OUT 1 Figure 7. Heavy Load Connected to a Positive Supply C2 ROUT OF SINGLE DEVICE ROUT = NUMBER OF DEVICES Figure 5. Paralleling MAX1697s to Reduce Output Resistance Chip Information TRANSISTOR COUNT: 275 10 ______________________________________________________________________________________ 60mA, SOT23 Inverting Charge Pump with Shutdown PACKAGE CODE DOCUMENT NO. 6 SOT23 U6F-6 21-0058 6LSOT.EPS PACKAGE TYPE PACKAGE OUTLINE, SOT 6L BODY 21-0058 I 1 2 ______________________________________________________________________________________ 11 MAX1697 Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. MAX1697 60mA, SOT23 Inverting Charge Pump with Shutdown Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE OUTLINE, SOT 6L BODY 21-0058 12 ______________________________________________________________________________________ I 2 2 60mA, SOT23 Inverting Charge Pump with Shutdown REVISION NUMBER REVISION DATE 3 12/08 DESCRIPTION Added additional available top mark for RoHS compliance PAGES CHANGED 1 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___________________ 13 (c) 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. MAX1697 Revision History