ANALOG DEVICES ADM8828 English products handbook Rev A
Contents
1. OUTPUT CURRENT Vy 4 75V OUTPUT VOLTAGE tf gt I I ul z i u OUTPUT CURRENT Vyy 3 15V G VOLTA tc 2 Q E 5 2 E E 5 OUTPUT CURRENT Viy 2 o 0 47 1 2 2 3 3 0 5 10 15 20 25 30 35 40 45 CAPACITANCE pF OUTPUT CURRENT mA Figure 4 Output Current vs Capacitance Figure 7 Output Voltage vs Output Current REV A 3 ADM8828 ADM8829 Perr Vin 5 0V 0 5 10 15 20 25 30 35 40 45 50 laur mA Figure 8 Power Efficiency vs Output Current 45 RESISTANCE Vi 1 5V RESISTANCE Q Vy 3 3V 15 RESISTANCE Vjy 5 0V OUTPUT RESISTANCE M a 0 50 30 10 10 25 40 60 80 90 110 125 TEMPERATURE C Figure 9 Output Resistance vs Temperature PUMP FREQUENCY Vin 3 3V PUMP FREQUENCY Vip 5 0V EQUENCY 5V PUMP FREQUENCY kHz 0 50 30 10 10 25 40 60 80 TEMPERATURE C 90 110 125 Figure 10 Charge Pump Frequency vs Temperature REV A ADM8828 ADM8829 GENERAL INFORMATION The ADM8828 ADM8829 is a switched capacitor voltage con verter that can be used to invert the input supply voltage The voltage conversion task is achieved using a switched capaci tor technique using two external charge storage capacitors An on chip oscillator and sw2. for the charge pump to reach its final value If the shutdown function is not being used SHDN should be hardwired to GND REV A Capacitor Selection The flying capacitor C1 can be increased to reduce the output resistance The output capacitor size C2 affects the output ripple Increas ing the capacitor size reduces the peak peak ripple The ESR affects both the output impedance and the output ripple Reducing the ESR reduces the output impedance and ripple For convenience it is recommended that both C1 and C2 be the same value The ac impedance of the ADM8828 ADM8829 may be reduced by using a bypass capacitor on the input supply This capacitor should be connected between the input supply and GND It will provide instantaneous current surges as required Suitable capaci tors of 1 uF or greater may be used 1 5V TO 5 5V INPUT CAP IN cit ADM8828 1pF ADM8829 SHUTDOWN CAP SHDN CONTROL INVERTED GND NEGATIVE C2 OUTPUT TRE Figure 12 Typical Circuit Configuration ADM8828 ADM8829 OUTLINE DIMENSIONS Dimensions shown in inches and mm 6 Lead SOT 23 RT 6 0 122 3 10 T 0106 270 0 071 1 80 3 0 118 3 00 0 059 1 50 1 1 a 0098 2 50 ewi7 E EB E 0 037 0 95 BSC 0 075 1 90 BSC 0 051 1 30 0 057 1 45 0 035 0 90 0 035 0 90 gt ja 10 gt e 0 006 0 15 0 020 0 50 SEATING 1
3. 009 0 23 0 0 022 0 55 0 000 0 00 0 010 0 25 PLANE 55030 08 0 08 0 014 0 35 6 REV A C3352a 0 10 99 PRINTED IN U S A
4. ANALOG DEVICES Switched Capacitor Voltage Inverter with Shutdown ADM8828 ADM8829 FEATURES Inverts Input Supply Voltage 99 Voltage Conversion Efficiency 25 mA Output Current Shutdown Function Requires Only Two Capacitors 1 pF Capacitors 18 Output Resistance 1 5 V to 5 5 V Input Range 600 pA Quiescent Current 20 nA Shutdown Current ADM8828 APPLICATIONS Handheld Instruments LCD Panels Cellular Phones PDAs Remote Data Acquisition Op Amp Power Supplies GENERAL DESCRIPTION The ADM8828 ADM8829 is a charge pump voltage inverter which may be used to generate a negative supply from a positive input Input voltages ranging from 1 5 V to 5 5 V can be inverted into a negative 1 5 V to 5 5 V output supply This inverting scheme is ideal for generating a negative rail in single power supply systems Only two small external capacitors are needed for the charge pump Output currents up to 25 mA with greater than 99 efficiency are achievable The ADM8828 also features a low power shutdown SHDN pin This can be used to disable the device and reduce the quies cent current to 20 nA The ADM8828 ADM8829 is available in a 6 lead SOT 23 package REV A Information furnished by Analog Devices is believed to be accurate and reliable However no responsibility is assumed by Analog Devices for its use nor for any infringements of patents or other rights of third parties which may result from its use No lice
5. Capacitor Terminal OUT Output Negative Voltage SHDN Shutdown Control Input This input when high is used to disable the charge pump thereby reducing the power consumption IN Positive Power Supply Input PIN CONFIGURATIONS our 1 e ADM8828 IN 2 TOP VIEW 5 SHDN CAP 3 Not to Scale 4 GND ADM8829 IN 2 TOP VIEW 5 nC NC lt NO CONNECT REV A Typical Performance Characteristics ADM8828 ADM8829 OUTPUT VOLTAGE RIPPLE pd Vin 4 75V OUTPUT VOLTAGE RIPPLE Vin 1 9V SUPPLY CURRENT mA o o o wo A a o M OUTPUT VOLTAGE RIPPLE mV p p 0 2 OUTPUT VOLTAGE RIPPLE wi Vin 3 15V 0 1 1 5 2 2 5 3 3 5 4 4 5 5 5 5 0 47 1 2 2 3 3 SUPPLY VOLTAGE V CAPACITANCE pF Figure 2 Power Supply Current vs Voltage Figure 5 Output Voltage Ripple vs Capacitance 35 30 2 o OUTPUT VOLTAGE RIPPLE s t Vin 4 75V Vout 4 0V 3 25 I amp 20 a OUTPUT VOLTAGE RIPPLE o 7 Vin 3 15V VoyT 2 5V a G 15 F E 2 o n gt 5 10 5 o a 2 5 o OUTPUT VOLTAGE RIPPLE Vin 1 9V Vout 1 5V 0 1 5 2 2 5 3 3 5 4 4 5 5 5 5 0 47 1 2 2 3 3 SUPPLY VOLTAGE V CAPACITANCE pF Figure 3 Output Source Resistance vs Supply Voltage Figure 6 Output Voltage Ripple vs Capacitance
6. capacitors High ESR will degrade performance Specifications subject to change without notice ABSOLUTE MAXIMUM RATINGS T4 25 C unless otherwise noted Input Voltage IN to GND 0 3 V to 6 V OUT to GND reete 6 0 V to 40 3 V OUT IN Output Current Continuous 50 mA Output Short Circuit Duration to GND 10 secs Power Dissipation RT 6 n 570 mW Derate 8 3 mW C above 70 C Oja Thermal Impedance 120 C W Operating Temperature Range Industrial A Version 40 C to 85 C Storage Temperature Range 65 C to 150 C Lead Temperature Range Soldering 10 sec 300 C Vapor Phase 70 sec 2 20 eee eee eee ee eee 215 C Infrated 15 8e 44 rac b tee ee 220 C ESD RatnDg Sese queer ERN EE 23500V This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation section ofthis specification is not implied Exposure to absolute maximum rating conditions for extended periods may affect device reliability ORDERING GUIDE Temperature Branding Package Model Range Information Option ADMS828ART 40 C to 85 C MMO RT 6 ADMS829ART 40 C to 85 C MNO RT 6 RT 6 6 lead SOT 23 PIN FUNCTION DESCRIPTIONS Mnemonic Function CAP Positive Charge Pump Capacitor Terminal GND Power Supply Ground CAP Negative Charge Pump
7. itching network transfers charge between the charge storage capacitors The basic principle behind the voltage conversion scheme is illustrated below I i S2 s4 y OUT V L CAP i Figure 11 Voltage Inversion Principle An oscillator generating antiphase signals 61 and 02 controls switches S1 S2 and S3 S4 During 1 switches S1 and S2 are closed while S3 and S4 are open thereby charging C1 up to the voltage at V During 02 S1 and S2 open and S3 and S4 close The positive terminal of C1 is connected to GND via S3 during this phase and the negative terminal of C1 connects to VouT via S4 The net result is voltage inversion at Vour wrt GND Charge on CI is transferred to C2 during 02 Capacitor C2 maintains this voltage during 91 The charge transfer efficiency depends on the on resistance of the switches the frequency at which they are being switched and also on the equivalent series resistance ESR of the external capacitors For maximum effi ciency capacitors with low ESR are therefore recommended Shutdown Input The ADM8828 contains a shutdown input that can be used to disable the device and hence reduce the power consumption A logic high level on the SHDN input shuts the device down reducing the quiescent current to 0 02 uA During shutdown the output voltage discharges to 0 V Therefore ground ref erenced loads are not powered during this state When exiting shutdown it takes several cycles approximately 175 us
8. nse is granted by implication or otherwise under any patent or patent rights of Analog Devices FUNCTIONAL BLOCK DIAGRAMS out i e e CAP ADM8828 IN LZ top view 5 SHDN CAP 3 Not to Scale 4 GND ADM8829 n 2 TOP VIEW 5 NC CAP 3 Not to Scale 4 GND NC lt NO CONNECT 1 5V TO 5 5V INPUT CAP IN cit ADM8828 1pF ADM8829 SHUTDOWN CAP ees CONTROL INVERTED GND NEGATIVE C2 OUTPUT rine Figure 1 Typical Circuit Configuration One Technology Way P O Box 9106 Norwood MA 02062 9106 U S A Tel 781 329 4700 World Wide Web Site http www analog com Fax 781 326 8703 Analog Devices Inc 1999 ADM8828 ADM8829 SPECIFICATION Vin 5V C1 C02 1 uE Ta lun to Tmax unless other wise noted Parameter Min Typ Max Units Test Conditions Comments Input Voltage IN 1 5 5 5 V Rp 10 KQ Supply Current 600 1000 UA Unloaded Output Current 25 mA Output Resistance 18 28 Q IL 5mA Output Ripple 25 mV p p IL 5mA 130 mV p p IL 25 mA Charge Pump Frequency 50 120 190 kHz 65 kHz Vin 2 25 V Power Efficiency 90 R 200 Q 87 R 1kQ Voltage Conversion Efficiency 99 5 99 96 No Load 98 Rp 1kQ 91 R 200 Q Shutdown Supply Current IsHpx 0 02 2 UA SHDN IN Shutdown Input Voltage VsHpN 2 0 V SHDN High Disabled 0 8 V SHDN Low Enabled Shutdown Exit Time 175 US IL 5mA NOTES 1C1 and C2 are low ESR 0 2 electrolytic
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ANALOG DEVICES ADM8828 English products handbook Rev A