02281305

AVO75 Series DC/DC Converter TRN AVO75 Series DC/DC Converter Technical Reference Notes Industry Standard Eighth Brick: 36~75V Input, 1.2V~12V Single Output Features • • • • • Industry standard eighth brick: 2.28” × 0.9’’ × 0.34’’ Options • • Choice of positive logic or negative logic for CNT function Choice of short pins or long pins Description • • • • • • • • • • • Delivers up to 25A output current Industry standard eighth brick foot print 57.9mm × 22.9mm × 8.5mm (2.28” × 0.9” × 0.34”) Basic isolation Ultra high efficiency: 92% at 5V full load (Vin = 48Vdc) Improved thermal performance: full load at 55ºC at 1m/s (200LFM) for 5Vo High power density Low output noise 2:1 wide input voltage of 36V-75V CNT function Remote sense Trim function: +10%/-20% Input under-voltage lockout Output over-current protection Output over-voltage protection Over-temperature protection RoHS compliant The AVO75 series DC/DC converter is a new open frame DC/DC converter for optimum efficiency and power density. The series provides up to 25A output current in an industry standard eighth brick, which makes it an ideal choice for small space, high current and low voltage applications. The AVO75 series uses an industry standard eighth brick: 57.9mm × 22.9mm × 8.9mm (2.28” × 0.9” × 0.35”) and standard pin-out configuration, provides CNT and trim functions. AVO75 series can provide 1.2V ~ 12V single output, and outputs are isolated from inputs. The series can achieve ultra high efficiency, and for most applications, a heat sink is not required. TEL: (86) 755-86010808 BOM: 31020683 www.emersonnetworkpower.com.cn DATE: 2008-12-03 1/32 REV1.3 AVO75 Series DC/DC Converter TRN Module Numbering AVO 75 - 48 S 1V5 P - 4 Pin length CNT logic, P---positive logic control, default is negative logic control . Output rated voltage: 1V2--1.2V, 1V5--1.5V, 1V8--1.8V, 2V5--2.5V, 3V3--3.3V, 05--5V, 12--12V Output number: S ---single output, D---dual output Input rated voltage Output rated power Series name TEL: (86) 755-86010808 www.emersonnetworkpower.com.cn 2/32 AVO75 Series DC/DC Converter TRN Electrical Specifications Unless otherwise indicated, specifications apply over all operating input voltage and temperature conditions. Standard test condition on a single unit is as follows: Tc (board): 25 °C +Vin: 48V± 2% -Vin: return pin for +Vin CNT: connected to -Vin for negative logic open for positive logic +Vout: -Vout: +Sense: -Sense: Trim (Vadj): connected to load connected to load (return) connected to +Vout connected to -Vout open Input Specifications Parameter Symbol Min Typ Max Unit VI 36 48 75 VDC II,max - - 2.5 A Input Reflected-ripple Current (5Hz to 20MHz, 12µH source impedance, TA = 25 ºC) II - - 20 mAp-p Supply Voltage Rejection (1kHz) - 50 60 - dB Operating Input Voltage Maximum Input Current (VI = 0 to VI,max, Io = Io,max) Caution: This power module is not internally fused. An input line fuse must always be used. TEL: (86) 755-86010808 www.emersonnetworkpower.com.cn 3/32 AVO75 Series DC/DC Converter TRN Absolute Maximum Ratings Stresses in excess of the absolute maximum ratings can cause permanent damage to the device. These are absolute stress ratings only. Functional operation of the device is not implied at these or any other conditions in excess of those given in the operational sections of the IPS. Exposure to absolute maximum ratings for extended periods can adversely affect device reliability. Parameter Device Symbol Min Typ Max Unit All VI 0 - 75 Vdc All VI, trans 0 - 100 Vdc All Ta -40 - 85 °C Operating Board Temperature All Tc - - 100 °C Storage Temperature All TSTG -55 - 125 °C Operating Humidity All - - - 85 % All - 2000 Vdc Continuous Input Voltage Transient (100ms) Operating Ambient Temperature (See Thermal Consideration) Basic Input-Output Isolation (Conditions: 1mA for 60 sec, slew rate of 1500V/10sec) Output Power TEL: (86) 755-86010808 1.2V 30 1.5V 37.5 1.8V 45 2.5V Po,max 0 - 62.5 3.3V 66 5V 75 12V 75 www.emersonnetworkpower.com.cn W 4/32 AVO75 Series DC/DC Converter TRN Output Specifications Parameter Output ripple and noise peak-to-peak (5Hz to 20MHz) (across 1µF @50V, X7R ceramic capacitor & 470µF @25V LOW ESR aluminum capacitor) External load capacitance Output voltage setpoint (VI=VI,min to VI,max: Io=Io,max; Ta=25°C) Output regulation Line (VI,min to VI,max) TEL: (86) 755-86010808 Device Symbol Min Typ 1.2V 50 1.5V 55 1.8V 45 2.5V - - 50 3.3V 50 5V 55 12V 55 Max Unit - mVp-p 1.2V 10,000 1.5V 10,000 1.8V 10,000 2.5V - 220 470 10,000 3.3V 10,000 5V 5000 12V 1000 1.2V 1.18 1.2 1.22 1.5V 1.48 1.5 1.52 1.8V 1.77 1.8 1.83 2.46 2.5 2.54 3.3V 3.25 3.3 3.35 5V 4.95 5 5.05 12V 11.85 12 12.15 2.5V Vo,set 1.2V 1 1.5V 1 1.8V 1 2.5V - - 1 3.3V 1 5V 4 12V 9 www.emersonnetworkpower.com.cn - µF Vdc mV 5/32 AVO75 Series DC/DC Converter TRN Parameter Load (Io,min to Io,max) Temperature (Tc=-40 °C to +100°C) Rated output current Output current-limit inception (hiccup) Efficiency (VI=VI,nom; 100%Io,max ; TA=25°C) Efficiency (VI=VI,nom ; 50%Io,max; Ta=25°C) TEL: (86) 755-86010808 Device Symbol Min Typ 1.2V 1 1.5V 1 1.8V 1 2.5V - - 1 3.3V 1 5V 5 12V 5 All - - - Max Unit - mV 0.02 %Vo/°C 1.2V, 25 1.5V 25 1.8V 25 2.5V Io 0 - 25 3.3V 20 5V 15 12V 6.3 1.2V 28 35 1.5V 28 35 1.8V 28 35 2.5V Io 28 - 35 3.3V 22 28 5V 16.5 21 12V 6.9 10 1.2V 88 1.5V 87 1.8V 89 2.5V - - 90.5 3.3V 91 5V 92 12V 91 1.2V 87 1.5V 88 1.8V 88.5 2.5V - - 89.5 3.3V 91 5V 91 12V 90 www.emersonnetworkpower.com.cn A A - % - % 6/32 AVO75 Series DC/DC Converter TRN Output Specifications (Cont) Parameter Device Load change from Io = 50% to 75% to 50% Io,max Symbol Min Typ 1.2V 60 1.5V 50 1.8V 50 2.5V - 60 3.3V 85 5V 110 Dynamic response 12V 150 (∆Io/∆t=1A/10µs, VI=VI,nom; Ta=25°C) 1.2V 300 1.5V 115 1.8V 125 Peak deviation settling Time (to Vo,nom) Load change from Io=50% to 75% to 50% Io,max 2.5V - 70 3.3V 70 5V 120 12V 120 1.2V 130 1.5V 130 1.8V 120 2.5V - 170 3.3V 130 Dynamic response 5V 130 (∆Io/∆t=1A/1µs; 12V 120 1.2V 300 1.5V 100 1.8V 115 VI=VI,nom; Ta=25°C, additional 220µF load capacitor) Peak deviation settling time (to Vo,nom) 2.5V Max - 150 3.3V 80 5V 130 12V 320 Unit mV - µsec - mv - µsec 20 msec Turn-On time (Io=Io,max; Vo within 1%) All - - - Output voltage overshoot (Io=Io,max; Ta=25°C) All - - 0 %Vo Switching frequency All - 310 kHz TEL: (86) 755-86010808 www.emersonnetworkpower.com.cn 7/32 AVO75 Series DC/DC Converter TRN Feature Specifications Parameter Device Symbol Min Typ Max Unit Logic low All -0.7 - 1.2 V Logic high All 3.5 - 12 V Enable pin current Logic low All - - 1.0 mA (leakage current, @10V) Logic high All - - - µA 80 - 110 %Vo Enable pin voltage Output voltage adjustment range Output over-voltage (hiccup) Over-temperature protection (auto-recovery) All* - 1.2V 1.4 2.0 1.5V 1.8 2.5 1.8V 2.2 3.0 2.5V Vo,clamp 3.0 - 3.8 V 3.3V 3.9 5.0 5V 6.0 7.5 12V 14.4 18 All 110 120 135 C Under-voltage Lockout Turn-on point All - 31 34 36 V Turn-off point All - 30 33 35 V AVO75-48S12-6/D under-voltage lockout Turn-on point All - 34.8 37 38 V Turn-off point All - 33.8 35.5 37 V Isolation capacitance All - - 1000 - PF Isolation resistance All - 10 - - MΩ Calculated MTBF (Io=Io,max; Tc=25°C) All - - 2,500,000 - Hours Weight All - - - 30 g(oz.) Note: Output voltage adjustment rang of 12V module is 90% to 110%. TEL: (86) 755-86010808 www.emersonnetworkpower.com.cn 8/32 AVO75 Series DC/DC Converter TRN Characteristic Curves 90 85 85 80 80 Vin=36V 75 Vin=48V Vin=75V 70 0 5 10 15 20 75 Efficiency (%) Effiency(%) 90 70 65 36V 48V 75V 60 25 55 Load(A) 0 5 10 15 20 25 Load (A) Fig. 1 Typical efficiency of AVO75-48S1V2 Fig. 2 Typical efficiency of AVO75-48S1V5 95 90 Effiency(%) Effiency(%) 90 85 80 Vin=36V 75 5 10 15 20 Vin=36V Vin=48V Vin=75V Vin=75V 0 80 75 Vin=48V 70 85 70 25 0 5 10 Load(A) Fig. 3 20 25 Load(A) Typical efficiency of AVO75-48S1V8 Fig. 4 95 Typical efficiency of AVO75-48S2V5 95 90 Effiency(%) 90 Ef f iciency(%) 15 85 80 36V 48V 75V 75 2 4 6 8 10 12 14 16 18 85 80 Vin=36V 75 Vin=48V Vin=75V 70 20 0 3 6 Typical efficiency of AVO75-48S3V3 TEL: (86) 755-86010808 12 15 Load(A) Load (A) Fig. 5 9 Fig. 6 Typical efficiency of AVO75-48S05 www.emersonnetworkpower.com.cn 9/32 AVO75 Series DC/DC Converter TRN 95 Effiency(%) 90 85 80 Vin=36V Vin=48V 75 Vin=75V 70 0 1 2 3 4 5 6 Output current(A) Typical efficiency of AVO75-48S12 1.4 1.2 1.6 1 0.8 0.6 0.4 1.2 1.4 0.2 0 0 Fig. 8 5 10 15 20 25 Output Current (A) 30 35 Output voltage (V) Output Voltage (V) Fig. 7 1 0.8 0.6 0.4 0.2 0 0 Typical output over-current of AVO75-48S1V2 Fig. 9 5 10 15 20 25 Output current (A) 30 35 40 Typical output over-current of AVO75-48S1V5 Output Voltage (V) Output Voltage (V) 3 1.8 1.5 1.2 0.9 0.6 0.3 2 1.5 1 0.5 0 0 0 Fig. 10 2.5 5 10 15 20 25 Output Current (A) 30 Typical output over-current of AVO75-48S1V8 TEL: (86) 755-86010808 0 35 Fig. 11 5 10 15 20 25 Output Current (A) 30 35 Typical output over-current of AVO75-48S2V5 www.emersonnetworkpower.com.cn 10/32 3.5 6 3 5 Output Voltage (V) Output Voltage（V） AVO75 Series DC/DC Converter TRN 2.5 2 1.5 1 0.5 4 3 2 1 0 0 0 0 5 10 15 20 25 30 35 4 8 12 Output Current (A) 40 16 20 Output Current（ A） Fig. 12 Typical output over-current of AVO75-48S3V3 Fig. 13 Typical output over-current of AVO75-48S05 14 Output Voltage (V) 12 10 8 6 4 2 0 0 Fig. 14 2 4 6 Output Current (A) 10 Typical output over-current of AVO75-48S12 7 5 6 4 3 2 Vin=36V 1 Vin=48V Vin=75V 0 0 5 10 15 20 25 Power dissipation (W) Dissipation(W) 8 5 4 3 2 36V 48V 75V 1 0 0 Load(A) 5 10 15 20 25 Load (A) Fig. 15 Typical power dissipation of AVO75-48S1V2 TEL: (86) 755-86010808 Fig. 16 Typical power dissipation of AVO75-48S1V5 www.emersonnetworkpower.com.cn 11/32 7 6 5 4 3 2 1 0 9 8 7 Dissipation(W) Dissipation(W) AVO75 Series DC/DC Converter TRN Vin=36V 0 5 10 15 6 5 4 3 Vin=48V 2 Vin=75V 1 20 Vin=36V Vin=48V Vin=75V 0 25 0 5 10 Load(A) Fig. 17 Fig. 18 8 25 Typical power dissipation of AVO75-48S2V5 8 Dissipation(W) Pow er Dissipation (W) 20 Load(A) Typical power dissipation of AVO75-48S1V8 6 4 2 36V 48V 75V 0 6 4 Vin=36V 2 Vin=48V Vin=75V 0 0 2 4 6 8 10 12 14 16 18 3 6 20 9 12 15 Load(A) Load (A) Fig. 19 15 Typical power dissipation of AVO75-48S3V3 Fig. 20 Typical power dissipation of AVO75-48S05 Dissipation(W) 10 8 6 4 Vin=36V 2 Vin=48V Vin=75V 0 0 1 2 3 4 5 6 Output current(A) Fig. 21 TEL: (86) 755-86010808 Typical power dissipation of AVO75-48S12 www.emersonnetworkpower.com.cn 12/32 AVO75 Series DC/DC Converter TRN Fig. 22 AVO75-48S1V2 typical transient response to step decrease in load from 50% to 25% of full load, room temperature, 48Vdc input Fig. 23 AVO75-48S1V2 typical transient response to step increase in load from 50% to 75% of full load, room temperature, 48Vdc input Fig. 24 AVO75-48S1V5 typical transient response to step decrease in load from 50% to 25% of full load, room temperature, 48Vdc input Fig. 25 AVO75-48S1V5 typical transient response to step increase in load from 50% to 75% of full load, Fig. 26 AVO75-48S1V5 typical transient response to step decrease in load from 50% to 25% of full load, Fig. 27 AVO75-48S1V5 typical transient response to step increase in load from 50% to 75% of full load, room temperature, 48Vdc input (∆Io/∆t=0.1A/1µs) room temperature, 48Vdc input (∆Io/∆t=0.1A/1µs) TEL: (86) 755-86010808 room temperature, 48Vdc input (∆Io/∆t=1A/1µs) www.emersonnetworkpower.com.cn 13/32 AVO75 Series DC/DC Converter TRN Fig. 28 AVO75-48S1V5 typical transient response to step decrease in load from 50% to 25% of full load, Fig. 29 AVO75-48S1V5 typical transient response to step increase in load from 50% to 75% of full load, room temperature, 48Vdc input (∆Io/∆t=1A/1µs) room temperature, 48Vdc input (∆Io/∆t=1A/1µs) Fig. 30 AVO75-48S1V8 typical transient response to step decrease in load from 50% to 25% of full load, Fig. 31 AVO75-48S1V8 typical transient response to step increase in load from 50% to 75% of full load, room temperature, 48Vdc input (∆Io/∆t=0.1A/1µs) room temperature, 48Vdc input (∆Io/∆t=0.1A/1µs) Fig. 32 AVO75-48S1V8 typical transient response to step decrease in load from 50% to 25% of full load, Fig. 33 AVO75-48S1V8 typical transient response to step increase in load from 50% to 75% of full load, room temperature, 48Vdc input (∆Io/∆t=1A/1µs) room temperature, 48Vdc input (∆Io/∆t=1A/1µs) TEL: (86) 755-86010808 www.emersonnetworkpower.com.cn 14/32 AVO75 Series DC/DC Converter TRN Fig. 34 AVO75-48S2V5 typical transient response to step decrease in load from 50% to 25% of full load, Fig. 35 AVO75-48S2V5 typical transient response to step increase in load from 50% to 75% of full load, room temperature, 48Vdc input (∆Io/∆t=0.1A/1µs) room temperature, 48Vdc input (∆Io/∆t=0.1A/1µs) Fig. 36 AVO75-48S2V5 typical transient response to step decrease in load from 50% to 25% of full load, Fig. 37 AVO75-48S2V5 typical transient response to step increase in load from 50% to 75% of full load, room temperature, 48Vdc input (∆Io/∆t=1A/1µs) room temperature, 48Vdc input (∆Io/∆t=1A/1µs) Fig. 38 AVO75-48S3V3 typical transient response to step decrease in load from 50% to 25% of full load, Fig. 39 AVO75-48S3V3 typical transient response to step increase in load from 50% to 75% of full load, room temperature, 48Vdc input (∆Io/∆t=0.1A/1µs) room temperature, 48Vdc input (∆Io/∆t=0.1A/1µs) TEL: (86) 755-86010808 www.emersonnetworkpower.com.cn 15/32 AVO75 Series DC/DC Converter TRN Fig. 40 AVO75-48S3V3 typical transient response to step decrease in load from 50% to 25% of full load, Fig. 41 AVO75-48S3V3 typical transient response to step increase in load from 50% to 75% of full load, room temperature, 48Vdc input (∆Io/∆t=1A/1µs) room temperature, 48Vdc input (∆Io/∆t=1A/1µs) Fig. 42 AVO75-48S05 typical transient response to step decrease in load from 50% to 25% of full load, Fig. 43 AVO75-48S05 typical transient response to step increase in load from 50% to 75% of full load, room temperature, 48Vdc input (∆Io/∆t=0.1A/1µs) room temperature, 48Vdc input (∆Io/∆t=0.1A/1µs) Fig. 44 AVO75-48S05 typical transient response to step decrease in load from 50% to 25% of full load, Fig. 45 AVO75-48S05 typical transient response to step increase in load from 50% to 75% of full load, room temperature, 48Vdc input (∆Io/∆t=1A/1µs) room temperature, 48Vdc input (∆Io/∆t=1A/1µs) TEL: (86) 755-86010808 www.emersonnetworkpower.com.cn 16/32 AVO75 Series DC/DC Converter TRN Fig. 46 AVO75-48S12 typical transient response to step decrease in load from 50% to 25% of full load, Fig. 47 AVO75-48S12 typical transient response to step increase in load from 50% to 75% of full load, room temperature, 48Vdc input (∆Io/∆t=0.1A/1µs) room temperature, 48Vdc input (∆Io/∆t=0.1A/1µs) Fig. 48 AVO75-48S12 typical transient response to step decrease in load from 50% to 25% of full load, Fig. 49 AVO75-48S12 typical transient response to step increase in load from 50% to 75% of full load, room temperature, 48Vdc input (∆Io/∆t=1A/1µs) room temperature, 48Vdc input (∆Io/∆t=1A/1µs) Fig. 50 Typical output ripple voltage of AVO75-48S1V2 room temperature, Io=Io,max Fig. 51 Typical output ripple voltage of AVO75-48S1V5 room temperature, Io=Io,max TEL: (86) 755-86010808 www.emersonnetworkpower.com.cn 17/32 AVO75 Series DC/DC Converter TRN Fig. 52 Typical output ripple voltage of AVO75-48S1V8 room temperature, Io=Io,max Fig. 53 Typical output ripple voltage of AVO75-48S2V5 room temperature, Io=Io,max Fig. 54 Typical output ripple voltage of AVO75-48S3V3 room temperature, Io=Io,max Fig. 55 Typical output ripple voltage of AVO75-48S05 room temperature, Io=Io,max Fig. 56 Typical output ripple voltage of AVO75-48S12 room temperature, Io=Io,max TEL: (86) 755-86010808 www.emersonnetworkpower.com.cn 18/32 AVO75 Series DC/DC Converter TRN Fig. 57 Fig. 59 Fig. 61 AVO75-48S1V2 typical start-up from power on AVO75-48S1V5 typical start-up from power on AVO75-48S1V8 typical start-up from power on TEL: (86) 755-86010808 Fig. 58 AVO75-48S1V2 typical start-up from CNT on Fig. 60 AVO75-48S1V5 typical start-up from CNT on Fig. 62 AVO75-48S1V8 typical start-up from CNT on www.emersonnetworkpower.com.cn 19/32 AVO75 Series DC/DC Converter TRN Fig. 63 AVO75-48S2V5 typical start-up from power on Fig. 65 Fig. 67 AVO75-48S3V3 typical start-up from power on AVO75-48S05 typical start-up from power on TEL: (86) 755-86010808 Fig. 64 AVO75-48S2V5 typical start-up from CNT on Fig. 66 AVO75-48S3V3 typical start-up from CNT on Fig. 68 AVO75-48S05 typical start-up from CNT on www.emersonnetworkpower.com.cn 20/32 AVO75 Series DC/DC Converter TRN Fig. 69 AVO75-48S12 typical start-up from power on TEL: (86) 755-86010808 Fig. 70 AVO75-48S12 typical start-up from CNT on www.emersonnetworkpower.com.cn 21/32 AVO75 Series DC/DC Converter TRN Feature Description CNT Function The converter is equipped with a primary ON/OFF pin used to remotely turn the converter on or off via a system signal. Two CNT logic options are available. For the positive logic model a system logic low signal will turn the unit off. For the negative logic model a system logic high signal will turn the converter off. For negative logic models where no control signal will be used the ON/OFF pin should be connected directly to -Vin to ensure proper operation. For positive logic models where no control signal will be used the ON/OFF pin should be left unconnected. The following Fig. shows a few simple CNT circuits. CNT CNT -Vin -Vin Simple CNT Transistor CNT CNT CNT -Vin -Vin Isolated CNT Fig. 71 Relay CNT CNT circuits drops in distribution and maintain a regulated voltage at the point of load. When the converter is supporting loads far away, or is used with undersized cabling, significant voltage drop can occur at the load. The best defense against such drops is to locate the load close to the converter and to ensure adequately sized cabling is used. When this is not possible, the converter can compensate for a drop of up to 10%Vo, through use of the sense leads. When used, the + Sense and - Sense leads should be connected from the converter to the point of load as shown in Fig. 72, using twisted pair wire, or parallel pattern to reduce noise effect. The converter will then regulate its output voltage at the point where the leads are connected. Care should be taken not to reverse the sense leads. If reversed, the converter will trigger OVP protection. When not used, the +Sense lead must be connected with +Vo, and -Sense with -Vo. Although the output voltage can be increased by both the remote sense and by the trim, the maximum increase for the output voltage is not the sum of both. The maximum increase is the larger of either the remote sense or the trim. Note that at elevated output voltages the maximum power rating of the module remains the same, and the output current capability will decrease correspondingly. Remote Sense +Vo The AVO75 converter can remotely sense both lines of its output which moves the effective output voltage regulation point from the output terminals of the unit to the point of connection of the remote sense pins. This feature automatically adjusts the real output voltage of the AVO75 in order to compensate for voltage TEL: (86) 755-86010808 +S +Sense Twisted pair Load -Sense -S -Vo Fig. 72 Sense connections www.emersonnetworkpower.com.cn 22/32 AVO75 Series DC/DC Converter TRN Trim △=(1.98-1.8)×100/1.8=10 The +Vo output voltage of the AVO75 series can be trimmed with the trim pin provided. Applying a resistor to the trim pin through a voltage divider from the output will cause the +Vo output to increase by up to 10%or decrease by up to 20%. Trimming up by more than 10% of the nominal output may activate the OVP circuit or damage the converter. Trimming down more than 20% can cause the converter to regulate improperly. If the trim pin is not needed, it should be left open. Radj −up = 5.1 × 1.8 × (100 + 10 ) 510 − − 10.2(kΩ ) 1.225 × 10 10 Radj −up = 21.23( kΩ ) Trim down With an external resistor between the TRIM and -SENSE pins, the output voltage set point decreases (see Fig. 74). Vo(+) Vi(+) SENSE(+) CNT TRIM Trim up With an external resistor connected between the TRIM and +SENSE pins, the output voltage set point increases (see Fig. 73). Vi(+) SENSE(+) Radj-up TRIM Vi(-) SENSE(-) Vi(-) Vo(-) Fig. 74 Trim down circuit The following equation determines the required external-resistor value to obtain a percentage output voltage change of 1%. For output voltage: 1.2V ~ 12V Vo(+) CNT RLOAD Radj-down RLOAD SENSE(-) Radj −down = Vo(-) 510 − 10.2(kΩ) ∆% Note: △= (Vnom-Vo) % 100/Vnom Fig. 73 Trim up circuit The following equation determines the required external-resistor value to obtain a percentage output voltage change of 1%. For Output Voltage: 1.5V ~ 12V 5.1× Vnom × (100 + ∆ % ) 510 Radj −up = − − 10.2(kΩ) 1.225 × ∆ % ∆% For output voltage: 1.2V 5.1× Vnom × (100 + ∆ % ) 510 Radj −up = − − 10.2(kΩ) 0. 6 × ∆ % ∆% Note: △=(Vnom-Vo)×100/Vnom Vtrim tolerance: < ±2%, Radj tolerance: ±1% For example: trim up the output of Vtrim tolerance: