Visit analog.com Project Code: APM_AO_2018 SIMPLE SUPPLY SOLUTION FOR ISOLATED MULTITAPS OUTPUTS Why Need Isolated Power Supply Topology Isolated power supply topology has been widely used in different industrial products and application for many years, like PLCs and DCSs. To achieve better performance, more and more end customers require isolation between digital zone and analog zone, or even physical isolation between channels. The main purposes for this are: X Safety X Reliability X Minimizing ground noise Most amplifiers, multiplexers, and DAC drivers need bipolar supply for normal operation, so an isolated triple tap output supply solution can easily fulfill most of those requirement. Popular Solutions in Market In the market there are mainly two kinds of solutions for isolated power supplies: traditional discrete fly-back ones and dc-to-dc modules. The first option usually needs specific deep design experience. These use plenty of discrete components, so the PCB size is always a headache issue. The second option’s advantage is small size and being easy to use, but their efficiency, load, and line regulation are still far from excellent. As a transformer constrains, dc-to-dc modules have to provide multiple isolated supply outputs, which still requires the customer to do their own, second-stage buck/boost regulation. Design Challenges For a general electronic engineer, it’s quite a challenge to design an isolated power supply from scratch without deep power design experience, especially when working on complicated transformer design and debugging. For a good isolated power design, the following challenges need to be solved: X Smaller PCB size and height X Cheaper cost X Transformer spec design X Load regulation, line regulation, and cross regulation between channels X Efficiency X Output power rate Total Solutions from ADI LT8301 and ADuM3471 are highly integrated power isolation solutions from ADI, which are suitable for isolated, multiple tap transformer control from a 2.5 watt to 5 watt power rate, and they can cover both efficiency, load, and line regulation requirements through different combination. To simplify the design effort, we give a few different examples for frequently used cases, and we also provide the key diodes P/N used and the suggested transformer P/N.
Transcript
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Project Code: APM_AO_2018
SIMPLE SUPPLY
SOLUTION FOR ISOLATED MULTITAPS OUTPUTS
Why Need Isolated Power Supply TopologyIsolated power supply topology has been widely used in different industrial products and application for many years, like PLCs and DCSs. To achieve better performance, more and more end customers require isolation between digital zone and analog zone, or even physical isolation between channels. The main purposes for this are:
X Safety
X Reliability
X Minimizing ground noise
Most amplifiers, multiplexers, and DAC drivers need bipolar supply for normal operation, so an isolated triple tap output supply solution can easily fulfill most of those requirement.
Popular Solutions in MarketIn the market there are mainly two kinds of solutions for isolated power supplies: traditional discrete fly-back ones and dc-to-dc modules. The first option usually needs specific deep design experience. These use plenty of discrete components, so the PCB size is always a headache issue. The second option’s advantage is small size and being easy to use, but their efficiency, load, and line regulation are still far from excellent. As a transformer constrains, dc-to-dc modules have to provide multiple isolated supply outputs, which still requires the customer to do their own, second-stage buck/boost regulation.
Design ChallengesFor a general electronic engineer, it’s quite a challenge to design an isolated power supply from scratch without deep power design experience, especially when working on complicated transformer design and debugging. For a good isolated power design, the following challenges need to be solved:
X Smaller PCB size and height
X Cheaper cost
X Transformer spec design
X Load regulation, line regulation, and cross regulation between channels
X Efficiency
X Output power rate
Total Solutions from ADILT8301 and ADuM3471 are highly integrated power isolation solutions from ADI, which are suitable for isolated, multiple tap transformer control from a 2.5 watt to 5 watt power rate, and they can cover both efficiency, load, and line regulation requirements through different combination.
To simplify the design effort, we give a few different examples for frequently used cases, and we also provide the key diodes P/N used and the suggested transformer P/N.
4 Simple Supply Solution for Isolated Multitaps Outputs
Transformers SelectionApplication Scenario Transformer P/N Total Allow Output Power Package
5 V/1 A, +15 V/10 mA, −15 V/10 mA 750343958 (wurth) 5 W (max) EP10 (15 × 13 × 11)
5 V/100 mA, +15 V/200 mA, −15 V/50 mA 750343958 (wurth) 5 W (max) EP10 (15 × 13 × 11)
5 V/500 mA, +15 V/10 mA, −15 V/10 mA 750343894 (wurth) 2.5 W (min) ER11 (13 × 12 × 6)
5 V/100 mA, +15 V/100 mA, −15 V/50 mA 750343896 (wurth) 2.5 W (min) ER11 (13 × 12 × 6)
Other Components SelectionItems Part Number Vendor
D1,D2,D3 DFLS260-7 Diodes Inc.
Q1 DMN6066SSD Diodes Inc.
Efficiency Plots
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Load Current (A)
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LT3801 750343896 (3.5 W)
UM3471 750343896 (3.5 W)
LT8301 750343958 (5 W)
UM3471 750343958 (5 W)
LT8301 750343894 (3.5 W)
UM3471 (Main Feedback 15 V)750343894 (3.5 W)
Figure 5. Comparative graph of different transformer efficiencies.
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Main Product IntroductionPart Number Description Key Features Benefits
Regulation
LT830142 VIN micropower no-opto isolated flyback converter with 65 V/1.2 A switch
X 2.7 V to 42 V input voltage range X 1.2 A, 65 V internal DMOS power switch X Boundary mode operation at heavy load X Low-ripple Burst Mode® operation at light load X Minimum load <0.5% (typical) of full output X VOUT set with a single external resistor X No transformer third winding or opto-isolator required for regulation X Accurate EN/UVLO threshold and hysteresis X Internal compensation and soft-start X Output short-circuit protection
Tiny size, high efficiency, suitable for isolated supply design
X Isolated PWM controller X Integrated transformer driver X Quad dc-to-25 Mbps (NRZ) signal isolation channels X 20-lead SSOP package X High common-mode transient immunity: >25 kV/μs X 200 kHz to 1 MHz adjustable oscillator frequency X Soft start function at power-up X Pulse-by-pulse overcurrent protection X Thermal shutdown X 2500 V rms isolation
Competitive isolated solution with 4-channel iCoupler® for SPI interface
4 mA to 20 mA Loop Driver
AD5755-1
Quad-channel, 16-bit, serial input, 4 mA to 20 mA and voltage output DAC, dynamic power control, HART connectivity
X 16-bit resolution and monotonicity X Dynamic power control for thermal management X Current and voltage output pins connectable to a single terminal X Current output ranges: 0 mA to 20 mA, 4 mA to 20 mA, or 0 mA
to 24 mA • ±0.05% total unadjusted error (TUE) maximum
X Voltage output ranges (with 20% overrange): 0 V to 5 V, 0 V to 10 V, ±5 V, and ±10 V
• ±0.04% total unadjusted error (TUE) maximum X User programmable offset and gain X On-chip diagnostics X On-chip reference (±10 ppm/°C maximum)
Ideal solution for multichannel AO modules without isolation between channels
AD5758
Single-channel, 16-bit current, and voltage output DAC with dynamic power control and HART connectivity
X 16-bit resolution and monotonicity X DPC for thermal management X Current/voltage output available on a single terminal X Current output ranges: 0 mA to 20 mA, 4 mA to 20 mA, 0 mA to
24 mA, ±20 mA, ±24 mA, −1 mA to +22 mA X Voltage output ranges (with 20% overrange): 0 V to 5 V, 0 V to 10 V,
±5 V, and ±10 V X Advanced on-chip diagnostics, including a 12-bit ADC
Ideal solution for multichannel AO module with isolation between channels
6 Simple Supply Solution for Isolated Multitaps Outputs
Part Number Description Key Features Benefits
AD5412/AD5422
Single-channel, 12-/16-bit, current source, and voltage output DAC, HART connectivity
X 12-/16-bit resolution and monotonicity X Current output ranges: 4 mA to 20 mA, 0 mA to 20 mA, or 0 mA
to 24 mA X ±0.01% FSR typical total unadjusted error (TUE) X ±3 ppm FSR/°C output drift X Voltage output ranges: 0 V to 5 V, 0 V to 10 V, ±5 V, or ±10 V
X On-chip output fault detection X On-chip reference: 10 ppm/°C maximum X Optional regulated DVCC output X Power supply range
• AVDD: 10.8 V to 40 V • AVSS: −26.4 V to −3 V/0 V
X Current loop compliance voltage: AVDD – 2.5 V X Temperature range: −40°C to +105°C X TSSOP and LFCSP packages
A complete, monolithic low level V-I loop signal conditioner
iCoupler
ADuM141ERobust, quad-channel isolator with output enable and 1 reverse channel
X High common-mode transient immunity: 100 kV/μs X High robustness to radiated and conducted noise X Low propagation delay
• 13 ns maximum for 5 V operation • 15 ns maximum for 1.8 V operation
X 150 Mbps maximum guaranteed data rate X Backward compatibility
• ADuM140E1/ADuM141E1/ADuM142E1 pin-compatible with ADuM1400/ADuM1401/ADuM1402
X Low dynamic power consumption X 1.8 V to 5 V level translation X High temperature operation: 125°C X Fail-safe high or low options X 16-lead, RoHS compliant, SOIC package
The newest iCoupler product with latest technology
Regulator
ADP1720 Linear regulator
X Supply range: 4 V to 28 V X Low light load current: 28 μA at 0 μA load X Low dropout: 275 mV @ 50 mA X Initial accuracy: ±0.5% X Logic controlled enable X Current and thermal overload protection
Low power consumption
REF
ADR3412 Low power reference
X 1.2 V precision output X Supply current: 100 μA max X Low noise (<10 Hz): 8 μV p-p typical X Supply range: 2.3 V to 5.5 V X Long term stability: 30 ppm/√1000 hr @ 50°C
In conclusion, ADI provides three kinds of transformers based and six kinds of solutions through LT8301 and ADuM3471, which could cover from 2.5 watt to 5 watt and 5 V @ 1 A or ±15 V @ 200 mA for different application required. You could easily choose one option for your bipolar supply analog input or analog output system. These solution can help greatly reduce your design effort, shrink your PCB space, and bring better efficiency and line/load regulation.
CFTL Link X PLC and DCS Universal Analog Input Using Either 4-Pin or 6-Pin
Terminal Block (CN-0325)— analog.com/en/cn-0325 X 16-Bit Isolated Industrial Voltage and Current Output DAC with Isolated
DC-to-DC Supplies (CN-0233)— analog.com/en/cn-0233 X Completely Isolated, Robust, 4-Channel, Multiplexed Data Acquisition
System for Industrial Level Signals (CN-0292)— analog.com/en/cn-0292 X Demo Manual DC2138B— analog.com/en/evaluation-kit-manuals/
DC2138BFA.pdf
What ADI Can Provide to Customers X ADC: ADIsimADC™; Σ-Δ ADC register configuration assistant
X DAC: ADIsimDAC™
X Amplifier: ADIsimOpAmp™; ADIsimDiffAmp™
X Power: EVB ADIsimPower
X Processor: EVB emulation tools and some software
For More Needs About Electromagnetic Flow Meter, Please Contact ADI.
Reference DesignThese reference designs will be provided separate for those who want to evaluate our power supply solution while working with AD5755-1. There are also two additional control method through SDP by using a PC or the touch screen control/display directly.
Figure 6. 4-channel current output design with AD5755-1 (with SDP board).
Figure 7. 4-channel current output design with AD5755-1 (with touch screen control).
Technical SupportEngage with the Analog Devices technology experts in our online support community. Ask your tough design questions, browse FAQs, or join a conversation.
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