L6728AH STMicroelectronics, L6728AH Datasheet
L6728AH
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L6728AH Summary of contents
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... EA. The integrated 0.8 V reference allows regulating output voltages with ±0.8% accuracy over line and temperature variations. Oscillator is internally fixed to 600 kHz. L6728AH provides programmable dual level over current protection as well as over and under voltage protection. Current information is monitored across the low-side MOSFET R saving the use of expensive and space- consuming sense resistors ...
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... Low-side-less start up (LSLess Over-current protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.1 Over-current threshold setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8 Output voltage setting and protections . . . . . . . . . . . . . . . . . . . . . . . . 13 9 Application details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 9.1 Compensation network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 9.2 Layout guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 10 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 10.1 Inductor design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 10.2 Output capacitor( 10.3 Input capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2/33 Doc ID 15726 Rev 1 L6728AH ...
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... L6728AH demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 11.1 Demonstration board description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 11.1.1 11.1.2 11.1.3 11.1.4 11.2 Demonstration board characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 12.1 Demonstration board description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 12.1.1 12.1.2 12.1.3 12.1.4 12.2 Demonstration board characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 13 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 14 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Power input (VIN Output (VOUT Signal input (VCC) ...
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... L6728AH 4 8 LGATE VSEN GND OCSET MONITOR OUT CONTROL LOGIC & PROTECTIONS CLOCK 600 kHz OSCILLATOR ERROR AMPLIFIER L6728AH L6728A Doc ID 15726 Rev 1.5V to 12V BULK OUT V OCTH OC HS VCC PWM OCSET L6728AH Vout LOAD BOOT UGATE PHASE LGATE / OC GND ...
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... PGOOD relative window. Pull voltage equal or lower than V Pins description and connection diagrams BOOT 1 10 PHASE 2 L6728A UGATE 3 L6728AH LGATE / OC 4 GND 5 Function . CC drop to measure the output current. This pin is also used by the DS(on the output regulated voltage. Output resistor divider may be ...
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... Thermal resistance junction to case TH(JC) T Maximum junction temperature MAX T Storage temperature range STG T Junction temperature range J P Maximum power dissipation at T TOT 6/33 Parameter = 25 °C A Doc ID 15726 Rev 1 L6728AH Value Unit 45 °C/W 5 °C/W 150 °C -40 to 150 °C -40 to 125 °C 2.25 W ...
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... L6728AH 3 Electrical specifications 3.1 Absolute maximum ratings Table 4. Absolute maximum ratings Symbol V to GND CC to PHASE GND BOOT, UGATE to GND; t < 200 ns to GND V PHASE to GND; t < 200 GND LGATE FB, COMP, VSEN to GND PGOOD to GND 3.2 Electrical characteristics Table 5. Electrical characteristics ...
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... Sourced from LGATE pin, during OC setting phase V rising LGATE/OC VSEN rising unlatch, VSEN falling VSEN falling Sourced from VSEN VSEN rising VSEN falling PGOOD Doc ID 15726 Rev 1 L6728AH Min. Typ. Max. Unit 1.5 A Ω 1.1 1.5 A Ω 0.65 μ 600 mV 0.90 1 ...
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... PGOOD in a compact VFQFPN10 3x3 mm. L6728AH is designed to operate from supply. The output voltage can be precisely regulated to as low as 0.8 V with ±1% accuracy over line and temperature variations. The switching frequency is internally set to 600 kHz. ...
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... Power dissipation L6728AH embeds high current MOSFET drivers for both high side and low side MOSFETs then important to consider the power that the device is going to dissipate in driving them in order to avoid overcoming the maximum junction operative temperature. ...
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... Low-side-less start up (LSLess) In order to avoid any kind of negative undershoot and dangerous return from the load during start-up, L6728AH performs a special sequence in enabling LS driver to switch: during the soft-start phase, the LS driver results disabled (LS = OFF) until the HS starts to switch. This avoid the dangerous negative spike on the output voltage that can happen if starting over a pre-biased output ...
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... The low side R DS(on) node when LS MOSFET is turned on with the programmed OCP thresholds voltages, internally held. If the monitored voltage is bigger than these thresholds, an over-current event is detected. For maximum safety and load protection, L6728AH implements a dual level over-current protection system: st ● 1 level threshold the user externally set threshold. If the monitored voltage on ...
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... L6728AH 8 Output voltage setting and protections L6728AH is capable to precisely regulate an output voltage as low as 0 fact, the device comes with a fixed 0.8 V internal reference that guarantee the output regulated voltage to be within ±1% tolerance over line and temperature variations (excluding output resistor divider tolerance, when present). ...
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... R 0dB /2π. To achieve a good phase margin, the control loop gain SW shows an asymptotic bode plot of a type III compensation. Doc ID 15726 Rev 1 depending on the L-C output OUT C OUT ESR and EA output with transfer OUT /R ratio, however, for F FB L6728AH IN ...
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... L6728AH Figure 6. Example of type III compensation open loop EA gain closed loop gain compensation open loop converter gain ● Open loop converter singularities --------------------------------- - LC 2π ESR ● Compensation network singularities frequencies ------------------------------ Z1 2π ---------------------------------------------------- - Z2 2π ------------------------------------------------- - P1 2π ------------------------------ - P2 2π place the poles and zeroes of the compensation network, the following suggestions may ...
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... Check phase margin obtained (it should be greater than 45°) and repeat if necessary. 9.2 Layout guidelines L6728AH provides control functions and high current integrated drivers to implement high- current step-down DC-DC converters. In this kind of application, a good layout is very important. The first priority when placing components for these applications has to be reserved to the power section, minimizing the length of each connection and loop as much as possible ...
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... Figure 7. Power connections (heavy lines) L6728A L6728AH Gate traces and phase trace must be sized according to the driver RMS current delivered to the power MOSFET. The device robustness allows managing applications with the power section far from the controller without losing performances. Anyway, when possible recommended to minimize the distance between controller and power section ...
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... When this condition is reached, the response time is limited by the time required to change the inductor current. 18/33 V – OUT OUT ⋅ ----------------------------- - -------------- L = ⋅ Δ the input voltage and V IN Doc ID 15726 Rev 1 L6728AH is the output OUT ...
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... L6728AH 10.2 Output capacitor(s) The output capacitors are basic components to define the ripple voltage across the output and for the fast transient response of the power supply. They depend on the output voltage ripple requirements, as well as any output voltage deviation requirement during a load transient ...
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... A demonstration board demonstration board L6728AH 20 A demonstration board realizes two-layer PCB, a step-down DC/DC converter and shows the operation of the device in a general-purpose high-current application. Different output voltage rails have been considered 3.3 V, 2.5 V, 1.25 V and 0.8 V. The input voltage can range from a bottom value that depends on the chosen rail buses (absolute maximum) ...
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... L6728AH Figure 11 demonstration board schematic Doc ID 15726 Rev demonstration board 21/33 ...
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... Resistor, 0R, 1/8W, 1% Not mounted Resistor 1/16W, 1% Resistor 1/16W, 1% Wurth SMD power inductor 670 nH - 1.75 mΩ P/N 744-315-067 Not mounted Diode, 1N4148 Not mounted STD70NH02L STD95NH02L Controller, L6728AH Doc ID 15726 Rev 1 Description Package Radial SMD0603 SMD1206 SMD0805 SMD1206 SMD0603 SMD0603 SMD0805 SMD0603 ...
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... L6728AH 11.1 Demonstration board description 11.1.1 Power input (V This is the input voltage for the power conversion. The high-side drain is connected to this input. This voltage can range from 1 bus. If the voltage is between 5 V and can supply also the device (through the V and in this case the R16 (0 Ω) resistor must be present. ...
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... Vout = 2.5 V 50% Vout = 5 V 40% 0,0 2,5 5,0 7,5 10,0 12,5 15,0 17,5 Output Current [A] Input Voltage @ 5 V 100% 90% 80% 70% 60% Vout = 0.8 V 50% Vout = 2 Output Current [A] L6728AH Vout = 1.25 V Vout = 3.3 V Vout = 8 V 20,0 22,5 25,0 Vout = 1.25 V Vout = 3 ...
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... L6728AH demonstration board L6728AH 5 A demonstration board realizes two-layer PCB, a step-down DC/DC converter and shows the operation of the device in a general-purpose high-current application. Different output voltage rails have been considered 3.3 V, 2.5 V, 1.25 V and 0.8 V. The input voltage can range from a bottom value that depends on the chosen rail buses (absolute maximum) ...
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... A demonstration board Figure 15 demonstration board schematic 26/33 Doc ID 15726 Rev 1 L6728AH ...
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... Resistor, 270 R, 1/ Resistor 1/ Resistor 1/ Wurth SMD power inductor 1.8 μH - 3.68 mΩ P/N 744-318-180 Diode, BAT54 Dual N-channel MOS, STS8DNF3LL (the STS8DNH3LL model can be used as well) Controller, L6728AH Doc ID 15726 Rev demonstration board Description Package SMD1206 SMD0603 SMD0805 SMD1206 SMD0603 ...
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... LGATE: Low-Side gate pin of the device; – HGATE: High-Side gate pin of the device. 28/ rail 3.3 V rail 240 Ω 430 Ω 680 Ω supply the controller no power is required at this input. IN Doc ID 15726 Rev 1 L6728AH 2.5 V rail 1.25 V rail 0.8 V rail 1 kΩ 3.9 kΩ Open CC ...
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... L6728AH 12.2 Demonstration board characterization Figure 16 and Figure 17 terms of accuracy and efficiency. Figure 16 demonstration board performances 0,3% 0,2% 0,1% 0,0% -0,1% -0,2% -0, 100% 90% 80% 70% 60% 50% 40% 0,0 0,5 1,0 1,5 Figure 17. Demonstration boards power consumption @ 0 A output current 5A Demoboard Power Consumption ...
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... Package mechanical data 13 Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ® ECOPACK packages, depending on their level of environmental compliance. ECOPACK specifications, grade definitions and product status are available at: www.st.com. ® ECOPACK trademark. 30/33 Doc ID 15726 Rev 1 L6728AH ® ...
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... L6728AH Table 10. VFDFPN10 3x3 mm mechanical data Dim. Min Figure 18. VFDFPN10 3x3 mm package drawing mm Typ. Max. Min. 0.90 1.00 31.49 0.02 0.05 0.70 0.20 0.23 0.30 7.086 3.00 2.26 2.31 87.00 3.00 1.64 1.74 58.66 0.50 0.4 0.5 11.81 ...
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... Revision history 14 Revision history Table 11. Document revision history Date 20-May-2009 32/33 Revision 1 Initial release Doc ID 15726 Rev 1 L6728AH Changes ...
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... L6728AH Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. ...