L6728A STMicroelectronics, L6728A Datasheet
L6728A
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L6728A Summary of contents
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... V as low as 1.5 V and device IN supply voltage ranging from L6728A provides simple control loop with voltage mode 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. ...
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... L6728A Contents 1 Typical application circuit and block diagram . . . . . . . . . . . . . . . . . . . . 4 1.1 Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 Pins description and connection diagrams . . . . . . . . . . . . . . . . . . . . . . 5 2.1 Pin descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3 Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4 Device description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5 Driver section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5 ...
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... L6728A 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 Mechanical data and package dimensions . . . . . . . . . . . . . . . . . . . . . . 30 14 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Power input (VIN Output (VOUT) ...
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... Typical application circuit and block diagram 1.1 Application circuit Figure 1. Typical application circuit 12V CC C DEC PGOOD L6728A Reference Schematic 1.2 Block diagram Figure 2. Block diagram VSEN PGOOD Typical application circuit and block diagram VCC 1 10 BOOT PGOOD 3 7 UGATE COMP ...
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... GND 6 VCC 7 COMP / DIS 8 FB Pins description and connection diagrams BOOT 1 10 PHASE 2 9 L6728A UGATE 3 8 LGATE / GND 5 6 Function HS driver supply. Connect through a capacitor (100 nF) to the floating node (LS-Drain) pin and provide necessary bootstrap diode from V HS driver return path, current-reading and adaptive-dead-time monitor. ...
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... L6728A Table 2. Pin description (continued) Pin # Name 9 VSEN 10 PGOOD 2.2 Thermal data Table 3. Thermal data Symbol Thermal resistance junction to ambient R TH(JA) (Device soldered on 2s2p board) R Thermal resistance junction to case TH(JC) T Maximum junction temperature MAX T Storage temperature range STG T Junction temperature range ...
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... L6728A 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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... L6728A Table 5. Electrical characteristics (continued Symbol Parameter Gate drivers I HS source current UGATE R HS sink resistance UGATE I LS source current LGATE R LS sink resistance LGATE Over-current protection I OCSET current source OCSET V OC switch-over threshold OC_SW Over and under-voltage protections OVP OVP threshold ...
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... PGOOD in a compact VFQFPN10 3x3 mm. L6728A 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 L6728A 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, L6728A 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, L6728A 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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... Output voltage setting and protections L6728A 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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... L6728A 9 Application details 9.1 Compensation network The control loop showed in regulated to the internal reference (when present, offset resistor between FB node and GND can be neglected in control loop calculation). Error amplifier output is compared to oscillator saw-tooth waveform to provide PWM signal to the driver section. PWM signal is then transferred to the switching node with V amplitude ...
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... L6728A 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 L6728A 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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... L6728A Figure 7. Power connections (heavy lines) L6728A 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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... L6728A 10 Application information 10.1 Inductor design The inductance value is defined by a compromise between the dynamic response time, the efficiency, the cost and the size. The inductor has to be calculated to maintain the ripple current (ΔI ) between 20% and 30% of the maximum output current (typ.). The inductance ...
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... L6728A 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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... L6728A demonstration board L6728A 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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... L6728A Figure 11 demonstration board schematic 20 A demonstration board 21/32 ...
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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, L6728A 20 A demonstration board Description Package Radial SMD0603 SMD1206 SMD0805 SMD1206 SMD0603 SMD0603 SMD0805 SMD0603 ...
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... L6728A 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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... L6728A 11.2 Demonstration board characterization Figure 12 and Figure 17 accuracy and efficiency. Figure 12 demonstration board performances Load / Line Regulation 0,3% 0,2% 0,1% 0,0% -0,1% -0,2% -0, 100% 90% 80% 70% 60% 50% 40% 0,0 2,5 5,0 7,5 show the electrical performances of the tamboured in terms 10A 15A ...
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... L6728A 12 5A demonstration board L6728A 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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... L6728A Figure 15 demonstration board schematic 5A demonstration board 26/32 ...
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... Resistor, 3K9, 1/ 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, L6728A 5A demonstration board Package SMD1206 SMD0603 SMD0805 SMD1206 SMD0603 SMD0603 na SOT23 ...
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... L6728A 12.1 Demonstration board description 12.1.1 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 Vcc pin) and in this case the R16 (0 Ω ...
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... L6728A 12.2 Demonstration board characterization Figure 16 and Figure 17 terms of accuracy and efficiency. Figure 16 demonstration board performances Load / Line Regulation 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 ...
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... L6728A 13 Mechanical data and package dimensions Figure 18. Mechanical data and package dimensions DIMENSIONS mm REF. MIN. TYP. MAX. MIN. A 0.80 0.90 A1 0.02 A2 0.70 A3 0.20 b 0.18 0.23 D 3.00 D2 2.21 2.26 E 3.00 E2 1.49 1.64 e 0.50 L 0.3 0.4 M 0.75 0.25 m Mechanical data and package dimensions mils TYP ...
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... L6728A 14 Revision history Table 10. Document revision history Date 01-Oct-2008 Revision 1 Initial release Revision history Changes 31/32 ...
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... L6728A 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. ...