L6728H STMicroelectronics, L6728H Datasheet
L6728H
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L6728H Summary of contents
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... DFN10 package. Device flexibility allows managing conversions with power input V supply voltage ranging from L6728H 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 300 kHz. ...
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... Low-side-less startup (LSLess Over current protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8.1 Over current threshold setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 9 Output voltage setting and protections . . . . . . . . . . . . . . . . . . . . . . . . 14 10 Application details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 10.1 Compensation network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 10.2 Layout guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 11 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 11.1 Inductor design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 11.2 Output capacitor( 11.3 Input capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2/32 Doc ID 15725 Rev 1 L6728H ...
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... L6728H demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 12.1 Board description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 12.1.1 12.1.2 12.1.3 12.1.4 12.1 demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 13.1 Board description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 13.1.1 13.1.2 13.1.3 13.1.4 13.1.5 14 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 15 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Power input (Vin Output (Vout Signal input (Vcc Test points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Board characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Power input (Vin Output (Vout) ...
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... L6728H 4 8 LGATE VSEN GND OCSET MONITOR OUT CONTROL LOGIC & PROTECTIONS CLOCK 600 kHz OSCILLATOR ERROR AMPLIFIER L6728A L6728H Doc ID 15725 Rev 1.5V to 12V BULK OUT V OCTH OC HS VCC PWM OCSET L6728H Vout LOAD BOOT UGATE PHASE LGATE / OC GND ...
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... Open drain output set free after SS has finished and pulled low when VSEN is outside the 10 PGOOD relative window. Pull voltage equal or lower than VCC. If not used it can be left floating. Pin description and connection diagrams L6728H Function R drop to measure the output current. This pin is also used by the DS(on) F Doc ID 15725 Rev 1 resistor greater than 5 kΩ ...
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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 6/32 Parameter = 25 °C A Doc ID 15725 Rev 1 L6728H 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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... L6728H 4 Electrical specifications 4.1 Absolute maximum ratings Table 4. Absolute maximum ratings Symbol VCC to GND 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 4.2 Electrical characteristics Table 5. Electrical characteristics Symbol ...
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... VCC = 5 V Sourced from LGATE pin, during OC setting phase. V rising LGATE/OC VSEN rising un-latch, VSEN falling VSEN falling Sourced from VSEN VSEN rising VSEN falling PGOOD Doc ID 15725 Rev 1 L6728H Min. Typ. Max. Unit 1.5 A Ω 1.1 1.5 A Ω 0.65 μ ...
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... PGOOD in a compact DFN10 3x3 mm. L6728H is designed to operate from supply. The output voltage can be precisely regulated to as low as 0.8 V with ±0.8% accuracy over line and temperature variations ...
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... Power dissipation L6728H 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 startup (LSLess) In order to avoid any kind of negative undershoot and dangerous return from the load during start-up, L6728H 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, L6728H implements a dual level over current protection system: st ● 1 level threshold the user externally set threshold ...
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... L6728H 8.1 Over current threshold setting L6728H allows to easily program a 1 550 mV, simply by adding a resistor (R will be automatically set accordingly. During a short period of time (about 5 ms) following VCC rising over UVLO threshold, an internal 10 µA current (I across R . This voltage drop will be sampled and internally held by the device as 1 OCSET level over current threshold ...
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... Output voltage setting and protections 9 Output voltage setting and protections L6728H 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 ±0.8% tolerance over line and temperature variations (excluding output resistor divider tolerance, when present) ...
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... L6728H 10 Application details 10.1 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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... ESR OUT 1 ⋅ ⋅ ⋅ ⋅ ⋅ ⎛ ⎞ ⋅ ⋅ -------------------- - ⎝ ⎠ ⋅ ⋅ order to obtain the desired closed loop regulator bandwidth F FB ΔV 0dB OSC ⋅ ------------------ - Doc ID 15725 Rev 20log ( 20log (V /Δ OSC Log (Freq) are in the range FB L6728H ...
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... Check phase margin obtained (it should be greater than 45°) and repeat if necessary. 10.2 Layout guidelines L6728H 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 8. Drivers turn-on and turn-off paths LS DRIVER VCC LGATE GND 18/ UGATE C IN PHASE LGATE GND LS MOSFET GATE INT Doc ID 15725 Rev OUT LOAD close to the device and avoid OCSET HS DRIVER HS MOSFET BOOT GATE INT UGATE C GS PHASE L6728H C DS ...
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... L6728H 11 Application information 11.1 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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... ESR L ΔI ⋅ OUT ⋅ ------------------------------------- - ⋅ ⋅ Δ OUT L for the load appliance or V OUT ) and the duty-cycle (D) for the regulation as follow: OUT ) 1 D – /2, with D = 0.5. The losses depends on the OUT 2 ) Doc ID 15725 Rev 1 for the load removal). L6728H OUT_C ...
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... buses and the output voltage is fixed at 1.25 V. The application can deliver an output current The switching frequency is 300 kHz. Figure 10 demonstration board (left) and components placement (right) Figure 11. L6728H - 20 A demonstration board top (left) and bottom (right) layers Figure 12. L6728H - 20 A demonstration board inner layers Doc ID 15725 Rev 1 ...
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... A demonstration board Figure 13 demonstration board schematic 22/32 Doc ID 15725 Rev 1 L6728H ...
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... Resistor, 2K2, 1/16W, 1% Resistor, 3K9, 1/16W, 1% Resistor, 18K, 1/16W, 1% Resistor, 22K, 1/16W, 1% Resistor, 20K, 1/16W, 1% Inductor, 1.25 μH, T60-18, 6 turns Easymagnet AP106019006P-1R1M Diode, 1N4148 or BAT54 STD70N02L STD95NH02LT4 Controller, L6728H Doc ID 15725 Rev demonstration board Description Package Radial SMD0603 SMD1206 SMD0805 SMD1206 ...
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... PGOOD: Signaling the regular functioning (active high); – VGDHS: The bootstrap diode anode; – PHASE: Phase node; – LGATE: Low-side gate pin of the device; – HGATE: High-side gate pin of the device. 12.1.5 Board characterization Figure 14 demonstration board efficiency 24/32 Doc ID 15725 Rev 1 L6728H ...
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... L6728H demonstration board L6728H demonstration board realizes in a two-layer PCB a step-down DC/DC converter and shows the operation of the device in a general-purpose low-current application. The input voltage can range from buses and the output voltage is fixed at 1.25 V. The application can deliver an output current in excess The switching frequency is 300 kHz ...
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... A demonstration board Figure 17 demonstration board schematic 26/32 GND Doc ID 15725 Rev 1 L6728H OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT COMP ...
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... Resistor, 0R, 1/ Resistor, 1R8, 1 Resistor, 15R, 1/ Resistor, 2K2, 1/ Resistor, 3K9, 1/ Resistor, 4K7, 1/ Resistor, 22K, 1/ Resistor, 10K, 1/ Inductor, 2.2 μH, WURTH 744324220LF Diode, BAT54 STS9D8NH3LL Controller, L6728H Doc ID 15725 Rev demonstration board Package SMD1206 SMD0603 SMD0805 SMD1206 SMD7343 SMD0603 SMD0603 SMD0603 SMD0805 ...
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... FB: The inverting input of the error amplifier; – PGOOD: Signaling the regular functioning (active high); – VGDHS: The bootstrap diode anode; – PHASE: Phase node; – LGATE: Low-side gate pin of the device; – HGATE: High-side gate pin of the device. 28/32 Doc ID 15725 Rev 1 L6728H ...
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... L6728H 13.1.5 Board characterization Figure 18 demonstration board efficiency Doc ID 15725 Rev demonstration board 29/32 ...
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... Doc ID 15725 Rev 1 L6728H mils Min. Typ. Max. 31.5 35.4 39.4 0.8 2.0 27.6 7.9 7.1 9.1 11.8 118.1 87.0 89.0 90.9 118.1 58 ...
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... L6728H 15 Revision history Table 9. Document revision history Date 20-May-2009 Revision 1 Initial release Doc ID 15725 Rev 1 Revision history Changes 31/32 ...
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... Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia - Malta - Morocco - Philippines - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America 32/32 Please Read Carefully: © 2009 STMicroelectronics - All rights reserved STMicroelectronics group of companies www.st.com Doc ID 15725 Rev 1 L6728H ...