L6727 STMicroelectronics, L6727 Datasheet
L6727
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L6727 Summary of contents
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... SO-8 package. Device flexibility allows managing conversions with power input V supply voltage in the range L6727 provides simple control loop with voltage- mode error-amplifier. The integrated 0.8 V reference allows regulating output voltages with ±1 % accuracy over line and temperature variations. Oscillator is internally fixed to 300 kHz. ...
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... Overcurrent protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 7.1 Overcurrent threshold setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8 Output voltage monitor and protections . . . . . . . . . . . . . . . . . . . . . . . . 14 8.1 Undervoltage protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 8.2 Overvoltage protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 8.3 Feedback disconnection protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 8.4 Undervoltage lock out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 9 Application details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 9.1 Output voltage selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 9.2 Compensation network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2/34 Doc ID 12933 Rev 4 L6727 ...
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... L6727 9.3 Layout guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 9.4 Embedding L6727-based VRs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 10 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 10.1 Output inductor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 10.2 Output capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 10.3 Input capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 11.1 Board description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 11.1.1 11.1.2 11.1.3 11.1.4 11.1 demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 12.1 Board description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 12.1.1 12.1.2 12.1.3 12.1.4 12.1.5 13 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 14 Revision history ...
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... D 1 BOOT 7 C BOOT COMP / 2 DIS / OC UGATE PHASE LGATE GND L6727 Reference Schematic (*) R not to be connected when VCC > 5V OCSET (**) Up to 12V with Vcc > 5V CONTROL LOGIC & PROTECTIONS DISABLE ERROR L6727 AMPLIFIER Doc ID 12933 Rev 1.5V to 19V (**) BULK HS gHS gLS LS ...
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... OC 8 PHASE Pins description and connection diagrams BOOT 1 8 UGATE 2 7 L6727 GND 3 6 LGATE driver supply. Connect through a capacitor (100 nF) to the floating node (LS-drain) pin and provide necessary bootstrap diode from VCC. HS driver output. Connect to HS MOSFET gate. All internal references, logic and drivers are connected to this pin. ...
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... GND to PHASE V to PHASE; t < UGATE to GND V to GND PHASE to GND V LGATE to GND; t < COMP to GND FB to GND 6/34 Parameter (1) Parameter -0 Doc ID 12933 Rev 4 L6727 Value Unit 85 °C/W 150 °C -40 to 150 °C -20 to 150 °C Value Unit -0 0.3 BOOT PHASE ...
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... L6727 3.2 Electrical characteristics = -20 °C to +85 °C, unless otherwise specified Table 5. Electrical characteristics Symbol Parameter Recommended operating conditions V Device supply voltage CC V Conversion input voltage IN Supply current and power-ON I VCC supply current CC I BOOT supply current BOOT VCC turn-ON UVLO Hysteresis ...
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... Fixed OC threshold OCTH Over and undervoltage protections OVP OVP threshold UVP UVP threshold 1. Guaranteed by design, not subject to test. 8/34 Test conditions VCC rising V to GND, VCC > V PHASE CC_OC FB rising FB falling Doc ID 12933 Rev 4 L6727 Min. Typ. Max. Unit 8 V -400 0.6 V ...
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... L6727 is designed to operate from supply bus. Thanks to the high precision 0.8V internal reference, the output voltage can be precisely regulated to as low as 0.8 V with ± ...
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... Power dissipation L6727 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. Two main terms contribute in the device power dissipation: bias power and drivers' power. ...
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... Low-side-less start up (LSLess) In order to manage start up over pre-biased output, L6727 performs a special sequence in enabling LS driver to switch: during the soft-start phase, LS driver results disabled (LS = OFF) until HS starts to switch. This avoids the dangerous negative spike on the output voltage that can happen if starting over a pre-biased output ...
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... COMP / DIS pin. Setting free the pin, this current pulls it over the threshold and the device enables again performing a new SS. To disable the device, the external pull-down needs to overcome COMP output current for about 15 μs. Once disabled, COMP output current drops to 20μA. Figure 5. Start up sequence; V 12/ (Left) overcurrent hiccup (Right) CC Doc ID 12933 Rev 4 L6727 ...
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... MOSFETs for 2048 clock cycles (plus internal SS remaining time, if triggered during a SS phase); then it will begin a new soft-start. If the overcurrent condition is not removed, the continuous fault will cause L6727 to go into a hiccup mode with a typical period of 13.6 ms and very low power dissipation. ...
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... UVLO is provided: the device will start up when VCC reaches UVLO upper threshold and will shutdown when VCC drops below UVLO lower threshold. The 4.1 V maximum UVLO upper threshold allows L6727 to be supplied from 5 V and 12 V busses in or-ing diode configuration. ...
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... Application details 9.1 Output voltage selection L6727 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 guarantees the output regulated voltage to be within ±1 % tolerance over line and temperature variations between 0 °C and +70 °C (excluding output resistor divider tolerance, when present) ...
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... F LC ESR 1 --------------------------------- - ⋅ 2π OUT 1 = ------------------------------------------- - ⋅ ⋅ 2π C ESR OUT 1 ------------------------------ ⋅ ⋅ 2π ---------------------------------------------------- - ⋅ ⋅ 2π ------------------------------------------------- - ⋅ ⎛ ⎞ ⋅ ⋅ -------------------- - 2π R ⎝ ⎠ ------------------------------ - ⋅ ⋅ 2π Doc ID 12933 Rev 4 /R ratio, however, for 20log ( 20log (V /Δ OSC Log (Freq) L6727 ...
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... Layout guidelines L6727 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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... LGATE GND 18/ near as possible to the load, minimizing parasitic OUT V IN UGATE C IN PHASE L6727 LGATE GND LS MOSFET GATE INT Doc ID 12933 Rev OUT LOAD close to the device and avoid OCSET in Figure 1 DRIVER HS MOSFET BOOT GATE INT UGATE PHASE PHASE L6727 Figure ...
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... L6727 9.4 Embedding L6727-based VRs When embedding the VR into the application, additional care must be taken since the whole switching DC/DC regulator and the most common system in which it has to work is a digital system such similar. In fact, latest MBs have become faster and more powerful: high speed data busses are more and more common and switching-induced noise produced by the VR can affect data integrity if additional layout guidelines are not followed ...
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... When this condition is reached, the response time is limited only by the time required to charge the inductor. Figure 10. Inductor current ripple vs output voltage 20/34 ), the output voltage (V IN OUT OUT Doc ID 12933 Rev 4 ) and the desired ripple current (ΔI L6727 ) ...
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... L6727 10.2 Output capacitors Output capacitors choice depends on the application constraints in point of output voltage ripple and output voltage deviation during a load transient. During steady-state conditions, the output voltage ripple is influenced by ESR and capacitance of the output capacitors as follows: ΔV ΔI = OUT_ESR L ΔV Δ ...
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... A demonstration board demonstration board L6727 demonstration board realizes on a four-layer PCB a step-down DC/DC converter and shows the operation of the device in a general purpose application. Input voltage can range from bus (when VCC > need to be removed). Output voltage is programmed to 1.25 V. The voltage regulator can deliver output current. The switching frequency is 300 kHz ...
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... L6727 Figure 13 demonstration board inner layers Doc ID 12933 Rev demonstration board 23/34 ...
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... A demonstration board Figure 14 demonstration board schematic PHASE PHASE HSD 24/34 GND GND PHASE HSD HSD Doc ID 12933 Rev 4 L6727 OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT PHASE FB COMP VCC_PIN ...
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... Resistor, 2R2, 1 Resistor, 1R8, 1 Resistor, 0R, 1/ Resistor, 2K2, 1/ Resistor, 3K9, 1/ Resistor, 33K, 1/ Resistor, 12K, 1/ Inductor, 1.25 μH, T60-18, 6Turns Easymagnet AP106019006P-1R1M Diode, 1N4148 or BAT54 STD55NH2LL STD90NH2LL Controller, L6727 Doc ID 12933 Rev demonstration board Description Package Radial SMD0603 SMD1206 SMD0805 Radial SMD0603 SMD0603 ...
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... COMP: output of the error amplifier; – FB: inverting input of the error amplifier; – PH: Phase pin of the device; – LG: Low-Side gate pin of the device; – UG: High-Side gate pin of the device. 11.1.5 Demonstration board efficiency Figure 15 demonstration board efficiency 26/34 Doc ID 12933 Rev 4 L6727 ...
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... L6727 demonstration board L6727 demonstration board realizes on a two-layer PCB a step-down DC/DC converter and shows the operation of the device in a general-purpose low-current application. Input voltage can range from bus. Output voltage is programmed 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 18 demonstration board schematic 28/34 L6727 L6727 GND Doc ID 12933 Rev 4 L6727 OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT COMP ...
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... MLCC, 220 pF, X7R Resistor, 1R8, 1 Resistor, 0R, 1/ Resistor, 3R3, 1/ Resistor, 15R, 1/ Resistor, 2K2, 1/ Resistor, 3K9, 1/ Resistor, 4K7, 1/ Inductor, 2.20 μH, Wurth 744324220LF Diode, BAT54 Mosfet, STS9D8NH3LL Controller, L6727 Doc ID 12933 Rev demonstration board Description Package SMD1206 SMD0603 SMD0805 SMD1206 Ω SMD7343 SMD0603 ...
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... COMP: output of the error amplifier; – FB: inverting input of the error amplifier; – PH: Phase pin of the device; – LG: Low-Side gate pin of the device; – UG: High-Side gate pin of the device. 12.1.5 Demonstration board efficiency Figure 19 demonstration board efficiency 30/34 Doc ID 12933 Rev 4 L6727 ...
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... L6727 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. Table 8. SO-8 mechanical data Dim ( ddd 1. D and F does not include mold flash or protrusions. Mold flash or potrusions shall not exceed 0.15mm ( ...
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... Package mechanical data Figure 20. Package dimensions 32/34 Doc ID 12933 Rev 4 L6727 ...
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... L6727 14 Revision history Table 9. Revision history Date 04-Dec-2006 28-Feb-2007 06-Jun-2007 23-Mar-2010 Revision 1 Initial release. 2 Updated V values in OCTH Updated Figure 1: Typical application circuit on page 3 Table 3 and Table 4 on page 6 Added Section 10: Application information on page 20 A demonstration board on page 4 demonstration board on page 27 Updated: ...
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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 34/34 Please Read Carefully: © 2010 STMicroelectronics - All rights reserved STMicroelectronics group of companies www.st.com Doc ID 12933 Rev 4 L6727 ...