LM5166DRCT.A

Part: LM5166 from Texas Instruments

Type: Synchronous Buck Converter

Key Specs:

• Input Voltage Range: 3 V to 65 V
• Output Current: up to 500 mA
• No-Load Quiescent Current: 9.7 μA
• Junction Temperature Range: –40°C to 150°C
• Switching Frequency: up to 600 kHz
• Internal Voltage Reference: 1.223 V ±1.2%

Features:

• Fixed (3.3-V, 5-V) or Adjustable VOUT Options
• Meets EN55022 / CISPR 22 EMI Standards
• Integrated 1-Ω PFET Buck Switch (Supports 100% Duty Cycle for Low Dropout)
• Integrated 0.5-Ω NFET Synchronous Rectifier (Eliminates External Schottky Diode)
• Programmable Peak Current Limit Supports: 500-mA, 300-mA, or 200-mA Loads
• Selectable PFM or COT Mode Operation
• 900-μs Internal or Externally-Adjustable Soft Start
• Diode Emulation and Pulse Skipping for Ultra-High Light-Load Efficiency
• No Loop Compensation or Bootstrap Components
• Precision Enable and Input UVLO With Hysteresis
• Open-Drain Power Good Indicator
• Thermal Shutdown Protection With Hysteresis
• Pin-to-Pin Compatible With the LM5165
• Create a Custom Regulator Design Using WEBENCH® Power Designer

Applications:

• Factory and Building Automation
• Automotive and Battery-Powered Applications
• High Voltage LDO Replacement
• Low Power Bias Supplies

Package:

• VSON (10-Pin): 3-mm × 3-mm

• ¹ Wide Input Voltage Range of 3 V to 65 V
• 9.7-μA No-Load Quiescent Current
• –40°C to 150°C Junction Temperature Range
• Fixed (3.3-V, 5-V) or Adjustable VOUT Options
• Meets EN55022 / CISPR 22 EMI Standards
• Integrated 1-Ω PFET Buck Switch
  • Supports 100% Duty Cycle for Low Dropout
• Integrated 0.5-Ω NFET Synchronous Rectifier
  • Eliminates External Schottky Diode
• Programmable Peak Current Limit Supports:
  • 500-mA, 300-mA, or 200-mA Loads
• Selectable PFM or COT Mode Operation
• 1.223-V ±1.2% Internal Voltage Reference
• Switching Frequency up to 600 kHz
• 900-μs Internal or Externally-Adjustable Soft Start
• Diode Emulation and Pulse Skipping for Ultra-High Light-Load Efficiency
• No Loop Compensation or Bootstrap Components
• Precision Enable and Input UVLO With Hysteresis
• Open-Drain Power Good Indicator
• Thermal Shutdown Protection With Hysteresis
• Pin-to-Pin Compatible With the LM5165
• 10-Pin, 3-mm × 3-mm VSON Package
• • Create a Custom Regulator Design Using WEBENCH® Power Designer

• Factory and Building Automation
• • Automotive and Battery-Powered Applications
• High Voltage LDO Replacement
• Low Power Bias Supplies

3 Description

The LM5166 is a compact, easy-to-use, 3-V to 65-V, ultra-low I^Q synchronous buck converter with high efficiency over wide input voltage and load current ranges. With integrated high-side and low-side power MOSFETs, up to 500 mA of output current can be delivered at fixed output voltages of 3.3 V or 5 V, or an adjustable output. The converter is designed to simplify implementation while providing options to optimize the performance for the target application. Pulse frequency modulation (PFM) mode is selected for optimal light-load efficiency or constant on-time (COT) control for nearly constant operating frequency. Both control schemes do not require loop compensation while providing excellent line and load transient response and short PWM on-time for large step-down conversion ratios.

The high-side P-channel MOSFET can operate at 100% duty cycle for lowest dropout voltage and does not require a bootstrap capacitor for gate drive. Also, the current limit setpoint is adjustable to optimize inductor selection for a particular load current requirement. Selectable and adjustable start-up timing options include minimum delay (no soft start), internally fixed (900 μs), and externally programmable soft start using a capacitor. An open-drain PGOOD indicator can be used for sequencing, fault reporting, and output voltage monitoring. The LM5166 is available in a 10-pin VSON package with 0.5-mm pin pitch.

Device Information(1)

Typical COT Mode Application Typical COT Mode Application Efficiency

Table of Contents

4 Revision History

• Changed data sheet status from product preview to production data.................................................................................... 1

5 Pin Configuration and Functions

LM5166X and LM5166Y Fixed Output DRC Package 10-Pin VSON Top View

LM5166 Adjustable Output DRC Package 10-Pin VSON Top View

Pin Functions

(1) P = Power, G = Ground, I = Input, O = Output.

Copyright © 2016–2017, Texas Instruments Incorporated

6 Specifications

6.1 Absolute Maximum Ratings

Over the recommended operating junction temperature range of –40°C to 150°C (unless otherwise noted).(1)(2)

⁽¹⁾ Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

6.2 ESD Ratings

⁽¹⁾ JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.

6.3 Recommended Operating Conditions

Over the recommended operating junction temperature range of –40°C to 150°C (unless otherwise noted).(1)

⁽¹⁾ Operating Ratings are conditions under which the device is intended to be functional. For specifications and test conditions, see Electrical Characteristics.

6.4 Thermal Information

⁽¹⁾ For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report.

Product Folder Links: LM5166

⁽²⁾ If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and specifications.

⁽³⁾ Fixed output setting.

⁽⁴⁾ Adjustable output setting.

⁽²⁾ JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

6.5 Electrical Characteristics

Typical values correspond to T_J = 25 °C. Minimum and maximum limits are based on T_J = -40 °C to +125 °C. V_IN = 12 V (unless otherwise noted). (1)(2)

⁽¹⁾ All hot and cold limits are specified by correlating the electrical characteristics to process and temperature variations and applying statistical process control.

Copyright © 2016-2017, Texas Instruments Incorporated Product Folder Links: LM5166

⁽²⁾ The junction temperature (T_J in °C) is calculated from the ambient temperature (T_A in °C) and power dissipation (P_D in Watts) as follows: T_J = T_A + (P_D bullet θ_JA) where θ_JA (in °C/W) is the package thermal impedance provided in Thermal Information.

Electrical Characteristics (continued)

Typical values correspond to T^J = 25°C. Minimum and maximum limits are based on T^J = –40°C to +125°C. VIN = 12 V (unless otherwise noted).(1)(2)

6.6 Switching Characteristics

Over operating free-air temperature range (unless otherwise noted)

Product Folder Links: LM5166

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6.7 Typical Characteristics

Unless otherwise specified, VIN = 12 V, VOUT = 5 V. Please refer to Typical Applications for circuit designs.

Unless otherwise specified, VIN = 12 V, VOUT = 5 V. Please refer to Typical Applications for circuit designs.

Unless otherwise specified, V_IN = 12 V, V_OUT = 5 V. Please refer to Typical Applications for circuit designs.

Unless otherwise specified, V_IN = 12 V , V_OUT = 5 V . Please refer to Typical Applications for circuit designs.

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Copyright © 2016–2017, Texas Instruments Incorporated

Unless otherwise specified, V_IN = 12 V, V_OUT = 5 V. Please refer to Typical Applications for circuit designs.

Unless otherwise specified, VIN = 12 V, VOUT = 5 V. Please refer to Typical Applications for circuit designs.

Unless otherwise specified, VIN = 12 V, VOUT = 5 V. Please refer to Typical Applications for circuit designs.

7 Detailed Description

7.1 Overview

The LM5166 regulator is an easy-to-use synchronous buck DC-DC converter that operates from a supply voltage ranging from 3 V to 65 V. The device is intended for step-down conversions from 5-V, 12-V, 24-V, and 48-V unregulated, semi-regulated, and fully-regulated supply rails. With integrated high-side and low-side power MOSFETs, the LM5166 delivers up to 500-mA DC load current with exceptional efficiency and ultra-low input quiescent current in a very small solution size. Designed for simple implementation, a choice of operating modes offers flexibility to optimize its usage according to the target application. Fixed-frequency, constant on-time (COT) operation with discontinuous conduction mode (DCM) at light loads is ideal for low-noise, high current, fast transient load requirements. Alternatively, pulse frequency modulation (PFM) mode, complemented by an adjustable current limit, achieves ultra-high light-load efficiency performance. Control loop compensation is not required with either operating mode, which reduces design time and external component count.

The LM5166 incorporates other features for comprehensive system requirements, including an open-drain Power Good circuit for power-rail sequencing and fault reporting, internally-fixed or externally-adjustable soft start, monotonic start-up into prebiased loads, precision enable with customizable hysteresis for programmable line undervoltage lockout (UVLO), and thermal shutdown with automatic recovery. These features enable a flexible and easy-to-use platform for a wide range of applications. The pin arrangement is designed for simple and optimized PCB Layout, requiring only a few external components.

7.2 Functional Block Diagram

Copyright © 2016, Texas Instruments Incorporated

7.3 Feature Description

7.3.1 Integrated Power MOSFETs

The LM5166 is a step-down buck converter with integrated high-side PMOS buck switch and low-side NMOS synchronous switch. During the high-side MOSFET on-time, the SW voltage V_SW swings up to approximately V_IN , and the inductor current increases with slope (V_IN-V_OUT)/L_F . When the high-side MOSFET is turned off by the control logic, the low-side MOSFET turns on after a fixed dead time. Inductor current flows through the low-side MOSFET with slope -V_OUT/L_F . Duty cycle D is defined as T_ON/T_SW , where T_ON is the high-side MOSFET conduction time and T_SW is the switching period.

7.3.2 Selectable PFM or COT Mode Converter Operation

Depending on how the RT pin is connected, the LM5166 operates in PFM or COT mode. With the RT pin tied to GND, the device operates in PFM mode. An R_RT resistor connected between the RT and GND pins enables COT control and sets the desired switching frequency as defined by Equation 4. Figure 39 and Figure 40 show converter schematics for PFM and COT modes of operation.

Figure 39. PFM Mode Converter Schematics: (a) Fixed Output Voltage of 5 V or 3.3 V, (b) Adjustable Output Voltage With Programmable Soft Start, Current Limit, and UVLO

Figure 40. COT Mode Converter Schematics: (a) Fixed Output Voltage of 5 V or 3.3 V, (b) Adjustable Output Voltage With Programmable Soft Start, Current Limit, and UVLO

Copyright © 2016–2017, Texas Instruments Incorporated

Feature Description (continued)

7.3.2.1 PFM Mode Operation

In PFM mode, the LM5166 behaves as a hysteretic voltage regulator operating in boundary conduction mode. The output voltage is regulated between upper and lower threshold levels according to the PFM feedback comparator hysteresis of 10 mV. Figure 41 shows the relevant output voltage and inductor current waveforms. The LM5166 provides the required switching pulses to recharge the output capacitor to the upper threshold, followed by a sleep period where most of the internal circuits are disabled. The load current is supported by the output capacitor during this time, and the LM5166 current consumption reduces to 9.7 μ A. The sleep period duration depends on load current and output capacitance.

Figure 41. PFM Mode Output Voltage and Inductor Current Representative Waveforms

When operating in PFM mode at given input and output voltages, the chosen filter inductance dictates the PFM pulse frequency as

$F_SW(PFM) = frac{V_OUT}{L_F · I_PK(PFM)} · ≤ft(1 - frac{V_OUT}{V_IN}right)where

I_PK(PFM) is one of the programmable levels for peak current limit. See Adjustable Current Limit for more detail.

One of the supported ILIM settings enables a function that modulates the peak current threshold levels during the first three switching cycles of each active period as illustrated in Figure 42. This function improves efficiency under most application conditions at the expense of slightly degraded load transient response.


Feature Description (continued)


Figure 42. PFM Mode With Modulated I_LIM, Output Voltage and Inductor Current Representative Waveforms

As expected, the choice of mode and switching frequency represents a compromise between conversion efficiency, quiescent current, and passive component size. Lower switching frequency implies reduced switching losses (including gate charge losses, transition losses, and so forth) and higher overall efficiency. Higher switching frequency, on the other hand, implies smaller LC output filter and hence, a more compact design. Lower inductance also helps transient response and reduces the inductor DCR conduction loss. The ideal switching frequency in a given application is a tradeoff and thus is determined on a case-by-case basis. It relates to the input voltage, output voltage, most frequent load current level(s), external component choices, and circuit size requirement. At light loads, the PFM converter has a relatively longer sleep time interval and thus operates at lower input quiescent current levels.

7.3.2.2 COT Mode Operation

In COT mode, the LM5166-based converter turns on the high-side MOSFET with constant on-time that adapts to V_IN, as defined by Equation 2, to operate with nearly fixed switching frequency when in continuous conduction mode (CCM). The high-side MOSFET turns on when the feedback voltage (VFB) falls below the reference voltage. The regulator control loop maintains a constant output voltage by adjusting the PWM off-time as defined with Equation 3. For stable operation, the feedback voltage must decrease monotonically in phase with the inductor current during the off-time as explained in Ripple Generation Methods.

t_ON[ns] = frac{175 · R_RT[kΩ]}{V_IN}$ (2)

$t_OFF = frac{L_F · Δ I_L(nom)}{V_OUT + (R_DCR + R_DSON2) · I_OUT}(3

Diode emulation mode (DEM) prevents negative inductor current, and pulse skipping maintains high efficiency at light load currents by decreasing the effective switching frequency. The COT-controlled LM5166 waveforms in CCM and DEM are shown in Figure 43.

Submit Documentation Feedback Copyright © 2016-2017, Texas Instruments Incorporated

LM5166X and LM5166Y Fixed Output DRC Package 10-Pin VSON Top View

LM5166 Adjustable Output DRC Package 10-Pin VSON Top View

Pin Functions

(1) P = Power, G = Ground, I = Input, O = Output.

Copyright © 2016–2017, Texas Instruments Incorporated

Typical values correspond to T_J = 25 °C. Minimum and maximum limits are based on T_J = -40 °C to +125 °C. V_IN = 12 V (unless otherwise noted). (1)(2)

⁽¹⁾ All hot and cold limits are specified by correlating the electrical characteristics to process and temperature variations and applying statistical process control.

Copyright © 2016-2017, Texas Instruments Incorporated Product Folder Links: LM5166

⁽²⁾ The junction temperature (T_J in °C) is calculated from the ambient temperature (T_A in °C) and power dissipation (P_D in Watts) as follows: T_J = T_A + (P_D bullet θ_JA) where θ_JA (in °C/W) is the package thermal impedance provided in Thermal Information.

Over the recommended operating junction temperature range of –40°C to 150°C (unless otherwise noted).(1)(2)

⁽¹⁾ Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

Over the recommended operating junction temperature range of –40°C to 150°C (unless otherwise noted).(1)

⁽¹⁾ Operating Ratings are conditions under which the device is intended to be functional. For specifications and test conditions, see Electrical Characteristics.

⁽¹⁾ For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report.

Product Folder Links: LM5166

⁽²⁾ If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and specifications.

⁽³⁾ Fixed output setting.

⁽⁴⁾ Adjustable output setting.

⁽²⁾ JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

6.5 Electrical Characteristics

Typical values correspond to T_J = 25 °C. Minimum and maximum limits are based on T_J = -40 °C to +125 °C. V_IN = 12 V (unless otherwise noted). (1)(2)

⁽¹⁾ All hot and cold limits are specified by correlating the electrical characteristics to process and temperature variations and applying statistical process control.

Copyright © 2016-2017, Texas Instruments Incorporated Product Folder Links: LM5166

⁽²⁾ The junction temperature (T_J in °C) is calculated from the ambient temperature (T_A in °C) and power dissipation (P_D in Watts) as follows: T_J = T_A + (P_D bullet θ_JA) where θ_JA (in °C/W) is the package thermal impedance provided in Thermal Information.