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LM5118, LM5118-Q1

www.ti.com

SNVS566H –APRIL 2008–REVISED JANUARY 2014

Wide Voltage Range Buck-Boost Controller

Check for Samples: LM5118, LM5118-Q1

FEATURES

DESCRIPTION

The LM5118 wide voltage range Buck-Boost

• LM5118-Q1 is an Automotive Grade product

switching regulator controller features all of the

that is AEC-Q100 grade 1 qualified (-40°C to

functions necessary to implement a high

125°C operating junction temperature)

performance, cost efficient Buck-Boost regulator

• Ultra-wide input voltage range from 3 V to 75 V

using a minimum of external components. The Buck-

Boost topology maintains output voltage regulation

• Emulated peak current mode control

when the input voltage is either less than or greater

• Smooth transition between step-down and

than the output voltage making it especially suitable

step- up modes

for automotive applications. The LM5118 operates as

• Switching frequency programmable to 500

a buck regulator while the input voltage is sufficiently

KHz

greater than the regulated output voltage and

gradually transitions to the buck-boost mode as the

• Oscillator synchronization capability

input voltage approaches the output. This dual mode

• Internal high voltage bias regulator

approach maintains regulation over a wide range of

• Integrated high and low-side gate drivers

input voltages with optimal conversion efficiency in

the buck mode and a glitch-free output during mode

• Programmable soft-start time

transitions. This easy to use controller includes

• Ultra low shutdown current

drivers for the high side buck MOSFET and the low

• Enable input wide bandwidth error amplifier

side boost MOSFET. The regulators control method

is based upon current mode control utilizing an

• 1.5% feedback reference accuracy

emulated current ramp. Emulated current mode

• Thermal shutdown

control reduces noise sensitivity of the pulse-width

• PACKAGE:

modulation circuit, allowing reliable control of the very

– HTSSOP-20 (Exposed pad)

small duty cycles necessary in high input voltage

applications. Additional protection features include

current limit, thermal shutdown and an enable input.

The device is available in a power enhanced

HTSSOP-20 package featuring an exposed die attach

pad to aid thermal dissipation.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (37 pages)

PAGE 1
LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 Wide Voltage Range Buck-Boost Controller Check for Samples: LM5118, LM5118-Q1 FEATURES DESCRIPTION • The LM5118 wide voltage range Buck-Boost switching regulator controller features all of the functions necessary to implement a high performance, cost efficient Buck-Boost regulator using a minimum of external components.
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LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com Typical Application Circuit VIN VCC HB LM5118 HO VOUT HS SS CS CSG RAMP LO RT VOUT FB GND COMP Connection Diagram VIN 1 20 HS UVLO 2 19 HO RT 3 18 HB EN 4 17 VCCX RAMP 5 16 VCC AGND 6 15 LO SS 7 14 PGND FB 8 13 CSG COMP 9 12 CS VOUT 10 11 SYNC Figure 1.
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LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 Pin Descriptions Pin Name Description 1 VIN 2 UVLO Input supply voltage. 3 RT The internal oscillator frequency is set with a single resistor between this pin and the AGND pin. The recommended frequency range is 50 kHz to 500 kHz. 4 EN If the EN pin is below 0.5 V, the regulator will be in a low power state drawing less than 10 µA from VIN. EN must be raised above 3 V for normal operation. 5 RAMP Ramp control signal.
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LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com Absolute Maximum Ratings (1) VIN, EN, VOUT to GND –0.3 V to 76 V VCC, LO, VCCX, UVLO to GND (2) –0.3 to 15 V HB to HS –0.3 to 15 V HO to HS –0.3 to HB +0.3 V HS to GND –4 V to 76 V CSG, CS to GND –0.3V to +0.3 V RAMP, SS, COMP, FB, SYNC, RT to GND –0.
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LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 Electrical Characteristics Limits in standard type are for TJ = 25°C only; limits in boldface type apply over the junction temperature range of –40°C to +125°C. Unless otherwise specified, the following conditions apply: VIN = 48 V, VCCX = 0 V, EN = 5 V, RT = 29.11 kΩ, No load on LO and HO (1). Symbol Parameter Conditions IBIAS VIN Operating Current IBIASX ISTDBY Min Typ Max Units VCCX = 0 V 4.5 5.
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LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com Electrical Characteristics (continued) Limits in standard type are for TJ = 25°C only; limits in boldface type apply over the junction temperature range of –40°C to +125°C. Unless otherwise specified, the following conditions apply: VIN = 48 V, VCCX = 0 V, EN = 5 V, RT = 29.11 kΩ, No load on LO and HO (1). Symbol Parameter Conditions Min Typ Max Units fSW1 Frequency 1 RT = 29.
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LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 Typical Characteristics 100 EFFICIENCY (%) x 90 3 AMP x 85 CURRENT LIMIT THRESHOLD (mV) xxx xx 95 x 1 AMP x 2 AMP x 80 75 -100 0 x 10 20 30 40 50 60 -125 -150 -175 -200 -225 -250 -275 65 70 70 75 VIN (V) 85 Figure 3. Current Limit Threshold vs VOUT/VIN VOUT = 12 V 10 8 8 6 6 VCC (V) 10 4 2 4 2 0 0 0 2 4 6 8 10 12 0 10 20 VIN (V) 30 150 4 40 120 3.
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LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com Typical Characteristics (continued) 600 500 FOSC (kHz) 400 300 200 100 0 0 20 40 60 80 100 120 140 160 RT (k:) Figure 8.
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LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 BLOCK DIAGRAM 17 LM5118 Vin VIN 1 VIN 4 EN VCCX VCC 16 7V REGULATOR VCC UVLO R8 C8 C2 C1 3.9V 3V 5 µA THERMAL SHUTDOWN SHUTDOWN AND STANDBY MODE CONTROL R1 2 HB 18 C13 DISABLE HB UVLO UVLO R2 C12 1.23V HICCUP MODE FAULT TIMER Vin 10 µA 7 SS Q1 CLK 5V PWM C4 S Q R Q HO 19 HS 20 L1 LEVEL SHIFT D2 VOUT 1.23V C1 1 I-LIMIT CLK 8 FB ERROR AMP C5 C6 Vth( buck) = 1.
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LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com DETAILED OPERATING DESCRIPTION The LM5118 high voltage switching regulator features all of the functions necessary to implement an efficient high voltage buck or buck-boost regulator using a minimum of external components. The regulator switches smoothly from buck to buck-boost operation as the input voltage approaches the output voltage, allowing operation with the input greater than or less than the output voltage.
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LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 VIN Buck Switch Current HB Q1 HO D2 VOUT HS D1 LM5118 Diode Current CS CSG Q2 LO Figure 10. Buck-Boost Mode Operation 100 90 70 60 50 40 30 DUTY CYCLE (%) 80 20 10 18 17 16 15 14 13 12 0 VIN (V) Figure 11.
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LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com OPERATION MODES Figure 11 illustrates how duty cycle effects the operational mode and is useful for reference in the following discussions. Initially, only the buck switch is active and the buck duty cycle increases to maintain output regulation as VIN decreases. When VIN is approximately equal to 15.5V, the boost switch begins to operate with a low duty cycle.
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LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 FUNCTIONAL DESCRIPTION High Voltage Start-Up Regulator The LM5118 contains a dual mode, high voltage linear regulator that provides the VCC bias supply for the PWM controller and the MOSFET gate driver. The VIN input pin can be connected directly to input voltages as high as 75 V. For input voltages below 10 V, an internal low dropout switch connects VCC directly to VIN. In this supply range, VCC is approximately equal to VIN.
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LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com If a current limit fault exists for more than 256 clock cycles, the regulator will enter a “hiccup” mode of current limiting and the UVLO pin will be pulled low by an internal switch. This switch turns off when the UVLO pin approaches ground potential allowing the UVLO pin to rise. A capacitor connected to the UVLO pin will delay the return to a normal operating level and thereby set the off-time of the hiccup mode fault protection.
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LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 v Buck: ( 5 PA x ( Vin - Vout ) + 50 PA ) x Emulated Ramp Buck - Boost: ( 5 PA x Vin + 50 PA ) x ton Cramp ton Cramp Pedestal Level = 10 x Rs (volts/amp) t Ton Figure 16. Composition of Emulated Current Signal Ramp Generator The ramp signal of a pulse-width modulator with current mode control is typically derived directly from the buck switch drain current.
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LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 RS x A = CRAMP = www.ti.com gm x L CRAMP gm x L A x RS (4) where • gm is the ramp generator transconductance (5 µA/V) • A is the current sense amplifier gain (10V/V) The ramp capacitor should be located very close to the device and connected directly to the RAMP and AGND pins. The relationship between the average inductor current and the pedestal value of the sampled inductor current can cause instability in certain operating conditions.
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LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 Current Limit In the buck mode the average inductor current is equal to the output current (IOUT). In buck-boost mode the average inductor current is approximately equal to: Iout x 1 + VOUT VIN (6) Consequently, the inductor current in buck-boost mode is much larger especially when VOUT is large relative to VIN. The LM5118 provides a current monitoring scheme to protect the circuit from possible over-current conditions.
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LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com Maximum Duty Cycle Each conduction cycle of the buck switch is followed by a forced minimum off-time of 400 ns to allow sufficient time for the recirculating diode current to be sampled. This forced off-time limits the maximum duty cycle of the controller. The actual maximum duty cycle will vary with the operating frequency as follows: DMAX = 1 - f x 400 x 10-9 (7) where • f is the oscillator frequency in Hz 1 MAX DUTY CYCLE 0.
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LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 HO Output The LM5118 contains a high side, high current gate driver and associated high voltage level shift. This gate driver circuit works in conjunction with an internal diode and an external bootstrap capacitor. A 0.1 µF ceramic capacitor, connected with short traces between the HB pin and HS pin is recommended for most circuit configurations. The size of the bootstrap capacitor depends on the gate charge of the external FET.
PAGE 20
LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com APPLICATION INFORMATION The procedure for calculating the external components is illustrated with the following design example. The designations used in the design example correlate to Figure 28. The design specifications are: • VOUT = 12 V • VIN = 5 V to 75 V • f = 300 kHz • Minimum load current (CCM operation) = 600 mA • Maximum load current = 3 A R7 = RT RT sets the oscillator switching frequency.
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LM5118, LM5118-Q1 www.ti.com L1 L1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 VOUT (VIN(MAX) VOUT ) VIN(MAX) u f u IRIPPLE Buck Mode (10) VIN(MIN) (VOUT ) (VOUT VIN(MIN) ) u f u IRIPPLE Buck-Boost Mode (11) where • VOUT is the output voltage • VIN(MAX) is the maximum input voltage • f is the switching frequency • IRIPPLE is the selected inductor peak to peak ripple current (1.
PAGE 22
LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com R13 = RSENSE To select the current sense resistor, begin by calculating the minimum K values for each mode using Equation 14 and Equation 15. K represents the slope compensation of the controller and is different for each mode, KBUCK and KBUCK-BOOST. 10 KBUCK t 1 VIN(MAX) VOUT (14) KBUCK BOOST t 1 • • 10 VIN(MIN) (15) KBUCK = 1.
PAGE 23
LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 C9 - C12 = Output Capacitors In buck-boost mode, the output capacitors C9 - C12 must supply the entire output current during the switch ontime. For this reason, the output capacitors are chosen for operation in buck-boost mode, the demands being much less in buck operation. Both bulk capacitance and ESR must be considered to ensure a given output ripple voltage.
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LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com C1 - C5 = Input Capacitor A typical regulator supply voltage has a large source impedance at the switching frequency. Good quality input capacitors are necessary to limit the ripple voltage at the VIN pin while supplying most of the switch current during the buck switch on-time.
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LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 R1, R3, C21 A voltage divider can be connected to the UVLO pin to set a minimum operating voltage VIN(UVLO) for the regulator. If this feature is required, the easiest approach to select the divider resistor values is to choose a value for R1 between 10 kΩ and 100 kΩ, while observing the minimum value of R1 necessary to allow the UVLO switch to pull the UVLO pin low.
PAGE 26
LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com The dominant, low frequency pole of the modulator is determined by the load resistance (RLOAD) and output capacitance (COUT). The corner frequency of this pole is: 1 DMAX fP(MOD) 2S u RLOAD u COUT (31) For this example, RLOAD = 4 Ω, DMAX = 0.705, and COUT = 454 µF, therefore: • fP(MOD) = 149 Hz • DC Gain(MOD) = 4.598 = 13.25 dB Additionally, there is a right-half plane (RHP) zero associated with the modulator.
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LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 Figure 20. Modulator Gain and Phase - Buck Mode Figure 21. Modulator Gain and Phase - Buck-Boost Mode Figure 22. Error Amplifier Gain and Phase - Buck Mode Figure 23. Error Amplifier Gain and Phase - BuckBoost Mode Figure 24. Overall Loop Gain and Phase - Buck Mode Figure 25.
PAGE 28
LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com Bias Power Dissipation Reduction Buck or Buck-boost regulators operating with high input voltage can dissipate an appreciable amount of power while supplying the required bias current of the IC. The VCC regulator must step-down the input voltage VIN to a nominal VCC level of 7 V. The large voltage drop across the VCC regulator translates into high power dissipation in the VCC regulator.
PAGE 29
LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 PCB Layout and Thermal Considerations In a buck-boost regulator, there are two loops where currents are switched very fast. The first loop starts from the input capacitors, and then to the buck switch, the inductor, the boost switch then back to the input capacitor. The second loop starts from the inductor, and then to the output diode, the output capacitor, the recirculating diode, and back to the inductor.
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LM5118, LM5118-Q1 SNVS566H – APRIL 2008 – REVISED JANUARY 2014 www.ti.com Typical Application Schematic Figure 28.
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LM5118, LM5118-Q1 www.ti.com SNVS566H – APRIL 2008 – REVISED JANUARY 2014 REVISION HISTORY Changes from Revision F (February 2013) to Revision G • Page Changed layout of National Data Sheet to TI format .......................................................................................................... 30 Changes from Revision G (February, 2013) to Revision H Page • Deleted VIN Range on Block Diagram ..............................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 18-Oct-2013 Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties.
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PACKAGE MATERIALS INFORMATION www.ti.com 11-Feb-2014 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) LM5118MHX/NOPB HTSSOP PWP 20 2500 330.0 16.4 LM5118Q1MHX/NOPB HTSSOP PWP 20 2500 330.0 16.4 Pack Materials-Page 1 B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 6.95 7.1 1.6 8.0 16.0 Q1 6.95 7.1 1.6 8.0 16.
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PACKAGE MATERIALS INFORMATION www.ti.com 11-Feb-2014 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM5118MHX/NOPB HTSSOP PWP 20 2500 367.0 367.0 38.0 LM5118Q1MHX/NOPB HTSSOP PWP 20 2500 367.0 367.0 35.
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MECHANICAL DATA PWP0020A MXA20A (Rev C) www.ti.
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