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LM5005

www.ti.com

SNVS397D –SEPTEMBER 2005–REVISED MARCH 2013

LM5005 High Voltage 2.5 Amp Buck Regulator

Check for Samples: LM5005

FEATURES

DESCRIPTION

The LM5005 high voltage switching regulator features

• Integrated 75V, 2.5A N-Channel Buck Switch

all of the functions necessary to implement an

• Ultra-wide input voltage range from 7V to 75V

efficient high voltage buck regulator using a minimum

• Internal high voltage bias regulator

of external components. This easy to use regulator

includes a 75V N-Channel buck switch with an output

• Adjustable output voltage from 1.225V

current capability of 2.5 Amps. The regulator control

• 1.5% feedback reference accuracy

method is based upon current mode control utilizing

• Current mode control with emulated inductor

an emulated current ramp. Current mode control

current ramp

provides inherent line feed-forward, cycle-by-cycle

current limiting and ease of loop compensation. The

• Single resistor oscillator frequency setting

use of an emulated control ramp reduces noise

• Oscillator synchronization input

sensitivity of the pulse-width modulation circuit,

• Programmable soft-start

allowing reliable control of very small duty cycles

necessary in high input voltage applications. The

• Shutdown / Standby input

operating frequency is programmable from 50kHz to

• Wide bandwidth error amplifier

500kHz. An oscillator synchronization pin allows

• Thermal Shutdown

multiple LM5005 regulators to self-synchronize or to

be synchronized to an external clock. Additional

protection features include: current limit, thermal

shutdown and remote shutdown capability. The

device is available in a power enhanced HTSSOP

package featuring an exposed die attach pad to aid

thermal dissipation.

Package

• HTSSOP (Exposed Pad)

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 (28 pages)

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LM5005 www.ti.com SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 LM5005 High Voltage 2.5 Amp Buck Regulator Check for Samples: LM5005 FEATURES DESCRIPTION • • • • • • The LM5005 high voltage switching regulator features all of the functions necessary to implement an efficient high voltage buck regulator using a minimum of external components. This easy to use regulator includes a 75V N-Channel buck switch with an output current capability of 2.5 Amps.
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LM5005 SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 www.ti.com Simplified Application Schematic VIN LM5005 BST VIN VOUT SW SD SYNC COMP IS GND OUT FB RAMP RT SS VCC Connection Diagram 1 VCC BST SD PRE VIN SW VIN SW 2 3 4 5 6 7 8 9 10 SYNC IS COMP IS FB PGND RT PGND RAMP OUT AGND SS 20 19 18 17 16 15 14 13 12 11 Figure 1.
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LM5005 www.ti.com SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 PIN DESCRIPTIONS Pin(S) Name 1 VCC Description Application Information Output of the bias regulator Vcc tracks Vin up to 9V, beyond 9V Vcc is regulated to 7 Volts. A 0.1uF to 1uF ceramic decoupling capacitor is required. An external voltage (7.5V – 14V) can be applied to this pin to reduce internal power dissipation. 2 SD Shutdown or UVLO input If the SD pin voltage is below 0.7V the regulator will be in a low power state.
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LM5005 SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 www.ti.com Absolute Maximum Ratings (1) (2) VIN to GND 76V BST to GND 90V PRE to GND 76V SW to GND (Steady State) -1.5V BST to VCC 76V VCC to GND 14V BST to SW 14V OUT to GND Limited to Vin SD, SYNC, SS, FB to GND 7V ESD Rating (3) Human Body Model 2kV Storage Temperature Range (1) (2) (3) -65°C to +150°C Absolute Maximum Ratings are limits beyond which damage to the device may occur.
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LM5005 www.ti.com SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 Electrical Characteristics (continued) Specifications with standard typeface are for TJ = 25°C, and those with boldface type apply over full Operating Junction Temperature range. VIN = 48V, RT = 32.4kΩ unless otherwise stated. Symbol Parameter Conditions Cycle by Cycle Current Limit RAMP = 0V Cycle by Cycle Current Limit Delay RAMP = 2.5V Min (1) Typ Max (1) Units 3 3.5 4.
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LM5005 SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics Oscillator Frequency vs Temperature FOSC = 200kHz Oscillator Frequency vs RT 100 10 1 10 100 1.010 NORMALIZED OSCILLATOR FREQUENCY OSCILLATOR FREQUENCY (kHz) 1000 1000 1.005 1.000 0.995 0.990 -50 -25 0 25 50 75 RT (k:) 100 125 o TEMPERATURE ( C) Figure 2. Figure 3. Soft Start Current vs Temperature VCC vs ICC, VIN = 12V 8 6 1.05 VCC (V) NORMALIZED SOFTSTART CURRENT 1.10 1.
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LM5005 www.ti.com SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 Typical Performance Characteristics (continued) Demoboard Efficiency vs IOUT and VIN 100 EFFICIENCY (%) 80 60 VIN = 24V VIN = 48V VIN = 7V 40 VIN = 75V 20 0 0.0 0.5 1.0 1.5 2.0 2.5 IOUT (A) Figure 8.
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LM5005 SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 www.ti.com Typical Application Circuit and Block Diagram VIN 7 ± 75V C1 2.2 3, 4 VIN C2 2.2 5 PA R1 OPEN LM5005 7V REGULATOR 1.225V 2 SD STANDBY VCC 0.7V C12 OPEN R2 OPEN 11 SS BST UVLO C7 0.022 DRIVER S Q 1.225V 20 VIN DIS CLK 10 PA C4 0.01 C8 0.47 THERMAL SHUTDOWN UVLO SHUTDOWN SD 1 R Q LEVEL SHIFT PWM 0.7V PRE 19 C_LIMIT 7 FB C6 open C5 0.01 R4 49.9k ERROR AMP 0.
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LM5005 www.ti.com SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 High Voltage Start-Up Regulator The LM5005 contains a dual mode internal high voltage startup regulator that provides the Vcc bias supply for the PWM controller and boot-strap MOSFET gate driver. The input pin (Vin) can be connected directly to the input voltage, as high as 75 Volts. For input voltages below 9V, a low dropout switch connects Vcc directly to Vin. In this supply range, Vcc is approximately equal to Vin.
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LM5005 SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 www.ti.com Oscillator and Sync Capability The LM5005 oscillator frequency is set by a single external resistor connected between the RT pin and the AGND pin. The RT resistor should be located very close to the device and connected directly to the pins of the IC (RT and AGND).
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LM5005 www.ti.com SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 5V SYNC 10k I = f(RT) 2.5V Q S Q R DEADTIME ONE-SHOT Figure 13. Simplified Oscillator Block Diagram and SYNC I/O Circuit Error Amplifier and PWM Comparator The internal high gain error amplifier generates an error signal proportional to the difference between the regulated output voltage and an internal precision reference (1.225V).
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LM5005 SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 www.ti.com RAMP (5P x (VIN ± VOUT) + 25P) x tON CRAMP Sample and Hold DC Level 0.5V/A TON Figure 14. Composition of Current Sense Signal The Sample and Hold DC level illustrated in Figure 14. is derived from a measurement of the re-circulating Schottky diode anode current. The re-circulating diode anode should be connected to the IS pin. The diode current flows through an internal current sense resistor between the IS and PGND pins.
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LM5005 www.ti.com SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 VCC RRAMP RAMP CRAMP Figure 15. RRAMP to VCC for VOUT > 7.5V Current Limit The LM5005 contains a unique current monitoring scheme for control and over-current protection. When set correctly, the emulated current sense signal provides a signal which is proportional to the buck switch current with a scale factor of 0.5 V / A. The emulated ramp signal is applied to the current limit comparator. If the emulated ramp signal exceeds 1.75V (3.
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LM5005 SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 www.ti.com APPLICATION INFORMATION EXTERNAL COMPONENTS The procedure for calculating the external components is illustrated with the following design example. The Bill of Materials for this design is listed in Table 1. The circuit shown in Figure 9 is configured for the following specifications: • VOUT = 5V • VIN = 7V to 75V • Fs = 300 KHz • Minimum load current (for CCM) = 250 mA • Maximum load current = 2.
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LM5005 www.ti.com SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 C3 (CRAMP) With the inductor value selected, the value of C3 (CRAMP) necessary for the emulation ramp circuit is: CRAMP = L x 10-5 where • L is in Henrys 9With L1 selected for 33µH the recommended value for C3 is 330pF) (6) C9, C10 The output capacitors C9 and C10 smooth the inductor ripple current and provide a source of charge for transient loading conditions.
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LM5005 SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 www.ti.com C8 The capacitor at the VCC pin provides noise filtering and stability for the VCC regulator. The recommended value of C8 should be no smaller than 0.1 µF, and should be a good quality, low ESR, ceramic capacitor. A value of 0.47 µF was selected for this design. C7 The bootstrap capacitor between the BST and the SW pins supplies the gate current to charge the buck switch gate at turn-on. The recommended value of C7 is 0.
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LM5005 www.ti.com SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 R4, C5, C6 These components configure the error amplifier gain characteristics to accomplish a stable overall loop gain. One advantage of current mode control is the ability to close the loop with only two feedback components, R4 and C5. The overall loop gain is the product of the modulator gain and the error amplifier gain.
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LM5005 SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 www.ti.com REF LEVEL 0.000 dB 0.0 deg /DIV 10.000 dB 45.000 deg PHASE GAIN 0 100 1k START 50.000 Hz 10k STOP 50 000.000 Hz Figure 18. Error Amplifier Gain and Phase The overall loop can be predicted as the sum (in dB) of the modulator gain and the error amp gain. REF LEVEL 0.000 dB 0.0 deg /DIV 10.000 dB 45.000 deg GAIN PHASE 0 100 1k START 50.000 Hz 10k STOP 50 000.000 Hz Figure 19.
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LM5005 www.ti.com SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 BIAS POWER DISSIPATION REDUCTION Buck regulators operating with high input voltage can dissipate an appreciable amount of power for the bias of the IC. The VCC regulator must step-down the input voltage VIN to a nominal VCC level of 7V. The large voltage drop across the VCC regulator translates into a large power dissipation within the Vcc regulator.
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LM5005 SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 www.ti.com PWB BOARD LAYOUT AND THERMAL CONSIDERATIONS The circuit in Figure 9 serves as both a block diagram of the LM5005 and a typical application board schematic for the LM5005. In a buck regulator there are two loops where currents are switched very fast. The first loop starts from the input capacitors, to the regulator VIN pin, to the regulator SW pin, to the inductor then out to the load.
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LM5005 www.ti.com SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 PCB Layout Figure 22. Component Side Figure 23. Solder Side Figure 24.
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LM5005 SNVS397D – SEPTEMBER 2005 – REVISED MARCH 2013 www.ti.com REVISION HISTORY Changes from Revision C (March 2013) to Revision D • 22 Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device LM5005MHX/NOPB Package Package Pins Type Drawing SPQ HTSSOP 2500 PWP 20 Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 330.0 16.4 Pack Materials-Page 1 6.95 B0 (mm) K0 (mm) P1 (mm) 7.1 1.6 8.0 W Pin1 (mm) Quadrant 16.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM5005MHX/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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