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LM5008

www.ti.com

SNVS280G –APRIL 2004–REVISED MARCH 2013

High-Voltage (100V) Step-Down Switching Regulator

Check for Samples: LM5008

FEATURES

DESCRIPTION

The LM5008 Step-Down Switching Regulator

• Integrated 100V, N-Channel buck switch

features all of the functions needed to implement a

• Internal V

regulator

low cost, efficient, Buck bias regulator. This high

• No loop compensation required

voltage regulator contains an 100 V N-Channel Buck

Switch. The device is easy to implement and is

• Ultra-Fast transient response

provided in the VSSOP-8 and the thermally enhanced

• On time varies inversely with line voltage

WSON-8 packages. The regulator is based on a

• Operating frequency remains constant with

hysteretic control scheme using an ON time inversely

varying line voltage and load current

proportional to V

. This feature allows the operating

frequency to remain relatively constant. The

• Adjustable output voltage

hysteretic control requires no loop compensation. An

• Highly efficient operation

intelligent current limit is implemented with forced

• Precision internal reference

OFF time, which is inversely proportional to Vout.

This scheme ensures short circuit protection while

• Low bias current

providing minimum foldback. Other protection

• Intelligent current limit protection

features include: Thermal Shutdown, V

under-

• Thermal shutdown

voltage lockout, Gate drive under-voltage lockout,

and Max Duty Cycle limiter

• VSSOP-8 and WSON-8 (4mm x 4mm) Packages

Connection Diagram

APPLICATIONS

• Non-Isolated Telecommunication Buck

Regulator

• Secondary High Voltage Post Regulator

• +42V Automotive Systems

Figure 1. 8-Lead VSSOP or WSON

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 (23 pages)

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LM5008 www.ti.com SNVS280G – APRIL 2004 – REVISED MARCH 2013 High-Voltage (100V) Step-Down Switching Regulator Check for Samples: LM5008 FEATURES DESCRIPTION • • • • • • The LM5008 Step-Down Switching Regulator features all of the functions needed to implement a low cost, efficient, Buck bias regulator. This high voltage regulator contains an 100 V N-Channel Buck Switch. The device is easy to implement and is provided in the VSSOP-8 and the thermally enhanced WSON-8 packages.
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LM5008 SNVS280G – APRIL 2004 – REVISED MARCH 2013 www.ti.com Typical Application Circuit and Block Diagram 7V SERIES REGULATOR 9.5 -95V Input LM5008 VCC 7 8 VIN C1 SD C5 ON TIMER START RON C3 THERMAL SHUTDOWN UVLO COMPLETE 6 SD / RON BST Ron START OVER-VOLTAGE COMPARATOR SHUTDOWN + - 2.875V UVLO 300 ns MIN OFF TIMER VIN SD C4 DRIVER COMPLETE LEVEL SHIFT 2.
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LM5008 www.ti.com SNVS280G – APRIL 2004 – REVISED MARCH 2013 These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Absolute Maximum Ratings (1) VIN to GND -0.3V to 100V BST to GND -0.3V to 114V SW to GND (Steady State) ESD Rating, Human Body Model -1V (2) 2kV BST to VCC 100V BST to SW 14V VCC to GND 14V All Other Inputs to GND -0.
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LM5008 SNVS280G – APRIL 2004 – REVISED MARCH 2013 www.ti.com Electrical Characteristics Specifications with standard typeface are for TJ = 25°C, and those with boldface type apply over full Operating Junction Temperature range. VIN = 48V, unless otherwise stated (1). Symbol Parameter Conditions Min Typ Max 7 7.4 Unit VCC Supply VCC Reg VCC Regulator Output 6.6 V VCC Current Limit (2) 9.5 mA VCC undervoltage Lockout Voltage (VCC increasing) 6.
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LM5008 www.ti.com SNVS280G – APRIL 2004 – REVISED MARCH 2013 Typical Performance Characteristics 2.0 8 RON = 500k 6 5 1.6 TON (Ps) ICC INPUT CURRENT (mA) 7 1.8 1.4 300k 4 3 2 1.2 100k 1 1.0 0 8 9 10 11 12 13 14 0 20 40 EXTERNALLY APPLIED VCC (V) 80 100 VIN (V) Figure 3. ICC Current vs Applied VCC Voltage Figure 4.
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LM5008 SNVS280G – APRIL 2004 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics (continued) 10.2 VOUT1 10.0 VOUT (V) 9.8 VOUT2 9.6 9.4 9.2 VIN = 48V 9.0 0 100 200 300 LOAD CURRENT (mA) Figure 9.
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LM5008 www.ti.com SNVS280G – APRIL 2004 – REVISED MARCH 2013 FUNCTIONAL DESCRIPTION The LM5008 Step Down Switching Regulator features all the functions needed to implement a low cost, efficient, Buck bias power converter. This high voltage regulator contains a 100 V N-Channel Buck Switch, is easy to implement and is provided in the VSSOP-8 and the thermally enhanced WSON-8 packages. The regulator is based on a hysteretic control scheme using an on-time inversely proportional to VIN.
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LM5008 SNVS280G – APRIL 2004 – REVISED MARCH 2013 www.ti.com L1 SW LM5008 R1 R3 FB VOUT2 R2 C2 Figure 10. Low Ripple Output Configuration High Voltage Start-Up Regulator The LM5008 contains an internal high voltage startup regulator. The input pin (VIN) can be connected directly to the line voltages up to 95 Volts, with transient capability to 100 volts. The regulator is internally current limited to 9.5mA at VCC.
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LM5008 www.ti.com SNVS280G – APRIL 2004 – REVISED MARCH 2013 Over-Voltage Comparator The feedback voltage at FB is compared to an internal 2.875V reference. If the voltage at FB rises above 2.875V the on-time pulse is immediately terminated. This condition can occur if the input voltage, or the output load, change suddenly. The buck switch will not turn on again until the voltage at FB falls below 2.5V.
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LM5008 SNVS280G – APRIL 2004 – REVISED MARCH 2013 www.ti.com During each off-time, the SW pin is at approximately 0V, and the bootstrap capacitor charges from Vcc through the internal diode. The minimum OFF timer, set to 300ns, ensures a minimum time each cycle to recharge the bootstrap capacitor. An external re-circulating diode (D1) carries the inductor current after the internal Buck switch turns off.
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LM5008 www.ti.com SNVS280G – APRIL 2004 – REVISED MARCH 2013 APPLICATIONS INFORMATION SELECTION OF EXTERNAL COMPONENTS A guide for determining the component values will be illustrated with a design example. Refer to Figure 2.
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LM5008 SNVS280G – APRIL 2004 – REVISED MARCH 2013 www.ti.com a) ESR and R3: A low ESR for C2 is generally desirable so as to minimize power losses and heating within the capacitor. However, a hysteretic regulator requires a minimum amount of ripple voltage at the feedback input for proper loop operation. For the LM5008 the minimum ripple required at pin 5 is 25 mVp-p, requiring a minimum ripple at VOUT1 of 100 mV.
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LM5008 www.ti.com SNVS280G – APRIL 2004 – REVISED MARCH 2013 D1: The important parameters are reverse recovery time and forward voltage. The reverse recovery time determines how long the reverse current surge lasts each time the buck switch is turned on. The forward voltage drop is significant in the event the output is short-circuited as it is only this diode’s voltage which forces the inductor current to reduce during the forced off-time.
PAGE 14
LM5008 SNVS280G – APRIL 2004 – REVISED MARCH 2013 12 - 95V Input www.ti.com VCC VIN 7 8 C1 1.0 PF C3 0.1 PF C5 0.1 PF BST RON 357k 2 RON / SD 6 LM5008 C4 0.01 PF L1 220 PH 10.0V SW VOUT1 1 SHUTDOWN D1 RCL R1 R3 3.01k 2.0 3 RCL 267k RTN VOUT2 FB R2 5 1.0k 4 C2 15 PF GND Figure 14. LM5008 Example Circuit Table 2.
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LM5008 www.ti.com SNVS280G – APRIL 2004 – REVISED MARCH 2013 REVISION HISTORY Changes from Revision F (March 2013) to Revision G • 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 14-Feb-2014 (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line.
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PACKAGE MATERIALS INFORMATION www.ti.com 11-Oct-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing LM5008SD WSON SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant NGU 8 1000 178.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1 LM5008SD/NOPB WSON NGT 8 1000 178.0 12.4 4.3 4.3 1.3 8.0 12.0 Q1 LM5008SDC/NOPB WSON NGU 8 1000 178.0 12.4 4.3 4.3 1.3 8.0 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 11-Oct-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM5008SD WSON NGU 8 1000 210.0 185.0 35.0 LM5008SD/NOPB WSON NGT 8 1000 210.0 185.0 35.0 LM5008SDC/NOPB WSON NGU 8 1000 210.0 185.0 35.0 LM5008SDCX/NOPB WSON NGU 8 4500 367.0 367.0 35.0 LM5008SDX/NOPB WSON NGT 8 4500 367.0 367.0 35.
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MECHANICAL DATA NGT0008A SDC08A (Rev A) www.ti.
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MECHANICAL DATA NGU0008B SDC08B (Rev A) www.ti.
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