National Semiconductor LM5010A Technical data

LM5010A High Voltage 1A Step Down Switching Regulator

January 25, 2008

General Description

The LM5010A Step Down Switching Regulator is an enhanced version of the LM5010 with the input operating range extended to 6V minimum. The LM5010A features all the functions needed to implement a low cost, efficient, buck regulator capable of supplying in excess of 1A load current. This high voltage regulator integrates an N-Channel Buck Switch, and is available in thermally enhanced LLP-10 and TSSOP-14EP packages. The constant on-time regulation scheme requires no loop compensation resulting in fast load transient response and simplified circuit implementation. The operating frequency remains constant with line and load variations due to the inverse relationship between the input voltage and the on-time. The valley current limit detection is set at 1.25A. Additional features include: VCC under-voltage lock-out, thermal shutdown, gate drive under-voltage lock-out, and maximum duty cycle limiter.

Features

Wide 6V to 75V Input Voltage Range

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Valley Current Limiting At 1.25A

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Programmable Switching Frequency Up To 1 MHz

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Integrated 80V N-Channel Buck Switch

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Integrated High Voltage Bias Regulator

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No Loop Compensation Required

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Ultra-Fast Transient Response

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Nearly Constant Operating Frequency With Line and Load

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Variations Adjustable Output Voltage

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2.5V, ±2% Feedback Reference

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Programmable Soft-Start

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Thermal shutdown

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Typical Applications

Non-Isolated Telecommunications Regulator

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Secondary Side Post Regulator

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Power Supply for Automotive Electronics

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Package

LLP-10 (4 mm x 4 mm)

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TSSOP-14EP

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Both Packages Have Exposed Thermal Pad For Improved

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Heat Dissipation

Basic Step Down Regulator

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Connection Diagrams

LM5010A

Ordering Information

20153802

20153803

Order Number Package Type NSC Package

Drawing

LM5010ASD LLP-10 (4x4) SDC10A −40°C to + 125°C 1000 Units on Tape and Reel

LM5010ASDX LLP-10 (4x4) SDC10A −40°C to + 125°C 4500 Units on Tape and Reel

LM5010AMH TSSOP-14EP MXA14A −40°C to + 125°C 94 Units in Rail

LM5010AMHE TSSOP-14EP MXA14A −40°C to + 125°C 250 Units on Tape and Reel

LM5010AMHX TSSOP-14EP MXA14A −40°C to + 125°C 2500 Units on Tape and Reel

LM5010AHMH TSSOP-14EP MXA14A −40°C to + 150°C Available Soon

LM5010AHMHX TSSOP-14EP MXA14A −40°C to + 150°C Available Soon

Junction Temperature Range Supplied As

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Pin Descriptions

Pin Number Name Description Application Information

LLP-10 TSSOP-14

1 2 SW Switching Node Internally connected to the buck switch source.

Connect to the inductor, free-wheeling diode, and bootstrap capacitor.

2 3 BST Boost pin for bootstrap capacitor Connect a capacitor from SW to the BST pin. The

capacitor is charged from VCC via an internal diode during the buck switch off-time.

3 4 ISEN Current sense During the buck switch off-time, the inductor current

flows through the internal sense resistor, and out of the ISEN pin to the free-wheeling diode. The current limit comparator keeps the buck switch off if the ISEN current exceeds 1.25A (typical).

4 5 SGND Current Sense Ground Re-circulating current flows into this pin to the current

sense resistor.

5 6 RTN Circuit Ground Ground return for all internal circuitry other than the

current sense resistor.

6 9 FB Voltage feedback input from the

regulated output

7 10 SS Softstart An internal 11.5 µA current source charges the SS pin

8 11 RON/SD On-time control and shutdown An external resistor from VIN to the RON/SD pin sets

9 12 VCC Output of the bias regulator The voltage at VCC is nominally equal to VIN for V

10 13 VIN Input supply voltage Nominal input range is 6V to 75V. Input bypass

1,7,8,14 NC No connection. No internal connection. Can be connected to ground

EP Exposed Pad Exposed metal pad on the underside of the device. It

Input to both the regulation and over-voltage comparators. The FB pin regulation level is 2.5V.

capacitor to 2.5V to soft-start the reference input of the regulation comparator.

the buck switch on-time. Grounding this pin shuts down the regulator.

< 8.9V, and regulated at 7V for VIN > 8.9V. Connect a 0.47 µF, or larger capacitor from VCC to ground, as close as possible to the pins. An external voltage can be applied to this pin to reduce internal dissipation if VIN is greater than 8.9V. MOSFET body diodes clamp VCC to VIN if VCC > VIN.

capacitors should be located as close as possible to the VIN pin and RTN pins.

plane to improve heat dissipation.

is recommended to connect this pad to the PC board ground plane to aid in heat dissipation.

LM5010A

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Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/

LM5010A

Distributors for availability and specifications.

VIN to RTN -0.3V to 76V BST to RTN -0.3V to 90V SW to RTN (Steady State) -1.5V BST to VCC 76V BST to SW 14V VCC to RTN -0.3V to 14V SGND to RTN -0.3V to +0.3V SS to RTN -0.3V to 4V

VIN to SW 76V All Other Inputs to RTN -0.3V to 7V ESD Rating (Note 2) Human Body Model 2kV Storage Temperature Range -65°C to +150°C Lead Temperature (Soldering 4 sec) (Note 4) 260°C

Operating Ratings (Note 1)

VIN Voltage 6.0V to 75V Junction Temperature LM5010A −40°C to + 125°C LM5010AH −40°C to + 150°C

Electrical Charateristics Specifications with standard type are for T

= 25°C only; limits in boldface type apply

over the full Operating Junction Temperature (TJ) range. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise stated the following conditions apply: VIN = 48V, RON = 200kΩ. See (Note 5).

Symbol Parameter Conditions Min Typ Max Units

VCC Regulator

VCCReg VCC regulated output 6.6 7 7.4 Volts

VIN - V

ICC = 0 mA, FS < 200 kHz, 6.0V ≤ VIN ≤ 8.5V

100 mV

VCC Bypass Threshold VIN Increasing 8.9 V

VCC Bypass Hysteresis VIN Decreasing 260 mV

VCC output impedance

VIN = 8.0V 50

(0 mA ≤ ICC ≤ 5 mA)

VIN = 6.0V 55

Ω

VIN = 48V 0.21

VCC current limit (Note 3) VIN = 48V, VCC = 0V 15 mA

UVLOVcc VCC under-voltage lock-out

VCC Increasing 5.25 V

threshold

UVLO

hysteresis VCC Decreasing 180 mV

VCC

filter delay 100 mV overdrive 3 µs

VCC

IIN operating current Non-switching, FB = 3V 675 950 µA

IIN shutdown current RON/SD = 0V 100 200 µA

Switch Characteristics

DS(on)

UVLO

Buck Switch R

DS(on)

200 mA

Gate Drive UVLO V

@ ISW =

TJ ≤ 125°C

TJ ≤ 150°C

- VSW Increasing 1.7 3.0 4.0 V

BST

0.35 0.80

0.85

Ω

UVLOGD hysteresis 400 mV

SOFT-START Pin

Internal current source 8.0 11.5 15 µA

Current Limit

LIM

Resistance from ISEN to SGND 130

Threshold Current out of I

SEN

1 1.25 1.5 A

mΩ

Response time 150 ns

On Timer, RON/SD Pin

tON - 1 On-time

tON - 2 On-time

VIN = 10V, RON = 200 kΩ

VIN = 75V, RON = 200 kΩ

2.1 2.75 3.4 µs

290 390 496 ns

Shutdown threshold Voltage at RON/SD rising 0.30 0.7 1.05 V

Threshold hysteresis 40 mV

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Symbol Parameter Conditions Min Typ Max Units

Off Timer

OFF

Minimum Off-time 260 ns

Regulation and Over-Voltage Comparators (FB Pin)

REF

FB regulation threshold

TJ ≤ 125°C

TJ ≤ 150°C

2.445

2.435

2.50 2.550 V

FB over-voltage threshold 2.9 V

FB bias current 1 nA

Thermal Shutdown

Thermal shutdown temperature 175 °C

Thermal shutdown hysteresis 20 °C

Thermal Resistance

Junction to Ambient, 0 LFPM Air Flow

Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device is intended to be functional. For guaranteed specifications and test conditions, see the Electrical Characteristics.

Note 2: The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.

Note 3: VCC provides bias for the internal gate drive and control circuits. Device thermal limitations limit external loading.

Note 4: For detailed information on soldering plastic TSSOP and LLP packages refer to the Packaging Data Book available from National Semiconductor

Corporation.

Note 5: Typical specifications represent the most likely parametric norm at 25°C operation.

Junction to Case SDC Package

SDC Package MXA Package

MXA Package

5.2

°C/W

LM5010A

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Typical Performance Characteristics

LM5010A

VCC vs V

ICC vs Externally Applied V

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VCC vs I

On-Time vs VIN and R

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Voltage at RON/SD Pin

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IIN vs V

20153807

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