Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - DC/DC voltage regulator Holder TSSOP 14

VIN

BST

LM2694

VCC

RON/SD

8V - 30V

Input

OUT

RTN

ISEN

SGND

SHUTDOWN

LM2694

www.ti.com

SNVS444A –MAY 2006–REVISED APRIL 2013

LM2694 30V, 600 mA Step Down Switching Regulator

Check for Samples: LM2694

FEATURES

DESCRIPTION

The LM2694 Step Down Switching Regulator features

• Integrated N-Channel Buck Switch

all of the functions needed to implement a low cost,

• Integrated Start-Up Regulator

efficient, buck bias regulator capable of supplying

• Input Voltage Range: 8V to 30V

0.6A to the load. This buck regulator contains an N-

Channel Buck Switch, and is available in the 3 x 3

• No Loop Compensation Required

thermally enhanced WSON-10 package and a

• Ultra-Fast Transient Response

TSSOP-14 package. The feedback regulation

• Operating Frequency Remains Constant with

scheme requires no loop compensation, results in

Load Current and Input Voltage Variations

fast load transient response, and simplifies circuit

implementation. The operating frequency remains

• Maximum Duty Cycle Limited During Start-Up

constant with line and load variations due to the

• Adjustable Output Voltage

inverse relationship between the input voltage and

• Valley Current Limit At 0.6A

the on-time. The valley current limit results in a

smooth transition from constant voltage to constant

• Maximum Switching Frequency: 1 MHz

current mode when current limit is detected, reducing

• Precision Internal Reference

the frequency and output voltage, without the use of

• Low Bias Current

foldback. Additional features include: VCC under-

voltage lockout, thermal shutdown, gate drive under-

• Highly Efficient Operation

voltage lockout, and maximum duty cycle limiter.

• Thermal Shutdown

Package

TYPICAL APPLICATIONS

• WSON-10 (3 mm x 3 mm) w/Exposed Pad

• High Efficiency Point-Of-Load (POL) Regulator

• TSSOP-14

• Non-Isolated Telecommunication Buck

Regulator

• Secondary High Voltage Post Regulator

Basic Step Down Regulator

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 (24 pages)

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LM2694 www.ti.com SNVS444A – MAY 2006 – REVISED APRIL 2013 LM2694 30V, 600 mA Step Down Switching Regulator Check for Samples: LM2694 FEATURES DESCRIPTION • • • • • • The LM2694 Step Down Switching Regulator features all of the functions needed to implement a low cost, efficient, buck bias regulator capable of supplying 0.6A to the load. This buck regulator contains an NChannel Buck Switch, and is available in the 3 x 3 thermally enhanced WSON-10 package and a TSSOP-14 package.
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LM2694 SNVS444A – MAY 2006 – REVISED APRIL 2013 www.ti.com Connection Diagrams 1 2 3 4 5 6 7 14 NC NC SW VIN BST VCC ISEN RON/SD SGND SS RTN FB NC NC 1 13 2 12 3 11 4 10 5 SW VIN BST VCC ISEN RON/SD SGND SS RTN FB 10 9 8 7 6 9 8 Figure 1. 14-Lead TSSOP Package See Package Number PW0014A Figure 2.
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LM2694 www.ti.com SNVS444A – MAY 2006 – REVISED APRIL 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) (2) (3) VIN to RTN 33V BST to RTN 47V SW to RTN (Steady State) ESD Rating (4) -1.5V Human Body Model 2kV BST to VCC 33V VIN to SW 33V BST to SW 14V VCC to RTN 14V SGND to RTN -0.3V to +0.
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LM2694 SNVS444A – MAY 2006 – REVISED APRIL 2013 www.ti.com Electrical Characteristics Specifications with standard type are for TJ = 25°C only; limits in boldface type apply over the full Operating Junction Temperature (TJ) range. Minimum and Maximum limits are ensured 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.
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LM2694 www.ti.com SNVS444A – MAY 2006 – REVISED APRIL 2013 Typical Performance Characteristics 7.5 8 VIN = 9V 6 FS = 100 kHz FS = 620 kHz 6.5 5 VCC (V) VCC (V) VIN t 10V 7 7.0 6.0 FS = 200 kHz VIN = 8V 4 3 2 5.5 VCC Externally Loaded Load Current = 300 mA ICC = 0 mA 5.0 6.5 7.0 7.5 8.0 1 8.5 9.0 FS = 200 kHz 0 10 9.5 0 2 4 6 8 10 VIN (V) ICC (mA) Figure 3. VCC vs VIN Figure 4. VCC vs ICC 10 8.0 7.0 RON = 500k 3.0 ON-TIME (Ps) ICC INPUT CURRENT(mA) FS = 550 kHz 6.
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LM2694 SNVS444A – MAY 2006 – REVISED APRIL 2013 www.ti.com Typical Application Circuit and Block Diagram 7V SERIES REGULATOR 8V-30V Input LM2694 VIN VCC C3 VCC UVLO THERMAL SHUTDOWN C5 C1 RON ON TIMER RON /SD RON START COMPLETE + OFF TIMER 0.8V START COMPLETE BST GATE DRIVE UVLO C4 VIN 2.5V 12 PA SS C6 DRIVER FB + REGULATION COMPARATOR + OVER2.
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LM2694 www.ti.com SNVS444A – MAY 2006 – REVISED APRIL 2013 VIN 7.0V UVLO VCC SW Pin Inductor Current 2.5V SS Pin VOUT t1 t2 Figure 9. Startup Sequence Functional Description The LM2694 Step Down Switching Regulator features all the functions needed to implement a low cost, efficient buck bias power converter capable of supplying at least 0.6A to the load.
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LM2694 SNVS444A – MAY 2006 – REVISED APRIL 2013 www.ti.com When in regulation, the LM2694 operates in continuous conduction mode at heavy load currents and discontinuous conduction mode at light load currents. In continuous conduction mode current always flows through the inductor, never reaching zero during the off-time. In this mode the operating frequency remains relatively constant with load and line variations.
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LM2694 www.ti.com SNVS444A – MAY 2006 – REVISED APRIL 2013 VCC C3 BST C4 L1 LM2694 D2 SW VOUT1 D1 ISEN R1 R3 SGND R2 C2 FB Figure 10. Self Biased Configuration Regulation Comparator The feedback voltage at FB is compared to the voltage at the Softstart pin (2.5V). In normal operation (the output voltage is regulated), an on-time period is initiated when the voltage at FB falls below 2.5V. The buck switch stays on for the programmed on-time, causing the FB voltage to rise above 2.5V.
PAGE 10
LM2694 SNVS444A – MAY 2006 – REVISED APRIL 2013 www.ti.com VIN Input Voltage RON LM2694 RON/SD STOP RUN Figure 11. Shutdown Implementation Current Limit Current limit detection occurs during the off-time by monitoring the recirculating current through the free-wheeling diode (D1). Referring to Typical Application Circuit and Block Diagram, when the buck switch is turned off the inductor current flows through the load, into SGND, through the sense resistor, out of ISEN and through D1.
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LM2694 www.ti.com SNVS444A – MAY 2006 – REVISED APRIL 2013 Softstart The softstart feature allows the converter to gradually reach a steady state operating point, thereby reducing start-up stresses and current surges. Upon turn-on, after VCC reaches the under-voltage threshold, an internal 12 µA current source charges up the external capacitor at the SS pin to 2.5V. The ramping voltage at SS (and the non-inverting input of the regulation comparator) ramps up the output voltage in a controlled manner.
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LM2694 SNVS444A – MAY 2006 – REVISED APRIL 2013 www.ti.com L1 Current IPK+ IO IOR IPK- 0 mA 1/Fs Figure 13. Inductor Current To keep the circuit in continuous conduction mode, the maximum allowed ripple current is twice the minimum load current, or 200 mAp-p. Using this value of ripple current, the inductor (L1) is calculated using the following: VOUT x (VIN(max) - VOUT) IOR x FS(min) x VIN(max) L1 = where • FS(min) is the minimum frequency of 189 kHz (252 kHz - 25%) 5V x (30V - 5V) L1 = 0.
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LM2694 www.ti.com SNVS444A – MAY 2006 – REVISED APRIL 2013 Normally a lower value can be used for C1 since the above calculation is a worst case calculation which assumes the power source has a high source impedance. A quality ceramic capacitor with a low ESR should be used for C1.
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LM2694 SNVS444A – MAY 2006 – REVISED APRIL 2013 www.ti.com FINAL CIRCUIT The final circuit is shown in Figure 14, and its performance is shown in Figure 15 and Figure 16. Current limit measured approximately 0.64A. 8V - 30V Input VIN VCC C5 0.1 PF C1 3.3 PF C3 0.1 PF LM2694 RON BST 140k 0.022 PF C4 L1 150 PH RON/SD SW 5V VOUT D1 SS ISEN R1 2.5k C6 0.022 PF R3 1.5 SGND FB C2 22 PF R2 2.5k RTN GND Figure 14. Example Circuit Item Description Value C1 Ceramic Capacitor 3.
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LM2694 www.ti.com SNVS444A – MAY 2006 – REVISED APRIL 2013 MINIMUM LOAD CURRENT The LM2694 requires a minimum load current of 500 µA. If the load current falls below that level, the bootstrap capacitor (C4) may discharge during the long off-time, and the circuit will either shutdown, or cycle on and off at a low frequency. If the load current is expected to drop below 500 µA in the application, R1 and R2 should be chosen low enough in value so they provide the minimum required current at nominal VOUT.
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LM2694 SNVS444A – MAY 2006 – REVISED APRIL 2013 www.ti.com PC BOARD LAYOUT and THERMAL CONSIDERATIONS The LM2694 regulation, over-voltage, and current limit comparators are very fast, and will respond to short duration noise pulses. Layout considerations are therefore critical for optimum performance. The layout must be as neat and compact as possible, and all the components must be as close as possible to their associated pins.
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LM2694 www.ti.com SNVS444A – MAY 2006 – REVISED APRIL 2013 REVISION HISTORY Changes from Original (April 2013) to Revision A • 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 (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing LM2694MTX TSSOP LM2694MTX/NOPB LM2694SD/NOPB LM2694SDX/NOPB SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant PW 14 2500 330.0 12.4 6.95 8.3 1.6 8.0 12.0 Q1 TSSOP PW 14 2500 330.0 12.4 6.95 8.3 1.6 8.0 12.0 Q1 WSON DSC 10 1000 178.0 12.4 3.3 3.3 1.0 8.0 12.
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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) LM2694MTX TSSOP PW 14 2500 367.0 367.0 35.0 LM2694MTX/NOPB TSSOP PW 14 2500 367.0 367.0 35.0 LM2694SD/NOPB WSON DSC 10 1000 210.0 185.0 35.0 LM2694SDX/NOPB WSON DSC 10 4500 367.0 367.0 35.
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MECHANICAL DATA DSC0010A SDA10A (Rev A) www.ti.
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