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LM26003

BOOT

COMP

VDD

PGND

FPWM

FREQ

SYNC

PGOOD

AVIN

VIN

VOUT

VIN

VDD

SYNC

VIN

AGND

VBIAS

PGOOD

LM26003

www.ti.com

SNVS576D –AUGUST 2008–REVISED MARCH 2013

LM26003/LM26003Q 3A Switching Regulator with High Efficiency Sleep Mode

Check for Samples: LM26003

FEATURES

DESCRIPTION

The LM26003 is a switching regulator designed for

• LM26003Q is an Automotive Grade Product

the high efficiency requirements of applications with

that is AEC-Q100 Grade 1 Qualified (-40°C to

stand-by modes. The device features a low-current

+125°C Operating Junction Temperature)

sleep mode to maintain efficiency under light-load

• High Efficiency Sleep Mode

conditions and current-mode control for accurate

regulation over a wide input voltage range. Quiescent

• 40 µA Typical Iq in Sleep Mode

current is reduced to 10.8 µA typically in shutdown

• 10.8 µA Typical Iq in Shutdown Mode

mode and less than 40 µA in sleep mode. Forced

• 3.0V Minimum Input Voltage

PWM mode is also available to disable sleep mode.

• 4.0V to 38V Continuous Input Range

The LM26003 can deliver up to 3A of continuous load

• 1.5% Reference Accuracy

current with a fixed current limit, through the internal

N-channel switch. The part has a wide input voltage

• Cycle-by-cycle Current Limit

range of 4.0V to 38V and can operate with input

• Adjustable Frequency (150 kHz to 500 kHz)

voltages as low as 3V during line transients.

• Synchronizable to an External Clock

Operating frequency is adjustable from 150 kHz to

• Power Good Flag

500 kHz with a single resistor and can be

• Forced PWM Function

synchronized to an external clock.

• Adjustable Soft-start

Other features include Power good, adjustable soft-

• TSSOP-20 Package

start, enable pin, input under-voltage protection, and

an internal bootstrap diode for reduced component

• Thermal Shut Down

count.

APPLICATIONS

• Automotive Telematics

• Navigation Systems

• In-Dash Instrumentation

• Battery Powered Applications

• Stand-by Power for Home Gateways/Set-top

Boxes

Typical Application Circuit

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)

PAGE 1
LM26003 www.ti.com SNVS576D – AUGUST 2008 – REVISED MARCH 2013 LM26003/LM26003Q 3A Switching Regulator with High Efficiency Sleep Mode Check for Samples: LM26003 FEATURES DESCRIPTION • The LM26003 is a switching regulator designed for the high efficiency requirements of applications with stand-by modes. The device features a low-current sleep mode to maintain efficiency under light-load conditions and current-mode control for accurate regulation over a wide input voltage range.
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LM26003 SNVS576D – AUGUST 2008 – REVISED MARCH 2013 www.ti.com Connection Diagram VIN 1 20 SW VIN 2 19 SW VIN 3 18 SW AVIN 4 17 BOOT PGOOD 5 16 VDD EN 6 15 VBIAS SS 7 14 SYNC COMP 8 13 FPWM FB 9 12 FREQ AGND 10 11 PGND Exposed Pad Connect to GND Figure 1.
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LM26003 www.ti.com SNVS576D – AUGUST 2008 – REVISED MARCH 2013 Absolute Maximum Ratings (1) (2) Voltages from the indicated pins to GND: VIN -0.3V to 40V SW (3) -1V to 40V VDD -0.3V to 7V VBIAS -0.3V to 10V FB -0.3V to 6V BOOT VSW-0.3V to VSW+7V PGOOD -0.3V to 7V FREQ -0.3V to 7V SYNC -0.3V to 7V EN -0.3V to 40V FPWM -0.3V to 7V Storage Temperature -65°C to +150°C Power Dissipation (4) Recommended Lead Temperature ESD Susceptibility (5) (1) (2) (3) (4) (5) 3.
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LM26003 SNVS576D – AUGUST 2008 – REVISED MARCH 2013 www.ti.com Electrical Characteristics Specifications in standard type are for TJ = 25°C only, and limits in boldface type apply over the junction temperature (TJ) range of -40°C to +125°C. Unless otherwise stated, Vin = 12V. Minimum and Maximum limits are ensured through test, design, or statistical correlation. Symbol Parameter Conditions Min Typ Max Unit (1) System ISD (2) Shutdown Current EN = 0V 10.
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LM26003 www.ti.com SNVS576D – AUGUST 2008 – REVISED MARCH 2013 Electrical Characteristics (continued) Specifications in standard type are for TJ = 25°C only, and limits in boldface type apply over the junction temperature (TJ) range of -40°C to +125°C. Unless otherwise stated, Vin = 12V. Minimum and Maximum limits are ensured through test, design, or statistical correlation. Symbol Parameter Conditions Min Typ Max Unit 4.7 6.
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LM26003 SNVS576D – AUGUST 2008 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics Unless otherwise specified the following conditions apply: Vin = 12V, TJ = 25°C. 6 Efficiency vs Load Current (300 kHz) Efficiency vs Load Current (500 kHz) Figure 2. Figure 3. VFB vs Temperature VFB vs Vin (IDC = 300 mA) Figure 4. Figure 5. IQ and IVBIAS vs Temperature (Sleep Mode) IQ and IVBIAS vs Temperature (PWM Mode) Figure 6. Figure 7.
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LM26003 www.ti.com SNVS576D – AUGUST 2008 – REVISED MARCH 2013 Typical Performance Characteristics (continued) Unless otherwise specified the following conditions apply: Vin = 12V, TJ = 25°C. Startup Waveforms Peak Current Limit vs Temperature Vout 1V/Div PGOOD 5V/Div SS 1V/Div EN 10V/Div 1 Ps/DIV Figure 8. Figure 9. Load Transient Response Normalized Switching Frequency vs Temperature (300kHz) Figure 10. Figure 11. UVLO Threshold vs Temperature (VDD = VIN) Figure 12.
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LM26003 SNVS576D – AUGUST 2008 – REVISED MARCH 2013 www.ti.com Block Diagram AVIN 5 PA BG IREF TSD SD on LDO UVLO VDD_low VDD qn EN Switchover control fpwm VBIAS Sync FPWM wake + - BG VREG Sleep Reset 0.6V + - Sleep Set FPWM / Sleep Peak Current Control EA + FB + BOOT + V clamp BG 0.9V + 0.
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LM26003 www.ti.com SNVS576D – AUGUST 2008 – REVISED MARCH 2013 OPERATION DESCRIPTION GENERAL The LM26003 is a current mode PWM buck regulator. At the beginning of each clock cycle, the internal high-side switch turns on, allowing current to ramp-up in the inductor. The inductor current is internally monitored during each switching cycle. A control signal derived from the inductor current is compared to the voltage control signal at the COMP pin, derived from the feedback voltage.
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LM26003 SNVS576D – AUGUST 2008 – REVISED MARCH 2013 www.ti.com When load current increases above this limit, the LM26003 is forced back into PWM operation. The sleep mode threshold varies with frequency, inductance, and duty-cycle as shown in Figure 15. Figure 15. Sleep Mode Threshold vs Vin Vout = 3.
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LM26003 www.ti.com SNVS576D – AUGUST 2008 – REVISED MARCH 2013 At very light load, in FPWM mode, the LM26003 may enter sleep mode. This is to prevent an over-voltage condition from occurring. However, the FPWM sleep threshold is much lower than in normal operation. ENABLE The LM26003 provides a shutdown function via the EN pin to disable the device when the output voltage does not need to be maintained. EN is an analog level input with typically 180 mV of hysteresis.
PAGE 12
LM26003 SNVS576D – AUGUST 2008 – REVISED MARCH 2013 www.ti.com During high over-current conditions, such as output short circuit, the LM26003 employs frequency foldback as a second level of protection. If the feedback voltage falls below the short circuit threshold of 0.9V, operating frequency is reduced, thereby reducing average switch current. This is especially helpful in short circuit conditions, when inductor current can rise very high during the minimum on-time.
PAGE 13
LM26003 www.ti.com SNVS576D – AUGUST 2008 – REVISED MARCH 2013 VBIAS The VBIAS pin is used to bypass the internal regulator which provides the bias voltage to the LM26003. When the VBIAS pin is connected to a voltage greater than 3V, the internal regulator automatically switches over to the VBIAS input. This reduces the current into VIN (Iq) and increases system efficiency. Using the VBIAS pin has the added benefit of reducing power dissipation within the device.
PAGE 14
LM26003 SNVS576D – AUGUST 2008 – REVISED MARCH 2013 www.ti.com PGOOD A power good pin, PGOOD, is available to monitor the output voltage status. The pin is internally connected to an open drain MOSFET, which remains open while the output voltage is within operating range. PGOOD goes low (low impedance to ground) when the output falls below 89% of nominal or EN is pulled low. When the output voltage returns to within 95% of nominal, as measured at the FB pin, PGOOD returns to a high state.
PAGE 15
LM26003 www.ti.com SNVS576D – AUGUST 2008 – REVISED MARCH 2013 Larger inductance values result in lower output ripple voltage and higher efficiency, but a slightly degraded transient response. Lower inductance values allow for smaller case size, but the increased ripple lowers the effective current limit threshold. Remember that inductor value also affects the sleep mode threshold as shown in Figure 15.
PAGE 16
LM26003 SNVS576D – AUGUST 2008 – REVISED MARCH 2013 www.ti.com INPUT CAPACITOR In a switching converter, very fast switching pulse currents are drawn from the input rail. Therefore, input capacitors are required to reduce noise, EMI, and ripple at the input to the LM26003. Capacitors must be selected that can handle both the maximum ripple RMS current at highest ambient temperature as well as the maximum input voltage.
PAGE 17
LM26003 www.ti.com SNVS576D – AUGUST 2008 – REVISED MARCH 2013 COMPENSATION The purpose of loop compensation is to ensure stable operation while maximizing dynamic performance. Stability can be analyzed with loop gain measurements, while dynamic performance is analyzed with both loop gain and load transient response. Loop gain is equal to the product of control-output transfer function (power stage) and the feedback transfer function (the compensation network).
PAGE 18
LM26003 SNVS576D – AUGUST 2008 – REVISED MARCH 2013 www.ti.com The control-output corner frequencies can be determined approximately by the following equations: fz = fp = 1 2S x Re x Co 0.5 1 + 20 x S x Ro x Co 2 x S x L x fsw x Co fn = fsw 2 (17) Where Co is the output capacitance, Ro is the load resistance, Re is the output capacitor ESR, and fsw is the switching frequency. The effects of slope compensation and current sense gain are included in this equation.
PAGE 19
LM26003 www.ti.com SNVS576D – AUGUST 2008 – REVISED MARCH 2013 A phase lead capacitor can also be added to increase the phase and gain margins. The phase lead capacitor is most helpful for high input voltage applications or when synchronizing to a frequency greater than nominal. This capacitor, shown as C11 in Figure 22, should be placed in parallel with the top feedback resistor, R1. C11 introduces an additional zero and pole to the compensation network.
PAGE 20
LM26003 SNVS576D – AUGUST 2008 – REVISED MARCH 2013 www.ti.com Vin Vout + GND SW EP GND Figure 23. Example PCB Layout It is a good practice to connect the EP, GND pin, and small signal components (COMP, FB, FREQ) to a separate ground plane, shown in Figure 23 as EP GND, and in the schematics as a signal ground symbol. Both the exposed pad and the GND pin must be connected to ground.
PAGE 21
LM26003 www.ti.com SNVS576D – AUGUST 2008 – REVISED MARCH 2013 To calculate the maximum allowable power dissipation, assume Tj = 125°C. To ensure that junction temperature does not exceed the maximum operating rating of 125°C, power dissipation should be verified at the maximum expected operating frequency, maximum ambient temperature, and minimum and maximum input voltage. The calculated maximum load current is based on continuous operation and may be exceeded during transient conditions.
PAGE 22
LM26003 SNVS576D – AUGUST 2008 – 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.
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PACKAGE MATERIALS INFORMATION www.ti.com 26-Mar-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) LM26003MHX/NOPB HTSSOP PWP 20 2500 330.0 16.4 LM26003QMHX/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 26-Mar-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM26003MHX/NOPB HTSSOP PWP 20 2500 367.0 367.0 35.0 LM26003QMHX/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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