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VIN (2.8V to 5.5V)

LMR70503

GND

VOUT

VIN

Cin

Cout

Refer to GND

VOUT

1.8V

(-0.9V to -5.5V)

VREF

Cff

0 30 60 90 120 150 180

EFFICIENCY (%)

LOAD (mA)

VIN = 2.8V

VIN = 3.3V

VIN = 4.0V

VIN = 5.0V

VIN = 5.5V

0 10 20 30 40 50 60 70 80 90 100

EFFICIENCY (%)

LOAD (mA)

VIN = 2.8V

VIN = 3.3V

VIN = 4.0V

VIN = 5.0V

VIN = 5.5V

LMR70503

www.ti.com

SNVS850A –JUNE 2012–REVISED APRIL 2013

LMR70503 SIMPLE SWITCHER

Buck-Boost Converter For Negative Output Voltage in

µSMD

Check for Samples: LMR70503

System Performance

FEATURES

• Tiny 8-Bump Thin DSBGA Package: 0.84 mm ×

1.615 mm × 0.6 mm

• 2.8 V to 5.5 V Input Voltage Range

• Adjustable Output Voltage: -0.9 V to -5.5 V

• 320 mA Switch Current Limit

• 500 kHz Minimum Switching Frequency

• Ground Referred Enable Input

• Under Voltage Lock Out (UVLO)

• No External Compensation

• Internal Soft Start

• 1 µA Shutdown Supply Current

Figure 1. Efficiency, V

OUT

= -5.0 V

• Small Output Voltage Ripple

• WEBENCH

Enabled

APPLICATIONS

• General Purpose Negative Voltage Supply

• Negative Rail / Bias Supply For Op-amp And

Data Converters

• LCD Biasing

PERFORMANCE BENEFITS

• Easy To Use

• Tiny Overall Solution Size Reduces System

Cost

Figure 2. Efficiency, V

OUT

= -2.5 V

DESCRIPTION

The LMR70503 is a buck-boost converter with

adjustable negative output voltage in a tiny 8-bump

Typical Application Circuit

thin DSBGA package. Its unique control method is

designed to provide fast transient response, low

output noise, high efficiency, and tight regulation in

the smallest possible PCB area. The LMR70503 has

built in soft start, peak current limit, minimum

switching frequency, and Under Voltage Lock Out

(UVLO), with no external compensation required. For

ease of use, the Enable pin is referred to the IC

ground, instead of the lowest potential of the IC: the

negative output voltage.

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.

2SIMPLE SWITCHER, WEBENCH are registered trademarks of Texas Instruments.

3All other 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)

PAGE 1
LMR70503 www.ti.com SNVS850A – JUNE 2012 – REVISED APRIL 2013 LMR70503 SIMPLE SWITCHER® Buck-Boost Converter For Negative Output Voltage in µSMD Check for Samples: LMR70503 FEATURES 1 • • • • • • • • • • • Tiny 8-Bump Thin DSBGA Package: 0.84 mm × 1.615 mm × 0.6 mm 2.8 V to 5.5 V Input Voltage Range Adjustable Output Voltage: -0.9 V to -5.
PAGE 2
LMR70503 SNVS850A – JUNE 2012 – REVISED APRIL 2013 www.ti.com Connection Diagram 1 2 A VREF FB B EN VOUT C GND GND D SW VIN Figure 3. LMR70503 Bump Locations - Top View 1 2 A B C D Figure 4. LMR70503 Package Marking - Top View (Diamond Denotes Bump A1) PIN DESCRIPTIONS 2 Pin Number Name Description A1 VREF Reference voltage output; connect to the bottom feedback resistor. B1 EN C1, C2 GND Analog ground for internal bias circuitry.
PAGE 3
LMR70503 www.ti.com SNVS850A – JUNE 2012 – 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) VIN to GND -0.5 V to 6.0 V VOUT to GND -6.5 V to 0.5 V SW to GND -6.5 V to VIN +0.2 V EN to GND -0.5 V to VIN FB to GND -0.5V to 5.
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LMR70503 SNVS850A – JUNE 2012 – REVISED APRIL 2013 www.ti.com ELECTRICAL CHARACTERISTICS (continued) Specifications with standard typeface are for TJ = 25°C only; limits in bold face type apply over the operating junction temperature (TJ) range of -40 °C to +125 °C. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. VIN = 3.3 V, VOUT = -5.0 V, VEN = 1.8 V, unless otherwise indicated in the conditions column.
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LMR70503 www.ti.com SNVS850A – JUNE 2012 – REVISED APRIL 2013 TYPICAL PERFORMANCE CHARACTERISTICS Unless otherwise specified, the following conditions apply: VIN = 3.3 V, VOUT = -5.0 V, VEN = 1.8 V, CIN = 10 µF 6.3 V X5R ceramic capacitor; COUT = 2 × 22 µF 6.3 V X5R ceramic capacitor; L = 6.8 µH (VLS2012ET-6R8M); TAMBIENT = 25 °C. Efficiency, VOUT = -5.0 V Output Regulation, VOUT = -5.0 V 80 5.10 |VOUT| REGULATION (V) 5.08 EFFICIENCY (%) 70 60 50 VIN = 2.8V VIN = 3.3V VIN = 4.0V VIN = 5.0V VIN = 5.
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LMR70503 SNVS850A – JUNE 2012 – REVISED APRIL 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) Unless otherwise specified, the following conditions apply: VIN = 3.3 V, VOUT = -5.0 V, VEN = 1.8 V, CIN = 10 µF 6.3 V X5R ceramic capacitor; COUT = 2 × 22 µF 6.3 V X5R ceramic capacitor; L = 6.8 µH (VLS2012ET-6R8M); TAMBIENT = 25 °C. Efficiency, VOUT = -1.5 V Output Regulation, VOUT = -1.5 V 1.60 80 1.58 |VOUT| REGULAITON (V) EFFICIENCY (%) 70 60 50 VIN = 2.8V VIN = 3.3V VIN = 4.
PAGE 7
LMR70503 www.ti.com SNVS850A – JUNE 2012 – REVISED APRIL 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) Unless otherwise specified, the following conditions apply: VIN = 3.3 V, VOUT = -5.0 V, VEN = 1.8 V, CIN = 10 µF 6.3 V X5R ceramic capacitor; COUT = 2 × 22 µF 6.3 V X5R ceramic capacitor; L = 6.8 µH (VLS2012ET-6R8M); TAMBIENT = 25 °C. No Load Supply Current Rds-on 3.0 2.0 1.8 NO LOAD CURRENT (mA) 2.5 1.6 RDS-ON ( ) 2.0 1.5 1.0 1.4 1.2 1.0 0.8 Vin = 2.8V Vin = 4.0V Vin = 5.5V 0.6 0.4 0.
PAGE 8
LMR70503 SNVS850A – JUNE 2012 – REVISED APRIL 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) Unless otherwise specified, the following conditions apply: VIN = 3.3 V, VOUT = -5.0 V, VEN = 1.8 V, CIN = 10 µF 6.3 V X5R ceramic capacitor; COUT = 2 × 22 µF 6.3 V X5R ceramic capacitor; L = 6.8 µH (VLS2012ET-6R8M); TAMBIENT = 25 °C. Soft Start And Soft Off Waveform VIN = 5.0 V, VOUT = -5.0 V, No Load Soft Start And Soft Off Waveform VIN = 5.0 V, VOUT = -5.
PAGE 9
LMR70503 www.ti.
PAGE 10
LMR70503 SNVS850A – JUNE 2012 – REVISED APRIL 2013 www.ti.com OPERATING DESCRIPTION The LMR70503 integrates an inverting buck-boost controller and a high-side MOSFET in one tiny 8-bump thin DSBGA package. A simplified buck-boost converter schematic is shown in Figure 29. VIN SW VOUT Figure 29. Buck Boost Converter The LMR70503 controller incorporates a unique peak current mode control method with a minimum switching frequency limit.
PAGE 11
LMR70503 www.ti.com SNVS850A – JUNE 2012 – REVISED APRIL 2013 Switching frequency FSW-MIN 0 Load current |VOUT| 0 Load current Peak Inductor Current IPEAK-MAX 0 Load current Dummy Load Ton-min (1) 0 Const Frequency (2) Const Peak Current (3) Load current Figure 31. The LMR70503 Operation Modes vs.
PAGE 12
LMR70503 SNVS850A – JUNE 2012 – REVISED APRIL 2013 www.ti.com DUMMY LOAD CURRENT (mA) 10 VIN=5.5V -40°C VIN=5.5V 25°C VIN=5.5V 125°C VIN=2.8V -40°C VIN=2.8V 25°C VIN=2.8V 125°C 9 8 7 6 5 4 3 2 1 0 -50 -40 -30 -20 -10 FB VOLTAGE (mV) 0 Figure 32. Dummy Load Current vs. FB Voltage Constant Peak Current Operation If the load current increases in the minimum switching frequency mode, the peak current limit will reach the maximum peak current limit (IPEAK-MAX).
PAGE 13
LMR70503 www.ti.com SNVS850A – JUNE 2012 – REVISED APRIL 2013 The built-in TOFF-MIN time is a function of both VIN and VOUT, as shown in Figure 34. 900 800 TOFF-MIN (ns) 700 600 500 400 300 VOUT = -0.9V VOUT = -1.5V VOUT = -2.5V VOUT = -3.3V VOUT = -5.0V 200 100 0 2.8 3.2 3.6 4.0 4.4 VIN (V) 4.8 5.2 Figure 34. Minimum Off Time vs.
PAGE 14
LMR70503 SNVS850A – JUNE 2012 – REVISED APRIL 2013 www.ti.com Soft Start And Soft Off The LMR70503 begins to operate when EN goes high with the presence of valid VIN, or VIN swings below UVLO level and back up with the presence of valid EN voltage. The soft start action is inherent with the maximum peak current limit and minimum off time.
PAGE 15
LMR70503 SNVS850A – JUNE 2012 – REVISED APRIL 2013 SOFT OFF RAMP TIME (90% TO 10%) ( s) www.ti.com 800 700 600 500 400 VIN = 2.8 V VIN = 4.0 V VIN = 5.0 V 300 0 10 20 30 40 50 60 70 80 90 TEMPERATURE (°C) Figure 38. Soft Off Time (90% To 10% Vout) vs. Temperature, VOUT = -5.5 V, No Load Short Circuit Protection Peak current mode control has inherent short circuit protection. The protection level is the maximum inductor current limit level.
PAGE 16
LMR70503 SNVS850A – JUNE 2012 – REVISED APRIL 2013 www.ti.com The output capacitor is responsible for filtering the output voltage and suppling load current during transients and during the power diode off-time. Best performance is achieved with ceramic capacitors. For most applications, a minimum value of 22 μF, 6.3 V capacitor is required at the output of the LMR70503.
PAGE 17
LMR70503 www.ti.com SNVS850A – JUNE 2012 – REVISED APRIL 2013 PC Board Layout Guidelines Board layout is critical for the proper operation of switching power converters. Switch mode converters are very fast switching devices. In such cases, the rapid increase of current combined with the parasitic trace inductance generates unwanted L·di/dt noise spikes. The magnitude of this noise tends to increase as the output current increases.
PAGE 18
LMR70503 SNVS850A – JUNE 2012 – REVISED APRIL 2013 www.ti.com LMR70503 Typical Application Circuit L VIN VIN SW Cin D Cout1 Cout2 VOUT VOUT LMR70503 Ren1 Cff Rb EN FB Ren2 Rt GND VREF LMR70503 Application Circuit Bill of Materials VIN = 2.8 V to 5.5 V, VOUT has options of -0.9 V, -1.5 V, -2.5 V, -3.3 V and -5.0 V. Optimized for minimum solution size. Table 1.
PAGE 19
LMR70503 www.ti.com SNVS850A – JUNE 2012 – REVISED APRIL 2013 REVISION HISTORY Changes from Original (April 2013) to Revision A • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
PAGE 20
PACKAGE OPTION ADDENDUM www.ti.
PAGE 21
PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-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) LMR70503TM/NOPB DSBGA YFX 8 250 178.0 8.4 LMR70503TMX/NOPB DSBGA YFX 8 3000 178.0 8.4 Pack Materials-Page 1 B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 0.91 1.69 0.7 4.0 8.0 Q1 0.91 1.69 0.7 4.0 8.
PAGE 22
PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LMR70503TM/NOPB DSBGA YFX LMR70503TMX/NOPB DSBGA YFX 8 250 210.0 185.0 35.0 8 3000 210.0 185.0 35.
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MECHANICAL DATA YFX0008xxx D 0.600±0.075 E TOP SIDE OF PACKAGE BOTTOM SIDE OF PACKAGE TMP08XXX (Rev A) D: Max = 1.64 mm, Min = 1.58 mm E: Max = 0.855 mm, Min =0.795 mm 4215093/A NOTES: A. All linear dimensions are in millimeters. Dimensioning and tolerancing per ASME Y14.5M-1994. B. This drawing is subject to change without notice. www.ti.
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