Datasheet

ManualsBrandsLinear Technology ManualsIntegrated Circuits (ICs)LDO Voltage Regulator, 0 ... 15V, DFN-10

LT3045

Rev. B

For more information www.analog.com

TYPICAL APPLICATION

FEATURES DESCRIPTION

20V, 500mA, Ultralow Noise,

Ultrahigh PSRR Linear Regulator

The LT

3045 is a high performance low dropout linear

regulator featuring LTC’s ultralow noise and ultrahigh

PSRR architecture for powering noise sensitive applica

tions. Designed as a precision current reference followed

by a high performance voltage buffer, the LT3045 can be

easily paralleled to further reduce noise, increase output

current and spread heat on the PCB.

The device supplies 500mA at a typical 260mV dropout

voltage. Operating quiescent current is nominally 2.2mA

and drops to <<1µA in shutdown. The LT3045’s wide

output voltage range (0V to 15V) while maintaining unity-

gain operation provides virtually constant output noise,

PSRR, bandwidth and load regulation, independent of the

programmed output voltage. Additionally, the regulator

features programmable current limit, fast start-up capa

bility and programmable power good to indicate output

voltage regulation.

The LT3045 is stable with a minimum 10µF ceramic output

capacitor. Built-in protection includes reverse-battery

protection, reverse-current protection, internal current

limit with foldback and thermal limit with hysteresis. The

LT3045 is available in thermally enhanced 12-Lead MSOP

and 10-Lead 3mm × 3mm DFN packages.

Power Supply Ripple Rejection

APPLICATIONS

Ultralow RMS Noise: 0.8µV

RMS

(10Hz to 100kHz)

Ultralow Spot Noise: 2nV/√Hz at 10kHz

Ultrahigh PSRR: 76dB at 1MHz

Output Current: 500mA

Wide Input Voltage Range: 1.8V to 20V

Single Capacitor Improves Noise and PSRR

100µA SET Pin Current: ±1% Initial Accuracy

Single Resistor Programs Output Voltage

High Bandwidth: 1MHz

Programmable Current Limit

Low Dropout Voltage: 260mV

Output Voltage Range: 0V to 15V

Programmable Power Good

Fast Start-Up Capability

Precision Enable/UVLO

Parallelable for Lower Noise and Higher Current

Internal Current Limit with Foldback

Minimum Output Capacitor: 10µF Ceramic

Reverse-Battery and Reverse-Current Protection

12-Lead MSOP and 10-Lead 3mm × 3mm DFN Packages

RF Power Supplies: PLLs, VCOs, Mixers, LNAs, PAs

Very Low Noise Instrumentation

High Speed/High Precision Data Converters

Medical Applications: Imaging, Diagnostics

Precision Power Supplies

Post-Regulator for Switching Supplies

All registered trademarks and trademarks are the property of their respective owners.

= 5V

SET

= 30.1k

SET

= 4.7µF

OUT

= 10µF

= 500mA

FREQUENCY (Hz)

100

10k

100k

10M

100

110

120

PSRR (dB)

3045 TA01b

–

100µA

EN/UV

GND

OUT

LT3045

ILIM PGFB

402k

10µF

4.7µF*

*OPTIONAL, SEE

APPLICATIONS

INFORMATION

5V ±5%

200k

4.7µF

OUT

OUT(MAX)

500mA

49.9k

3045 TA01a

249Ω

30.1k

SET

OUTS

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Summary of content (32 pages)

PAGE 1
LT3045 20V, 500mA, Ultralow Noise, Ultrahigh PSRR Linear Regulator FEATURES DESCRIPTION Ultralow RMS Noise: 0.8µVRMS (10Hz to 100kHz) nn Ultralow Spot Noise: 2nV/√Hz at 10kHz nn Ultrahigh PSRR: 76dB at 1MHz nn Output Current: 500mA nn Wide Input Voltage Range: 1.
PAGE 2
LT3045 ABSOLUTE MAXIMUM RATINGS (Note 1) IN Pin Voltage..........................................................±22V EN/UV Pin Voltage...................................................±22V IN-to-EN/UV Differential..........................................±22V PG Pin Voltage (Note 10)................................–0.3V, 22V ILIM Pin Voltage (Note 10)................................–0.3V, 1V PGFB Pin Voltage (Note 10)............................–0.3V, 22V SET Pin Voltage (Note 10).......................
PAGE 3
LT3045 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. PARAMETER CONDITIONS MIN Input Voltage Range l Minimum IN Pin Voltage ILOAD = 500mA, VIN UVLO Rising VIN UVLO Hysteresis (Note 2) l 2 1.78 75 Output Voltage Range VIN > VOUT l 0 SET Pin Current (ISET) VIN = 2V, ILOAD = 1mA, VOUT = 1.
PAGE 4
LT3045 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. PARAMETER CONDITIONS EN/UV Pin Current VEN/UV = 0V, VIN = 20V VEN/UV = 1.24V, VIN = 20V VEN/UV = 20V, VIN = 0V MIN TYP VIN = 6V Quiescent Current in Shutdown (VEN/UV = 0V) TJ ≤ 125°C (E/I-Grade) TJ ≤ 150°C (H-/MP-Grade) ±1 UNITS 15 0.3 1 10 20 µA µA µA 850 0.
PAGE 5
LT3045 ELECTRICAL CHARACTERISTICS Note 9: The LT3045 is tested and specified under pulsed load conditions such that TJ ≈ TA. The LT3045E is 100% tested at 25°C and performance is guaranteed from 0°C to 125°C. Specifications over the –40°C to 125°C operating temperature range are assured by design, characterization, and correlation with statistical process controls. The LT3045I is guaranteed over the full –40°C to 125°C operating temperature range.
PAGE 6
LT3045 TYPICAL PERFORMANCE CHARACTERISTICS SET Pin Current 101.0 2.0 100.2 100.0 99.8 99.6 99.4 1.5 0.5 0 –0.5 99.0 –2.0 3 4.5 6 7.5 9 10.5 12 13.5 15 OUTPUT VOLTAGE (V) 0 1.5 8 2.0 1.5 1.0 0.08 0.06 0.04 ISET 0.02 3 4.5 6 7.5 9 10.5 12 13.5 15 OUTPUT VOLTAGE (V) 0 –75 –50 –25 Quiescent Current 3.0 VEN/UV = VIN IL = 10µA RSET = 33.2k 2.5 40 35 30 VIN = 20V 25 20 VIN = 2V 15 0 0 25 50 75 100 125 150 TEMPERATURE (°C) 3045 G09 VEN/UV = 0V 45 2.5 0.
PAGE 7
LT3045 TYPICAL PERFORMANCE CHARACTERISTICS GND Pin Current 22 VIN = 5V RSET = 33.2k 18 18 GND PIN CURRENT (mA) IL = 500mA 12 10 IL = 300mA 8 6 IL = 100mA 4 2 0 –75 –50 –25 16 14 12 10 8 6 150°C 125°C 25°C –55°C 4 2 IL = 1mA 0 0 25 50 75 100 125 150 TEMPERATURE (°C) 0 1.30 1.00 0.75 0.50 0 25 50 75 100 125 150 TEMPERATURE (°C) 1.26 1.24 VIN = 2V 1.22 VIN = 10V 1.5 150°C 125°C 25°C –55°C 1.0 0.
PAGE 8
LT3045 TYPICAL PERFORMANCE CHARACTERISTICS Input Pin Current Internal Current Limit 0.3 1000 150°C 125°C 25°C –55°C 900 Internal Current Limit 600 RILIM = 0Ω VOUT = 0V 500 0.2 0.1 CURRENT LIMIT (mA) 800 CURRENT LIMIT (mA) INPUT CURRENT (µA) VIN = 2V TJ = 25°C, unless otherwise noted.
PAGE 9
LT3045 TYPICAL PERFORMANCE CHARACTERISTICS PG Output Low Voltage ISET During Start-Up with Fast Start-Up Enabled PG Pin Leakage Current 100 50 VIN = 2V VPGFB = 290mV IPG = 100µA 80 70 30 60 IPG (nA) 35 25 20 40 30 10 20 5 10 0.5 3045 G35 ISET During Start-Up with Fast Start-Up Enabled 12 VPGFB = 290mV VSET = 1.3V OUTPUT SINK CURRENT (mA) ISET (mA) 2.5 2.0 1.5 1.0 0.
PAGE 10
LT3045 TYPICAL PERFORMANCE CHARACTERISTICS Power Supply Ripple Rejection as a Function of Error Amplifier Input Pair Power Supply Ripple Rejection 140 120 120 100 90 80 10 100 70 60 VIN = 5V RSET = 30.1k COUT = 10µF CSET = 0.47µF 1k 10k 100k FREQUENCY (Hz) 1M 20 10M 40 10 100 10 1k 10k 100k FREQUENCY (Hz) 1M 0 10M 0.8 0.6 0.4 7 6 5 4 3 2 1 0.2 0.1 1 10 SET PIN CAPACITANCE (µF) 3045 G46 1.4 1.2 1.0 0.8 0.6 0.4 0 100 Noise Spectral Density 1M 10M 3045 G49 1.5 3 4.5 6 7.
PAGE 11
LT3045 TYPICAL PERFORMANCE CHARACTERISTICS Noise Spectral Density as a Function of Error Amplifier Input Pair TJ = 25°C, unless otherwise noted. Output Noise: 10Hz to 100kHz Load Transient Response OUTPUT NOISE (nV/√Hz) 1000 VOUT ≥ 1.3V 0.6V < VOUT < 1.3V VOUT ≤ 0.6V 100 OUTPUT CURRENT 500mA/DIV 5µV/DIV VIN = 5V RSET = 33.2k COUT = 10µF CSET = 4.7µF IL = 500mA 10 1 V =V IN OUT + 2V IL = 500mA COUT = 10µF CSET = 4.7µF 0.
PAGE 12
LT3045 PIN FUNCTIONS (DFN/MSOP) IN (Pins 1, 2/Pins 1, 2, 3): Input. These pins supply power to the regulator. The LT3045 requires a bypass capacitor at the IN pin. In general, a battery’s output impedance rises with frequency, so include a bypass capacitor in battery-powered applications. While a 4.7µF input bypass capacitor generally suffices, applications with large load transients may require higher input capacitance to prevent input supply droop.
PAGE 13
LT3045 PIN FUNCTIONS OUTS (Pin 9/Pin 10): Output Sense. This pin is the noninverting input to the error amplifier. For optimal transient performance and load regulation, Kelvin connect OUTS directly to the output capacitor and the load. Also, tie the GND connections of the output capacitor and the SET pin capacitor directly together. A parasitic substrate diode exists between OUTS and GND pins of the LT3045; do not drive OUTS more than 0.3V below GND during normal operation or during a fault condition.
PAGE 14
LT3045 BLOCK DIAGRAM VIN EN/UV CIN IN CURRENT REFERENCE 2mA 100µA – + ENABLE COMPARATOR + – + V – FAST START-UP 1.24V – 300mV INPUT UVLO V + – – COUT INTERNAL CURRENT LIMIT – + RPG GND 215Ω + – 300mV + V PG VOUT RL 1.
PAGE 15
LT3045 APPLICATIONS INFORMATION The LT3045 is a high performance low dropout linear regulator featuring LTC’s ultralow noise (2nV/√Hz at 10kHz) and ultrahigh PSRR (76dB at 1MHz) architecture for powering noise sensitive applications. Designed as a precision current source followed by a high performance rail-to-rail voltage buffer, the LT3045 can be easily paralleled to further reduce noise, increase output current and spread heat on the PCB.
PAGE 16
LT3045 APPLICATIONS INFORMATION on the guard ring width. Leakages of 100nA into or out of the SET pin creates a 0.1% error in the reference voltage. Leakages of this magnitude, coupled with other sources of leakage, can cause significant errors in the output voltage, especially over wide operating temperature range. Figure 2 illustrates a typical guard ring layout technique.
PAGE 17
LT3045 APPLICATIONS INFORMATION X5R and X7R dielectrics result in more stable characteristics and are thus more suitable for LT3045. The X7R dielectric has better stability across temperature, while the X5R is less expensive and is available in higher values. Nonetheless, care must still be exercised when using X5R and X7R capacitors. The X5R and X7R codes only specify operating temperature range and the maximum capacitance change over temperature.
PAGE 18
LT3045 APPLICATIONS INFORMATION a ceramic output capacitor. Similarly, due to LT3045’s ultrahigh PSRR, negligible output noise is generated using a ceramic input capacitor. Nonetheless, given the high SET pin impedance, any piezoelectric response from a ceramic SET pin capacitor generates significant output noise – peak-to-peak excursions of hundreds of µVs.
PAGE 19
LT3045 APPLICATIONS INFORMATION parasitic LC resonance frequency. Besides, it is generally a very common (and a preferred) practice to bypass regulator input with some capacitance. So this option is fairly limited in its scope and not the most palatable solution. To that end, LTC recommends using the LT3045 demo board layout for achieving the best possible PSRR performance.
PAGE 20
LT3045 APPLICATIONS INFORMATION regulator is in current limit, dropout, thermal shutdown or input voltage is below minimum VIN. If fast start-up capability is not used, tie PGFB to IN or to OUT for output voltages above 300mV. Note that doing so also disables power good functionality. ENABLE/UVLO The EN/UV pin is used to put the regulator into a micropower shutdown state. The LT3045 has an accurate 1.24V turn-on threshold on the EN/UV pin with 130mV of hysteresis.
PAGE 21
LT3045 APPLICATIONS INFORMATION If OUTS is externally held above SET, the current sink turns ON in an attempt to restore OUTS to its programmed voltage. The current sink remains ON until the external circuitry releases OUTS. LT3045 IN VIN 5V ±5% 100µA 10µF – + EN/UV OUT PGFB 20mΩ OUTS SET GND ILIM PG VOUT 3.3V IOUT(MAX) 1A LT3045 IN 100µA – + EN/UV OUT PGFB 20mΩ OUTS SET GND ILIM PG 10µF 3045 F07 16.5k Direct Paralleling for Higher Current 10µF 0.47µF Figure 7.
PAGE 22
LT3045 APPLICATIONS INFORMATION Thermal Considerations Table 3. Measured Thermal Resistance for DFN Package The LT3045 has internal power and thermal limiting circuits that protect the device under overload conditions. The thermal shutdown temperature is nominally 165°C with about 8°C of hysteresis. For continuous normal load conditions, do not exceed the maximum junction temperature (125°C for E- and I-grades and 150°C for H- and MP-Grades).
PAGE 23
LT3045 TYPICAL APPLICATIONS Overload Recovery Protection Features Like many IC power regulators, the LT3045 incorporates safe-operating-area (SOA) protection. The SOA protection activates at input-to-output differential voltages greater than 12V. The SOA protection decreases the current limit as the input-to-output differential increases and keeps the power transistor inside a safe operating region for all values of input-to-output voltages up to the LT3045’s absolute maximum ratings.
PAGE 24
LT3045 TYPICAL APPLICATIONS 12VIN to 3.3VOUT with 0.8µVRMS Integrated Noise LT3045 IN VIN 12V ±5% 4.7µF 100µA – + EN/UV 200k VOUT 3.3V IOUT 200mA OUT PG OUTS GND SET ILIM 10µF PGFB 453k 33.2k 4.7µF 750Ω 49.9k 3045 TA02 Low Noise CC/CV Lab Power Supply LT3045 IN VIN 4.7µF Ultralow Noise Current Source for RF Biasing Applications VIN 1.8V to 20V 100µA EN/UV OUT PG 0.47µF ROUT = R1 + RLOAD EN/UV PGFB VOUT OUTS SET 100µA 4.
PAGE 25
LT3045 TYPICAL APPLICATIONS Programming Undervoltage Lockout VIN 4V Turn-ON 3.4V Turn-OFF 4.7µF ⎛ 110k ⎞ VIN(UVLO)RISING =1.24V • ⎜1+ ⎟ ⎝ 49.9k ⎠ LT3045 IN 100µA PGFB REN2 110k PG – + VOUT 3.3V IOUT(MAX) 500mA OUT EN/UV REN1 49.9k OUTS SET 10µF GND ILIM 3045 TA05 0.47µF 33.2k Ratiometric Tracking LT3045 IN 100µA – + EN/UV PGFB VIN 5.5V TO 20V PG LT3045 IN SET EN/UV 0.1µF PGFB OUT PG OUTS SET 0.1µF GND ILIM 10µF VOUT 5V OUTS 100µA 10µF OUT 16.
PAGE 26
LT3045 TYPICAL APPLICATIONS Ultralow 1/f Noise Reference Buffer VIN 6V ±5% LT3045 IN 100µA 4.7µF – + EN/UV PGFB 1,2 PG 6,7 LTC6655-5 OUTS SET 3,4,5 VOUT = 5V IOUT(MAX) 500mA OUT GND 10µF ILIM 1k 3045 TA07 10µF 49.9k 4.7µF Paralleling Multiple Devices Using ILIM (Current Monitor) to Cancel Ballast Resistor Drop LT3045 IN 10µF LT3045 100µA EN/UV VOUT = 3.
PAGE 27
LT3045 TYPICAL APPLICATIONS Paralleling Multiple LT3045s for 2A Output Current LT3045 IN VIN 5V ±5% 22µF LT3045 100µA IN 100µA – + 200k OUT PG OUT 20mΩ OUTS SET ILIM GND + – EN/UV PGFB 20mΩ 10µF EN/UV PGFB PG OUTS ILIM 10µF GND SET 453k 49.9k VOUT = 3.3V IOUT(MAX) = 2A DROPOUT = 300mV 0.8µVRMS 4 = 0.4µVRMS OUTPUT NOISE = LT3045 IN LT3045 100µA 100µA – + PGFB OUT PG OUT 20mΩ OUTS SET GND + – EN/UV IN ILIM 10µF 4.
PAGE 28
LT3045 TYPICAL APPLICATIONS Low Noise Wheatstone Bridge Power Supply LT1763 NOISE: 20µVRMS (10Hz TO 100kHz) LT3045 NOISE: 0.8µVRMS (10Hz TO 100kHz) LT3045 IN VIN 5V ±5% 4.7µF 100µA EN/UV 200k – + OUT PG RESISTOR TOLERANCE BRIDGE PSRR NOISE AT VBRIDGE USING LT1763 NOISE AT VBRIDGE USING LT3045 PERFECT MATCHING INFINITE – – 1% 40dB 200nVRMS 8nVRMS 5% 26dB 1000nVRMS 42.5nVRMS VOUT: 3.3V AND IOUT(MAX): 500mA R1 OUTS SET GND ILIM PGFB 10µF R3 VBRIDGE 453k + R2 4.7µF – R4 49.
PAGE 29
LT3045 PACKAGE DESCRIPTION DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1699 Rev C) 0.70 ±0.05 3.55 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC 2.38 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ±0.10 (4 SIDES) R = 0.125 TYP 6 0.40 ±0.10 10 1.65 ±0.10 (2 SIDES) PIN 1 NOTCH R = 0.20 OR 0.35 × 45° CHAMFER PIN 1 TOP MARK (SEE NOTE 6) 0.200 REF 0.75 ±0.05 0.00 – 0.05 5 1 (DD) DFN REV C 0310 0.25 ±0.05 0.50 BSC 2.38 ±0.
PAGE 30
LT3045 PACKAGE DESCRIPTION MSE Package 12-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1666 Rev G) BOTTOM VIEW OF EXPOSED PAD OPTION 2.845 ±0.102 (.112 ±.004) 5.10 (.201) MIN 2.845 ±0.102 (.112 ±.004) 0.889 ±0.127 (.035 ±.005) 6 1 1.651 ±0.102 (.065 ±.004) 1.651 ±0.102 3.20 – 3.45 (.065 ±.004) (.126 – .136) 12 0.65 0.42 ±0.038 (.0256) (.0165 ±.0015) BSC TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 0.35 REF 4.039 ±0.102 (.159 ±.004) (NOTE 3) 0.
PAGE 31
LT3045 REVISION HISTORY REV DATE DESCRIPTION A 10/17 Added H-grade options Modified Quiescent Current in Shutdown specs B 10/19 PAGE NUMBER 2, 23 4 Modified Note 9 5 Modified PGFB description 12 Added MP-Grade option 2, 3, 4, 5, 22, 23 Rev. B Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use.
PAGE 32
LT3045 TYPICAL APPLICATION Parallel Devices VIN 5V ±5% LT3045 IN 100µA 10µF – + EN/UV OUT PGFB 20mΩ OUTS SET GND ILIM PG 10µF VOUT 3.3V IOUT(MAX) 1A LT3045 IN 100µA – + EN/UV OUT PGFB 20mΩ OUTS SET GND ILIM PG 10µF 3045 TA13 16.5k 0.47µF RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1761 100mA, Low Noise LDO 300mV Dropout Voltage, Low Noise: 20µVRMS, VIN = 1.8V to 20V, TSOT-23 Package LT1763 500mA, Low Noise LDO 300mV Dropout Voltage, Low Noise: 20μVRMS, VIN = 1.