Datasheet

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

LT3042

3042fb

For more information www.linear.com/LT3042

TYPICAL APPLICATION

FEATURES DESCRIPTION

20V, 200mA, Ultralow Noise,

Ultrahigh PSRR RF Linear Regulator

The LT

3042 is a high performance low dropout linear

regulator featuring LTC’s ultralow noise and ultrahigh PSRR

architecture for powering noise sensitive RF applications.

Designed as a precision current reference followed by a

high performance voltage buffer, the LT3042 can be easily

paralleled to further reduce noise, increase output current

and spread heat on the PCB.

The device supplies 200mA at a typical 350mV dropout

voltage. Operating quiescent current is nominally 2mA

and drops to <<1µA in shutdown. The LT3042’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 LT3042 is stable with a minimum 4.7µF ceramic

output capacitor. Built-in protection includes reverse bat

tery protection, reverse current protection, internal current

limit with foldback and thermal limit with hysteresis. The

LT3042 is available in thermally enhanced

10-Lead MSOP

and 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: 79dB at 1MHz

Output Current: 200mA

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: 350mV

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: 4.7µF Ceramic

Reverse Battery and Reverse Current Protection

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

RF Power Supplies: PLLs, VCOs, Mixers, LNAs

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. Patents

Pending.

FREQUENCY (Hz)

PSRR (dB)

120

100

10 100 10k 100k 1M 10M

3042 TA01b

110

= 5V

SET

= 33.2kΩ

SET

= 4.7µF

OUT

= 4.7µF

= 200mA

–

100µA

EN/UV

GND

OUT

LT3042

ILIM PGFB

453k

4.7µF

5V ±5%

200k

4.7µF

OUT

3.3V

OUT(MAX)

200mA

49.9k

3042 TA01a

499Ω

33.2k

SET

OUTS

Downloaded from Arrow.com.

Summary of content (32 pages)

PAGE 1
LT3042 20V, 200mA, Ultralow Noise, Ultrahigh PSRR RF Linear Regulator FEATURES DESCRIPTION Ultralow RMS Noise: 0.8µVRMS (10Hz to 100kHz) nn Ultralow Spot Noise: 2nV/√Hz at 10kHz nn Ultrahigh PSRR: 79dB at 1MHz nn Output Current: 200mA nn Wide Input Voltage Range: 1.
PAGE 2
LT3042 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
LT3042 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 Minimum IN Pin Voltage ILOAD = 200mA, VIN UVLO Rising (Note 2) VIN UVLO Hysteresis VIN = 2V, ILOAD = 1mA, VOUT = 1.3V SET Pin Current (ISET) 2V < VIN < 20V, 0V < VOUT < 15V, 1mA < ILOAD < 200mA (Note 3) l l Fast Start-Up Set Pin Current VPGFB = 289mV, VIN = 2.8V, VSET = 1.
PAGE 4
LT3042 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 Quiescent Current in VIN = 6V Shutdown (VEN/UV = 0V) Internal Current Limit (Note 12) TYP MAX 0.
PAGE 5
LT3042 ELECTRICAL CHARACTERISTICS Note 10: Parasitic diodes exist internally between the ILIM, PG, PGFB, SET, OUTS, and OUT pins and the GND pin. Do not drive these pins more than 0.3V below the GND pin during a fault condition. These pins must remain at a voltage more positive than GND during normal operation. Note 11: The current limit programming scale factor is specified while the internal backup current limit is not active.
PAGE 6
LT3042 TYPICAL PERFORMANCE CHARACTERISTICS 100.4 100.2 100.0 99.8 99.6 99.4 1.0 0.5 0 –0.5 –1.0 20 14 0.08 6 1.5 3 4.5 6 7.5 9 10.5 12 13.5 15 OUTPUT VOLTAGE (V) Quiescent Current in Shutdown 20 VIN = 2V VEN/UV = VIN 2.5 IL = 10µA RSET = 13kΩ QUIESCENT CURRENT (µA) 1.5 1.0 0.5 Quiescent Current 2.5 VEN/UV = 0V 18 2.0 0 0 25 50 75 100 125 150 TEMPERATURE (°C) 3042 G09 16 14 12 VIN = 20V 10 8 VIN = 2V 6 4 QUIESCENT CURRENT (mA) Quiescent Current 0.04 0.02 3042 G08 3.0 0.
PAGE 7
LT3042 TYPICAL PERFORMANCE CHARACTERISTICS GND Pin Current GND Pin Current 8 VIN = 5V RSET = 33.2kΩ 9 6 IL = 150mA 5 4 IL = 100mA 3 2 GND PIN CURRENT (mA) IL = 1mA 7 6 5 4 3 2 0 50 75 100 125 150 175 200 OUTPUT CURRENT (mA) Minimum Input Voltage RSET = 33.2kΩ 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 10 9 3042 G18 EN/UV Turn-On Threshold EN/UV Pin Hysteresis 1.32 250 1.30 225 1.50 TURN-ON THRESHOLD (V) FALLING UVLO 1.25 1.00 0.75 0.50 EN/UV PIN HYSTERESIS (mV) RISING UVLO 1.
PAGE 8
LT3042 TYPICAL PERFORMANCE CHARACTERISTICS Input Pin Current Internal Current Limit 150°C 125°C 25°C –55°C 450 Internal Current Limit 300 RILIM = 0Ω VOUT = 0V 250 400 0.2 0.1 350 CURRENT LIMIT (mA) VIN = 2V 500 CURRENT LIMIT (mA) INPUT CURRENT (mA) 0.3 TJ = 25°C, unless otherwise noted. VIN = 7.5V 300 250 VIN = 2.
PAGE 9
LT3042 TYPICAL PERFORMANCE CHARACTERISTICS PG Output Low Voltage 30 60 25 20 ISET (mA) 70 50 40 15 30 10 20 5 10 10 VPGFB = 290mV VSET = 1.3V OUTPUT SINK CURRENT (mA) 2.0 1.5 1.0 0.5 2 8 4 2 VOUT Forced Above VOUT(NOMINAL) 0 5 PSRR (dB) CURRENT (mA) 8 6 OUTPUT CURRENT 0 4 5 6 7 8 9 10 11 12 13 14 15 OUTPUT VOLTAGE (V) 3042 G40 3 2 0 –75 –50 –25 20 3042 G39 Power Supply Ripple Rejection 120 110 90 CSET = 0.
PAGE 10
LT3042 TYPICAL PERFORMANCE CHARACTERISTICS Power Supply Ripple Rejection as a Function of Error Amplifier Input Pair 100 110 110 90 100 100 80 90 90 70 80 80 60 70 60 30 20 10 100 70 60 50 IL = 200mA IL = 100mA IL = 50mA IL = 1mA 10k 100k 1k FREQUENCY (Hz) 1M VIN = VOUT + 2V IL = 200mA COUT = 4.7µF CSET = 0.47µF 40 30 20 10M 10 100 10k 100k 1k FREQUENCY (Hz) 9 1.2 1.0 0.8 0.6 0.4 0 7 6 5 4 3 2 0.1 1 10 SET PIN CAPACITANCE (µF) 3042 G46 0.1 1.6 1.4 1.2 1.0 0.8 0.6 0.
PAGE 11
LT3042 TYPICAL PERFORMANCE CHARACTERISTICS Noise Spectral Density as a Function of Error Amplifier Input Pair OUTPUT NOISE (nV/√Hz) 1000 Output Noise: 10Hz to 100kHz Load Transient Response VOUT ≥ 1.3V 0.6V < VOUT < 1.3V VOUT ≤ 0.6V 100 200mA/DIV 5µV/DIV 10mV/DIV 10 1 0.1 TJ = 25°C, unless otherwise noted. VIN = 5V RSET = 33.2kΩ COUT = 4.7µF CSET = 4.7µF IL = 200mA VIN = VOUT + 2V IL = 200mA COUT = 4.7µF CSET = 4.
PAGE 12
LT3042 PIN FUNCTIONS IN (Pins 1, 2): Input. These pins supply power to the regulator. The LT3042 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
LT3042 PIN FUNCTIONS OUTS (Pin 9): 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. Moreover, place the input and output capacitors (and their GND connections) very close together.
PAGE 14
LT3042 APPLICATIONS INFORMATION The LT3042 is a high performance low dropout linear regulator featuring LTC’s ultralow noise (2nV/√Hz at 10kHz) and ultrahigh PSRR (79dB 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 LT3042 can be easily paralleled to further reduce noise, increase output current and spread heat on the PCB.
PAGE 15
LT3042 APPLICATIONS INFORMATION 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 2illustrates a typical guard ring layout technique.
PAGE 16
LT3042 APPLICATIONS INFORMATION –40 –60 Y5V –80 –100 0 2 4 16 14 6 12 8 10 DC BIAS VOLTAGE (V) 3042 F04 Figure 4. Ceramic Capacitor DC Bias Characteristics 40 BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10µF 20 X5R 0 –20 –40 Y5V –60 LT3042 applications in high vibration environments have three distinct piezoelectric noise generators: ceramic output, input, and SET pin capacitors.
PAGE 17
LT3042 APPLICATIONS INFORMATION and ESL tolerance, any non-piezoelectrically responsive (tantalum, electrolytic, or film) capacitor can be used at the SET pin – although electrolytic capacitors tend to have high 1/f noise. In any case, use of surface mount capacitor is highly recommended. Stability and Input Capacitance The LT3042 is stable with a minimum 4.7µF IN pin capacitor. LTC recommends using low ESR ceramic capacitors.
PAGE 18
LT3042 APPLICATIONS INFORMATION To that end, LTC recommends using the LT3042 demo board (DC2246B) layout for achieving the best possible PSRR performance. The LT3042 demo board layout utilizes magnetic field cancellation techniques to prevent PSRR degradation caused by this high-frequency current flow—while utilizing the input capacitor.
PAGE 19
LT3042 APPLICATIONS INFORMATION ENABLE/UVLO The EN/UV pin is used to put the regulator into a micropower shutdown state. The LT3042 has an accurate 1.24V turn-on threshold on the EN/UV pin with 170mV of hysteresis. This threshold can be used in conjunction with a resistor divider from the input supply to define an accurate undervoltage lockout (UVLO) threshold for the regulator.
PAGE 20
LT3042 APPLICATIONS INFORMATION PCB Layout Considerations Table 2. PC Board Trace Resistance WEIGHT (oz) 10mil WIDTH 20mil WIDTH 1 54.3 27.1 2 27.1 13.6 Trace resistance is measured in mΩ/in. The small worst-case offset of 2mV for each paralleled LT3042 minimizes the required ballast resistor value. Figure 7 illustrates that two LT3042s, each using a 50mΩ PCB trace ballast resistor, provide better than 20% accurate output current sharing at full load.
PAGE 21
LT3042 APPLICATIONS INFORMATION Thermal Considerations Table 3. Measured Thermal Resistance for DFN Package The LT3042 has internal power and thermal limiting circuits that protect the device under overload conditions. The thermal shutdown temperature is nominally 162°C with about 8°C of hysteresis. For continuous normal load conditions, do not exceed the maximum junction temperature, (125°C for E-, I-grades and 150°C for H-, MP-grades).
PAGE 22
LT3042 APPLICATIONS INFORMATION The maximum junction temperature equals the maximum ambient temperature plus the maximum junction temperature rise above ambient: TJMAX = 85°C + 20.7°C = 105.7°C Overload Recovery Like many IC power regulators, the LT3042 incorporates safe-operating-area (SOA) protection. The SOA protection activates at input-to-output differential voltages greater than 12V.
PAGE 23
LT3042 TYPICAL APPLICATIONS 12VIN to 3.3VOUT with 0.8µVRMS Integrated Noise VIN 12V ±5% LT3042 IN 4.7µF 100µA EN/UV 200k – + VOUT 3.3V IOUT(MAX) 100mA OUT PG OUTS SET ILIM GND PGFB 4.7µF 453k 1k 33.2k 4.7µF 49.9k 3042 TA02 PGFB Disabled without Reverse Input Protection LT3042 IN VIN 4.7µF PGFB Disabled with Reverse Input Protection 4.7µF 100µA – + EN/UV – + 1N4148 OUT PG 0.47µF 100µA EN/UV PGFB OUT VOUT PGFB OUTS SET LT3042 IN VIN GND ILIM PG 4.7µF RSET 0.
PAGE 24
LT3042 TYPICAL APPLICATIONS Programming Undervoltage Lockout VIN 4V Turn-ON 3.4V Turn-OFF 4.7µF ⎛ 110k ⎞⎟ VIN(UVLO) = 1.24V • ⎜⎜ 1+ ⎟ ⎝ 49.9k ⎠ LT3042 IN 100µA PGFB REN2 110k PG – + VOUT 3.3V IOUT(MAX) 200mA OUT EN/UV REN1 49.9k OUTS SET 4.7µF GND ILIM 3042 TA06 0.47µF 33.2k Ratiometric Tracking LT3042 IN 100µA – + EN/UV PGFB IN VIN 5.5V TO 20V EN/UV 0.1µF PGFB OUT PG OUTS SET 0.1µF 24 Downloaded from Arrow.com. GND ILIM 4.7µF VOUT 5V OUTS SET 100µA 4.
PAGE 25
LT3042 TYPICAL APPLICATIONS Ultralow 1/f Noise Reference Buffer VIN 6V ±5% LT3042 IN 100µA 4.7µF – + EN/UV PGFB 1,2 PG 6,7 LTC6655-5 OUTS SET 3,4,5 VOUT = 5V IOUT(MAX) 200mA OUT GND 4.7µF ILIM 1k 3042 TA08 10µF 49.9k 4.7µF Paralleling Multiple Devices Using ILIM (Current Monitor) to Cancel Ballast Resistor Drop LT3042 IN 22µF LT3042 100µA EN/UV VOUT = 3.3V IOUT(MAX) = 400mA PGFB OUT PG OUTS SET IN 100µA – + GND ILIM + – VIN 5V ±5% OUT 50mΩ 50mΩ 4.7µF 4.
PAGE 26
LT3042 TYPICAL APPLICATIONS Paralleling Multiple LT3042s for Higher Output Current LT3042 IN VIN 5V ±5% 4.7µF LT3042 100µA IN 100µA EN/UV PNP Q1 PNP Q2 OUT OUT 200k PG 50mΩ OUTS SET ILIM GND PGFB 50mΩ 4.7µF + – – + EN/UV PGFB PG OUTS ILIM 4.7µF GND SET 453k 49.9k VOUT = 3.3V IOUT(MAX) = 800mA DROPOUT = 350mV 0.8µVRMS 4 = 0.4µVRMS OUTPUT NOISE = LT3042 IN LT3042 100µA 100µA PNP Q4 PGFB PNP Q3 OUT PG OUT OUTS SET GND ILIM 4.7µF 50mΩ 50mΩ 4.7µF 4.
PAGE 27
LT3042 TYPICAL APPLICATIONS Ultralow Noise Higher Current Regulator with External PNP VIN 5.5V ±5% 22µF 47µF 0.2Ω 10Ω D45VH10G 150k PGFB LT3042 100µA EN/UV 49.9k IN – + VOUT 3.3V IOUT(MAX) 1.5A 10µF OUT PG OUTS SET 4.7µF GND ILIM 750Ω 33.2k 3042 TA11 Ultralow Noise Higher Current Regulator with External NPN VIN 5V ±5% 47µF LT3042 IN 100µA – + EN/UV 4.7µF OUT PG D44VH10 10µF 10k OUTS SET 4.7µF 20k GND ILIM PGFB 750Ω 249k VOUT 2V 10µF IOUT(MAX) 1A 49.
PAGE 28
LT3042 TYPICAL APPLICATIONS Low Noise Wheatstone Bridge Power Supply LT1763 NOISE: 20µVRMS (10Hz TO 100kHz) LT3042 NOISE: 0.8µVRMS (10Hz TO 100kHz) LT3042 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 LT3042 PERFECT MATCHING INFINITE – – 1% 40dB 200nVRMS 8nVRMS 5% 26dB 1000nVRMS 42.5nVRMS VOUT: 3.3V AND IOUT(MAX): 200mA R1 OUTS SET GND ILIM PGFB 4.7µF 453k + R2 4.7µF 33.
PAGE 29
LT3042 PACKAGE DESCRIPTION Please refer to http://www.linear.com/product/LT3042#packaging for the most recent package drawings. DD Package Package 10-Lead Plastic DFNDD (3mm × 3mm) 10-Lead Plastic DFN (3mm (Reference LTC DWG # 05-08-1699 Rev C)× 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.
PAGE 30
LT3042 PACKAGE DESCRIPTION Please refer to http://www.linear.com/product/LT3042#packaging for the most recent package drawings. MSE Package 10-Lead Plastic MSOP, Exposed Die Pad MSE Package (Reference LTC DWG # 05-08-1664 Rev I) 10-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1664 Rev I) BOTTOM VIEW OF EXPOSED PAD OPTION 1.88 ±0.102 (.074 ±.004) 5.10 (.201) MIN 1 0.889 ±0.127 (.035 ±.005) 1.68 ±0.102 (.066 ±.004) 0.05 REF 10 3.00 ±0.102 (.118 ±.
PAGE 31
LT3042 REVISION HISTORY REV DATE DESCRIPTION A 6/15 Updated text in the second paragraph 1 Updated Line Reg ∆VOS, Change in VOS, Output Noise Spectral Density specs 3 Updated text to clarify fast start-up test condition 4 Updated text to clarify Notes 5, 6, and 7 4 Updated text to clarify Note 10 5 Updated Graph 10 and Graph 12 6 Updated conditions on Graph 18 and Graph 24 7 Updated conditions on Graph 28 8 Updated title of Graph 40 Updated Output Voltage section B 11/17 PAGE NUMBER
PAGE 32
LT3042 TYPICAL APPLICATION Parallel Devices LT3042 IN VIN 5V ±5% 100µA 10µF – + EN/UV OUT PGFB 50mΩ OUTS SET ILIM GND PG 4.7µF VOUT 3.3V IOUT(MAX) 400mA LT3042 IN 100µA – + EN/UV OUT PGFB 50mΩ OUTS SET GND ILIM PG 4.7µF 3042 TA14 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 LT1763 500mA, Low Noise LDO 300mV Dropout Voltage, Low Noise: 20μVRMS, VIN = 1.