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LT3050 Series

3050fa

TYPICAL APPLICATION

DESCRIPTION

100mA, Linear Regulator

with Precision Current Limit

and Diagnostic Outputs

The LT

3050 series are micro-power, low noise, low

dropout voltage (LDO) linear regulators. The devices

supply 100mA of output current with a dropout voltage of

340mV. A 10nF bypass capacitor reduces output noise to

30V

RMS

in a 10Hz to 100kHz bandwidth and soft-starts

the reference. The LT3050’s ±45V input voltage rating

combined with its precision current limit and diagnostic

functions make the IC an ideal choice for robust, high

reliability applications.

A single resistor programs the LT3050’s current limit, accurate

to ±5% over a wide input voltage and temperature range.

A single resistor programs the LT3050’s minimum output

current monitor, useful for detecting open-circuit conditions.

The current monitor function sources a current equal to

1/100th of output current. A logic FAULT pin asserts low if

the LT3050 is in current limit, operating below its minimum

output current (open-circuit) or is in thermal shutdown.

The LT3050 optimizes stability and transient response

with low ESR ceramic capacitors, requiring a minimum of

2.2F. The LT3050 is available in ﬁ xed output voltages of

3.3V and 5V, and as an adjustable version with an output

voltage range down to the 0.6V reference.The LT3050 is

available in the thermally-enhanced 12-Lead 3mm × 2mm

DFN and MSOP packages.

5V Supply with 100mA Precision Current Limit, 10mA I

MIN

FEATURES

APPLICATIONS

Output Current Monitor: 1/100

of I

OUT

Fault Indicator: Current Limit, Minimum I

OUT

Thermal Limit

Output Current: 100mA

Dropout Voltage: 340mV

Input Voltage Range: 1.6V to 45V

Programmable Precision Current Limit: ±5%

Programmable Minimum I

OUT

Monitor

Low Noise: 30μV

RMS

(10Hz to 100kHz)

Adjustable Output (V

REF

= V

OUT(MIN)

= 0.6V)

Fixed Output Voltages: 3.3V, 5V

Output Tolerance: ±2% Over Line, Load and Temperature

Stable with Low ESR, Ceramic Output Capacitors

(2.2F minimum)

Shutdown Current: <1A

Reverse-Battery, Reverse-Output and

Reverse-Current Protection

Thermal Limit Protection

12-Lead 3mm × 2mm DFN and MSOP Packages

Protected Antenna Supplies

Automotive Telematics

Industrial Applications (Trucks, Forklifts, etc.)

High Reliability Applications

External Current Limit R

IMAX

= 1.15k

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

1µF

12V

MON

MAX

MIN

FAULT

SHDN

GND

OUT

REF/BYP

LT3050-5

2.2µF

0.1µF

10nF

(ADC FULL SCALE = 3V)

TO µP ADC

0.1µF

11.3k

(THRESHOLD = 10mA)

10nF

1.15k

(THRESHOLD = 100mA)

120k

3050 TA01

TEMPERATURE (°C)

CURRENT LIMIT FAULT THRESHOLD (mA)

105

100

101

102

103

104

3050 TA01a

–75 –50 –25 0 –25 50 75 100 125 150 175

= 5.6V

= 12V

= 15V

OUT

= 5V

Summary of content (26 pages)

PAGE 1
LT3050 Series 100mA, Linear Regulator with Precision Current Limit and Diagnostic Outputs DESCRIPTION FEATURES n n n n n n n n n n n n n n n n Output Current Monitor: 1/100th of IOUT Fault Indicator: Current Limit, Minimum IOUT or Thermal Limit Output Current: 100mA Dropout Voltage: 340mV Input Voltage Range: 1.6V to 45V Programmable Precision Current Limit: ±5% Programmable Minimum IOUT Monitor Low Noise: 30μVRMS (10Hz to 100kHz) Adjustable Output (VREF = VOUT(MIN) = 0.6V) Fixed Output Voltages: 3.
PAGE 2
LT3050 Series ABSOLUTE MAXIMUM RATINGS (Note 1) IN Pin Voltage ........................................................ ±50V OUT Pin Voltage ..................................................... ±50V Input-to-Output Differential Voltage ....................... ±50V ADJ Pin Voltage (Note 16) ..................................... ±50V REF/BYP Pin Voltage ........................................–0.3V, 1V SHDN Pin Voltage ...................................................±50V IMON Pin Voltage ...............
PAGE 3
LT3050 Series ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3050EDDB-5#PBF LT3050EDDB-5#TRPBF LFWS 12-Lead (3mm × 2mm) Plastic DFN –40°C to 125°C LT3050IDDB-5#PBF LT3050IDDB-5#TRPBF LFWS 12-Lead (3mm × 2mm) Plastic DFN –40°C to 125°C LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3050EMSE LT3050EMSE#TR 3050 12-Lead Plastic MSOP –40°C to 125°C LT3050IMSE LT3050IMSE#TR 3050 12-Lead Plast
PAGE 4
LT3050 Series ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. (Note 2) PARAMETER CONDITIONS MIN Dropout Voltage VIN = VOUT(NOMINAL) (Notes 5, 6) ILOAD = 1mA ILOAD = 1mA l ILOAD = 10mA ILOAD = 10mA l ILOAD = 50mA ILOAD = 50mA l ILOAD = 100mA ILOAD = 100mA l GND Pin Current VIN = VOUT(NOMINAL) + 0.
PAGE 5
LT3050 Series ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum IMIN Threshold Accuracy (Notes 6, 9) LT3050-3.3: 3.9V < VIN < 13.3V, RIMIN = 110K LT3050, LT3050-5: 5.6V < VIN < 15V, RIMIN = 110K l l 0.92 0.9 1.03 1 1.13 1.1 mA mA IMIN Threshold Accuracy (Notes 6, 9) LT3050-3.3: 3.9V < VIN < 13.3V, RIMIN = 11.3K LT3050, LT3050-5: 5.
PAGE 6
LT3050 Series TYPICAL PERFORMANCE CHARACTERISTICS Guaranteed Dropout Voltage 550 550 500 500 TJ ≤ 125°C 400 350 300 250 TJ ≤ 25°C 200 150 Dropout Voltage 600 =TEST POINTS 550 TJ = 125°C 400 350 TJ = 25°C 300 250 200 150 450 350 250 200 100 50 50 0 0 0 –75 –50 –25 0 25 50 75 100 125 150 175 TEMPERATURE (°C) 10 20 30 40 50 60 70 80 90 100 OUTPUT CURRENT (mA) 3050 G01 IL = 1mA 150 100 0 IL = 10mA 300 50 10 20 30 40 50 60 70 80 90 100 OUTPUT CURRENT (mA) IL = 50mA 400 100 0 IL
PAGE 7
LT3050 Series TYPICAL PERFORMANCE CHARACTERISTICS GND Pin Current LT3050-5 5.0 VIN = 5.6V 4.5 VOUT = 5V 2.25 1.50 1.25 RL = 100Ω, IL = 50mA 1.00 0.75 RL = 5k, IL = 1mA 0.50 4.0 0 1 2 3.5 3.0 2.5 2.0 1.5 1.0 RL = 500Ω, IL = 10mA 0.25 SHDN PIN THRESHOLD (V) RL = 50Ω, IL = 100mA 1.75 GND PIN CURRENT (mA) GND PIN CURRENT (mA) 2.00 0.5 0 3 4 5 6 7 8 9 10 11 12 INPUT VOLTAGE (V) 0 10 20 30 40 50 60 70 80 90 100 ILOAD (mA) 3050 G07 2.0 1.5 1.0 0.5 ADJ Pin Bias Current 2.0 50 1.8 45 1.
PAGE 8
LT3050 Series TYPICAL PERFORMANCE CHARACTERISTICS Reverse Output Current Reverse Output Current VOUT = VADJ = 1.2V 45 VIN = 0 0.8 40 0.7 35 ALL PINS GROUNDED EXCEPT FOR OUT 0.6 0.5 0.4 25 20 15 0.2 10 0.1 5 20 30 VOUT (V) 40 IADJ IOUT 0 –75 –50 –25 0 25 50 75 100 125 150 175 TEMPERATURE (°C) 50 Input Ripple Rejection 90 80 70 RIPPLE REJECTION (dB) 40 30 20 IL = 100mA COUT = 10μF 10 VOUT = 5V VIN = 5.
PAGE 9
LT3050 Series TYPICAL PERFORMANCE CHARACTERISTICS Output Noise Spectral Density vs CREF/BYP, CFF = 0 1 VOUT = 5V VOUT = 3.3V VOUT = 2.5V VOUT = 1.8V VOUT = 1.5V VOUT = 1.2V VOUT = 0.6V 0.1 0.01 10 100 COUT = 10μF IL = 100mA 1K 10K FREQUENCY (Hz) 10 CREF/BYP = 100pF VOUT = 5V 1 VOUT = 0.6V 0.1 CREF/BYP = 10nF CREF/BYP = 1nF COUT = 10μF IL = 100mA 0.
PAGE 10
LT3050 Series TYPICAL PERFORMANCE CHARACTERISTICS 5V Transient Response CFF = 0, IOUT = 10mA to 100mA TJ = 25°C, unless otherwise noted.
PAGE 11
LT3050 Series TYPICAL PERFORMANCE CHARACTERISTICS External Current Limit RIMAX = 1.5k 78.00 VIN = 15V 76.50 VIN = 12V 75.75 75.00 VIN = 5.6V 74.25 73.50 72.75 104 103 VIN = 15V 102 101 100 VIN = 12V 99 VIN = 5.6V 98 97 96 72.00 –75 –50 –25 0 25 50 75 100 125 150 175 TEMPERATURE (°C) 95 –75 –50 –25 0 –25 50 75 100 125 150 175 TEMPERATURE (°C) 3050 G35 VOUT = 3.3V 1.10 1.07 VIN = 13.3V 1.04 1.01 VIN = 3.9V 0.98 0.95 0.92 –75 –50 –25 0 25 50 75 100 125 150 175 TEMPERATURE (°C) 11.
PAGE 12
LT3050 Series TYPICAL PERFORMANCE CHARACTERISTICS IOUT/IMON Current Ratio VOUT = 5V, VIN = 12V IOUT/IMON Current Ratio VOUT = 5, VIN = 5.6V 102 102 102 101 101 100 100 VIMON = 3.
PAGE 13
LT3050 Series PIN FUNCTIONS REF/BYP (Pin 1): Bypass/Soft-Start. Connecting a single capacitor from this pin to GND bypasses the LT3050’s reference noise and soft-starts the reference. A 10nF bypass capacitor typically reduces output voltage noise to 30μVRMS in a 10Hz to 100kHz bandwidth. Soft-start time is directly proportional to the REF/BYP capacitor value. If the LT3050 is placed in shutdown, REF/BYP is actively pulled low by an internal device to reset soft-start.
PAGE 14
LT3050 Series PIN FUNCTIONS For detailed information on how to set the IMAX pin resistor value, please see the Operation section. The IMAX pin requires a 10nF decoupling capacitor to ground. If not used, tie IMAX to GND. IMON (Pin 12): Output Current Monitor. This pin is the collector of a PNP current mirror that outputs 1/100th of the power PNP current. When OUT = IMON, the pin current exactly equals 1/100th that of the output current.
PAGE 15
LT3050 Series OPERATION IMON Pin Operation (Current Monitor) The IMON pin is the collector of a PNP which mirrors the LT3050 output PNP at a ratio of 1:100 (see block diagram on page 11). The current sourced by the IMON pin is ~1/100th of the current sourced by the OUT pin when the IMON and OUT pin voltages are equal and the device is not operating in dropout.
PAGE 16
LT3050 Series OPERATION External Programmable Current Limit (IMAX Pin) The IMAX pin is the collector of a PNP which mirrors the LT3050 output at a ratio of approximately 1:200 (see Block Diagram). The IMAX pin is also the input to the precision current limit ampliﬁer. If the output load increases to the point where it causes the IMAX pin voltage to reach 0.6V, the current limit ampliﬁer takes control of output regulation so that the IMAX pin clamps at 0.6V, regardless of the output voltage.
PAGE 17
LT3050 Series APPLICATIONS INFORMATION The LT3050 is a micropower, low noise and low dropout voltage, 100mA linear regulator with micropower shutdown, programmable current limit, and diagnostic functions. The device supplies up to 100mA at a typical dropout voltage of 340mV and operates over a 2.2V to 45V input range. A single external capacitor can provide low noise reference performance and output soft-start functionality.
PAGE 18
LT3050 Series APPLICATIONS INFORMATION Table 1. Output Voltage Resistor Divider Valves VOUT (V) R1 (kΩ) R2 (kΩ) 1.2 118 118 1.5 121 182 1.8 124 249 2.5 115 365 3 124 499 3.3 124 562 5 115 845 Bypass Capacitance, Output Voltage Noise and Transient Response The LT3050 regulator provides low output voltage noise over the 10Hz to 100kHz bandwidth while operating at full load with the addition of a reference bypass capacitor (CREF/BYP) from the REF/BYP pin to GND.
PAGE 19
LT3050 Series APPLICATIONS INFORMATION Start-up time is also affected by the presence of a feedforward capacitor. Start-up time is directly proportional to the size of the feedforward capacitor and the output voltage, and is inversely proportional to the feedback resistor divider current, slowing to 15ms with a 4.7nF feedforward capacitor and a 10μF output capacitor for an output voltage set to 5V by a 5μA feedback resistor divider.
PAGE 20
LT3050 Series APPLICATIONS INFORMATION VOUT = 5V COUT = 10μF CREF/BYP = 10nF VOUT 1mV/DIV 3050 F06 10ms/DIV Figure 6. Noise Resulting from Tapping on a Ceramic Capacitor Voltage and temperature coefﬁcients are not the only sources of problems. Some ceramic capacitors have a piezoelectric response. A piezoelectric device generates voltage across its terminals due to mechanical stress, similar to the way a piezoelectric accelerometer or microphone works.
PAGE 21
LT3050 Series APPLICATIONS INFORMATION For surface mount devices, heat sinking is accomplished by using the heat spreading capabilities of the PC board and its copper traces. Copper board stiffeners and plated through-holes also can spread the heat generated by power devices. The following tables list thermal resistance as a function of copper area in a ﬁxed board size.
PAGE 22
LT3050 Series APPLICATIONS INFORMATION The LT3050 IN pin withstands reverse voltages of 50V. The device limits current ﬂow to less than 300μA (typically less than 10μA) and no negative voltage appears at OUT. The device protects both itself and the load against batteries that are plugged in backwards. The SHDN pin cannot be driven below GND unless tied to the IN pin. If the SHDN pin is driven below GND while IN is powered, the output may turn on. SHDN pin logic cannot be referenced to a negative rail.
PAGE 23
LT3050 Series PACKAGE DESCRIPTION DDB Package 12-Lead Plastic DFN (3mm × 2mm) (Reference LTC DWG # 05-08-1723 Rev Ø) 0.64 ±0.05 (2 SIDES) 3.00 ±0.10 (2 SIDES) R = 0.05 TYP R = 0.115 TYP 7 0.40 ± 0.10 12 0.70 ±0.05 2.55 ±0.05 1.15 ±0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.45 BSC 2.00 ±0.10 (2 SIDES) PIN 1 BAR TOP MARK (SEE NOTE 6) 0.200 REF 0.75 ±0.05 0.64 ± 0.10 (2 SIDES) 6 0.23 ± 0.05 2.39 ±0.
PAGE 24
LT3050 Series PACKAGE DESCRIPTION MSE Package 12-Lead Plastic MSOP Exposed Die Pad (Reference LTC DWG # 05-08-1666 Rev B) BOTTOM VIEW OF EXPOSED PAD OPTION 2.845 p 0.102 (.112 p .004) 5.23 (.206) MIN 2.845 p 0.102 (.112 p .004) 0.889 p 0.127 (.035 p .005) 6 1 1.651 p 0.102 3.20 – 3.45 (.065 p .004) (.126 – .136) 0.12 REF 12 0.65 0.42 p 0.038 (.0256) (.0165 p .0015) BSC TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 0.35 REF 4.039 p 0.102 (.159 p .
PAGE 25
LT3050 Series REVISION HISTORY REV DATE DESCRIPTION PAGE NUMBER A 6/10 Updated data sheet to include ﬁxed voltage options. 1-14, 17-26 3050fa Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
PAGE 26
LT3050 Series TYPICAL APPLICATION 5V Protected Antenna Supply with 100mA Current Limit, 10mA IMIN IN 12V VIN 1μF 120k OUT 5V CFF 10nF SHDN 10μF ADJ FAULT LT3050-5 IMAX 10nF 1.15k (THRESHOLD = 100mA) IMON IMIN 0.1μF 11.3k (THRESHOLD = 10mA) TO μP ADC 3k (ADC FULL SCALE = 3V) 0.1μF REF/BYP 10nF GND 3050 TA02 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1761 100mA, Low Noise LDO 300mV Dropout Voltage, Low Noise: 20μVRMS , VIN = 1.