MIC5270YM5 - Micrel Semiconductor, Inc.

May 2005 1 M9999-052705

MIC5270 Micrel, Inc.

MIC5270

µCap Negative Low-Dropout Regulator

General Description

The MIC5270 is a µCap 100mA negative regulator in a

SOT-23-5 package. With better than 2% initial accuracy, this

regulator provides a very accurate supply voltage for applica-

tions that require a negative rail. The MIC5270 sinks 100mA

of output current at very low dropout voltage (600mV maxi-

mum at 100mA of output current).

The µCap regulator design is optimized to work with low-

value, low-cost ceramic capacitors. The output typically re-

quires only a 1µF capacitance for stability.

Designed for applications where small packaging and effi-

ciency are critical, the MIC5270 combines LDO design exper-

tise with IttyBitty® packaging to improve performance and

reduce power dissipation. Ground current is optimized to help

improve battery life in portable applications.

The MIC5270 is available in the SOT-23-5 package for space

saving applications and it is available with fixed –3.0V, –4.1V,

–5.0V, and adjustable outputs.

Data sheets and support documentation can be found on

Micrel’s web site at www.micrel.com.

Typical Application

Features

•Stable with ceramic or tantalum capacitor

•Low dropout voltage: 500mV @ 100mA

•Low ground current: 35µA @ load = 100µA

•Tight initial accuracy: ±2%

•Tight load and line regulation

•Thermal shutdown

•Current limiting

•IttyBitty® SOT-23-5 packaging

Applications

•GaAsFET bias

•Portable cameras and video recorders

•PDAs

•Battery-powered equipment

IttyBitty is a registered trademark of Micrel, Inc.

Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

Ordering Information

Part Number Junction

Standard Marking Code PbFree Marking Code Voltage Temp. Range Package

MIC5270BM5 LLAA MIC5270YM5 LLAA Adj. –40°C to +125°CSOT-23-5

MIC5270-3.0BM5 LL30 MIC5270-3.0YM5 LL30 –3.0V –40°C to +125°CSOT-23-5

MIC5270-4.1BM5 LL41 MIC5270-4.1YM5 LL41 –4.1V –40°C to +125°CSOT-23-5

MIC5270-5.0BM5 LL50 MIC5270-5.0YM5 LL50 –5.0V –40°C to +125°CSOT-23-5

MIC5270-5.0BM5

GND

–OUT–IN

1µF10µF

–5.0V–6.0V

VIN

VOUT

Regulator With Fixed Output

MIC5270BM5

GND

–OUT–IN

1µF 10µF

–5.0V

–6.0V

OUT

ADJ

Regulator With Adjustable Output

MIC5270 Micrel, Inc.

M9999-052705 2May 2005

Pin Configuration

–IN–OUT

ADJ

LLAA

GND

MIC5270BM5

Adjustable Voltage

Pin Description

Pin Number Pin Number Pin Name Pin Function

(Adj.) (Fixed)

11 NC Not internally connected.

22 GND Ground.

3NCNot internally connected.

3ADJ Adjustable (Input): Adjustable feedback output connects to resistor voltage

divider.

44 –OUT Negative Regulator Output.

55 –IN Negative Supply Input.

–IN

–

OUT

LLxx

GND

MIC5270-x.xBM5

Fixed Output Voltage

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MIC5270 Micrel, Inc.

Absolute Maximum Ratings (Note 1)

Input Voltage (VIN)....................................... –20V to +0.3V

Power Dissipation (PD)............................ Internally Limited

Junction Temperature (TJ)....................... –40°C to +125°C

Lead Temperature (soldering, 5 sec.) ....................... 260°C

Storage Temperature (TS)....................... –65°C to +150°C

ESD Rating, Note 3

Operating Ratings (Note 2)

Input Voltage (VIN)....................................... –16V to –3.3V

Junction Temperature (TJ)....................... –40°C to +125°C

Thermal Resistance (θJA)........................................ Note 4

Electrical Characteristics (Note 5)

VIN = VOUT – 1.0V; COUT = 4.7µF, IOUT = 100µA; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted.

Symbol Parameter Condition Min Typ Max Units

VOUT Output Voltage Accuracy Variation from nominal VOUT –2 2 %

–3 3 %

∆VOUT/∆TOutput Voltage Temperature Note 6 100 ppm/°C

Coefficient

∆VOUT/VOUT Line Regulation VIN = VOUT – 1V to –16V 0.05 0.15 %/V

0.2

∆VOUT/VOUT Load Regulation IOUT = 100µA to 100mA, Note 7 1.5 1.8 %

2.0 %

VIN – VOUT Dropout Voltage, Note 8 IOUT = 100µA40mV

IOUT = 50mA 360 500 mV

IOUT = 100mA 500 700 mV

900

IGND Ground Current, Note 9 IOUT = 100µA35100 µA

IOUT = 50mA 0.7 mA

IOUT = 100mA 2.1 3.0 mA

PSRR Ripple Rejection f = 120Hz 50 dB

ILIMIT Current Limit VOUT = 0V 160 300 mA

∆VOUT/∆PDThermal Regulation Note 10 0.05 %/W

Note 1. Exceeding the absolute maximum rating may damage the device.

Note 2. The device is not guaranteed to function outside its operating rating.

Note 3. Devices are ESD sensitive. Handling precautions recommended.

Note 4. The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(max), the junction-to-ambient thermal

resistance, θJA, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using:

PD(max) = (T

J(max) –

A) ÷ θJA, where θJA is 235°C/W. Exceeding the maximum allowable power dissipation will result in excessive die

temperature, and the regulator will go into thermal shutdown. See the “Thermal Considerations” section for details.

Note 5. Specification for packaged product only.

Note 6. Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.

Note 7. Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load

range from 100µA to 100mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.

Note 8. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1V

differential.

Note 9. Ground pin current is the regulator quiescent current plus pass transistor base current. The total current drawn from the supply is the sum of

the load current plus the ground pin current.

Note 10. Thermal regulation is defined as the change in output voltage at a time “t” after a change in power dissipation is applied, excluding load or line

regulation effects. Specifications are for a 100mA load pulse at VIN = –16V for t = 10ms.

MIC5270 Micrel, Inc.

M9999-052705 4May 2005

Typical Characteristics

-0.5

-1

-1.5

-2

-2.5

-3

-3.5

0-1-2-3-4-5

OUTPUT VOLTAGE (V)

SUPPLY VOLTAGE (V)

Dropout

Characteristics

0 Load

-100mA Load

-3.26

-3.265

-3.27

-3.275

-3.28

-3.285

-3.29

-3.295

-3.3

-3.305

0 -20 -40 -60 -80 -100

OUTPUT VOLTAGE (V)

OUTPUT CURRENT (mA)

Output Voltage

vs. Out

ut Current

-3.2

-3.22

-3.24

-3.26

-3.28

-3.3

-3.32

-3.34

-3.36

-3.38

-3.4

-40 -20 0 20 40 60 80 100 120

UTPUT V

LTAGE (V)

TEMPERATURE (°C)

Output Voltage

vs. Temperature

-0.5

-1

-1.5

-2

-2.5

0-20-40-60 -80 -100

GROUND CURRENT (mA)

OUTPUT CURRENT (mA)

Ground Current

vs. Output Current

-10

-20

-30

-40

-50

-60

-70

-80

-90

0-1-2-3-4-5

GROUND CURRENT (µA)

SUPPLY VOLTAGE (V)

Ground Current

Characteristics

0µA Load

-100µA Load

-1mA Load

-0.5

-1

-1.5

-2

-2.5

0-1-2-3-4-5

UND

URRENT (mA)

SUPPLY VOLTAGE (V)

Ground Current

Characteristics

-100mA Load

-50mA Load

-10mA Load

-5

-10

-15

-20

-25

-30

-40 -20 0 20 40 60 80 100 120

UND

URRENT (µA)

TEMPERATURE (°C)

Ground Current

vs. Temperature

0A Load

-1mA Load

-0.5

-1

-1.5

-2

-2.5

-3

-3.5

-40 -20 0 20 40 60 80 100 120

GROUND CURRENT (µA)

TEMPERATURE (°C)

Ground Current

vs. Temperature

-50A Load

-100mA Load

-0.2

-0.4

-0.6

-0.8

-1

-1.2

-1.4

-1.6

-4 -7 -10 -13 -16

ENABLE THRESHOLD (V)

SUPPLY VOLTAGE (V)

Negative Enable Threshold

vs. Supply Voltage

Enable Off

Enable On

-100

-200

-300

-400

-500

-600

0-20-40-60 -80 -100

DROPOUT VOLTAGE (mV)

OUTPUT CURRENT (mA)

Dropout

vs. Output Current

-50

-100

-150

-200

-250

-300

-350

-400

-40 -20 0 20 40 60 80 100 120

DROPOUT VOLTAGE (mV)

TEMPERATURE (°C)

Dropout

vs. Temperature

0A Load

-10mA Load

-100

-200

-300

-400

-500

-600

-700

-40 -20 0 20 40 60 80 100 120

UT V

LTAGE (mV)

TEMPERATURE (°C)

Dropout

vs. Temperature

-50mA Load

-100mA Load

May 2005 5 M9999-052705

MIC5270 Micrel, Inc.

Functional Characteristics

Load Transient

TIME (2ms/div.)

-100mA

OUT

= 1µF Ceramic

= 5V

OUT

= 3V

-10mA

Output Current

(50mA/div.)

OUT

(10mV/div.)

Load Transient

TIME (2ms/div.)

-100mA C

OUT

= 1µF Ceramic

= 5V

OUT

= 3V

-10mA

Output Current

(50mA/div.)

OUT

(10mV/div.)

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MIC5270 Micrel, Inc.

M9999-052705 6May 2005

Functional Diagram

VIN VOUT

GND

MIC5270-x.x

May 2005 7 M9999-052705

MIC5270 Micrel, Inc.

Applications Information

The MIC5270 is a general-purpose negative regulator that

can be used in any system that requires a clean negative

voltage from a negative output. This includes post regulating

of DC-DC converters (transformer based or charge pump

based voltage converters). These negative voltages typically

require a negative low-dropout voltage regulator to provide a

clean output from typically noisy lines.

Input Capacitor

A 1µF input capacitor should be placed from IN to GND if

there is more than 2 inches of wire or trace between the input

and the AC filter capacitor, or if a battery is used as the input.

Output Capacitor

The MIC5270 requires an output capacitor for stable opera-

tion. A minimum of 1µF of output capacitance is required. The

output capacitor can be increased without limitation to im-

prove transient response. The output does not require ESR

to maintain stability, therefore a ceramic capacitor can be

used. High-ESR capacitors may cause instability. Capacitors

with an ESR of 3Ω or greater at 100kHz may cause a high

frequency oscillation.

Low-ESR tantalums are recommended due to the tight ca-

pacitance tolerance over temperature.

Ceramic chip capacitors have a much greater dependence

on temperature, depending upon the dielectric. The X7R is

recommended for ceramic capacitors because the dielectric

will change capacitance value by approximately 15% over

temperature. The Z5U dielectric can change capacitance

value by as much 50% over temperature, and the Y5V

dielectric can change capacitance value by as much as 60%

over temperature. To use a ceramic chip capacitor with the

Y5V dielectric, the value must be much higher than a tanta-

lum to ensure the same minimum capacitor value over

temperature.

No-Load Stability

The MIC5270 does not require a load for stability.

Thermal Considerations

Absolute values will be used for thermal calculations to clarify

what is meant by power dissipation and voltage drops across

the part.

Proper thermal design for the MIC5270-5.0BM5 can be

accomplished with some basic design criteria and some

simple equations. The following information must be known

to implement your regulator design:

VIN = input voltage

VOUT = output voltage

IOUT = output current

TA = ambient operating temperature

IGND = ground current

Maximum power dissipation can be determined by knowing

the ambient temperature, TA, the maximum junction tem-

perature, 125°C, and the thermal resistance, junction to

ambient. The thermal resistance for this part, assuming a

minimum footprint board layout, is 235°C/W. The maximum

power dissipation at an ambient temperature of 25°C can be

determined with the following equation:

PTT

D(max)

J(max) A

=−

P125 C 25 C

235 C/W

D(max) =°−°

P 425mW

D(max) =

The actual power dissipation of the regulator circuit can be

determined using one simple equation.

PVV I VI

DIN

OUT OUT IN GND

=−

()

+⋅

Substituting PD(max), determined above, for PD and solving

for the operating conditions that are critical to the application

will give the maximum operating conditions for the regulator

circuit. The maximum power dissipation number cannot be

exceeded for proper operation of the device. The maximum

input voltage can be determined using the output voltage of

5.0V and an output current of 100mA. Ground current, of 1mA

for 100mA of output current, can be taken from the “Electrical

Characteristics ” section of the data sheet.

425mW V 5.0V 100mA V 1mA

IN IN

=−

()

+×

425mW 100mA V 1mA V 500mW

IN IN

=×+×

()

−

925mW 101mA V

=×

V9.16Vmax

IN =

Therefore, a –5.0V application at 100mA of output current

can accept a maximum input voltage of –9.16V in a SOT-23-5

package. For a full discussion of heat sinking and thermal

effects on voltage regulators, refer to Regulator Thermals

section of Micrel’s “Designing with Low-Dropout Voltage

Regulators ” handbook.

Adjustable Regulator Application

MIC5270BM

GND

–OUT–IN

–V

OUT

ADJ

Figure 1. Adjustable Voltage Application

The MIC5270BM5 can be adjusted from 1.20V to 14V by

using two external resistors (Figure 1). The resistors set the

output voltage based on the following equation:

VOUT  = VREF (1 +

)

Where VREF = 1.20V

MIC5270 Micrel, Inc.

M9999-052705 8May 2005

Package Information

0.20 (0.008)

0.09 (0.004)

0.60 (0.024)

0.10 (0.004)

3.02 (0.119)

2.80 (0.110) 10°

0°

3.00 (0.118)

2.60 (0.102)

1.75 (0.069)

1.50 (0.059)

0.95 (0.037) REF

1.30 (0.051)

0.90 (0.035)

0.15 (0.006)

0.00 (0.000)

DIMENSIONS:

MM (INCH)

0.50 (0.020)

0.35 (0.014)

1.90 (0.075) REF

SOT-23-5 (M5)

MICREL INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL + 1 (408) 944-0800 FAX + 1 (408) 474-1000 WEB http://www.micrel.com

This information furnished by Micrel in this data sheet is believed to be accurate and reliable. However no responsibility is assumed by Micrel for its use.

Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.

Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can

reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into

the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s

use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify

Micrel for any damages resulting from such use or sale.