MIC5321-SOYD6 - Micrel Semiconductor, Inc.

MIC5321

Dual, High Performance 150mA µCap ULDO™

ULDO is a trademark of Micrel, Inc.

MLF and MicroLeadFrame are registered trademarks of Amkor Technology, 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

July 2006

M9999-073106

General Description

The MIC5321 is a tiny Dual Ultra Low-Dropout

(ULDO™) linear regulator ideally suited for those

applications that require high PSRR because it

provides a bypass pin for those noise sensitive

portable electronics. The MIC5321 integrates two

high-performance; 150mA ULDOs into a very compact

1.6mm x 1.6mm leadless MLF ® package that

provides exceptional thermal package characteristics.

The MIC5321 is a µCap design which enables

operation with very small ceramic output capacitors

for stability, thereby reducing required board space

and component cost. The combination of extremely

low-drop-out voltage, very high power supply

rejection, very low output noise and exceptional

thermal package characteristics makes it ideal for

powering RF application, cellular phone camera

modules, imaging sensors for digital still cameras,

PDAs, MP3 players and WebCam applications.

The MIC5321 ULDO™ is available in fixed-output

voltages in the tiny 6-pin 1.6mm x 1.6mm leadless

MLF ® package which is only 2.56mm

in area, less

than 30% the area of the SOT-23, TSOP and MLF

3x3 packages. It’s also available in the thin SOT-23-6

lead package. Additional voltage options are

available. For more information, contact Micrel

marketing department.

Data sheets and support documentation can be found

on Micrel’s web site at www.micrel.com.

Features

• 2.3V to 5.5V input voltage range

• Ultra-low dropout voltage ULDO™ 35mV @

150mA

• Tiny 6-pin 1.6mm x 1.6mm MLF

leadless

package

• Low cost TSOT-23-6 package

• Bypass pin for improved noise performance

High PSRR – >75dB on each LDO

• Ultra low noise output - > 30µVrms

• Dual 150mA outputs

• µCap stable with 1µF ceramic capacitor

• Low quiescent current – 150µA

• Fast turn-on time – 45µs

• Thermal shutdown protection

• Current Limit protection

Applications

• Mobile phones

• PDAs

• GPS receivers

• Portable electronics

• Portable media players

• Digital still and video cameras

Typical Application

VIN

VOUT 1

VOUT 2

GND

MIC5321-x.xYML

1µF

0.01µF

BYP 1µF

Rx/Synth

Transceiver

1µF

RF Power Supply Circuit

Micrel, Inc. MIC5321

July 2006

2 M9999-073106

Ordering Information

Part number Manufacturing

Part Number

Voltage Junction

Temperature Range

Package

MIC5321-1.8/1.5YML MIC5321-GFYML 1.8V/1.5V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-1.8/1.6YML MIC5321-GWYML 1.8V/1.6V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.5/1.8YML MIC5321-JGYML 2.5V/1.8V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.5/2.5YML MIC5321-JJYML 2.5V/2.5V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.6/1.85YML MIC5321-KDYML 2.6V/1.85 –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.6/1.8YML MIC5321-KGYML 2.6V/1.8V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.7/2.7YML MIC5321-LLYML 2.7V/2.7V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.8/1.5YML MIC5321-MFYML 2.8V/1.5V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.8/1.8YML MIC5321-MGYML 2.8V/1.8V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.8/2.6YML MIC5321-MKYML 2.8V/2.6V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.8/2.8YML MIC5321-MMYML 2.8V/2.8V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.8/2.85YML MIC5321-MNYML 2.8V/2.85V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.85/1.85YML MIC5321-NDYML 2.85V/1.85V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.85/2.6YML MIC5321-NKYML 2.85V/2.6V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.85/2.85YML MIC5321-NNYML 2.85V/2.85V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.9/1.5YML MIC5321-OFYML 2.9V/1.5V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.9/1.8YML MIC5321-OGYML 2.9V/1.8V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-2.9/2.9YML MIC5321-OOYML 2.9V/2.9V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.0/1.8YML MIC5321-PGYML 3.0V/1.8V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.0/2.5YML MIC5321-PJYML 3.0V/2.5V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.0/2.6YML MIC5321-PKYML 3.0V/2.6V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.0/2.8YML MIC5321-PMYML 3.0V/2.8V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.0/2.85YML MIC5321-PNYML 3.0V/2.85V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.0/3.0YML MIC5321-PPYML 3.0V/3.0V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.3/1.5YML MIC5321-SFYML 3.3V/1.5V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.3/1.8YML MIC5321-SGYML 3.3V/1.8V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.3/2.5YML MIC5321-SJYML 3.3V/2.5V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.3/2.6YML MIC5321-SKYML 3.3V/2.6V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.3/2.7YML MIC5321-SLYML 3.3V/2.7V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.3/2.8YML MIC5321-SMYML 3.3V/2.8V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.3/2.85YML MIC5321-SNYML 3.3V/2.85V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.3/2.9YML MIC5321-SOYML 3.3V/2.9V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.3/3.0YML MIC5321-SPYML 3.3V/3.0V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.3/3.2YML MIC5321-SRYML 3.3V/3.2V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-3.3/3.3YML MIC5321-SSYML 3.3V/3.3V –40°C to +125°C 6-Pin 1.6x1.6 MLF

MIC5321-1.8/1.5YD6 MIC5321-GFYD6 1.8V/1.5V –40°C to +125°C 6-Pin TSOT-23

MIC5321-1.8/1.6YD6 MIC5321-GWYD6 1.8V/1.6V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.5/1.8YD6 MIC5321-JGYD6 2.5V/1.8V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.5/2.5YD6 MIC5321-JJYD6 2.5V/2.5V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.6/1.85YD6 MIC5321-KDYD6 2.6V/1.85 –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.6/1.8YD6 MIC5321-KGYD6 2.6V/1.8V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.7/2.7YD6 MIC5321-LLYD6 2.7V/2.7V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.8/1.5YD6 MIC5321-MFYD6 2.8V/1.5V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.8/1.8YD6 MIC5321-MGYD6 2.8V/1.8V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.8/2.6YD6 MIC5321-MKYD6 2.8V/2.6V –40°C to +125°C 6-Pin TSOT-23

Micrel, Inc. MIC5321

July 2006

3 M9999-073106

MIC5321-2.8/2.8YD6 MIC5321-MMYD6 2.8V/2.8V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.8/2.85YD6 MIC5321-MNYD6 2.8V/2.85V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.85/1.85YD6 MIC5321-NDYD6 2.85V/1.85V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.85/2.6YD6 MIC5321-NKYD6 2.85V/2.6V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.85/2.85YD6 MIC5321-NNYD6 2.85V/2.85V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.9/1.5YD6 MIC5321-OFYD6 2.9V/1.5V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.9/1.8YD6 MIC5321-OGYD6 2.9V/1.8V –40°C to +125°C 6-Pin TSOT-23

MIC5321-2.9/2.9YD6 MIC5321-OOYD6 2.9V/2.9V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.0/1.8YD6 MIC5321-PGYD6 3.0V/1.8V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.0/2.5YD6 MIC5321-PJYD6 3.0V/2.5V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.0/2.6YD6 MIC5321-PKYD6 3.0V/2.6V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.0/2.8YD6 MIC5321-PMYD6 3.0V/2.8V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.0/2.85YD6 MIC5321-PNYD6 3.0V/2.85V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.0/3.0YD6 MIC5321-PPYD6 3.0V/3.0V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.3/1.5YD6 MIC5321-SFYD6 3.3V/1.5V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.3/1.8YD6 MIC5321-SGYD6 3.3V/1.8V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.3/2.5YD6 MIC5321-SJYD6 3.3V/2.5V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.3/2.6YD6 MIC5321-SKYD6 3.3V/2.6V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.3/2.7YD6 MIC5321-SLYD6 3.3V/2.7V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.3/2.8YD6 MIC5321-SMYD6 3.3V/2.8V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.3/2.85YD6 MIC5321-SNYD6 3.3V/2.85V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.3/2.9YD6 MIC5321-SOYD6 3.3V/2.9V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.3/3.0YD6 MIC5321-SPYD6 3.3V/3.0V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.3/3.2YD6 MIC5321-SRYD6 3.3V/3.2V –40°C to +125°C 6-Pin TSOT-23

MIC5321-3.3/3.3YD6 MIC5321-SSYD6 3.3V/3.3V –40°C to +125°C 6-Pin TSOT-23

Note:

1. Other Voltages available. Contact Micrel for details.

Micrel, Inc. MIC5321

July 2006

4 M9999-073106

Pin Configuration

1VIN

GND

BYP

6 VOUT1

VOUT2

VIN GND

VOUT1 EN

BYP

VOUT2

6-Pin 1.6mm x 1.6mm MLF (ML)

Top View

TSOT-23-6 (D6)

Top View

Pin Description

Pin Number

MLF-6

Pin Number

TSOT-23-6

Pin Name

Pin Function

1 3 VIN Supply Input.

2 2 GND Ground

3 1 BYP

Reference Bypass: Connect external 0.01µF to GND to reduce output noise.

May be left open.

4 6 EN

Enable Input (both regulators): Active High Input. Logic High = On; Logic

Low = Off; Do not leave floating.

5 5 VOUT2 Regulator Output – LDO2

6 4 VOUT1 Regulator Output – LDO1

Micrel, Inc. MIC5321

July 2006

M9999-073106

Absolute Maximum Ratings(1)

Supply Voltage (V

) .....................................0V to +6V

Enable Input Voltage (V

)...........................0V to +6V

Power Dissipation………………….Internally Limited

(3)

Lead Temperature (soldering, 3sec)..................260°C

Storage Temperature (T

)................ –65°C to +150°C

ESD Rating

(4)

.........................................................2kV

Operating Ratings(2)

Supply Voltage (V

).............................. +2.3V to +5.5V

Enable Input Voltage (V

).............................. 0V to V

Junction Temperature (T

) ................. –40°C to +125°C

Junction Thermal Resistance

MLF-6 (θ

) ............................................. 100°C/W

TSOT-6 (θ

) ........................................... 235°C/W

Electrical Characteristics(5)

= EN = V

OUT

+ 1.0V; higher of the two regulator outputs, I

OUTLDO1

= I

OUTLDO2

= 100µA; C

OUT1

= C

OUT2

= 1µF;

BYP

= 0.01µF; T

= 25°C, bold values indicate –40°C ≤ T

≤ +125°C, unless noted.

Parameter Conditions Min Typ Max Units

Variation from nominal V

OUT

-2.0

+2.0

% Output Voltage Accuracy

Variation from nominal V

OUT

; –40°C to +125°C

-3.0

+3.0

Line Regulation V

= V

OUT

+ 1V to 5.5V; I

OUT

= 100µA 0.02 0.3

0.6

%/V

Load Regulation I

OUT

= 100µA to 150mA 0.5

2.0

Dropout Voltage

(6)

OUT

= 100µA

OUT

= 50mA

OUT

= 100mA

OUT

= 150mA

0.1

100

Ground Current EN = High; I

OUT1

= 150mA, I

OUT2

= 150mA 150

190

µA

Ground Current in Shutdown EN1 ≤ 0.2V 0.01

µA

Ripple Rejection f = 1kHz; C

OUT

= 1.0µF; C

BYP

= 0.1µF

f = 20kHz; C

OUT

= 1.0µF; C

BYP

= 0.1µF

Current Limit V

OUT

= 0V

300

550

950

Output Voltage Noise C

OUT

= 1.0µF; C

BYP

= 0.01µF; 10Hz to 100kHz 30 µV

RMS

Enable Inputs (EN)

Logic Low

0.2

V Enable Input Voltage

Logic High

1.1

≤ 0.2V 0.01 1 µA Enable Input Current

≥ 1.0V 0.01 1 µA

Turn-on Time (See Timing Diagram)

Turn-on Time (LDO1 and 2) C

OUT

= 1.0µF; No C

BYP

OUT

= 1.0µF; C

BYP

= 0.01µF

100

µs

Notes:

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

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

3. The maximum allowable power dissipation of any T

(ambient temperature) is P

D(max)

= (T

J(max)

– T

) / θ

. Exceeding the maximum allowable

power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown.

4. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.

5. Specification for packaged product only.

6. Dropout voltage is defined as the input-to-output differential at which the output voltage drops 2% below it’s nominal V

OUT

. For outputs below 2.3V,

the dropout voltage is the input-to-output differential with the minimum input voltage 2.3V

Micrel, Inc. MIC5321

July 2006

M9999-073106

Functional Diagram

Enable

Reference

LDO1

LDO2

BYP

VIN VOUT 1

VOUT 2

GND

MIC5321 Block Diagram

Micrel, Inc. MIC5321

July 2006

M9999-073106

Typical Characteristics

-10

-20

-30

-40

-50

-60

-70

-80

-90

Power Supply

Rejection Ratio

FREQUENCY (kHz)

0.1 10 100 1,000

= V

OUT

+1V

OUT

= 2.8V

OUT

= 1µF

BYP

= 0.1µF

50mA

150mA

0 25 50 75 100 125 150

OUTPUT CURRENT (mA)

Dropout Voltage

vs. Output Current

OUT

= 2.8V

OUT

= 1µF

= V

OUT

+ 1V

EN = V

2.50

2.55

2.60

2.65

2.70

2.85

2.90

2.95

3.00

Output Voltage

vs. Temperature

20 40 60 80

TEMPERATURE (°C)

2.75

2.80

= V

OUT

+ 1V

OUT

= 2.8V

OUT

= 1µF

EN = V

120

125

130

140

145

150

155

160

20 40 60 80

TEMPERATURE (°C)

Ground Current

vs. Temperature

100µA

= V

OUT

+ 1V

OUT

= 3V

OUT

= 1µF

EN = V

135

120

125

130

145

150

155

160

Ground Current

vs. Temperature

20 40 60 80

TEMPERATURE (°C)

150mA

= V

OUT

+ 1V

OUT

= 3V

OUT

= 1µF

EN = V

135

140

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0123456

INPUT VOLTAGE (V)

Output Voltage

vs. Input Voltage

2.8V

1.5V

2.5

OUT

= 100µA

OUT

= 1µF

Dropout Voltage

vs. Temperature

20 40 60 80

TEMPERATURE (°C)

100µA

10mA

50mA

100mA

150mA

= V

OUT

+ 1V

OUT

= 2.8V

OUT

= 1µF

2.70

2.75

2.80

2.85

2.90

0 25 50 75 100 125 150

OUTPUT CURRENT (mA)

Output Voltage

vs. Output Current

= V

OUT

+ 1V

OUT

= 2.8V

OUT1

= C

OUT2

= 1µF

EN = V

1.40

1.45

1.50

1.55

1.60

0 25 50 75 100 125 150

OUTPUT CURRENT (mA)

Output Voltage

vs. Output Current

= V

OUT

+ 1V

OUT

= 1.5V

OUT1

= C

OUT2

= 1µF

EN = V

138

142

146

150

154

158

162

0 25 50 75 100 125 150

OUTPUT CURRENT (mA)

Ground Current

vs. Output Current

= V

OUT

+ 1V

OUT

= 2.85V

EN = V

OUT1

= C

OUT2

= 1µF

510

520

530

540

550

560

570

580

590

600

610

3 3.5 4 4.5 5 5.5

INPUT VOLTAGE (V)

Current Limit

vs. Input Voltage

EN = V

OUT

= 1µF

0.001

0.01

0.1

Output Noise

Spectral Density

FREQUENCY (kHz)

0.10.01 10 100 1,000 10,000

= 3.8V

OUT

= 2.8V

OUT

= 1µF

BYP

= 0.01µF

Micrel, Inc. MIC5321

July 2006

M9999-073106

Functional Characteristics

Enable Turn-On

Enable

(1V/div)

VOUT2

(1V/div)

Time (10µs/div)

VOUT1

(1V/div)

= V

OUT

+ 1V

OUT1

= V

OUT2

= 3.0V

OUT

= 1µF

BYP

= 0.1µF

Load Transient

Output Volta

(20mV/div)

Output Current

(50mA/div)

Time (40µs/div)

= V

OUT

+ 1V

OUT

= 2.8V

OUT

= 1µF

150mA

10mA

BYP

= 0.1µF

Line Transient

Input Volta

(2V/div)

Output Volta

(50mV/div)

Time (40µs/div)

= V

OUT

+ 1V

OUT

= 2.8V

OUT

= 1µF

OUT

= 10mA

5.5V

Micrel, Inc. MIC5321

July 2006

M9999-073106

Applications Information

Enable/Shutdown

The MIC5321 comes with a single active-high enable

pin that allows both regulators to be disabled

simultaneously. Forcing the enable pin low disables

the regulator and sends it into a “zero” off-mode-

current state. In this state, current consumed by the

regulator goes nearly to zero. Forcing the enable pin

high enables the output voltage. The active-high

enable pin uses CMOS technology and the enable pin

cannot be left floating; a floating enable pin may

cause an indeterminate state on the output.

Input Capacitor

The MIC5321 is a high-performance, high bandwidth

device. Therefore, it requires a well-bypassed input

supply for optimal performance. A 1µF capacitor is

required from the input to ground to provide stability.

Low-ESR ceramic capacitors provide optimal

performance at a minimum of space. Additional high-

frequency capacitors, such as small-valued NPO

dielectric-type capacitors, help filter out high-

frequency noise and are good practice in any RF-

based circuit.

Output Capacitor

The MIC5321 requires an output capacitor of 1µF or

greater to maintain stability. The design is optimized

for use with low-ESR ceramic chip capacitors. High

ESR capacitors may cause high frequency oscillation.

The output capacitor can be increased, but

performance has been optimized for a 1µF ceramic

output capacitor and does not improve significantly

with larger capacitance.

X7R/X5R dielectric-type ceramic capacitors are

recommended because of their temperature

performance. X7R-type capacitors change

capacitance by 15% over their operating temperature

range and are the most stable type of ceramic

capacitors. Z5U and Y5V dielectric capacitors change

value by as much as 50% and 60%, respectively, over

their operating temperature ranges. To use a ceramic

chip capacitor with Y5V dielectric, the value must be

much higher than an X7R ceramic capacitor to ensure

the same minimum capacitance over the equivalent

operating temperature range.

Bypass Capacitor

A capacitor can be placed from the noise bypass pin

to ground to reduce output voltage noise. The

capacitor bypasses the internal reference. A 0.1µF

capacitor is recommended for applications that require

low-noise outputs. The bypass capacitor can be

increased, further reducing noise and improving

PSRR. Turn-on time increases slightly with respect to

bypass capacitance. A unique, quick-start circuit

allows the MIC5321 to drive a large capacitor on the

bypass pin without significantly slowing turn-on time.

Refer to the Typical Characteristics section for

performance with different bypass capacitors.

No-Load Stability

Unlike many other voltage regulators, the MIC5321

will remain stable and in regulation with no load. This

is especially important in CMOS RAM keep-alive

applications.

Thermal Considerations

The MIC5321 is designed to provide 150mA of

continuous current for both outputs in a very small

package. Maximum ambient operating temperature

can be calculated based on the output current and the

voltage drop across the part. Given that the input

voltage is 3.3V, the output voltage is 2.8V for VOUT1,

2.5V for VOUT2 and the output current = 150mA. The

actual power dissipation of the regulator circuit can be

determined using the equation:

PD = (VIN – VOUT1) IOUT1 + (VIN – VOUT2) IOUT2+ VIN IGND

Because this device is CMOS and the ground current

is typically <150µA over the load range, the power

dissipation contributed by the ground current is < 1%

and can be ignored for this calculation.

PD = (3.3V – 2.8V) × 150mA + (3.3V -1.5) × 150mA

D = 0.345W

To determine the maximum ambient operating

temperature of the package, use the junction-to-

ambient thermal resistance of the device and the

following basic equation:

D(MAX)

J(MAX)

- T

⎝

⎛

TJ(max) = 125°C, the maximum junction temperature of

the die θJA thermal resistance = 100°C/W.

The table below shows junction-to-ambient thermal

resistance for the MIC5321 in the MLF® package.

Micrel, Inc. MIC5321

July 2006 10

M9999-073106

Package

Recommended

Minimum

Footprint

6-Pin 1.6x1.6 MLF

100°C/W 2°C/W

Thermal Resistance

Substituting P

for P

D(max)

and solving for the ambient

operating temperature will give the maximum

operating conditions for the regulator circuit. The

junction-to-ambient thermal resistance for the

minimum footprint is 100°C/W.

The maximum power dissipation must not be

exceeded for proper operation.

For example, when operating the MIC5321-MFYML at

an input voltage of 3.3V and 150mA loads at each

output with a minimum footprint layout, the maximum

ambient operating temperature T

can be determined

as follows:

0.345W = (125°C – T

)/(100°C/W)

=90.5°C

Therefore, a 2.8V/1.5V application with 150mA at

each output current can accept an ambient operating

temperature of 90.5°C in a 1.6mm x 1.6mm MLF

package. For a full discussion of heat sinking and

thermal effects on voltage regulators, refer to the

“Regulator Thermals” section of

Micrel’s Designing

with Low-Dropout Voltage Regulators

handbook. This

information can be found on Micrel's website at:

http://www.micrel.com/_PDF/other/LDOBk_ds.pdf

Micrel, Inc. MIC5321

July 2006 11

M9999-073106

Package Information

6-Pin 1.6mm x 1.5mm MLF (ML)

6-Pin TSOT-23 (D6)

Micrel, Inc. MIC5321

July 2006 12

M9999-073106

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

The 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.