MIC37500-1.8BR - Micrel, Inc.

July 2003 1 MIC37500/37501/37502

MIC37500/37501/37502 Micrel

MIC37500/37501/37502

5A, Low Voltage µCap LDO Regulator

General Description

The MIC37500/01/02 is a 5A low dropout linear voltage

regulator that provides a low voltage, high current output with

a minimum of external components. It offers high precision,

ultra-low dropout (500mV), and low ground current.

The MIC37500/01/02 operates from an input of 2.3V to 6.0V.

It is designed to drive digital circuits requiring low voltage at

high currents (i.e., PLDs, DSPs, microcontrollers, etc.). It is

available in fixed and adjustable output voltages. Fixed

voltages include 1.5V, 1.65V, 1.8V, 2.5V and 3.3V. The

adjustable version is capable of 1.24V to 5.5V.

Features of the MIC37500/01/02 LDO include thermal and

current limit protection, and reverse current protection. Logic

enable and error flag pins are available.

Junction temperature range of the MIC37500/01/02 is from

–40°C to 125°C.

For applications requiring input voltage greater than 6.0V,

see MIC3910x, MIC3915x, MIC3930x, and MIC3950x LDOs.

Data sheets and support documentation can be found on

Micrel’s web site at www.micrel.com.

Typical Application

VOUTVIN

FLG

GND

VEN

OUT

100µF, Ceramic

100k

MIC37501

= 3.0V V

OUT

= 2.5V

Fixed 2.5V Regulator with Error Flag

VOUTVIN

ADJ

GND

VEN C

OUT

100µF, Ceramic

1.3V

MIC37502

Adjustable Regulator

Features

•5A minimum guaranteed output current

•500mV maximum dropout voltage

Ideal for 3.0V to 2.5V conversion

Ideal for 2.5V to 1.8V, 1.65V, or 1.5V conversion

•Stable with ceramic or tantalum capacitor

•Wide input voltage range:

VIN: 2.3V to 6.0V

•±1.0% initial output tolerance

•Fixed and adjustable output voltages

MIC37500—3 terminal fixed voltage

MIC37501—5 terminal fixed voltage

MIC37502—5 terminal adjustable voltage

•Excellent line and load regulation specifications

•Logic controlled shutdown

•Thermal shutdown and current limit protection

•Reverse-leakage protection

•Low profile S-Pak and TO-263 packages

Applications

•LDO linear regulator for low-voltage digital IC

•PC add-in cards

•High efficiency linear power supplies

•SMPS post regulator

•Battery charger

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com

100

150

200

250

300

350

400

450

012345

DROPOUT (mV)

OUTPUT CURRENT (A)

Dropout

vs. Output Current

2.5VOUT

MIC37500/37501/37502 Micrel

MIC37500/37501/37502 2 July 2003

Ordering Information

Output

Part Number Current Voltage* Junction Temp. Range Package

MIC37500-1.5BR 5A 1.5V –40°C to +125°C S-Pak-5

MIC37500-1.65BR 5A 1.65V –40°C to +125°C S-Pak-5

MIC37500-1.8BR 5A 1.8V –40°C to +125°C S-Pak-5

MIC37500-2.5BR 5A 2.5V –40°C to +125°C S-Pak-5

MIC37500-3.3BR 5A 3.3V –40°C to +125°C S-Pak-5

MIC37501-1.5BR 5A 1.5V –40°C to +125°C S-Pak-7

MIC37501-1.65BR 5A 1.65V –40°C to +125°C S-Pak-7

MIC37501-1.8BR 5A 1.8V –40°C to +125°C S-Pak-7

MIC37501-2.5BR 5A 2.5V –40°C to +125°C S-Pak-7

MIC37501-3.3BR 5A 3.3V –40°C to +125°C S-Pak-7

MIC37502BR 5A ADJ. –40°C to +125°C S-Pak-7

MIC37502BU 5A ADJ –40°C to +125°C TO-263-5

*For other voltages contact Micrel.

Pin Configurations

TAB

5 VOUT

4 VOUT

3 GND

2 VIN

1 VIN

S-PAK-5

Pin Descriptions

Pin Number Pin Number Pin Number Pin Name Pin Function

TO-263-5 S-PAK-5 S-PAK-7

1—1 EN Enable (Input): CMOS compatible input. Logic high = enable, logic

low = shutdown

2 1, 2 2, 3 VIN Input voltage which supplies current to the output power device. Connect

pins 2 and 3 together externally.

3 3 4 GND Ground (TAB is connected to ground on S-Pak)

4 4, 5 5, 6 VOUT Regulator Output: Connect pins 5 and 6 together externally.

—— 7 FLG Error Flag (Output): Open collector output. Active low indicates an

output fault condition.

5—7 ADJ Adjustable regulator feedback input. Connect to resistor voltage divider.

TAB

7 FLG/ADJ

6 VOUT

5 VOUT

4 GND

3 VIN

2 VIN

1EN

S-PAK-7

TAB

5 ADJ

4 VOUT

3 GND

2 VIN

1EN

TO-263-5

July 2003 3 MIC37500/37501/37502

MIC37500/37501/37502 Micrel

Electrical Characteristics (Note 5)

TA = 25°C with VIN = VOUT + 1V; VEN = VIN; bold values indicate –40°C < TJ < +125°C; unless otherwise noted.

Parameter Condition Min Typ Max Units

Output Voltage Accuracy IL = 10mA –1+1%

10mA < IOUT < IL(max), VOUT + 1 ≤ VIN ≤ 6V –2+2%

Output Voltage Line Regulation VIN = VOUT +1.0V to 6.0V 0.06 0.5 %

Output Voltage Load Regulation IL = 10mA to 5A 0.2 1%

VIN – VOUT, Dropout Voltage, IL = 2.5A 350 mV

Note 6 IL = 5A 330 500 mV

Ground Pin Current, Note 7 IL = 5A 57 100 mA

Ground Pin Current in Shutdown VIL < 0.5V, VIN = VOUT + 1V 1.0 µA

Current Limit VOUT = 0 5 7.5 10 A

Start-up Time VEN = VIN, IOUT = 10mA, COUT = 100µF 170 500 µs

Enable Input

Enable Input Threshold Regulator enable 2.25 V

Regulator shutdown 0.8 V

Enable Pin Input Current VIL < 0.8V (Regulator shutdown) 2 µA

4µA

VIH > 2.25V (Regulator enabled) 1 15 30 µA

75 µA

Flag Output

IFLG(LEAK) VOH = 6V 1µA

2µA

VFLG(LO) VIN = 2.25V, IOL = 250µA, Note 8 210 400 mV

500 mV

VFLG Low threshold, % of VOUT below nominal 93 %

Hysteresis 2 %

High threshold, % of VOUT below nominal 99.2 %

MIC37502 Only

Reference Voltage 1.228 1.240 1.252 V

1.215 1.265 V

Adjust Pin Bias Current 40 80 nA

120 nA

Absolute Maximum Rating (Note 1)

Supply Voltage (VIN) ....................................................6.5V

Enable Input Voltage (VEN) ..........................................6.5V

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

Junction Temperature ........................–40°C ≤ TJ ≤ +125°C

Storage Temperature ........................ –65°C ≤ TJ ≤ +150°C

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

ESD, Note 3

Operating Maximum Rating (Note 2)

Supply Voltage (VIN) ....................................... 2.3V to 6.0V

Enable Input Voltage (VEN) ................................ 0V to 6.0V

Junction Temperature Range............ –40°C ≤ TJ ≤ +125°C

Maximum Power Dissipation.................................... Note 4

Package Thermal Resistance

S-Pak(θJC).........................................................2°C/W

TO-263(θJC) ......................................................2°C/W

MIC37500/37501/37502 Micrel

MIC37500/37501/37502 4 July 2003

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

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

Note 3. Device is ESD sensitive. Handling precautions recommended.

Note 4. PD(MAX) = (TJ(MAX) – TA) / θJA, where θJA, depends upon the printed circuit layout. See

“Applications Information.”

Note 5. Specification for packaged product only.

Note 6. VDO = VIN – VOUT when VOUT decreased to 98% of its nominal output voltage with VIN = VOUT +1V. For output voltages below 1.75V, dropout

voltage specification does not apply due to a minimum input operating voltage of 2.3V.

Note 7. IGND is the quiescent current. IIN = IGND + IOUT.

Note 8. For a 2.5V device, VIN = 2.3V (device is in dropout).

July 2003 5 MIC37500/37501/37502

MIC37500/37501/37502 Micrel

Typical Characteristics

100

150

200

250

300

350

400

450

012345

DROPOUT (mV)

OUTPUT CURRENT (A)

Dropout

vs. Output Current

2.5VOUT

250

300

350

400

450

500

-40 -20 0 20 40 60 80 100120

DROPOUT (mV)

TEMPERATURE (°C)

Dropout

vs. Temperature

2.5VOUT

0.2

0.4

0.6

0.8

1.2

1.4

1.6

1.5 1.7 1.9 2.1 2.3 2.5

OUTPUT VOLTAGE (V)

INPUT VOLTAGE (V)

Dropout Characteristics

(1.5V)

10mA load

5A load

0.2

0.4

0.6

0.8

1.2

1.4

1.6

1.8

1.5 1.7 1.9 2.1 2.3 2.5 2.7

OUTPUT VOLTAGE (V)

INPUT VOLTAGE (V)

Dropout Characteristics

(1.8V)

5A load

10mA load

0.5

1.0

1.5

2.0

2.5

3.0

1.5 2.0 2.5 3.0 3.5

OUTPUT VOLTAGE (V)

INPUT VOLTAGE (V)

Dropout Characteristics

(2.5V)

5A load

10mA load

0.5

1.0

1.5

2.0

2.5

3.0

3.5

1.5

1.8

2.0

2.3

2.5

2.8

3.0

3.3

3.5

3.8

4.0

4.3

OUTPUT VOLTAGE (V)

INPUT VOLTAGE (V)

Dropout Characteristics

(3.3V)

10mA load

5A load

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

GROUND CURRENT (mA)

OUTPUT CURRENT (A)

Ground Current

vs. Output Current

2.5VOUT

0.1

0.2

0.3

0.4

0.5

0.6

0.7

012345

GROUND CURRENT (mA)

INPUT VOLTAGE (V)

Ground Current

vs. Suppl

Volta

e (1.5V)

10mA

100mA

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

GROUND CURRENT (mA)

INPUT VOLTAGE (V)

Ground Current

vs. Supply (1.5V)

2.5A

0.1

0.2

0.3

0.4

0.5

0.6

0.7

012345

GROUND CURRENT (mA)

INPUT VOLTAGE (V)

Ground Current

vs. Supply (1.8V)

10mA

100mA

012345

GROUND CURRENT (mA)

INPUT VOLTAGE (V)

Ground Current

vs. Suppl

(1.8V)

2.5A

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

012345

GROUND CURRENT (mA)

INPUT VOLTAGE (V)

Ground Current

vs. Supply (2.5V)

10mA

100mA

MIC37500/37501/37502 Micrel

MIC37500/37501/37502 6 July 2003

0.02

0.04

0.06

0.08

0.10

0.12

012345

GROUND CURRENT (mA)

INPUT VOLTAGE (V)

Ground Current

vs. Suppl

(2.5V)

2.5A

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

012345

GROUND CURRENT (mA)

INPUT VOLTAGE (V)

Ground Current

vs. Suppl

(3.3V)

100mA

10mA

100

120

012345

GROUND CURRENT (mA)

INPUT VOLTAGE (V)

Ground Current

vs. Suppl

(3.3V)

2.5A

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

-40 -20 0 20 40 60 80 100120

GROUND CURRENT (mA)

TEMPERATURE (°C)

Ground Current

vs. Temperature

100mA

10mA

-40 -20 0 20 40 60 80 100120

GROUND CURRENT (mA)

TEMPERATURE (°C)

Ground Current

vs. Temperature

2.5A

2.40

2.42

2.44

2.46

2.48

2.50

2.52

2.54

2.56

2.58

2.60

-40 -20 0 20 40 60 80 100120

OUTPUT VOLTAGE (V)

TEMPERATURE (°C)

Output Voltage

vs. Temperature

2.25 3 3.75 4.5 5.25 6

SHORT CIRCUIT CURRENT (A)

SUPPLY VOLTAGE (V)

Short Circuit Current

vs. Suppl

Volta

-40 -20 0 20 40 60 80 100120

OUTPUT VOLTAGE (V)

TEMPERATURE (°C)

Short Circuit Current

vs. Temperature

0.01 0.1 1 10 100 100010000

ERROR FLAG (V)

RESISTANCE (kΩ)

Error Fla

Pull-Up Resistor

VIN = 5V

Flag High (OK)

Flag Low (FAULT)

-40 -20 0 20 40 60 80 100120

ENABLE CURRENT (µA)

TEMPERATURE (°C)

Enable Current

vs. Temperature

July 2003 7 MIC37500/37501/37502

MIC37500/37501/37502 Micrel

Functional Characteristics

TIME (20µs/div.)

ENABLE

(1V/div.) OUTPUT VOLTAGE

(1V/div.)

VIN = 3.3V

VOUT = 2.5V

COUT = 100µF Ceramic

IOUT = 5A

Enable T ransient Response

TIME (100µs/div.)

INPUT V OLTAGE

(2V/div.) OUTPUT VOLTAGE

(20mV/div.)

VIN = 3.3V

VOUT = 2.5V

COUT = 100µF Ceramic

Line T ransient Response

3.3V

TIME (100µs/div.)

LOAD TRANSIENT

(2A/div.) OUTPUT VOLTAGE

(100mV/div.)

VIN = 3.3V

VOUT = 2.5V

COUT = 100µF Ceramic

Load T ransient Response

TIME (100µs/div.)

LOAD TRANSIENT

(2A/div.) OUTPUT VOLTAGE

(100mV/div.)

VIN = 3.3V

VOUT = 2.5V

COUT = 100µF Ceramic

Load T ransient Response

100mA

MIC37500/37501/37502 Micrel

MIC37500/37501/37502 8 July 2003

Applications Information

The MIC37500/01/02 is a high-performance low dropout

voltage regulator suitable for moderate to high-current regu-

lator applications. Its 500mV dropout voltage at full load

makes it especially valuable in battery-powered systems and

as high-efficiency noise filters in post-regulator applications.

Unlike older NPN-pass transistor designs, there the minimum

dropout voltage is limited by the based-to-emitter voltage

drop and collector-to-emitter saturation voltage, dropout per-

formance of the PNP output of these devices is limited only

by the low VCE saturation voltage.

A trade-off for the low dropout voltage is a varying base drive

requirement. Micrel’s Super Beta PNP™ process reduces

this drive requirement to only 2% to 5% of the load current.

The MIC37500/01/02 regulator is fully protected from dam-

age due to fault conditions. Current limiting is provided. This

limiting is linear; output current during overload conditions is

constant. Thermal shutdown disables the device when the

die temperature exceeds the maximum safe operating tem-

perature. The output structure of these regulators allows

voltages in excess of the desired output voltage to be applied

without reverse current flow.

Thermal Design

Linear regulators are simple to use. The most complicated

design parameters to consider are thermal characteristics.

Thermal design requires the following application-specific

parameters:

•Maximum ambient temperature (TA)

•Output current (IOUT)

•Output voltage (VOUT)

•Input voltage (VIN)

•Ground current (IGND)

First, calculate the power dissipation of the regulator from

these numbers and the device parameters from this datasheet.

PD = (VIN – VOUT) IOUT + VIN IGND

where the ground current is approximated by using numbers

from the

“Electrical Characteristics”

“Typical Characteris-

tics.”

Then the heat sink thermal resistance is determined

with this formula:

θSA = ((TJ(MAX) – TA)/ PD) – (θJC + θCS)

Where TJ(MAX) ≤ 125°C and θCS is between 0°C and 2°C/W.

The heat sink may be significantly reduced in applications

where the minimum input voltage is known and is large

compared with the dropout voltage. Use a series input

resistor to drop excessive voltage and distribute the heat

between this resistor and the regulator. The low dropout

properties of Micrel Super Beta PNP regulators allow signifi-

cant reductions in regulator power dissipation and the asso-

ciated heat sink without compromising performance. When

this technique is employed, a capacitor of at least 1.0µF is

needed directly between the input and regulator ground.

Refer to

“Application Note 9”

for further details and examples

on thermal design and heat sink applications.

Output Capacitor

The MIC37500/01/02 requires an output capacitor for stable

operation. As a µCap LDO, the MIC37500/01/02 can operate

with ceramic output capacitors as long as the amount of

capacitance is 100µF or greater. For values of output capaci-

tance lower than 100µF, the recommended ESR range is

200mΩ to 2Ω. The minimum value of output capacitance

recommended for the MIC37500/01/02 is 47µF.

For 100µF or greater the ESR range recommended is less

than 1Ω. Ultra-low ESR, ceramic capacitors are recom-

mended for output capacitance of 100µF or greater to help

improve transient response and noise reduction at high

frequency. 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 capaci-

tor with Y5V dielectric, the value must be much higher than an

X7R ceramic capacitor to ensure the same minimum capaci-

tance over the equivalent operating temperature range.

Input Capacitor

An input capacitor of 1.0µF or greater is recommended when

the device is more than 4 inches away from the bulk supply

capacitance, or when the supply is a battery. Small, surface-

mount chip capacitors can be used for the bypassing. The

capacitor should be place within 1” of the device for optimal

performance. Larger values will help to improve ripple rejec-

tion by bypassing the input to the regulator, further improving

the integrity of the output voltage.

Transient Response and 3.3V to 2.5V, 2.5V to 1.8V or

1.65V, or 2.5V to 1.5V Conversions

The MIC37500/01/02 has excellent transient response to

variations in input voltage and load current. The device has

been designed to respond quickly to load current variations

and input voltage variations. Large output capacitors are not

required to obtain this performance. A standard 47µF output

capacitor, is all that is required. Larger values help to improve

performance even further.

By virtue of its low dropout voltage, this device does not

saturate into dropout as readily as similar NPN-based de-

signs. When converting from 3.3V to 2.5V, 2.5V to 1.8V or

1.65V, or 2.5V to 1.5V, the NPN-based regulators are already

operating in dropout, with typical dropout requirements of

1.2V or greater. To convert down to 2.5V without operating in

dropout, NPN-based regulators require an input voltage of

3.7V at the very least. The MIC37500/01/02 regulator will

provide excellent performance with an input as low as 3.0V or

2.25V, respectively. This gives the PNP-based regulators a

distinct advantage over older, NPN-based linear regulators.

July 2003 9 MIC37500/37501/37502

MIC37500/37501/37502 Micrel

Minimum Load Current

The MIC37500/01/02 regulator is specified between finite

loads. If the output current is too small, leakage currents

dominate and the output voltage rises. A 10mA minimum load

current is necessary for proper operation.

Error Flag

The MIC37501 features an error flag circuit that monitors the

output voltage and signals an error condition when the

voltage 5% below the nominal output voltage. The error flag

is an open-collector output that can sink 10mA during a fault

condition.

Low output voltage can be caused by a number of problems,

including an overcurrent fault (device in current limit) or low

input voltage. The flag is inoperative during overtemperature

shutdown.

Enable Input

The MIC37501/37502 also feature an enable input for on/off

control of the device. Its shutdown state draws “zero” current

(only microamperes of leakage). The enable input is TTL/

CMOS compatible for simple logic interface, but can be

connected to up to VIN. When enabled, it draws approxi-

mately 15µA.

Adjustable Regulator Design

IN R1 V

OUT

ADJ

GND

MIC37502

ENABLE

SHUTDOWN

V 1.240V 1 R1

OUT











Figure 2. Adjustable Regulator with Resistors

The MIC37502 allows programming the output voltage any-

where between 1.24V and the 5.5V maximum operating

rating of the family. Two resistors are used. Resistors can be

quite large, up to 1MΩ, because of the very high input

impedance and low bias current of the sense comparator:

The resistor values are calculated by:

R1 R2 V

1.240 1

OUT

=−











Where VOUT is the desired output voltage. Figure 2 shows

component definition. Applications with widely varying load

currents may scale the resistors to draw the minimum load

current required for proper operation (see above).

MIC37500/37501/37502 Micrel

MIC37500/37501/37502 10 July 2003

Package Information

0.370±0.005

9.395±0.125

0.355±0.005

9.015±0.125

0.315±0.005

8.000±0.130 0.415±0.005

10.54±0.130

0.028±0.003

0.710±0.080

0.075±0.005

1.905±0.125

0.040±0.005

1.015±0.125

0.003±0.002

0.080±0.050

0.036±0.005

0.915±0.125

INCHES

MILLIMETER

0° min

6° max

0.010

0.250

0.010

0.250

0.067

1.700

0.040±0.010

1.015±0.255 0.256

6.50

5-Lead S-PAK (R)

SCALE 20:1

0.375 (9.52)

0.365 (9.27)

0.360 (9.14)

0.350 (8.89) 0.080 (2.03)

0.070 (1.78) 0.010 BSC

(0.25 BSC)

0.045 (1.14)

0.035 (0.89)

0.316 BSC

(8.03 BSC)

0.256 BSC

(6.50 BSC)

0.031 (0.79)

0.025 (0.63)

0.005 (0.13)

0.001 (0.03)

6°

0°

0.010 BSC

(0.25 BSC)

0.050 BSC

(1.27 BSC)

0.420 (10.67)

0.410 (10.41)

0.050 (1.27)

0.030 (0.76)

0.320 (8.13)

0.310 (7.87)

DIMENSIONS:

INCH (MM)

7-Lead S-PAK (R)

July 2003 11 MIC37500/37501/37502

MIC37500/37501/37502 Micrel

MICREL, INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB http://www.micrel.com

The information furnished by Micrel in this datasheet 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 at Purchaser’s own risk and Purchaser agrees to fully indemnify

Micrel for any damages resulting from such use or sale.

0.067±0.005 0.032 ±0.003

0.360±0.005

0.600±0.025

0.405±0.005

0.060±0.005

0.176±0.005

8° MAX 0.100±0.01

0.050±0.005

0.015 ±0.002

0.004+0.004

–0.008

SEATING PLANE

0.065±0.010

20°±2°

DIM. = INCH

5-Lead TO-263 (U)