Rainbow Electronics MAX15011 User Manual

General Description

The MAX15009 includes a 300mA LDO regulator, a
switched output, and an overvoltage protection (OVP)
controller to protect downstream circuits from high-volt­age load dump. The MAX15011 includes only the 300mA
LDO regulator and switched output. Both devices operate
over a wide supply voltage range from 5V to 40V and are
able to withstand load-dump transients up to 45V. The
MAX15009/MAX15011 feature short-circuit and thermal­shutdown protection. These devices offer highly integrat­ed power management solutions for automotive
applications such as instrument clusters, climate control,
and a variety of automotive power-supply circuits.

The 300mA LDO regulator consumes 67µA quiescent
current at light loads and is well suited to power
always-on circuits during “key off” conditions. The LDO
features independent enable and hold inputs, as well
as a microprocessor (µP) reset output with adjustable
reset timeout period.

The switched output of the MAX15009/MAX15011
incorporates a low R

DS(ON)

(0.28Ω, typ) pass transistor
switch internally connected to the output of the LDO
regulator. This switch features accurate current-limit
sensing circuitry and is capable of controlling remote
loads. The MAX15009/MAX15011 feature an adjustable
current limit and a programmable delay timer to set the
overcurrent detection blanking time of the switch and
autoretry timeout.

The MAX15009 OVP controller operates with an external
enhancement mode n-channel MOSFET. While the moni­tored voltage remains below the adjustable threshold, the
MOSFET stays on. When the monitored voltage exceeds
the OVP threshold, the OVP controller quickly turns off the
external MOSFET. The OVP controller is configurable as a
load-disconnect switch or a voltage limiter.

The MAX15009/MAX15011 are available in a thermally
enhanced, 32-pin (5mm x 5mm), TQFN package and are
fully specified over the -40°C to +125°C automotive oper­ating temperature range.

Applications

Instrument Clusters

Climate Control

AM/FM Radio Power Supply

Multimedia Power Supply

Telematics Power Supply

Features

o 300mA LDO Regulator, Switched Output, and OVP

Controller (MAX15009)

o 300mA LDO Regulator and Switched Output

(MAX15011)

o 5V to 40V Wide Operating Supply Voltage Range

o 45V Load Dump Protection

o 67µA Quiescent Current LDO Regulator

o OVP Controller Disconnects or Limits Output

Voltage During Battery Overvoltage Conditions

o LDO Regulator with Enable, Hold, and Reset

Features

o Internal 0.28Ω (typ) n-Channel Switch for

Switched Output

o 100mA Switched Output with Adjustable Current-

Limit Blanking/Autoretry Delay

MAX15009/MAX15011

Automotive 300mA LDO Regulators with

Switched Output and Overvoltage Protector

________________________________________________________________

Maxim Integrated Products

1

Pin Configurations

19-0923; Rev 1; 2/08

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

Typical Operating Circuits and Selector Guide appear at end
of data sheet.

Pin Configurations continued at end of data sheet.

Ordering Information

+

Denotes a lead-free package.

For tape and reel, add a T after “+.”

*

EP = Exposed pad.

EVALUATION KIT

AVAILABLE

PART

TEMP RANGE

PIN­PACKAGE

PKG

CODE

MAX15009ATJ+

T3255-4

MAX15011ATJ+

T3255-4

-40°C to +125°C 32 TQFN-EP*

-40°C to +125°C 32 TQFN-EP*

TOP VIEW

OC_DELAY

OUT_LDO

IN

OUT_LDO

21

MAX15009

4567

3

N.C.

N.C.

SGND

TQFN

(5mm x 5mm)

IN

*EP

PGND

EN_PROT

EN_SW

17

8

N.C.

RESET

16

15

14

13

12

11

10

9

EN_LDO

FB_LDO

N.C.

SOURCE

GATE

N.C.

FB_PROT

CT

HOLD

N.C.

OUT_SW

OUT_SW

N.C.

N.C.

N.C.

N.C.

*EP = EXPOSED PAD

ILIM

2324 22 20 19 18

25

26

27

28

29

30

31

+

32

12

N.C.

N.C.

MAX15009/MAX15011

Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VIN= +14V, V

SGND

= V

PGND

= 0V, C

GATE

= 6000pF, CIN= 10µF (ESR < 1.5Ω), C

OUT_LDO

= 22µF (ceramic), C

OUT_SW

= 1µF,

V

OUT_LDO

= 5V, CT= open, TA= TJ= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

(All pins referenced to SGND, unless otherwise noted.)

IN, GATE.................................................................-0.3V to +45V

EN_LDO, EN_SW, EN_PROT ......................-0.3V to (V

IN

+ 0.3V)

SOURCE ......................................................-0.3V to (V

IN

+ 0.3V)

OUT_LDO, FB_LDO, FB_PROT, RESET,

OC_DELAY .........................................................-0.3V to +12V

GATE to SOURCE ..................................................-0.3V to +12V

OUT_SW, ILIM, HOLD ......................-0.3V to (V

OUT_LDO

+ 0.3V)

OUT_SW to OUT_LDO ...........................................-12V to +0.3V

CT to SGND............................................................-0.3V to +12V

SGND to PGND .....................................................-0.3V to +0.3V

IN, OUT_LDO Current .......................................................700mA

OUT_SW Current...............................................................350mA

Current Sink/Source (all remaining pins) ............................50mA

Continuous Power Dissipation (T

A

= +70°C)

32-Pin TQFN (derate 34.5mW/°C above +70°C).............2.7W*

Thermal Resistance

θ

JA

..............................................................................29.0°C/W

θ

JC

................................................................................1.7°C/W

Operating Temperature Range .........................-40°C to +125°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-60°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

*

As per JEDEC 51 Standard, Multilayer Board (PCB).

Supply Voltage Range V

Supply Current I

Shutdown Supply Current I

IN Undervoltage Lockout V

IN Undervoltage Lockout
Hysteresis

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

SHDN

V

UVLO_HYST

V

≥ V

IN

IN

UVLO

IN

MAX15009

MAX15011

EN_LDO = EN_SW =
EN_PROT = SGND,
measured from
SGND

VIN falling, GATE disabled 4.10 4.27 4.45 V

+ 1.5V 5 40 V

OUT

EN_LDO = IN, EN_SW =
EN_PROT = 0V, I
= 0µA, LDO on, switch off,
protector off, measured
from SGND

EN_LDO = EN_SW = IN,
EN_PROT = 0V, LDO ON,
I

OUT_LDO

on, I

OUT_SW

protector off, measured
from SGND

EN_LDO = EN_SW =
EN_PROT = IN, LDO ON,
I

OUT_LDO

on, I

OUT_SW

protector on, measured
from SGND

EN_LDO = EN_SW = IN,
LDO ON, I
100µA, switch on, I
= 0µA, measured from
SGND

OUT_LDO

= 100µA, switch

= 0µA,

= 100µA, switch

= 0µA,

OUT_LDO

TA = -40°C to
+85°C

T

A

+125°C

=

OUT_SW

= -40°C to

67 85

290 360

360 500

268 360

16 30

40

260 mV

µA

µA

MAX15009/MAX15011

Automotive 300mA LDO Regulators with

Switched Output and Overvoltage Protector

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VIN= +14V, V

SGND

= V

PGND

= 0V, C

GATE

= 6000pF, CIN= 10µF (ESR < 1.5Ω), C

OUT_LDO

= 22µF (ceramic), C

OUT_SW

= 1µF,

V

OUT_LDO

= 5V, CT= open, TA= TJ= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

Dual Mode is a trademark of Maxim Integrated Products, Inc.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Thermal-Shutdown
Temperature

Thermal Hysteresis T

LDO

Output Voltage V

FB_LDO Set-Point Voltage V

Dual Mode™ FB_LDO
Threshold

FB_LDO Input Current I

LDO Output Voltage V

LDO Dropout Voltage V

LDO Output Current I

LDO Output Current Limit I

OUT_LDO Line Regulation

OUT_LDO Load Regulation

OUT_LDO Power-Supply
Rejection Ratio

OUT_LDO Startup Delay
Time

t

T

SHDN

HYST

OUT_LDO I

FB_LDO

V

FB_LDO_TH

FB_LDO

LDO_ADJ

DO

OUT_LDO

LIM_LDO

ΔV

/

OUT

ΔV

IN

ΔV

/

OUT

ΔI

OUT

PSRR

STARTUP_DELAY

I

= 1mA, FB_LDO = SGND 4.92 5.00 5.09

LOAD

= 300mA, VIN = 8V,

LOAD

FB_LDO = SGND

With respect to SGND, I
V

OUT_LDO

= 5V, adjustable output option

FB_LDO rising 0.125

FB_LDO falling 0.064

V

= 1V -100 +100 nA

FB_LDO

Adjustable output option (Note 2) 1.8 11.0 V

I

= 300mA (Note 3) 800 1500

LOAD

I

= 200mA (Note 3) 520 1000

LOAD

(Note 4) 300 mA

OUT_LDO = SGND, VIN = 6V 330 500 700 mA

6V ≤ VIN ≤ 40V, I
V

OUT_LDO

6V ≤ VIN ≤ 40V, I

LOAD

= 5V

LOAD

FB_LDO = SGND, V

6V ≤ VIN ≤ 40V, I

LOAD

FB_LDO = SGND, V

6V ≤ VIN ≤ 40V, I
V

OUT_LDO

LOAD

= 3.3V

1mA to 300mA, VIN = 8V,
FB_LDO = SGND

1mA to 300mA, VIN = 6.3V,
V

OUT_LDO

I

LOAD

V

OUT_LDO

I

OUT_LDO

10% of V

= 3.3V

= 10mA, f = 100Hz, 500mV

= 5V

= 0mA, from EN_LDO rising to

OUT_LDO

(nominal),

FB_LDO = SGND

LOAD

= 1mA,

= 1mA,

OUT_LDO

= 20mA,

OUT_LDO

= 20mA,

= 1mA,

= 3.3V

= 5V

P-P

,

+160 °C

20 °C

4.88 5.00 5.11

1.21 1.235 1.26 V

mV

0.03 0.2

0.03 0.1

mV/V

0.27 1

0.27 0.5

0.054 0.15

mV/mA

0.038 0.100

60 dB

30 µs

V

V

MAX15009/MAX15011

Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(VIN= +14V, V

SGND

= V

PGND

= 0V, C

GATE

= 6000pF, CIN= 10µF (ESR < 1.5Ω), C

OUT_LDO

= 22µF (ceramic), C

OUT_SW

= 1µF,

V

OUT_LDO

= 5V, CT= open, TA= TJ= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

OUT_LDO Overvoltage
Protection Threshold

OUT_LDO Overvoltage
Protection Sink Current

ENABLE/HOLD INPUTS

EN_LDO to EN_PROT Input
Threshold Voltage

E N _LD O, E N _P ROT, E N _S W
Input Pulldown Current

HOLD Input Threshold
Voltage

HOLD Input Pullup I

RESET

RESET Voltage Threshold
HIGH

RESET Voltage Threshold
LOW

V

OUT_LDO

to RESET Delay t

CT Ramp Current I

CT Ramp Threshold V

RESET Output-Voltage Low V
RESET Open-Drain

Leakage Current

LOAD DUMP PROTECTOR (MAX15009 only)

FB_PROT Threshold
Voltage

FB_PROT Threshold
Hysteresis

FB_PROT Input Current I

Startup Response Time t

V

I

EN_PD

HOLD_PU

V

R ESET_H

V

RESET_L

RESET_FALL

I

LEAK_RESET

V

TH_PROT

V

FB_PROT

OV_TH

I

OV

V

IH

V

IL

1mA sink from OUT_LDO 105 110 %V

V

OUT_LDO

= V

OUT

EN_ is internally pulled low to SGND 1 µA

V

IH

V

IL

HOLD is internally pulled high to
OUT_LDO

RESET goes HIGH when rising
V

OUT_LDO

crosses this threshold,

FB_LDO = SGND

RESET goes HIGH when rising
V

crosses this threshold

FB_LDO

RESET goes LOW when falling
V

OUT_LDO

crosses this threshold,

FB_LDO = SGND

RESET goes LOW when falling

CT

CT_TH

OL

V

V

VCT = 0V 1.50 2 2.35 µA

VCT rising 1.190 1.235 1.270 V

I

SINK

crosses this threshold

FB_LDO

OUT_LDO

falling, 0.1V/µs 19 µs

= 1mA, output asserted 0.1 V

Output not asserted 150 nA

FB_PROT rising 1.20 1.235 1.27 V

HYST

START

V

FB_PROT

EN_PROT rising, EN_LDO = IN, to
V

GATE

= 1.4V -100 +100 nA

= 0.5V

(nominal) x 1.15 8 19 mA

2

1.4

0.6 µA

90.0 92.5 95.0 %V

90.0 92.5 95.0 %V

88 90 92 %V

88 90 92 %V

4%V

20 µs

0.7

0.4

OUT_LDO

V

V

OUT_LDO

FB_LDO

OUT_LDO

FB_LDO

TH_PROT

GATE Rise Time t

GATE

GATE rising to +8V, V

= 0V 1 ms

SOURCE

MAX15009/MAX15011

Automotive 300mA LDO Regulators with

Switched Output and Overvoltage Protector

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS (continued)

(VIN= +14V, V

SGND

= V

PGND

= 0V, C

GATE

= 6000pF, CIN= 10µF (ESR < 1.5Ω), C

OUT_LDO

= 22µF (ceramic), C

OUT_SW

= 1µF,

V

OUT_LDO

= 5V, CT= open, TA= TJ= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

Note 1: Specifications to -40°C are guaranteed by design and not production tested.
Note 2: 1.8V is the minimum limit for proper HOLD functionality.
Note 3: Dropout is defined as V

IN

- V

OUT_LDO

when V

OUT_LDO

is 98% of the value of V

OUT_LDO

for VIN= V

OUT_LDO

+ 1.5V.

Note 4: Maximum output current may be limited by the power dissipation of the package.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

FB_PROT to GATE Turn-Off
Propagation Delay

GATE Output High Voltage V

GATE Output Pulldown
Current

GATE Charge-Pump
Current

GATE-to-SOURCE Clamp
Voltage

SWITCH

Switch Dropout ΔV

Switch Current Limit I

Current-Limit Selector ILIM
Voltage

OC_DELAY Timeout
Threshold

OC_DELAY Timeout Pullup
Current

OC_DELAY Timeout
Pulldown Current

Minimum OC_DELAY
Timeout

EN_SW to OUT_SW
Turn-On Time

EN_SW to OUT_SW
Turn-Off Propagation Delay

I

OC_DELAY_DOWN

t

t

OV

- V

GATE

I

V

OC_DELAY

I

OC_DELAY_UP

OC_DELAY_MIN

GATEPD

I

GATE

V

CLMP

SW

SW_LIM

V

ILIM

t

OV_SW

IN

FB_PROT rising from V
250mV to V

V

SOURCE

R

GATE

V

SOURCE

R

GATE

V

GATE

TH_PROT

= VIN = 5.5V,

to IN = 1MΩ

= VIN; VIN ≥ 14V,

to IN = 1MΩ

= 5V, V

EN_PROT

GATE = SGND 45 µA

ΔVSW = V
I

OUT_SW

OUT_LDO

= 100mA, V

no external MOSFET

ILIM = OUT_LDO, VIN = 8V 170 200 240

R

= 100kΩ to SGND,

LIM

V

OUT_LDO

R

LIM

V

OUT_LDO

R

LIM

V

OC_DELAY

V

OC_DELAY

C

OC_DELAY

= 5V, VIN = 8V

= 39kΩ to SGND,

= 5V, VIN = 8V

= 100kΩ

= 0.5V rising

= 0.5V, falling

is unconnected

OUT_SW rising to +0.5V,

OUT_SW

= 1kΩ

R

EN_SW falling, V
rising to +1V, R
V

OUT_LDO

OUT_SW

= 5V

V

+

VIN +

IN

3.2

V

IN

7.0

3.5

+

VIN +

8.1

0.6 µs

VIN +

3.8

VIN +

9.5

TH_PROT

+ 250mV

-

= 0V 63 100 mA

12 16 18 V

- V

OUT_LDO

OUT_SW

,
= 5V,

36 70 mV

85 100 120

30 40 50

0.395 V

1.194 1.235 1.270 V

12.5 16.0 21.3 µA

0.75 1.00 1.40 µA

12 µs

38 µs

OUT_LDO

- V

= 1kΩ,

OUT_SW

18 µs

V

mA

MAX15009/MAX15011

Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector

6 _______________________________________________________________________________________

Typical Operating Characteristics

(VIN= V

EN_LDO

= V

EN_PROT

= V

EN_SW

= +14V, CIN= 10µF, C

OUT_LDO

= 22µF, C

OUT_SW

= 1µF, V

OUT_LDO

= +5V, FB_LDO = SGND,

T

A

= +25°C, unless otherwise specified.)

LDO GROUND CURRENT

vs. LOAD CURRENT

MAX15009 toc01

LOAD CURRENT (mA)

0 0.3 0.6 0.90.1 0.4 0.70.2 0.5 0.8 1.0

74

72

70

68

66

64

62

60

58
56

54

52

GROUND CURRENT (μA)

TA = -40°C

TA = +25°C

TA = +125°C

TA = +85°C

LDO GROUND CURRENT

vs. LOAD CURRENT

MAX15009 toc02

LOAD CURRENT (mA)

0 75 150 22525 100 17550 125 200 250 275 300

100

110

90

80

70

60

50

GROUND CURRENT (μA)

TA = -40°C

TA = +25°C

TA = +85°C

TA = +125°C

SHUTDOWN SUPPLY CURRENT

vs. TEMPERATURE

MAX15009 toc03

TEMPERATURE (°C)

-60 0-40 1008060 120-20 20 40 140

30

25

35

20

15

10

5

0

I

SHDN

(μA)

LDO LOAD-TRANSIENT RESPONSE

MAX15009 toc09

400μs/div

I

OUT_LDO

100mA/div

0A

V

OUT_LDO

5V, AC-COUPLED

100mV/div

LDO POWER-SUPPLY

REJECTION RATIO vs. FREQUENCY

MAX15009 toc04

FREQUENCY (Hz)

10 100k10k100 1k 1M

-10

-20

0

-30

-40

-50

-60

-70

-80

-90

LDO PSRR (dB)

I

OUT_LDO

= 10mA

VIN UVLO HYSTERESIS

vs. TEMPERATURE

MAX15009 toc05

TEMPERATURE (°C)

-50 7525-25 125500 100 150

400

350

300

250

200

150

100

UVLO HYSTERESIS (mV)

LDO LOAD REGULATION

MAX15009 toc06

I

OUT_LDO

(mA)

0 200100 300

5.10

5.08

5.06

5.04

5.02

5.00

4.98

4.96

4.94

4.92

4.90

V

OUT_LDO

(V)

LDO LOAD-TRANSIENT RESPONSE

MAX15009 toc08

2ms/div

V

OUT_LDO

5V, AC-COUPLED

20mV/div

I

OUT_LDO

100mA/div

0A

LDO OUTPUT VOLTAGE

vs. INPUT VOLTAGE

MAX15009 toc07

VIN (V)

025155352010 30 40

6

5

4

3

2

1

0

V

OUT_LDO

(V)

I

OUT_LDO

= 10mA

I

OUT_LDO

= 300mA

(PULSED)

MAX15009/MAX15011

Automotive 300mA LDO Regulators with

Switched Output and Overvoltage Protector

_______________________________________________________________________________________

7

Typical Operating Characteristics (continued)

(VIN= V

EN_LDO

= V

EN_PROT

= V

EN_SW

= +14V, CIN= 10µF, C

OUT_LDO

= 22µF, C

OUT_SW

= 1µF, V

OUT_LDO

= +5V, FB_LDO = SGND,

T

A

= +25°C, unless otherwise specified.)

STARTUP RESPONSE THROUGH V

IN

MAX15009 toc17

20ms/div

V

IN

20V/div

0V

0V

0V

0V

V

RESET

5V/div

V

OUT_LDO

5V/div

V

OUT_SW

5V/div

I

OUT_LDO

= 100mA

I

OUT_SW

= 70mA

EN_LDO = EN_SW = IN

5.10

5.05

5.00

(V)

4.95

OUT_LDO

V

4.90

4.85

4.80

10V/div

V

OUT_LDO

3.3V, AC-COUPLED
20mV/div

V

3.3V, AC-COUPLED

OUT_SW

20mV/div

V

OUT_PROT

10V/div

LDO OUTPUT VOLTAGE

vs. TEMPERATURE

I

= 100μA

OUT_LDO

I

= 100mA

OUT_LDO

-50 7525-25 125500 100 150
TEMPERATURE (°C)

LINE-TRANSIENT RESPONSE

V

IN

I

OUT_LDO

40ms/div

I

OUT_LDO

= 300mA

= 10mA

VIN = 8V

MAX15009 toc13

SWITCH LOAD-TRANSIENT RESPONSE

MAX15009 toc10

I

OUT_SW

100mA/div

V

OUT_SW

5V, AC-COUPLED

100mV/div

V

OUT_LDO

5V, AC-COUPLED

100mV/div

LDO DROPOUT VOLTAGE

1000

900

0V

0V

800

700

600

500

400

300

LDO DROPOUT VOLTAGE (mV)

200

100

0

0 200100 300

400μs/div

I

OUT_LDO

I

OUT_SW

vs. LOAD CURRENT

I

(mA)

OUT_LDO

MAX15009 toc11

= 100mA

= 100mA

0A

MAX15009 toc14

20V/div

V

OUT_LDO

3.3V, AC-COUPLED
50mV/div

V

3.3V, AC-COUPLED

OUT_SW

50mV/div

V

OUT_PROT

20V/div

SWITCH DROPOUT VOLTAGE (mV)

LINE-TRANSIENT RESPONSE

V

IN

SWITCH DROPOUT VOLTAGE

vs. LOAD CURRENT

40

35

30

25

20

15

10

5

0

0 10050

40ms/div

I

OUT_SW

(mA)

I

OUT_LDO

MAX15009 toc12

0V

0V

MAX15009 toc15

= 10mA

SWITCH DROPOUT VOLTAGE

vs. TEMPERATURE

60

I

= 10mA

OUT_LDO

50

40

I

= 100mA

30

20

SWITCH DROPOUT VOLTAGE (mV)

10

0

-45 105 13053055-20 80
TEMPERATURE (°C)

I

OUT_SW

OUT_SW

= 10mA

MAX15009 toc16

MAX15009/MAX15011

Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector

8 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VIN= V

EN_LDO

= V

EN_PROT

= V

EN_SW

= +14V, CIN= 10µF, C

OUT_LDO

= 22µF, C

OUT_SW

= 1µF, V

OUT_LDO

= +5V, FB_LDO = SGND,

T

A

= +25°C, unless otherwise specified.)

PROTECTOR GATE VOLTAGE

vs. INPUT VOLTAGE (MAX15009 ONLY)

MAX15009 toc24

VIN (V)

20 2515 30 4010 3550

50

40

30

20

45

35

25

10

0

15

5

GATE VOLTAGE (V)

V

GATE

V

IN

GROUND CURRENT DISTRIBUTION

HISTOGRAM (T

A

= +125°C)

MAX15009 toc23

GROUND CURRENT (μA)

67 69 7165

6361

57

59

55

5351

90

40

30

20

10

80

70

60

50

0

NUMBER OF PARTS

STARTUP RESPONSE THROUGH EN

V

IN

V

EN_LDO

5V/div

I

= 100mA

OUT_LDO

= 70mA

I

OUT_SW

V

RESET

5V/div

V

OUT_LDO

5V/div

V

OUT_SW

5V/div

V

EN_LDO

5V/div

V

OUT_LDO

5V/div

HOLD

5V/div

RESET

5V/div

= VEN_SW

V

EN_LDO

20ms/div

LDO, EN_LDO, AND HOLD TIMING

HOLD PULLED UP
TO OUT_LDO

200ms/div

MAX15008 toc18

14V

0V

0V

V

0V

0V

MAX15009 toc21

0V

0V

0V

0V

SHUTDOWN RESPONSE THROUGH V

V

IN

I

OUT_LDO

10V/div

I

OUT_SW

EN_LDO = VEN_SW = IN

V

RESET

5V/div

OUT_LDO

5V/div

V

OUT_SW

5V/div

70

60

50

40

30

NUMBER OF PARTS

20

10

0

67

MAX15008 toc19

= 100mA

= 70mA

2ms/div

GROUND CURRENT DISTRIBUTION

HISTOGRAM (T

GROUND CURRENT (μA)

= -40°C)

A

737169

79

IN

817775

0V

0V

0V

0V

MAX15009 toc22

20V/div

V

EN_LDO

5V/div

V

5V/div

V

OUT_LDO

5V/div

V

OUT_SW

5V/div

SHUTDOWN RESPONSE THROUGH EN

V

IN

I

= 100mA

OUT_LDO

= 70mA

I

RESET

OUT_SW

EN_LDO = EN_SW

MAX15008 toc20

6V

0V

0V

0V

0V

PROTECTOR STARTUP RESPONSE

V

IN

10V/div

V

GATE

10V/div

V

OUT_PROT

10V/div

10ms/div

I

OUT_PROT

MAX15009 toc25

= 1A

0V

0V

0V

MAX15009/MAX15011

Automotive 300mA LDO Regulators with

Switched Output and Overvoltage Protector

_______________________________________________________________________________________

9

Typical Operating Characteristics (continued)

(VIN= V

EN_LDO

= V

EN_PROT

= V

EN_SW

= +14V, CIN= 10µF, C

OUT_LDO

= 22µF, C

OUT_SW

= 1µF, V

OUT_LDO

= +5V, FB_LDO = SGND,

T

A

= +25°C, unless otherwise specified.)

RESET TIMEOUT DELAY

vs. TEMPERATURE

MAX15009 toc29

TEMPERATURE (°C)

-25 250 100 12550 15075-50

0

0.6

1.2

1.8

0.4

1.0

1.6

0.2

0.8

1.4

2.0

RESET TIMEOUT DELAY (ms)

C

RESET

= 2.2nF

C

RESET

= 220pF

RESET TIMEOUT DELAY

vs. C

RESET

MAX15009 toc28

C

RESET

(nF)

8621040

7

5

3

6

4

2

0

1

RESET TIMEOUT DELAY (ms)

SWITCH CURRENT LIMIT

vs. ILIM RESISTANCE

MAX15009 toc30

ILIM RESISTANCE (kΩ)

180120 140 1606040 100 2008020

20

60

120

180

40

100

160

80

140

200

SWITCH CURRENT LIMIT (mA)

TA = +125°C

TA = -40°C

TA = +25°C

TA = +85°C

INTERNAL PRESET SWITCH CURRENT LIMIT

vs. TEMPERATURE

MAX15009 toc31

TEMPERATURE (°C)

-25 25 500 125100 15075-50

150

180

210

240

170

160

200

230

190

220

250

PRESET CURRENT LIMIT (mA)

I

OC_DELAY_UP

AND I

OC_DELAY_DOWN

vs. TEMPERATURE

MAX15009 toc32

TEMPERATURE (°C)

-25 25 500 125100 15075-50

0

6

12

4

2

10

16

8

14

18

OC_DELAY PULLUP/PULLDOWN CURRENT (μA)

I

OC_DELAY_DOWN

I

OC_DELAY_UP

OVERVOLTAGE SWITCH FAULT

V

IN

10V/div

20V/div

V

OUT_PROT

20V/div

V

GATE

I

OUT_PROT

= 25V

V

OV

400μs/div

= 1A

MAX15009 toc26

0V

0V

0V

20V/div

V

20V/div

V

OUT_PROT

20V/div

V

IN

GATE

I

OUT_PROT

OV THRESHOLD = 35V

OVERVOLTAGE LIMIT FAULT

= 1A

MAX15009 toc27

40ms/div

0V

0V

0V

MAX15009/MAX15011

Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector

10 ______________________________________________________________________________________

Pin Description

PIN

1–4, 8, 11,

14, 26, 29–32

1–4, 8,

10–14, 18,

26, 29–32

5 SGND SGND Signal Ground

6 PGND PGND

7 RESET RESET

MAX15009 MAX15011

NAME

N.C. —

— N.C.

FUNCTION

No Connection. Not internally connected.

Ground. PGND is also the return path for the overvoltage protector pulldown current
for the MAX15009. In this case, connect PGND to SGND at the negative terminal of the
bypass capacitor connected to the source of the external MOSFET. For the
MAX15011, connect PGND to SGND together to the local ground plane.

Active-Low Open-Drain Reset Output. RESET is low while OUT_LDO is below the reset
threshold. Once OUT_LDO has exceeded the reset threshold, RESET remains low for
the duration of the reset timeout period then goes high.

9CTCT

10 FB_PROT —

12 GATE —

13 SOURCE —

Reset Timeout Adjust Input. Connect a capacitor (C
the reset timeout period. See the Setting the

Overvoltage-Threshold Adjustment Input. Connect FB_PROT to an external resistive
voltage-divider network to adjust the desired overvoltage threshold. Use FB_PROT to
monitor a system input or output voltage. See the Setting the Overvoltage Threshold
(MAX15009 Only) section.

Protector Gate Drive Output. Connect GATE to the gate of an external n-channel
MOSFET. GATE is the output of a charge pump with a 45µA pullup current to 8.1V
(typ) above IN during normal operation. GATE is quickly turned off through a 63mA
internal pulldown during an overvoltage condition. GATE then remains low until
FB_PROT has decreased below 96% of the overvoltage threshold. GATE pulls low
when EN_PROT is low.

Output-Voltage Sense Input. Connect SOURCE to the source of the external n-channel
MOSFET.

) from CT to ground to adjust

RESET

RESET

Timeout Period section.

MAX15009/MAX15011

Automotive 300mA LDO Regulators with

Switched Output and Overvoltage Protector

______________________________________________________________________________________ 11

Pin Description (continued)

PIN

15 FB_LDO FB_LDO

16 EN_LDO EN_LDO

17 EN_SW EN_SW

18 EN_PROT —

19, 20 IN IN Regulator Input. Bypass IN to SGND with a 10µF capacitor with an ESR < 1.5Ω.

21, 22 OUT_LDO OUT_LDO

23 OC_DELAY OC_DELAY

MAX15009 MAX15011

NAME

FUNCTION

LDO Voltage Feedback Input. Connect FB_LDO to SGND to select the preset +5V
output voltage. Connect FB_LDO to an external resistive voltage-divider for adjustable
output operation. See the Setting the Output Voltage section.

Active-High LDO Enable Input. Connect EN_LDO to IN or to a logic-high voltage to
turn on the regulator. To place the LDO in shutdown, pull EN_LDO low or leave
unconnected and leave HOLD unconnected. EN_LDO is internally pulled to SGND
through a 1µA current sink. See the Control Logic section.

Active-High Switch Enable Input. Connect EN_SW to IN or to a logic-high voltage to
turn on the switch. Pull EN_SW low or leave unconnected to place the switch in
shutdown. EN_SW is internally pulled to SGND through a 1µA current sink.

Protector Enable Input. Drive EN_PROT low to force GATE low and turn off the external
n-channel MOSFET. EN_PROT is internally pulled to SGND by a 1µA sink current.
Connect EN_PROT to IN for normal operation.

LDO Regulator Output. Bypass OUT_LDO to SGND with a ceramic capacitor with a
minimum value of 22µF. OUT_LDO has a fixed 5V output or can be adjusted from1.8V
to 11V. See the Setting the Output Voltage section.

Switch Overcurrent Blanking Time Programming Input. Leave OC_DELAY
unconnected to select the minimum delay timeout before turning the switch off.
OC_DELAY is internally pulled to SGND through a 1µA current source. See the
Programming the Switch Overcurrent Blanking Time section.

Switch Current-Limit Set Input. Connect a 10kΩ to 200kΩ resistor from ILIM to SGND to

24 ILIM ILIM

25 HOLD HOLD

27, 28 OUT_SW OUT_SW Switch Output. Bypass OUT_SW to SGND with a minimum 0.1µF ceramic capacitor.

—EPEP

select the current limit for the internal switch. Connect ILIM to OUT_LDO to select the
internal 170mA (min) current-limit threshold. Do not leave ILIM unconnected. See the
Setting the Switch Current Limit section.

Active-Low Hold Input. If EN_LDO is high when HOLD is forced low, the regulator
latches the state of the EN_LDO input and allows the regulator to remain turned on
when EN_LDO is subsequently pulled low. To shut down the regulator, release HOLD
after EN_LDO is pulled low. If HOLD functionality is unused, connect HOLD to
OUT_LDO or leave unconnected. HOLD is internally pulled up to OUT_LDO through a

0.6µA current source. See the Control Logic section.

Exposed Pad. Connect EP to SGND plane. EP also functions as a heatsink to maximize
thermal dissipation. Do not use as the main ground connection.

MAX15009/MAX15011

Functional Diagram

Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector

12 ______________________________________________________________________________________

ENABLE LDO

HOLD

IN

V

IN

IN

EN_LDO

HOLD

CONTROL

LOGIC

LDO

BIAS AND VOLTAGE

REFERENCE

V

1.235V

REF

5V LDO

OUT_LDO

M
U
X

FB_LDO

OUTPUT

0.925 x V

REF

ENABLE SWITCH

ILIM

EN_SW

OC_DELAY

2μA

V

REF

16μA

V

REF

0.1V

1μA

SWITCH

OUT_SW

VGATE

S

Q

R

0.124V

RESET

OUT_LDO

OUT_SW

CT

RESET
OUTPUT

SWITCH
OUTPUT

IN

GATE UVLO

ENABLE

PROTECTOR

EN_PROT

4.75V

V

REF

OVERVOLTAGE PROTECTOR

EP SGND PGND

(MAX15009 ONLY)

GATE

SOURCE

FB_PROT

V

IN

PROTECTOR
OUTPUT

Detailed Description

The MAX15009/MAX15011 integrate a 300mA LDO
voltage regulator, a current-limited switched output,
and an OVP controller (MAX15009 only). These devices
operate over a wide supply voltage range from 5V to
40V and are able to withstand load-dump transients up
to 45V.

The MAX15009/MAX15011 feature a 300mA LDO regu­lator that consumes 70µA of current under light-load
conditions and feature a fixed 5V or an adjustable out­put voltage (1.8V to 11V). Connect FB_LDO to ground
to select a fixed 5V output voltage or select the LDO
output voltage by connecting an external resistive volt­age-divider at FB_LDO. The regulator sources at least
300mA of current and includes a current limit of 330mA
(min). Enable the LDO by pulling EN_LDO high.

The switch features accurate current-limit sensing cir­cuitry and is capable of controlling remote loads. Once
enabled, an internal charge pump generates the over­drive voltage for an internal MOSFET. The switch then
starts to conduct and OUT_SW is charged up to
V

OUT_LDO

. The switch is enabled when the output volt-

age of the LDO is above the RESET threshold voltage
(92.5% of the LDO nominal output value).

An overcurrent condition exists when the current at
OUT_SW, I

OUT_SW

, exceeds the 200mA (typ) internal
factory-set current-limit threshold or the externally
adjustable current-limit threshold. During a continuous
overcurrent event, the capacitor connected at
OC_DELAY, C

OC_DELAY

, is charged up to a voltage of

1.235V with a current, I

OC_DELAY_UP

. When this voltage
is reached, an overcurrent latch is set and the gate of
the internal MOSFET is discharged, reducing I

OUT_SW

.

C

OC_DELAY

is then discharged through a pulldown cur-

rent, I

OC_DELAY_DOWN(IOC_DELAY_UP

/ 16) and the

internal MOSFET remains off until C

OC_DELAY

has been
discharged to 0.1V. After this user-programmable turn­off delay, the switch turns back on. This charge/
discharge is repeated if the overcurrent condition per­sists. The switch returns to normal operation once the
overcurrent condition has been removed.

The OVP controller (MAX15009 only) relies on an exter­nal MOSFET with adequate voltage rating (V

DSS

) to
protect downstream circuitry from overvoltage tran­sients. The OVP controller drives the gate of the exter­nal n-channel MOSFET, and is configurable to operate
as an overvoltage protection switch or as a closed-loop
voltage limiter.

GATE Voltage (MAX15009 Only)

The MAX15009 uses a high-efficiency charge pump to
generate the GATE voltage for the external n-channel
MOSFET. Once the input voltage, V

IN

, exceeds the
undervoltage lockout (UVLO) threshold, the internal
charge pump fully enhances the external n-channel
MOSFET. An overvoltage condition occurs when the
voltage at FB_PROT goes above the threshold voltage,
V

TH_PROT

. After V

TH_PROT

is exceeded, GATE is quick­ly pulled to PGND with a 63mA pulldown current. The
MAX15009 includes an internal clamp from GATE to
SOURCE that ensures that the voltage at GATE never
exceeds one diode drop below SOURCE during gate
discharge. The voltage clamp also prevents the GATE­to-SOURCE voltage from exceeding the absolute maxi­mum rating for the V

GS

of the external MOSFET in case

the source terminal is accidentally shorted to 0V.

Overvoltage Monitoring (MAX15009 Only)

The OVP controller monitors the voltage at FB_PROT
and controls an external n-channel MOSFET, isolating,
or limiting the load during an overvoltage condition.
Operation in OVP switch mode or limiter mode
depends on the connection between FB_PROT and the
external MOSFET.

Overvoltage Switch Mode

When operating in OVP switch mode, the FB_PROT
divider is connected to the drain of the external MOS­FET. The feedback path consists of the voltage-divider
tapped at FB_PROT, FB_PROT’s internal comparator,
the internal gate charge pump/gate pulldown, and the
external n-channel MOSFET (Figure 1). When the pro­grammed overvoltage threshold is exceeded, the inter­nal comparator quickly pulls GATE to ground and turns

MAX15009/MAX15011

Automotive 300mA LDO Regulators with

Switched Output and Overvoltage Protector

______________________________________________________________________________________ 13

Figure 1. Overvoltage-Limiter Switch Configuration (MAX15009)

V

IN

IN

FB_PROT

GATE

MAX15009

SOURCE

SGND

PROTECTOR

OUTPUT

MAX15009/MAX15011

Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector

14 ______________________________________________________________________________________

off the external MOSFET, disconnecting the power
source from the load. In this configuration, the voltage
at the source of the MOSFET is not monitored. When
the voltage at FB_PROT decreases below the overvolt­age threshold, the MAX15009 raises the voltage at
GATE, reconnecting the load to the power source.

Overvoltage-Limiter Mode (MAX15009 Only)

When operating in overvoltage-limiter mode, the feed­back path consists of SOURCE, FB_PROT’s internal
comparator, the internal gate charge pump/gate pull­down, and the external n-channel MOSFET (Figure 2).
This configuration results in the external MOSFET oper­ating as a hysteretic voltage regulator.

During normal operation, GATE is enhanced 8.1V above
VIN. The external MOSFET source voltage is monitored
through a resistive voltage-divider between SOURCE
and FB_PROT. When V

SOURCE

exceeds the adjustable
overvoltage threshold, an internal pulldown switch
discharges the gate voltage and quickly turns the
MOSFET off. Consequently, the source voltage begins
to fall. The V

SOURCE

fall time is dependent on the MOS­FET’s gate charge, the internal charge-pump current,
the output load, and any load capacitance at SOURCE.
When the voltage at FB_PROT is below the overvoltage
threshold by an amount equal to the hysteresis, the
charge pump restarts and turns the MOSFET back on.
In this way, the OVP controller attempts to regulate
V

SOURCE

around the overvoltage threshold. SOURCE
remains high during overvoltage transients and the
MOSFET continues to conduct during an overvoltage
event. The hysteresis of the FB_PROT comparator and
the gate turn-on delay force the external MOSFET to
operate in a switched on/off sequence during an over­voltage event.

Exercise caution when operating the MAX15009 in volt­age-limiting mode for long durations. Care must be
taken against prolonged or repeated exposure to over­voltage events while delivering large amounts of load
current as the power dissipation in the external MOS­FET may be high under these conditions. To prevent
damage to the MOSFET, implement proper heatsinking.
The capacitor tied between SOURCE and ground may
also be damaged if the ripple current rating for the
capacitor is exceeded.

As the transient voltage decreases, the voltage at
SOURCE falls. For fast-rising transients and very large
MOSFETs, connect an additional capacitor from GATE
to PGND. This capacitor acts as a voltage-divider work­ing against the MOSFET’s drain-to-gate capacitance. If
using a very low gate charge MOSFET, additional
capacitance from GATE to ground might be required to
reduce the switching frequency.

Control Logic

The MAX15009/MAX15011 LDO features two logic
inputs, EN_LDO and HOLD, making these devices suit­able for automotive applications. For example, when
the ignition key signal drives EN_LDO high, the regula­tor turns on and remains on even if EN_LDO goes low,
as long as HOLD is forced low and stays low after initial
regulator power-up. In this state, releasing HOLD turns
the regulator output (OUT_LDO) off. This feature makes
it possible to implement a self-holding circuit without
external components. Forcing EN_LDO low and HOLD
high (or unconnected) places the regulator into shut­down mode, reducing the supply current to less than
16µA. Table 1 shows the state of OUT_LDO with
respect to EN_LDO and HOLD. Leave HOLD uncon-
nected or connect directly to OUT_LDO to allow the
EN_LDO input to act as a standard on/off logic input for
the regulator.

Figure 2. Overvoltage Limiter (MAX15009)

V

IN

IN

GATE

MAX15009

SOURCE

FB_PROT

SGND

PROTECTOR

OUTPUT

Applications Information

Load Dump

Most automotive applications run off a multicell 12V
lead-acid battery with a nominal voltage that swings
between 9V and 16V, depending on load current,
charging status, temperature, and battery age, etc. The
battery voltage is distributed throughout the automobile
and is locally regulated down to voltages required by
the different system modules. Load dump occurs when
the alternator is charging the battery and the battery
becomes disconnected. Power in the alternator (behav­ing now essentially as an inductor) flows into the dis­tributed power system and elevates the voltage seen at
each module. The voltage spikes have rise times typi­cally greater than 5ms and decay within several hun­dred milliseconds but can extend out to 1s or more
depending on the characteristics of the charging sys­tem. These transients are capable of destroying semi­conductors on the first fault event.

The MAX15009/MAX15011 feature load-dump transient
protection up to +45V.

Setting the Output Voltage

The MAX15009/MAX15011 feature dual-mode opera­tion: these devices operate in either a preset voltage
mode or an adjustable mode. In preset voltage mode,
internal feedback resistors set the linear regulator out­put voltage (V

OUT_LDO

) to 5V. To select the preset 5V

output voltage, connect FB_LDO to SGND.

To select an adjustable output voltage between 1.8V
and 11V, use two external resistors connected as a
voltage-divider to FB_LDO (Figure 3). Set the output
voltage using the following equation:

V

OUT_LDO

= V

FB_LDO

x (R1+ R2) / R

2

where V

FB_LDO

= 1.235V and R2≤ 50kΩ.

Setting the

RESET

Timeout Period

The reset timeout period is adjustable to accommodate
a variety of applications. Set the reset timeout period by
connecting a capacitor, C

RESET

, between CT and
SGND. Use the following formula to select the reset
timeout period, t

RESET

:

t

RESET

= C

RESET

x V

CT_TH

/ I

CT

where t

RESET

is in seconds and C

RESET

is in µF.

V

CT_TH

is the CT ramp threshold in volts and ICTis the

CT ramp current in µA, as described in the

Electrical

Characteristics

table.

MAX15009/MAX15011

Automotive 300mA LDO Regulators with

Switched Output and Overvoltage Protector

______________________________________________________________________________________ 15

Figure 3. Setting the LDO Output Voltage

Table 1. EN_LDO/

HHOOLLDD

Truth/State Table

OPERATION STATE EN_LDO HOLD OUT_LDO COMMENT

Initial State Low Don’t care OFF

Turn-On State High Don’t care ON

Hold Setup State High Low ON

Hold State Low Low ON

Off State Low

High or

unconnected

OFF

EN_LDO is pulled to SGND through an internal pulldown. HOLD
is unconnected and is internally pulled up to OUT_LDO. The
regulator is disabled.

EN_LDO is externally driven high turning regulator on. HOLD is
pulled up to OUT_LDO.

HOLD is externally pulled low while EN_LDO remains high
(latches EN_LDO state).

EN_LDO is driven low or left unconnected. HOLD remains
externally pulled low keeping the regulator on.

HOLD is driven high or left unconnected while EN_LDO is low.
The regulator is turned off and EN_LDO/HOLD logic returns to the
initial state.

V

IN

IN

MAX15009
MAX15011

OUT_LDO

FB_LDO

SGND

R1

R2

MAX15009/MAX15011

Leave CT open to select a typical reset timeout of 19µs.
To maintain reset accuracy, use a low-leakage type of
capacitor.

Setting the Switch Current Limit

The switch block features accurate current-limit sens­ing circuitry. A resistor connected from ILIM to SGND
can be used to select the current-limit threshold using
the following relationship:

I

SW_LIM

(mA) = R

ILIM

(kΩ) x 1mA / kΩ

where 20kΩ ≤ R

ILIM

≤ 200kΩ.

Connect ILIM to OUT_LDO to select the default current
limit of 200mA (typ).

Programming the Switch

Overcurrent Blanking Time

The switch provides an adjustable overcurrent blanking
time to allow the safe charge of large capacitive loads.
When an overcurrent event is detected, a delay period
elapses before the condition is latched and the internal
MOSFET is turned off. This period is the overcurrent
delay, t

OC_DELAY

. Set the overcurrent delay using the

following equation:

t

OC_DELAY

= C

OC_DELAY

x V

OC_DELAY

/ I

OC_DELAY_UP

where t

OC_DELAY

is in seconds and C

OC_DELAY

is in

µF. V

OC_DELAY

is the overcurrent delay timeout thresh-

old voltage in volts and I

OC_DELAY_UP

is the overcur-

rent delay timeout pullup current in µA as seen in the

Electrical Characteristics

table.

Ensure that the switch is not disabled due to a large
startup inrush current by selecting a large enough
value for overcurrent blanking time. Assume that the
current available for charging the total switch output
capacitance, C

OUT_SW

, is the difference between the

current-limit threshold value, I

SW_LIM

, and the nominal

DC load current at OUT_SW, I

OUT_SW_NOM

and select

the C

OC_DELAY

using the following relationship:

C

OC_DELAY

also affects the length of time before the
MAX15009/MAX15011 attempt to turn the switch back
on. Set the autoretry delay using the following equation:

t

OC_RETRY

= C

OC_DELAY

x

V

OC_DELAY/IOC_DELAY_DOWN

where t

OC_RETRY

is in seconds, C

OC_DELAY

is in µF,

V

OC_DELAY

is in volts, and I

OC_DELAY_DOWN

is in µA.

C

OC_DELAY

should be a low-leakage type of capacitor

with a minimum value of 100pF.

Setting the Overvoltage Threshold

(MAX15009 Only)

The MAX15009 provides an accurate means to set the
overvoltage threshold for the OVP controller using
FB_PROT. Use a resistive voltage-divider to set the
desired overvoltage threshold (Figure 4). FB_PROT has
a rising 1.235V threshold with a 4% falling hysteresis.

Begin by selecting the total end-to-end resistance,
R

TOTAL

= R3+ R4. Choose R

TOTAL

to yield a total current

equivalent to a minimum of 100 x I

FB_PROT

(FB_PROT’s
input maximum bias current) at the desired overvoltage
threshold. See the

Electrical Characteristics

table.

For example:

With an overvoltage threshold (VOV) set to 20V, R

TOTAL

< 20V / (100 x I

FB_PROT

), where I

FB_PROT

is FB_PROT’s

maximum 100nA bias current:

R

TOTAL

< 2MΩ

Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector

16 ______________________________________________________________________________________

Figure 4. Setting the Overvoltage Threshold (MAX15009)

C

OC_DELAY

IVC

OC_DELAY_UP OUT_LDO OUT_SW

≥

V(II )

OC_DELAY SW_LIM OUT_SW_NOM

×−

××

V

IN

R5

R6

IN

FB_PROT

MAX15009

SGND

GATE

PROTECTOR

OUTPUT

SOURCE

V

IN

IN

GATE

MAX15009

SOURCE

FB_PROT

SGND

PROTECTOR

OUTPUT

R3

R4

Use the following formula to calculate R4:

R4= V

TH_PROT

x R

TOTAL

/ V

OV

where V

TH_PROT

is the 1.235V FB_PROT rising threshold

and VOVis the desired overvoltage threshold. R4= 124kΩ:

R

TOTAL

= R3+ R

4

where R3= 1.88MΩ. Use a standard 1.87MΩ resistor.

A lower value for total resistance dissipates more
power, but provides better accuracy and robustness
against external disturbances.

Input Transients Clamping

When the external MOSFET is turned off during an
overvoltage event, stray inductance in the power path
may cause additional input-voltage spikes that exceed
the V

DSS

rating of the external MOSFET or the absolute
maximum rating for the MAX15009. Minimize stray
inductance in the power path using wide traces and
minimize the loop area included by the power traces
and the return ground path.

For further protection, add a zener diode or transient
voltage suppressor (TVS) rated below the absolute
maximum rating limits (Figure 5).

External MOSFET Selection

Select the external MOSFET with adequate voltage rating,
V

DSS

, to withstand the maximum expected load-dump
input voltage. The on-resistance of the MOSFET,
R

DS(ON)

, should be low enough to maintain a minimal
voltage drop at full load, limiting the power dissipation
of the MOSFET.

During regular operation, the power dissipated by the
MOSFET is:

P

NORMAL

= I

LOAD

2

x R

DS(ON)

Normally, this power loss is small and is safely handled
by the MOSFET. However, when operating the
MAX15009 in overvoltage limiter mode under pro­longed or frequent overvoltage events, select an exter­nal MOSFET with an appropriate power rating.

During an overvoltage event, the power dissipation in
the external MOSFET is proportional to both load cur­rent and to the drain-source voltage, resulting in high
power dissipated in the MOSFET (Figure 6). The power
dissipated across the MOSFET is:

P

OV_LIMITER

= VQ1x I

LOAD

where VQ1is the voltage across the MOSFET’s drain
and source during overvoltage limiter operation, and
I

LOAD

is the load current.

MAX15009/MAX15011

Automotive 300mA LDO Regulators with

Switched Output and Overvoltage Protector

______________________________________________________________________________________ 17

Figure 5. Protecting the MAX15009 Input from High-Voltage
Transients

Figure 6. Power Dissipated Across MOSFETs During an
Overvoltage Fault (Overvoltage Limiter Mode)

V

IN

IN

TVS

MAX15009

GATE

SOURCE

SGND

LOAD

V

MAX

GATE

SOURCE

FB_PROT

+ VQ1 -

I

LOAD

V

LOAD

V

SOURCE

IN

TVS

MAX15009

SGND

SOURCE

V

OV

MAX15009/MAX15011

Overvoltage-Limiter Mode

Switching Frequency

When the MAX15009 is configured in overvoltage­limiter mode, the external n-channel MOSFET is subse­quently switched on and off during an overvoltage
event. The output voltage at OUT_PROT resembles a
periodic sawtooth waveform. Calculate the period of
the waveform, t

OVP

, by summing three time intervals

(Figure 7):

t

OVP

= t1+ t2+ t

3

where t1is the V

SOURCE

output discharge time, t2 is the

GATE delay time, and t3is the V

SOURCE

output charge

time.

During an overvoltage event, the power dissipated
inside the MAX15009 is due to the gate pulldown cur­rent, I

GATEPD

. This amount of power dissipation is

worse when I

SOURCE

= 0 (C

SOURCE

is discharged only

by the internal current sink).

The worst-case internal power dissipation contribution
in overvoltage limiter mode, P

OVP

, in watts can be

approximated using the following equation:

where V

OV

is the overvoltage threshold voltage in volts

and I

GATEPD

is 100mA (max) GATE pulldown current.

Output Discharge Time (t1)

When the voltage at SOURCE exceeds the adjusted
overvoltage threshold, GATE’s internal pulldown is
enabled until V

SOURCE

drops by 4%. The internal cur-

rent sink, I

GATEPD

, and the external load current,

I

LOAD

, discharge the external capacitance from

SOURCE to ground.

Calculate the discharge time, t

1

, using the following

equation:

where t1is in ms, VOVis the adjusted overvoltage
threshold in volts, I

LOAD

is the external load current in

mA, and I

GATEPD

is the 100mA (max) internal pulldown

current of GATE. C

SOURCE

is the value of the capacitor
connected between the source of the MOSFET and
PGND in µF.

GATE Delay Time (t2)

When SOURCE falls 4% below the overvoltage-threshold
voltage, the internal current sink is disabled and the
internal charge pump begins recharging the external
GATE voltage. Due to the external load, the SOURCE
voltage continues to drop until the gate of the MOSFET is
recharged. The time needed to recharge GATE and re­enhance the external MOSFET is approximately:

where t2is in µs, C

iss

is the input capacitance of the

MOSFET in pF, and V

GS(TH)

is the GATE-to-SOURCE
threshold voltage of the MOSFET in volts. VFis the 0.7V
(typ) internal clamp diode forward voltage of the MOS­FET in volts, and I

GATE

is the charge-pump current
45µA (typ). Any external capacitance between GATE
and PGND adds up to C

iss

.

During t2, the SOURCE capacitance, C

SOURCE

, loses
charge through the output load. The voltage across
C

SOURCE

, ΔV2, decreases until the MOSFET reaches

its V

GS(TH)

threshold. Approximate ΔV2using the fol-

lowing formula:

SOURCE Output Charge Time (t3)

Once the GATE voltage exceeds the GATE-to-SOURCE
threshold, V

GS(TH)

, of the external MOSFET, the MOS­FET turns on and the charge through the internal
charge pump with respect to the drain potential, QG,
determines the slope of the output voltage rise. The
time required for the SOURCE voltage to rise again to
the overvoltage threshold is:

Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector

18 ______________________________________________________________________________________

Figure 7. MAX15009 Timing Diagram

GATE

SOURCE

t

2

t

1

t

3

t

OVP

PV I

=×× ×0981.

OVP OV GATEPD

t

t

OVP

tC

=×

1 SOURCE

0.04 V

×

OV

II

+

LOAD GATEPD

tC

=×

2

VV

GS TH F

iss

+

()

I

GATE

It

×

ΔV

LOAD

=

2

C

2

SOURCE

CV

×Δ

rss SOURCE

t

=

3

I

GATE

where V

SOURCE

= (VOVx 0.04) + V2 in volts, and C

rss

is the MOSFET’s reverse transfer capacitance in pF.
Any external capacitance between GATE and PGND
adds up to C

rss

.

Power Dissipation/Junction Temperature

During normal operation, the MAX15009/MAX15011
have two main sources of internal power dissipation:
the LDO and the switched output.

The internal power dissipation due to the LDO can be
calculated as:

where VINis the LDO input supply voltage in volts,
V

OUT_LDO

is the output voltage of the LDO in volts,

I

OUT_LDO

is the LDO total load current in mA, and

I

OUT_SW

is the switch load current in mA.

Calculate the power dissipation due to the switch as:

where ΔVSWis the switch dropout voltage in volts for
the given I

OUT_SW

current in mA.

The total power dissipation P

DISS

in mW as:

P

DISS

= P

LDO

+ P

SW

For prolonged exposure to overvoltage events, use the
VINvoltage expected during overvoltage conditions.
Under these circumstances the corresponding internal
power dissipation contribution, P

OVP

, calculated in the
previous section should also be included in the total
power dissipation, P

DISS

.

For a given ambient temperature, T

A

, calculate the

junction temperature, TJ, as follows:

TJ= TA+ P

DISS

x θ

JA

where TJand TAare in °C and θJAis the junction-to­ambient thermal resistance in °C/W as listed in the

Absolute Maximum Ratings

section.

The junction temperature should never exceed +150°C
during normal operation.

Thermal Protection

When the junction temperature exceeds TJ= +160°C,
the MAX15009/MAX15011 shut down to allow the
device to cool. When the junction temperature drops to
+140°C, the thermal sensor turns all enabled blocks on
again, resulting in a cycled output during continuous
thermal-overload conditions. Thermal protection pro­tects the MAX15009/MAX15011 from excessive power
dissipation. For continuous operation, do not exceed
the absolute maximum junction temperature rating of
+150°C.

MAX15009/MAX15011

Automotive 300mA LDO Regulators with

Switched Output and Overvoltage Protector

______________________________________________________________________________________ 19

P(VV )(I I )

=− × +

IN OUT_LDO OUT_LDO OUT_SWLDO

PVI

=×Δ

SW SW

OUT SW_

MAX15009/MAX15011

Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector

20 ______________________________________________________________________________________

Typical Operating Circuits

DC-DC

MAX5073

C

SOURCE

SOURCE FB_PROT

5V TO 40V INPUT

C

SWITCH ON/OFF

PROTECTOR ON/OFF

R

ILIM

GATE

OUT_SW

OUT_LDO

FB_LDO

RESET

C

OC_DELAY

PGND

SGND

R

PU

SWITCH OUTPUT

C

OUT_SW

5V

300mA

C

OUT_LDO

V

CC

RESET/EN
I/O

μC

IN

IN

EN_LDOLDO ON/OFF

MAX15009

EN_SW

EN_PROT

HOLDHOLD

ILIM

CT OC_DELAY

C

RESET

V

OUT1

V

OUT2

5V TO 40V INPUT

C

IN

R

ILIM

IN

OUT_SW

EN_LDOLDO ON/OFF

EN_SWSWITCH ON/OFF

HOLDHOLD

ILIM

CT PGND SGND

C

RESET

MAX15011

OC_DELAY

C

OC_DELAY

OUT_LDO

FB_LDO

RESET

C

OUT_SW

R

PU

SWITCH OUTPUT

5V

300mA

C

OUT_LDO

V

CC

RESET/EN
I/O

μC

MAX15009/MAX15011

Automotive 300mA LDO Regulators with

Switched Output and Overvoltage Protector

______________________________________________________________________________________ 21

Chip Information

PROCESS: BiCMOS

MAX15011

TQFN

(5mm x 5mm)

+

TOP VIEW

29

30

28

27

12

11

13

N.C.

N.C.

SGND

PGND

RESET

14

N.C.

OC_DELAY

OUT_LDO

IN

ILIM

IN

N.C.

12

OUT_SW

4567

2324 22 20 19 18

N.C.

N.C.

N.C.

N.C.

N.C.

N.C.

N.C.

OUT_LDO

3

21

31

10

N.C.

N.C.

32

9

N.C.

CT

OUT_SW

26

15

FB_LDO

*EP

*EP = EXPOSED PAD

N.C.

25

16

EN_LDO

N.C.

EN_SW

8

17

HOLD

Pin Configurations (continued)

PART LDO

SWITCHED

OUTPUT

OVP

CONTROLLER

MAX15009 √√ √
MAX15011 √√ —

Selector Guide

MAX15009/MAX15011

Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector

22 ______________________________________________________________________________________

Package Information

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages

.)

QFN THIN.EPS

MAX15009/MAX15011

Automotive 300mA LDO Regulators with

Switched Output and Overvoltage Protector

______________________________________________________________________________________ 23

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages

.)

MAX15009/MAX15011

Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

24

____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

Revision History

REVISION

NUMBER

0 8/07 Initial release —

1 1/08

REVISION

DATE

Removed future product asterisks, updated Electrical Characteristics table and
Typical Operating Characteristics section.

DESCRIPTION

PAGES

CHANGED

1, 2, 6, 8