Rainbow Electronics MAX15022 User Manual

General Description

The MAX15022 is a dual-output, pulse-width-modulated
(PWM), step-down DC-DC regulator with dual LDO con­trollers. The device operates from 2.5V to 5.5V and
each output can be adjusted from 0.6V to the input
supply (V

AVIN

). The MAX15022 delivers up to 4A (regu­lator 1) and 2A (regulator 2) of output current with two
LDO controllers that can be used to drive two external
PNP transistors to provide two additional outputs. This
device offers the ability to adjust the switching frequen­cy from 500kHz to 4MHz and provides the capability of
optimizing the design in terms of size and performance.

The MAX15022 utilizes a voltage-mode control scheme
with external compensation to provide good noise
immunity and maximum flexibility in selecting inductor
values and capacitor types. The dual switching regula­tors operate 180° out-of-phase, thereby reducing the
RMS input ripple current and thus the size of the input
bypass capacitor significantly.

The MAX15022 offers the ability to track (coincident or
ratiometric) or sequence during power-up and power­down operation. When sequencing, it powers up glitch­free into a prebiased output.

Additional features include an internal undervoltage
lockout with hysteresis and a digital soft-start/soft-stop
for glitch-free power-up and power-down. Protection
features include lossless cycle-by-cycle current limit,
hiccup-mode output short-circuit protection, and ther­mal shutdown.

The MAX15022 is available in a space-saving, 5mm x
5mm, 28-pin TQFN-EP package and is specified for
operation from -40°C to +125°C temperature range.

Applications

RFID Reader Cards

Power-over-Ethernet (PoE) IP Phones

Automotive Multimedia

Multivoltage Supplies

Networking/Telecom

Features

o 2.5V to 5.5V Input-Voltage Range

o Dual-Output Synchronous Buck Regulators

o Integrated Switches for 4A and 2A Output

Currents

o 180° Out-Of-Phase Operation

o Output Voltage Adjustable from 0.6V to V

AVIN

o Two LDO Controllers

o Lossless, Cycle-by-Cycle Current Sensing

o External Compensation for Maximum Flexibility

o Digital Soft-Start and Soft-Stop for Tracking

Applications

o Digital Soft-Start into a Prebiased Load for

Sequencing Applications

o Sequencing or Coincident/Ratiometric Tracking

o Programmable Switching Frequency from 500kHz

to 4MHz

o Thermal Shutdown and Hiccup-Mode Short-

Circuit Protection

o 30µA Shutdown Current

o 100% Maximum Duty Cycle

o Space-Saving (5mm x 5mm) 28-Pin TQFN

Package

MAX15022

Dual, 4A/2A, 4MHz, Step-Down DC-DC

Regulator with Dual LDO Controllers

________________________________________________________________

Maxim Integrated Products

1

Pin Configuration

Ordering Information

19-4107; Rev 0; 5/08

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.

EVALUATION KIT

AVAILABLE

PART TEMP RANGE PIN-PACKAGE

MAX15022ATI+

-40°C to +125°C 28 TQFN-EP*

+

Denotes a lead-free package.

*

EP = Exposed pad.

TOP VIEW

EN4

LX2

PVIN2

18

4

PGND2

DVDD2

EN3

*EP

567

14

FB3

B3

13

12

COMP1

FB1

11

10

EN1

DVDD1

9

8

PGND1

COMP2

FB2

EN2

SGND

AVIN

FB4

2021 19 17 16 15

B4

22

23

24

25

26

27

28

RT

1+2

MAX15022

3

*EP = EXPOSED PAD.

SEL

LX1

PGND1

THIN QFN

(5mm x 5mm)

PVIN1

PVIN1

LX1

PGND1

MAX15022

Dual, 4A/2A, 4MHz, Step-Down DC-DC
Regulator with Dual LDO Controllers

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(V

AVIN

= V

PVIN_

= V

DVDD_

= 3.3V, V

PGND_

= V

SGND

= 0V, RT= 25kΩ, and TA= TJ= -40°C to +125°C, unless otherwise noted.

Typical values are at T

A

= +25°C.) (Note 3)

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.

Note 1: LX has internal diodes to PGND_ and PVIN_. Applications that forward bias these diodes should take care not to exceed

the IC’s package power dissipation limits.

Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-

layer board. For detailed information on package thermal considerations see www.maxim-ic.com/thermal-tutorial

.

AVIN, PVIN_, B_, DVDD_, EN_, FB_, RT,

SEL to SGND .........................................................-0.3V to +6V

COMP_ to SGND .....................................-0.3V to (V

AVIN

+ 0.3V)

PGND_ to SGND ...................................................-0.3V to +0.3V

LX Current (Note 1)

Regulator 1...............................................................................6A

Regulator 2...............................................................................3A

Current into Any Pin Other than PVIN_,

LX_ and PGND_.............................................................±50mA

Continuous Power Dissipation (T

A

= +70°C)

28-Pin TQFN (derate 34.5mW/°C above +70°C) .....2758.6mW

Junction-to-Case Thermal Resistance (θ

JC

)(Note 2) .........2°C/W

Junction-to-Ambient Thermal Resistance (θ

JA

)(Note 2) ..29°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

SYSTEM SPECIFICATIONS

Input-Voltage Range

Undervoltage Lockout Threshold AVIN rising 2.1 2.2 2.3 V

Undervoltage Lockout Hysteresis 0.12 V

Operating Supply Current V

Shutdown Supply Current V

PWM DIGITAL SOFT-START/SOFT-STOP

Soft-Start/Soft-Stop Duration 4096

Reference Voltage Steps 64 Steps

PWM ERROR AMPLIFIERS

FB1, FB2 Input Bias Current -1 +1 μA

FB1, FB2 Voltage Set-Point 0.593 0.599 0.605 V

COMP1, COMP2 Voltage Range I

Error-Amplifier Open-Loop Gain 80 dB

Error-Amplifier Unity-Gain
Bandwidth

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

V

= V

AVIN

V

DVDD2

= 1.3V, V

EN_

= 0V 30 65 μA

EN_

_ = -250μA to +250μA 0.3 V

COMP

PVIN1

= V

FB_

= V

PVIN2

= 0.8V 3.5 6 mA

DVDD1

=

2.5 5.5 V

AVIN

12 MHz

- 0.5 V

Clock

Cycles

MAX15022

Dual, 4A/2A, 4MHz, Step-Down DC-DC

Regulator with Dual LDO Controllers

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(V

AVIN

= V

PVIN_

= V

DVDD_

= 3.3V, V

PGND_

= V

SGND

= 0V, RT= 25kΩ, and TA= TJ= -40°C to +125°C, unless otherwise noted.

Typical values are at T

A

= +25°C.) (Note 3)

LDO CONTROLLERS

FB3, FB4 Input Bias Current -250 +250 nA

FB3, FB4 Voltage Set-point 5mA sink current, VB_ = 0.5V to 5.5V 0.585 0.600 0.615 V

FB3, FB4 to B3, B4
Transconductance

B3, B4 Driver Sink Current V

LDO Soft-Start Duration

LDO Reference Voltage Steps 64 Steps

POWER MOSFETS

Regulator 1 p-Channel MOSFET
R

DSON

Regulator 1 n-Channel MOSFET
R

DSON

Regulator 1 Gate Charge V

Maximum LX1 RMS Current 4A

Regulator 2 p-Channel MOSFET
R

DSON

Regulator 2 n-Channel MOSFET
R

DSON

Regulator 2 Gate Charge V

Maximum LX2 RMS Current 2A

PWM CURRENT LIMIT AND HICCUP MODE

Regulator 1 Peak Current Limit

Regulator 1 Valley Current Limit

Regulator 2 Peak Current Limit

Regulator 2 Valley Current Limit

Number of Cumulative Current­Limit Events to Hiccup

Number of Consecutive Noncurrent
Limit Cycles to Clear N

Hiccup Timeout N

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

CL

2.5mA to 10mA sink current,
V

= 0.5V to 5.5V

B_

FB3, VFB4

V

DVDD1

V

DVDD1

DVDD1

V

DVDD2

V

DVDD2

DVDD2

V

PVIN

V

PVIN

V

PVIN

V

PVIN

V

PVIN

V

PVIN

V

PVIN

V

PVIN

N

CL

N

CLR

HT

= 0V, VB_ = 0.5V to 5.5V 20 mA

= 5V 50 90 mΩ

= 5V 30 50 mΩ

= 5V 8 nC

= 5V 100 180 mΩ

= 5V 60 100 mΩ

= 5V 4 nC

= V

= V

= V

= V

= V

= V

= V

= V

= 3.3V 4.5 4.9 5.3

AVIN

= 2.5V 3.40 3.65 3.95

AVIN

= 3.3V 4.0 5.0 5.65

AVIN

= 2.5V 3.0 3.7 4.25

AVIN

= 3.3V 2.25 2.45 2.65

AVIN

= 2.5V 1.70 1.85 1.98

AVIN

= 3.3V 2.0 2.5 2.83

AVIN

= 2.5V 1.5 1.85 2.13

AVIN

0.56 1.20 2.30 S

512

4

3

8192

Clock

Cycles

Clock

Cycles

Clock

Cycles

Clock

Cycles

A

A

A

A

MAX15022

Dual, 4A/2A, 4MHz, Step-Down DC-DC
Regulator with Dual LDO Controllers

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(V

AVIN

= V

PVIN_

= V

DVDD_

= 3.3V, V

PGND_

= V

SGND

= 0V, RT= 25kΩ, and TA= TJ= -40°C to +125°C, unless otherwise noted.

Typical values are at T

A

= +25°C.) (Note 3)

Note 3: Specifications are 100% production tested at TA= +25°C and TA= +125°C. Maximum and minimum specifications over

temperature are guaranteed by design.

Note 4: When operating with V

AVIN

= 2.5V, the maximum operating frequency should be derated to 3MHz.

ENABLE/SEL

EN_ Threshold V

EN_ Hysteresis 0.12 V

EN_ Input Current -2.5 +2.5 μA

SEL High Threshold 0.85 x V

SEL Low Threshold 0.2 x V

SEL Input Bias Current Present only during startup -100 +100 μA

OSCILLATOR

Switching Frequency Range f

Oscillator Accuracy

Phase Shift Between Regulators 180 Degrees

RT Current 0 < VRT < 1.067V 31.30 32.00 32.58 μA

RT Voltage Range V

Minimum Controllable On-Time 60 ns

Minimum Controllable Off-Time 60 ns

PWM Ramp Amplitude V

PWM Ramp Valley 0.3 V

THERMAL SHUTDOWN

Thermal Shutdown Temperature Temperature rising +160 °C

Thermal Shutdown Hysteresis 15 °C

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

SW

RT

rising 1.207 1.225 1.243 V

EN_

f

= 4MHz x [VRT(V)/1.067(V)] (Note 4) 4000 kHz

SW

fSW ≤ 1500kHz -6 +6

f

> 1500kHz -10 +10

SW

0.130 1.067 V

AVIN

/4 V

AVIN

AVIN

V

V

%

MAX15022

Dual, 4A/2A, 4MHz, Step-Down DC-DC

Regulator with Dual LDO Controllers

_______________________________________________________________________________________

5

Typical Operating Characteristics

(V

AVIN

= V

DVDD1

= V

DVDD2

= V

PVIN1

= V

PVIN2

= 5V, V

OUT1

= 3.3V, V

OUT2

= 1.5V, V

PGND_

= 0V, RT= 16.5kΩ. TA= +25°C, unless

otherwise noted.)

CHANNEL 1 EFFICIENCY

vs. LOAD CURRENT

MAX15022 toc01

LOAD CURRENT (mA)

EFFICIENCY (%)

1000

10

20

30

40

50

60

70

80

90

100

0

100 5000

V

PVIN1

= 3.3V

V

PVIN1

= 5V

V

OUT1

= 1.8V

f

SW

= 2MHz

EN2 = 0V

CHANNEL 1 EFFICIENCY

vs. LOAD CURRENT

MAX15022 toc02

LOAD CURRENT (mA)

EFFICIENCY (%)

1000

10

20

30

40

50

60

70

80

90

100

0

100 5000

V

PVIN1

= 5V

f

SW

= 2MHz

EN2 = 0V

V

OUT1

= 3.3V

V

OUT1

= 1.8V

V

OUT1

= 1.0V

CHANNEL 2 EFFICIENCY

vs. LOAD CURRENT

MAX15022 toc03

LOAD CURRENT (mA)

EFFICIENCY (%)

1000

10

20

30

40

50

60

70

80

90

100

0

100 3000

P

VIN2

= 5V

P

VIN2

= 3.3V

V

OUT2

= 1.5V

f

SW

= 2MHz

EN1 = 0V

CHANNEL 2 EFFICIENCY

vs. LOAD CURRENT

MAX15022 toc04

LOAD CURRENT (mA)

EFFICIENCY (%)

1000

10

20

30

40

50

60

70

80

90

100

0

100 3000

V

OUT2

= 1.0V

V

OUT2

= 1.5V

V

OUT2

= 2.5V

V

PVIN2

= 5V

f

SW

= 2MHz

EN1 = 0V

CHANNEL 1

LOAD REGULATION

MAX15022 toc05

LOAD CURRENT (A)

V

OUT1

(V)

3.302

3.304

3.306

3.308

3.310

3.312

3.314

3.316

3.318

3.320

3.300

3.53.02.52.01.51.00.50 4.0

V

PVIN1

= 5V

f

SW

= 2MHz

CHANNEL 2

LOAD REGULATION

MAX15022 toc06

LOAD CURRENT (A)

V

OUT2

(V)

1.251.00

0.75

0.50

0.25

1.5025

1.5030

1.5035

1.5040

1.5045

1.5050

1.5055

1.5060

1.5065

1.5070

1.5020
0

1.50 1.75 2.00

fSW = 2MHz

V

PVIN2

= 5V

V

PVIN2

= 3.3V

SWITCHING FREQUENCY

vs. RT RESISTANCE

MAX15022 toc07

RT RESISTANCE (kΩ)

SWITCHING FREQUENCY (MHz)

35

30

20 2510

15

5

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0

0

SWITCHING FREQUENCY

vs. TEMPERATURE

MAX15022 toc08

TEMPERATURE (°C)

CHANGE IN SWITCHING FREQUENCY (%)

1109565 80-10 5 20 35 50-25

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

-0.5

-40 125

fSW = 2MHz

MAX15022

Dual, 4A/2A, 4MHz, Step-Down DC-DC
Regulator with Dual LDO Controllers

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(V

AVIN

= V

DVDD1

= V

DVDD2

= V

PVIN1

= V

PVIN2

= 5V, V

OUT1

= 3.3V, V

OUT2

= 1.5V, V

PGND_

= 0V, RT= 16.5kΩ. TA= +25°C, unless

otherwise noted.)

EN_ THRESHOLD

vs. TEMPERATURE

MAX15022 toc12

TEMPERATURE (°C)

EN_ THRESHOLD (V)

11095-25 -10 5 35 50 6520 80-40 125

1.215

1.220

1.225

1.230

1.235

1.240

1.245

1.250

1.255

1.260

1.210

5.00

4.75

4.50

4.25

4.00

3.75

3.50

3.25

QUIESCENT CURRENT (mA)

3.00

2.75

2.50

1.030

1.025

1.020

1.015

1.010

1.005

1.000

0.995

0.990

0.985

NORMALIZED UVLO THRESHOLD

0.980

0.975

0.970

QUIESCENT CURRENT

vs. TEMPERATURE

NO SWITCHING

-40 125

TEMPERATURE (°C)

1109565 80-10 5 20 35 50-25

NORMALIZED UNDERVOLTAGE LOCKOUT

THRESHOLD vs. TEMPERATURE

V

(NOM) = 2.2V

UVLO

-40 125

TEMPERATURE (°C)

1109565 80-10 5 20 35 50-25

MAX15022 toc09

MAX15022 toc11

27
26

25

24

23

22

21
20
19

18

17
16

SWITCHING CURRENT (mA)

15

14

13

12

-40 125

SWITCHING CURRENT

vs. TEMPERATURE

REGULATOR 1 ENABLED
V

REGULATOR 2 ENABLED
V

OUT2

TEMPERATURE (°C)

OUT1

= 3.3V

= 1.5V

MAX15022 toc10

1109565 80-10 5 20 35 50-25

COINCIDENT TRACKING SOFT-START

1ms/div

MAX15022 toc13

V

AVIN

5V/div
0V

V

OUT1

1V/div

V

OUT2

1V/div

0V

COINCIDENT TRACKING SOFT-STOP

V

OUT1

EN1

V

OUT2

400μs/div

MAX15022 toc14

V

AVIN

5V/div
0V

1V/div

0V

MAX15022

Dual, 4A/2A, 4MHz, Step-Down DC-DC

Regulator with Dual LDO Controllers

_______________________________________________________________________________________

7

Typical Operating Characteristics (continued)

(V

AVIN

= V

DVDD1

= V

DVDD2

= V

PVIN1

= V

PVIN2

= 5V, V

OUT1

= 3.3V, V

OUT2

= 1.5V, V

PGND_

= 0V, RT= 16.5kΩ. TA= +25°C, unless

otherwise noted.)

CHANNEL 1 LOAD STEP RESPONSE

MAX15022 toc15

V

PVIN1

5V/div

V

OUT1

3.3V, AC-COUPLED
100mV/div

I

OUT1

2A/div

0V

0A

20μs/div

EN2 = 0V

CHANNEL 1 LOAD STEP RESPONSE

MAX15022 toc16

V

PVIN1

5V/div

V

OUT1

3.3V, AC-COUPLED
100mV/div

I

OUT1

2A/div

0V

0A

20μs/div

EN2 = 0V

CHANNEL 2 LOAD STEP RESPONSE

EN1 = 0V

180° OUT-OF-PHASE OPERATION

IOUT1 = 3A
IOUT2 = 1.5A

20μs/div

200ns/div

MAX15022 toc17

MAX15022 toc19

V

PVIN2

5V/div

0V

V

OUT2

1.5V, AC-COUPLED
100mV/div

I

OUT2

1A/div
0A

PVIN1 = PVIN2
5V/div

0V

V

LX1

5V/div

0V

V

LX2

5V/div
0V

CHANNEL 2 LOAD STEP RESPONSE

EN1 = 0V

20μs/div

CHANNEL 3 AND CHANNEL 4 OUTPUT-

VOLTAGE DEVIATION vs. LOAD CURRENT

14

CHANNEL 3, VIN = 3.3V,

= 2.5V

V

OUT3

12

NJT403OP PNP

10

8

6

4

OUTPUT-VOLTAGE DEVIATION (mV)

2

0

0 500

CHANNEL 4, VIN = 2.5V,

= 1.5V

V

OUT4

NJT403OP PNP

LOAD CURRENT (mA)

MAX15022 toc18

450 40035030025020015010050

V

PVIN2

5V/div
0V

V

OUT2

1.5V, AC-COUPLED
100mV/div

I

OUT2

1A/div
0A

MAX15022 toc20

MAX15022

Dual, 4A/2A, 4MHz, Step-Down DC-DC
Regulator with Dual LDO Controllers

8 _______________________________________________________________________________________

Pin Description

Typical Operating Characteristics (continued)

(V

AVIN

= V

DVDD1

= V

DVDD2

= V

PVIN1

= V

PVIN2

= 5V, V

OUT1

= 3.3V, V

OUT2

= 1.5V, V

PGND_

= 0V, RT= 16.5kΩ. TA= +25°C, unless

otherwise noted.)

2.500

2.495

2.490

2.485

2.480

2.475

2.470

OUTPUT VOLTAGE (V)

2.465

2.460

2.455

2.450

2.90 5.50

CHANNEL 3 OUTPUT VOLTAGE

vs. INPUT VOLTAGE

I

= 10mA

OUT3

I

OUT3

SUPPLY VOLTAGE (V)

= 500mA

V

OUT3

4.984.463.943.42

= 2.5V

MAX15022 toc21

CHANNEL 4 OUTPUT VOLTAGE

vs. INPUT VOLTAGE

1.215

1.210

I

= 500mA

1.205

1.200

1.195

1.190

1.185

OUTPUT VOLTAGE (V)

1.180

1.175

1.170

OUT4

I

OUT4

2.90 5.50
SUPPLY VOLTAGE (V)

= 10mA

V

= 1.5V

OUT4

4.984.463.943.42

-10

MAX15022 toc22

-20

-30

-40

PSRR (dB)

-50

-60

-70

-80

LDO POWER-SUPPLY REJECTION RATIO

0

10 1000

V

= 3.3V, V

IN

= 10mA,

I

OUT3

100mV
APPLIED TO V

100

FREQUENCY (Hz)

P-P

OUT3

SIGNAL

IN

= 2.5V,

MAX15022 toc23

PIN NAME FUNCTION

Track/Sequence Select Input. Connect SEL to SGND to configure the device as a sequencer. Connect

1 SEL

2, 7, 8 PGND1

3, 6 LX1

4, 5 PVIN1

9 DVDD1 Switch Driver Supply for Regulator 1. Connect externally to PVIN1.

10 EN1

11 FB1

12 COMP1 Error-Amplifier Output for Regulator 1. Connect COMP1 to the compensation feedback network.

SEL to AVIN for tracking with output 1 as the master. Leave SEL unconnected for tracking with output 2
as the master. Use the output with the higher voltage as the master and the output with the lower voltage
as the slave.

Power Ground Connection for Regulator 1. Connect the negative terminals of the input and output filter
capacitors to PGND1. Connect PGND1 externally to SGND at a single point, typically at the negative
terminal of the input bypass capacitor.

Inductor Connection for Regulator 1. LX1 is the drain connection of the internal high-side p-channel
MOSFET and the drain connection of the internal synchronous n-channel MOSFET for regulator 1.

Input Supply Voltage for Regulator 1. Connect PVIN1 to an external voltage source from 2.5V to 5.5V.
Bypass PVIN1 to PGND1 with a 1μF (min) ceramic capacitor.

Enable Input for Regulator 1. When configured as a sequencer, EN1 must exceed 1.225V (typ) for the
PWM controller to begin regulating output 1. When configured as a tracker, connect EN1 to the center
tap of a resistive divider from the regulator 2 output.

Feedback Regulation Point for Regulator 1. Connect FB1 to the center tap of a resistive divider from the
regulator 1 output to SGND to set the output voltage. The FB1 voltage regulates to 0.6V (typ).

MAX15022

Dual, 4A/2A, 4MHz, Step-Down DC-DC

Regulator with Dual LDO Controllers

_______________________________________________________________________________________ 9

Pin Description (continued)

PIN NAME FUNCTION

13

14

15

16 DVDD2 Switch Driver Supply for Regulator 2. Connect externally to PVIN2.

17 PGND2

18 LX2

19 PVIN2

20 EN4

21 FB4

22 B4

23 COMP2 Error-Amplifier Output for Regulator 2. Connect COMP2 to the compensation feedback network.

24 FB2

25 EN2

B3

FB3

EN3

Transconductance Amplifier Open-Drain Output for LDO Controller 3. Connect B3 to the base of an
external PNP transistor to regulate output 3.

Feedback Regulation Point for LDO Controller 3. Connect to the center tap of a resistive divider from the
output 3 to SGND to set the output voltage. The FB3 voltage regulates to 0.6V (typ).

LDO Enable Input for LDO Controller 3. EN3 must exceed 1.225V (typ) for the LDO controller to begin
regulating output 3.

Power Ground Connection for Regulator 2. Connect the negative terminals of the input and output filter
capacitors to PGND2. Connect PGND2 externally to SGND at a single point, typically at the negative
terminal of the input bypass capacitor.

Inductor Connection for Regulator 2. LX2 is the drain connection of the internal high-side p-channel
MOSFET and the drain connection of the internal synchronous n-channel MOSFET for Regulator 2.

Input Supply Voltage for Regulator 2. Connect to an external voltage source from 2.5V to 5.5V. Bypass
PVIN2 to PGND2 with a 1μF (min) ceramic capacitor.

LDO Enable Input for LDO Controller 4. EN4 must exceed 1.225V (typ) for the LDO controller to begin
regulating output 4.

Feedback Regulation Point for LDO Controller 4. Connect to the center tap of a resistive divider from
output 4 to SGND to set the output voltage. The FB4 voltage regulates to 0.6V (typ).

Transconductance Amplifier Open-Drain Output for LDO Controller 4. Connect B4 to the base of an
external PNP transistor to regulate output 4.

Feedback Regulation Point for Regulator 2. Connect to the center tap of a resistive divider from the
regulator 2 output to SGND to set the output voltage. The FB2 voltage regulates to 0.6V (typ).

Enable Input for Regulator 2. When configured as a sequencer, EN2 must exceed 1.225V (typ) for the
PWM controller to begin regulating output 1. When configured as a tracker, connect EN2 to the center
tap of a resistive divider from the regulator 1 output.

26 SGND

27 AVIN Input Voltage. Bypass AVIN to SGND with a 100nF (min) ceramic capacitor.

28 RT

—EP

Signal Ground. Connect SGND to PGND_ at a single point, typically near the negative terminal of the
input bypass capacitor.

Oscillator Timing Resistor Connection. Connect a 4.2kΩ to 33kΩ resistor from RT to SGND to program
the switching frequency from 500kHz to 4MHz.

Exposed Paddle. Connect EP to a large copper plane at SGND potential to improve thermal dissipation.
Do not use as the main SGND connection.