Datasheet MAX17552AUB+ Datasheet (FREI)

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Page 1

EVALUATION KIT AVAILABLE

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MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency,

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

General Description

The MAX17552/MAX17552A high-efficiency, high-voltage, synchronous step-down DC-DC converters with integrated MOSFETs operate over a 4V to 60V input voltage range. The converters can deliver output current up to 100mA at output voltages of 0.8V to 0.9 x VIN. The output voltage is accurate to within ±1.75% over the -40°C to +125°C temperature range.

The devices employ a peak-current-mode control architecture with a MODE pin that can be used to operate the device in pulse-width modulation (PWM) or pulsefrequency modulation (PFM) control schemes. PWM operation provides constant frequency operation at all loads and is useful in applications sensitive to variable switching frequency. PFM operation disables negative inductor current and additionally skips pulses at light loads for high efficiency. The converters consume only 22µA of no-load supply current in PFM mode. The low-

resistance, on-chip MOSFETs ensure high efficiency at full load and simplify PCB layout.

The devices offer programmable switching frequency to optimize solution size and efficiency. Programmable softstart allows the user to reduce the inrush currents. During overload, the MAX17552 implements a hysteretic cycleby-cycle peak-current-limit protection scheme, while the MAX17552A implements a HICCUP-type overload protection scheme to protect the inductor and the internal FETs. An EN/UVLO pin allows the user to turn on/off the device at the desired input-voltage level. An open-drain RESET pin allows output-voltage monitoring. The devices operate over the -40°C to +125°C industrial temperature range and is available in a compact 10-pin (3mm x 2mm) TDFN

and 10-pin (3mm x 3mm) μMAX® packages. Simulation

models are available.

Applications

● Industrial Sensors and Process Control

● 4mA–20mA Current-Loop Powered Sensors

● High-Voltage LDO Replacement

● Battery-Powered Equipment

● HVAC and Building Control

● General-Purpose Point of Load

Benets and Features

●

Eliminates External Components and Reduces Total Cost

• No Schottky—Synchronous Operation for High

E󰀩ciency and Reduced Cost

• Internal Compensation

• Fixed Internal 5.1ms or Programmable Soft-Start

• All-Ceramic Capacitors, Ultra-Compact Layout

● Reduces Number of DC-DC Regulators to Stock

• Wide 4V to 60V Input Voltage Range

• Adjustable 0.8V to 0.9 x VIN Output Voltages

• Delivers Up to 100mA Load Current

• 100kHz to 2.2MHz Adjustable Switching Frequency Range with External Synchronization

• Congurable Between PFM and Forced-PWM Modes

● Reduces Power Dissipation

• 22µA No Load Supply Current

• Peak E󰀩ciency > 90%

• PFM Feature for High Light-Load E󰀩ciency

• 1.2μA (typ) Shutdown Current

● Operates Reliably in Adverse Industrial Environments

• Peak Current-Limit Protection

● Built-In Output-Voltage Monitoring with Open-Drain

RESET Pin

• Programmable EN/UVLO Threshold

• Monotonic Startup into Prebiased Output

• Overtemperature Protection

• High Industrial -40°C to +125°C Ambient Operating Temperature Range / -40°C to +150°C Junction Temperature Range

Ordering Information appears at end of data sheet.

µMAX is a registered trademark of Maxim Integrated Products, Inc.

19-6903; Rev 5; 8/18

Page 2

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Typical Application Circuit—High-E󰀩ciency 5V, 100mA Regulator

6V TO 60V

1µF

191k

SWITCHING FREQUENCY = 220kHz L1 COILCRAFT LPS5030-224M C C

MAX17552/

MAX17552A

EN/UVLO

MODE

RT/SYNC

Ω

MURATA 10µF/X7R/6.3V/1206 (GRM31CR70J106K)

OUT

MURATA 1µF/X7R/100V/1206 (GRM31CR72A105K)

GND

OUT

RESET

0.22

220

22.1

10µF

Ω

49.9k

OUT

Ω

261k

OUT

5V, 100mA

Ω

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Page 3

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Absolute Maximum Ratings (Note 1)

IN, EN/UVLO, V

LX to GND ....................................................... -0.3V to IN +0.3V

RT/SYNC, SS, FB, MODE to GND .........................-0.3V to +6V

LX Total RMS Current ........................................................ ±1.6A

Output Short-Circuit Duration .................................... Continuous

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: Junction temperature greater than +125°C degrades operating lifetimes.

Package Information

PACKAGE TYPE: 10 TDFN

Package Code T1032N+1

Outline Number 21-0429

Land Pattern Number 90-0082

THERMAL RESISTANCE, FOUR-LAYER BOARD

Continuous Power Dissipation (TA = +70°C) (derate 14.9mW/°C above +70°C)

Junction to Ambient (θJA) 67.3°C/W Junction to Case (θJC) 18.2°C/W

, RESET to GND...................-0.3V to +70V

OUT

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

Storage Temperature Range ............................ -65°C to +150°C

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

Soldering Temperature (reflow) ....................................... +260°C

1188.7mW

PACKAGE TYPE: 10 µMAX

Package Code U10+5

Outline Number 21-0061

Land Pattern Number 90-0330

THERMAL RESISTANCE, FOUR-LAYER BOARD

Continuous Power Dissipation (TA = +70°C) (derate 8.8mW/°C above +70°C)

Junction to Ambient (θJA) 113.1°C/W Junction to Case (θJC) 42°C/W

For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.

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, refer to www.maximintegrated.com/thermal-tutorial.

707.3mW

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Page 4

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Electrical Characteristics

(VIN = 24V, V TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to GND, unless otherwise noted) (Note 2)

INPUT SUPPLY (IN)

Input Voltage Range V

Input Shutdown Current I

Input Supply Current

EXTERNAL BIAS (V

Switchover Threshold 2.96 3.05 3.12 V

OUT

ENABLE/UVLO (EN/UVLO)

EN/UVLO Threshold

EN/UVLO Leakage Current I

POWER MOSFETs

High-Side pMOS On-Resistance R

Low-Side nMOS On-Resistance R

LX Leakage Current I

SOFT-START (SS)

Soft-Start Time t

SS Charging Current I

FEEDBACK (FB)

FB Regulation Voltage V

FB Input Leakage Current I

CURRENT LIMIT

Peak Current-Limit Threshold I

Negative Current-Limit Threshold I

PFM Current Level I

OSCILLATOR (RT/SYNC)

Switching Frequency f

GND

= 0V, V

= 3.3V, VFB = 0.85V, V

VOUT

EN/UVLO

= 1.5V, RT/SYNC = 191kΩ, LX = SS = MODE = RESET = unconnected;

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

4 60 V

µA

-1 +1 µA

4.7 5 5.3 µA

185 210 235 mA

OUT)

IN-SH

Q-PFM

Q-PWM

ENR

ENF

EN-TRUESDVEN/UVLO

DS-ONH

DS-ONL

LX-LKG

EN/UVLO

MODE

Normal switching mode, VIN = 24V 245 525 760

EN/UVLO

ILX = 0.1A (sourcing) 1.5 2.7 5.1 Ω

ILX = 0.1A (sinking) 0.8 1.4 2.6 Ω

VEN = 0V, TA = +25°C, VLX = (V

SS = unconnected 4.4 5.1 5.8 ms

MODE = GND 0.786 0.8 0.814

FB-REG

PEAK-LIMIT

SINK-LIMIT

PFM

MODE = unconnected 0.786 0.812 0.826

VFB = 1V, TA = 25°C -100 +100 nA

MODE

= 0V, TA = +25°C 0.67 1.2 2.25

= unconnected (Note 3) 18 32

rising 1.2 1.25 1.3

falling 1.1 1.15 1.2

falling, true shutdown 0.7

= 1.3V, TA = +25°C -100 +100 nA

+ 1V) to (VIN - 1V)

GND

= GND 79 105 130

= unconnected 0.01

= unconnected 50 72 90 mA

RRT = 422kΩ 90 100 111

RRT = 191kΩ 205 220 235

RRT = 130kΩ 295 319 340

RRT = 69.8kΩ 540 592 638

kHz

RRT = 45.3kΩ 813 900 973

RRT = 19.1kΩ 1.86 2.08 2.3 MHz

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Page 5

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Electrical Characteristics (continued)

(VIN = 24V, V TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to GND, unless otherwise noted) (Note 2)

Switching Frequency Adjustable Range

SYNC Input Frequency 1.1 x f SYNC Pulse Minimum O󰀨-Time 40 ns

SYNC Rising Threshold V

Hysteresis V

Number of SYNC Pulses to Enable Synchronization

TIMING

Minimum On-Time t

Maximum Duty Cycle D

Hiccup Timeout MAX17552A 51 ms

RESET

FB Threshold for RESET Rising V FB Threshold for RESET Falling V

RESET Delay after FB Reaches 95% Regulation

RESET Output Level Low I RESET Output Leakage Current VFB = 1.01 x V

MODE

MODE PFM Threshold V

MODE Hysteresis V

MODE Internal Pullup Resistor

THERMAL SHUTDOWN

Thermal-Shutdown Threshold Temperature rising 160 °C

Thermal-Shutdown Hysteresis 20 °C

Note 2: Limits are 100% tested at TA = +25°C. Limits over the operating temperature range and relevant supply voltage range are

guaranteed by design and characterization.

Note 3: Actual I

example, I

GND

= 0V, V

= 3.3V, VFB = 0.85V, V

VOUT

EN/UVLO

= 1.5V, RT/SYNC = 191kΩ, LX = SS = MODE = RESET = unconnected;

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

See the Switching Frequency (RT/ SYNC) section for details

SYNC-H

SYNC-HYS

100 2200 kHz

2200 kHz

1 1.22 1.44

0.115 0.18 0.265

1 Cycles

ON-MIN

MAX

FB-OKR

FB-OKF

fSW ≤ 600kHz, VFB = 0.98 x V

FB-REG

fSW > 600kHz, VFB = 0.98 x V

FB-REG

VFB rising 93 95 97 %

VFB falling 90 92 94 %

46 82 128 ns

90 94 98

87 92

2.1 ms

= 1mA 0.23 V

RESET

FB-REG

MODE-PFM

MODE-HYS

= unconnected

MODE

(MAX17552) V

= unconnected

MODE

(MAX17552A)

= GND 1390

MODE

in the application circuit is higher due to additional current in the output voltage feedback resistor divider. For

Q-PFM

(MODE = unconnected) = 26µA for Figure 6, 22µA for Figure 7, and 78µA for Figure 11.

Q-PFM

TA = +25°C 1 µA

1 1.22 1.44 V

0.19 V

235

123

kΩ

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Page 6

(MAX17552)

(MAX17552A)

EFFICIENCY vs. LOAD CURRENT

(MAX17552A)

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Typical Operating Characteristics

(VIN = 24V, V

GND

= 0V, V

OUT

= 3.3V, V

EN/UVLO

= 1.5V, RT/SYNC = 191kΩ, CIN = 1μF, TA = +25°C unless otherwise noted.)

EFFICIENCY vs.

100

VIN= 12V

EFFICIENCY (%)

1 10 100

100

EFFICIENCY (%)

VIN= 24V

VIN= 12V

1 10 100

LOAD CURRENT

VIN= 24V

FIGURE 6 APPLICATION

CIRCUIT, PFM MODE

fSW = 220kHz (RRT = 191k)

LOAD CURRENT (mA)

= 36V

VIN= 48V

FIGURE 7 APPLICATION

CIRCUIT, PFM MODE

= 220kHz(RRT= 191k)

LOAD CURRENT (mA)

VIN= 36V

VIN= 60V

= 3.3V

OUT

toc1

EFFICIENCY (%)

= 5V

OUT

1 10 100

VIN= 24V

VIN= 12V

VIN= 36V

VIN= 48V

FIGURE 6 APPLICATION

CIRCUIT, PFM MODE

= 220kHz (RRT = 191k)

VIN= 60V

OUT

toc2

EFFICIENCY (%)

= 5V

EFFICIENCY vs. LOAD CURRENT

EFFICIENCY vs.

100

VIN= 12V

1 10 100

LOAD CURRENT (mA)

EFFICIENCY vs LOAD CURRENT

toc4

EFFICIENCY (%)

VIN= 24V

VIN= 12V

1 10 100

FIGURE 6 APPLICATION CIRCUIT,

LOAD CURRENT (mA)

VIN= 48V

VIN= 36V

PFM MODE, V = 600kHz (RRT= 69.8k)

VIN= 60V

= 5V

OUT

toc5

EFFICIENCY vs. LOAD CURRENT

100

VIN= 12V

EFFICIENCY (%)

1 10 100

LOAD CURRENT

(MAX17552)

VIN= 24V

VIN= 36V

FIGURE 7 APPLICATION

CIRCUIT, PFM MODE

= 3.3V

VIN= 36V

OUT

= 3.3V

fSW= 220kHz (RRT= 191k)

LOAD CURRENT (mA)

VIN= 24V

FIGURE 7 APPLICATION CIRCUIT,

PFM MODE, V

= 600kHz (RRT= 69.8k)

LOAD CURRENT (mA)

toc3

toc6

100

EFFICIENCY (%)

020406080100

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EFFICIENCY vs.

LOAD CURRENT

(MAX17552)

VIN=24V

VIN=36V

VIN=48V

VIN=60V

FIGURE 6APPLICATION CIRCUIT,

LOAD CURRENT(mA)

VIN=12V

PWM MODE, V

= 220kHz (RRT = 191k)

OUT

= 5V

EFFICIENCY vs.LOADCURRENT

toc7

100

(MAX17552A)

EFFICIENCY (%)

VIN=36V

VIN=48V

VIN=60V

020406080100

VIN=12V

VIN=24V

FIGURE 6APPLICATION CIRCUIT,

PWM MODE, V

= 220kHz (RRT = 191k)

toc8

EFFICIENCY (%)

= 5V

OUT

EFFICIENCY

100

VIN= 60V

0 20 40 60 80 100

LOAD CURRENT(mA)

VS.

LOAD CURRENT

(MAX17552)

VIN= 12V

VIN= 24V

VIN= 36V

VIN= 48V

FIGURE 7 APPLICATION CIRCUIT,

PWM MODE, V

= 220kHz (RRT= 191k)

LOAD CURRENT (mA)

Maxim Integrated

OUT

= 3.3V

toc9

│

Page 7

100

0 20 40 60 80 100

EFFICIENCY

(%)

LOAD CURRENT (mA)

EFFICIENCYVS. LOAD CURRENT

(MAX17552A)

toc14

VIN= 36V

VIN= 12V

VIN= 24V

FIGURE 7 APPLICATION CIRCUIT,

PWM MODE, V

OUT

= 3.3V

FSW= 600kHz (RRT= 69.8k)

OUTPUT VOLTAGE (V)

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Typical Operating Characteristics (continued)

(VIN = 24V, V

GND

= 0V, V

OUT

= 3.3V, V

EN/UVLO

= 1.5V, RT/SYNC = 191kΩ, CIN = 1μF, TA = +25°C unless otherwise noted.)

EFFICIENCY VS. LOAD CURRENT

100

EFFICIENCY (%)

0 20 40 6 0 80 100

100

EFFICIENCY (%)

0 20 40 60 80 100

(MAX17552A)

VIN= 12V

VIN= 24V

VIN= 36V

VIN= 48V

FIGURE 7 APPLICATION CIRCUIT,

VIN= 60V

EFFICIENCY VS. LOAD CURRENT

PWM MODE, V

= 220kHz (RRT= 191k)

LOAD CURRENT (mA)

(MAX17552)

VIN= 24V

VIN= 36V

FIGURE 7 APPLICATION CIRCUIT,

LOAD CURRENT (mA)

VIN= 12V

PWM MODE, V

= 600kHz (RRT= 69.8k)

EFFICIENCY vs. LOAD CURRENT

toc10

= 3.3V

OUT

toc13

= 3.3V

OUT

100

EFFICIENCY (%)

VIN= 60V

0 20 40 60 80 100

(MAX17552)

VIN= 12V

VIN= 24V

VIN= 36V

VIN= 48V

FIGURE 6 APPLICATION CIRCUIT,

PWM MODE, V

= 600kHz (RRT= 69.8k)

LOAD CURRENT (mA)

OUT

toc11

= 5V

OUTPUT VOLTAGE (V)

EFFICIENCY vs. LOAD CURRENT

100

EFFICIENCY (%)

0 20 40 60 80 100

OUTPUT VOLTAGE vs. LOAD CURRENT

5.10

5.07

5.04

5.01

VIN= 12V

4.98

4.95

4.92 0 20 40 60 80 100

(MAX17552A)

VIN= 24V

VIN= 36V

VIN= 48V

VIN= 60V

FIGURE 6 APPLICATION CIRCUIT,

PWM MODE, V

= 600kHz (RRT= 69.8k)

LOAD CURRENT (mA)

FIGURE 6 APPLICATION

CIRCUIT, PFM MODE

VIN= 36V

VIN= 48V

VIN= 60V

VIN= 24V

LOAD CURRENT (mA)

VIN= 12V

OUT

toc12

= 5V

toc15

OUTPUT VOLTAGE vs. LOAD CURRENT

3.42

3.40

3.38

3.36

3.34 VIN= 12V,24V

3.32

OUTPUT VOLTAGE (V)

3.30

3.28

0 20 40 60 80 100

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FIGURE 7 APPLICATION CIRCUIT,

LOAD CURRENT (mA)

VIN= 36V

VIN= 48V

VIN= 60V

PFM MODE

toc16

OUTPUT VOLTAGE vs. LOAD CURRENT

4.947

4.945

4.943 VIN= 12V

4.941

4.939

4.937

0 20 40 60 80 100

FIGURE6 APPLICATION

CIRCUIT, PWM MODE

VIN= 36V

VIN= 24V

LOAD CURRENT (mA)

VIN= 48V

toc17

VIN= 60V

OUTPUT VOLTAGE vs. LOAD CURRENT

3.330

3.328

3.326

3.324

VIN= 12V

3.322

3.320

OUTPUT VOLTAGE (V)

3.318

3.316 0 20 40 60 80 100

FIGURE 7 APPLICATION CIRCUIT,

VIN= 24V

LOAD CURRENT (mA)

VIN= 36V

VIN= 48V

Maxim Integrated

PWM MODE

VIN= 60V

toc18

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Page 8

OUTPUT VOLTAGE (V)

FEEDBACK VOLTAGE (V)

SHUTDOWN CURRENT (µA)

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Typical Operating Characteristics (continued)

(VIN = 24V, V

GND

= 0V, V

OUT

= 3.3V, V

EN/UVLO

= 1.5V, RT/SYNC = 191kΩ, CIN = 1μF, TA = +25°C unless otherwise noted.)

OUTPUT VOLTAGE vs. LOAD CURRENT

5.14

5.10

5.06

5.02 VIN=12V

VIN= 12V

VIN=24V

VIN= 24V

4.98

OUTPUT VOLTAGE (V)

4.94

4.90

0 20 40 60 80 100

FIGURE 8 APPLICATION

VIN=36V

VIN= 36V

VIN= 48V

VIN= 60V

LOAD CURRENT (mA)

FIGURE8 APPLICATION

CIRCUIT, PFM MODE

OUTPUT VOLTAGE vs. LOAD CURRENT

3.329

3.327

3.325

3.323

OUTPUT VOLTAGE (V)

3.321 0 20 40 60 80 100

FIGURE 9 APPLICATION CIRCUIT,

VIN= 12V

VIN= 24V

LOAD CURRENT (mA)

VIN= 36V

PWM MODE

toc19

toc22

3.48

3.44

3.40

3.36

VIN= 12V

3.32

3.28

OUTPUT VOLTAGE (V)

3.24

3.20

0.82

0.81

0.80

0.79

0.78

VIN= 24V

0 20 40 60 80 100

-40 -20 0 20 40 60 80 100 120

VIN= 36V

FIGURE 9 APPLICATION CIRCUIT,

LOAD CURRENT (mA)

FEEDBACK VOLTAGE

VS. TEMPERATURE

TEMPERATURE (°C)

PFM MODE

OUTPUT VOLTAGE vs. LOAD CURRENT

toc20

toc23

OUTPUT VOLTAGE vs. LOAD CURRENT

4.960

4.959

4.958

4.957

4.956

4.955

4.954

4.953

4.952

4.951

4.950

4.949 0 20 40 60 80 100

100

NO LOAD SUPPLY CURRENT (µA)

5 15 25 35 45 55

FIGURE 8 APPLICATION CIRCUIT,

VIN= 24V

VIN= 12V

VIN= 36V

LOAD CURRENT (mA)

NO LOAD SUPPLY CURRENT

vs. INPUT VOLTAGE

INPUT VOLTAGE (V)

VIN= 48V

PFM MODE

toc21

PWM MODE

VIN= 60V

toc24

SHUTDOWN CURRENT

vs. INPUT VOLTAGE

4.0

2.5

1.0

SHUTDOWN CURRENT (µA)

-0.5

-2.0 5 15 25 35 45 55

INPUT VOLTAGE (V)

toc25

2.0

1.7

1.4

1.1

0.8

0.5

SHUTDOWN CURRENT

vs. TEMPERATURE

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

toc26

250

200

150

100

SWITCH CURRENT LIMIT (mA)

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SWITCH CURRENT LIMIT

vs. INPUT VOLTAGE

SWITCH PEAK

CURRENT LIMIT

SWITCH NEGATIVE

CURRENT LIMIT

5 15 25 35 45 55

INPUT VOLTAGE (V)

Maxim Integrated

toc27

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Page 9

SWITCH CURRENT LIMIT (mA)

V (

LOAD TRANSIENT RESPONSE

STEPPED FROM 50mA TO 100mA)

EN/UVLO THRESHOLD VOLTAGE (V)

V (

LOAD TRANSIENT RESPONSE,

FROM 5mA to 50mA)

V (

LOAD TRANSIENT RESPONSE

STEPPED FROM 50mA TO 100mA)

V (

LOAD TRANSIENT RESPONSE

FROM 5mA to 50mA)

V (

LOAD TRANSIENT RESPONSE

FROM NO-LOAD TO 50mA)

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Typical Operating Characteristics (continued)

(VIN = 24V, V

GND

= 0V, V

OUT

= 3.3V, V

EN/UVLO

= 1.5V, RT/SYNC = 191kΩ, CIN = 1μF, TA = +25°C unless otherwise noted.)

SWITCH CURRENT LIMIT

250

200

150

100

-40 -20 0 20 40 60 80 100 120

RESET THRESHOLD (%)

-40 -20 0 20 40 60 80 100 120

vs. TEMPERATURE

SWITCH PEAK

CURRENT LIMIT

SWITCH NEGATIVE

CURRENT LIMIT

TEMPERATURE (°C)

RESET THRESHOLD

vs. TEMPERATURE

RISING

FALLING

TEMPERATURE (°C)

toc28

toc31

EN/UVLO THRESHOLD VOLTAGE

1.30

1.26

1.22

1.18

1.14

1.10

-40 -20 0 20 40 60 80 100 120

vs. TEMPERATURE

RISING

FALLING

TEMPERATURE (°C)

PFM MODE (LOAD CURRENT STEPPED

OUT

AC)

FIGURE6

APPLICATION

FIGURE 6

CIRCUIT APPLICATION CIRCUIT V

OUT

200µs/div

= 5V

OUT

SWITCHING FREQUENCY

toc29

1000

)

800

600

400

SWITCHING FREQUENCY (KH

200

-40 -20 0 20 40 60 80 100 120

vs. TEMPERATURE

RT= 45.3kΩ

RT= 69.8kΩ

RT= 191kΩ

RT= 422kΩ

TEMPERATURE (°C)

toc30

PFM MODE (LOAD CURRENT STEPPED

toc32

OUT

100mV/div

=5V

OUT

50mA/div

AC)

APPLICATION

FIGURE 7 APPLICATION CIRCUIT

= 3.3V

OUT

200µs/div

FIGURE7

CIRCUIT

=3.3V

OUT

toc33

100mV/div

50mA/div

PFM OR PWM MODE (LOAD CURRENT

OUT

AC)

OUT

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FIGURE 6 APPLICATION CIRCUIT V

= 5V

OUT

100µs/div

toc34

100mV/div

50mA/div

PFM OR PWM MODE (LOAD CURRENT

OUT

AC)

OUT

FIGURE 7 APPLICATION CIRCUIT V

= 3.3V

OUT

100µs/div

toc35

100mV/div

50mA/div

PWM MODE (LOAD CURRENT STEPPED

OUT

AC)

FIGURE 6 APPLICATION CIRCUIT V

= 5V

OUT

100µs/div

Maxim Integrated

toc36

100mV/div

50mA/div

│

Page 10

V (

LOAD TRANSIENT RESPONSE

FROM NO-LOAD TO 50mA)

2V/div

5V/div

toc43

2ms/div

EN/UVLO

OUT

50mA/div

5V/div

SHUTDOWN WITH ENABLE

RESET

OUT

FIGURE 6 APPLICATION CIRCUIT

OUT

= 5V

V (

(PFM MODE)

EN/UVLO

(AC)

(PWM OR PFM MODE)

RT/SYNC

V (

2V/div

5V/div

toc41

1ms/div

EN/UVLO

OUT

50mA/div

5V/div

SOFT START

OUT

RESET

FIGURE 6 APPLICATION CIRCUIT V

OUT

= 5V

EN/UVLO

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Typical Operating Characteristics (continued)

(VIN = 24V, V

GND

= 0V, V

OUT

= 3.3V, V

EN/UVLO

= 1.5V, RT/SYNC = 191kΩ, CIN = 1μF, TA = +25°C unless otherwise noted.)

PWM MODE (LOAD CURRENT STEPPED

OUT

AC)

FIGURE 7 APPLICATION CIRCUIT V

= 3.3V

OUT

100µs/div

NO LOAD SWITCHING WAVEFORMS

(PWM MODE)

FIGURE 6 APPLICATION CIRCUIT V

= 5V

OUT

4µs/div

AC)

OUT

toc37

toc40

100mV/ div

50mA/div

20mV/div

10V/div

100mA/div

AC)

SWITCHING WAVEFORMS

FIGURE 6 APPLICATION CIRCUIT V

= 5V,LOAD = 20mA

OUT

10µs/div

toc38

100mV/div

10V/div

100mA/div

FULL LOAD-SWITCHING WAVEFORMS

FIGURE 6 APPLICATION CIRCUIT V

= 5V, LOAD = 100mA

OUT

4µs/div

SOFT START

RESET

OUT

FIGURE 7 APPLICATION CIRCUIT V

OUT

1ms/div

toc39

20mV/div

10V/div

100mA/div

toc42

5V/div

1V/div

50mA/div

2V/div

= 3.3V

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SOFT START WITH 3V PREBIAS

OUT

RESET

FIGURE 6 APPLICATION CIRCUIT NO LOAD PWM MODE

1ms/div

toc44

5V/div

1V/div

5V/div

EXTERNAL SYNCHRONIZATION WITH

300kHz CLOCK FREQUENCY

FIGURE 6 APPLICATION CIRCUIT 100mA LOAD PWM MODE

4µs/div

Maxim Integrated

toc45

10V/div

2V/div

│

Page 11

toc50

CONDUCTED EMI CURVE

(5V OUT PUT, 100m A LOAD CURRENT)

0.15

AVERAGE EMISSIONS

PEAK EMISSIONS

CONDUCTED EMI (dBµV)

FREQUE NCY (MHz )

QUASI-PEAK LIMIT

AVERAGE LIMIT

Class B limit

Horizontal limit

Vertical limit

toc51

RADIATED EMI CURVE

(5V OUT PUT, 100m A LOAD CURRENT)

100

500

1000

-10

AMP LITUDE (dBuV/ m)

FREQUE NCY (MHz )

CLASS B LIMIT

HORIZONT AL

VERTICALEMISSION

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Typical Operating Characteristics (continued)

(VIN = 24V, V

GND

= 0V, V

OUT

= 3.3V, V

EN/UVLO

= 1.5V, RT/SYNC = 191kΩ, CIN = 1μF, TA = +25°C unless otherwise noted.)

OVERLOAD PROTECTION

(MAX17552)

OUT

FIGURE 6 APPLICATION CIRCUIT

= 5V

OUT

1ms/div

BODE PLOT

-10

FCR= 8.5KHz, PHASE MARGIN =

-20

-30

-40

-50 1k 10k 100k

64°

FIGURE 6 APPLICATION CIRCUIT V

= 5V

OUT

PHA

GAIN

toc46

toc48

5V/div

100mA/div

180

144

108

-36

-72

-108

-144

-180

OVERLOAD PROTECTION

(MAX17552A)

20ms/div

BODE PLOT

FCR= 10.5KHz,

-10 PHASE MARGIN = 61°

-20

-30

-40

-50

1k 10k 100k

FIGURE 7 APPLICATION CIRCUIT

= 3.3V

OUT

PHASE

GAIN

toc47

toc49

100mA/div

180

144

108

-36

-72

-108

-144

-180

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Page 12

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Pin Conguration

TOP VIEW

GND

MODE

10 8 79 6

MAX17552/

MAX17552A

IN RT/

UVLO

3 4

SYNC

TDFN

3mm x 2mm

Pin Description

PIN NAME FUNCTION

1 IN Switching Regulator Input. Connect a X7R 1µF ceramic capacitor from IN to GND for bypassing.

Active-High, Enable/Undervoltage-Detection Input. Pull EN/UVLO to GND to disable the regulator

2 EN/UVLO

3 RT/SYNC

4 SS

5 FB

6 VOUT

output. Connect EN/UVLO to IN for always-on operation. Connect a resistor-divider between IN, EN/UVLO, and GND to program the input voltage at which the device is enabled and turns on.

Oscillator Timing Resistor Input. Connect a resistor from RT/SYNC to GND to program the switching frequency from 100kHz to 2.2MHz. See the Switching Frequency (RT/SYNC) section for details. An external pulse can be applied to RT/SYNC through a coupling capacitor to synchronize the internal clock to the external pulse frequency. See the External Synchronization section for details.

Soft-Start Capacitor Input. Connect a capacitor from SS to GND to set the soft-start time. Leave SS unconnected for default 5.1ms internal soft-start.

Output Feedback Connection. Connect FB to a resistor-divider between V output voltage. See the Adjusting the Output Voltage section for details.

External Bias Input for Internal Control Circuitry. Decouple to GND with a 0.22μF capacitor and connect to output capacitor positive terminal with a 22.1Ω resistor for applications with an output voltage from 3.3V to

5V. Connect to GND for output voltages < 3.3V and > 5V. See the External Bias section for details.

RESET

SSEN/

OUT

1 LXIN

EN/UVLO

RT/SYNC

MAX17552/

MAX17552A

µMAX

GND

MODE

RESET

OUT

3mm x 3mm

and GND to set the

OUT

7 RESET

pulls low if FB voltage drops below 92% of its set value. RESET goes high impedance 2ms after FB voltage rises above 95% of its set value.

Open-Drain Reset Output. Pull up RESET to an external power supply with an external resistor. RESET

8 MODE

9 GND

10 LX

PFM/PWM Mode-Selection Input. Connect MODE to GND to enable the xed-frequency PWM

operation. Leave MODE unconnected for light-load PFM operation.

Ground. Connect GND to the power ground plane. Connect all the circuit ground connections together at a single point. See the PCB Layout Guidelines section.

Inductor Connection. Connect LX to the switching side of the inductor. LX is high impedance when the device is in shutdown.

— EP Exposed Pad (TDFN Only). Connect to the GND pin to the IC.

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MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Block Diagram

INTERNAL

OUT

EN/UVLO

RT/SYNC

MODE

INTERNAL OR

EXTERNAL

SOFT-START

CONTROL

CLK

1.25V

OSCILLATOR

VCC_INT

1.22V

ERROR

AMPLIFIER

THERMAL

SHUTDOWN

SLOPE

POK

CHIPEN

CLK

MODE SELECT

PWM

MAX17552/MAX17552A

LDO

REGULATOR

VCC_INT

PFM/PWM CONTROL

LOGIC

PEAK-LIMIT

CURRENT-

PFM

SINK-LIMIT

SENSE

LOGIC

0.76V

HIGH-SIDE

DRIVER

LOW-SIDE

DRIVER

CURRENT-

SENSE

AMPLIFIER

CURRENT

SENSE

AMPLIFIER

2ms

DELAY

NEGATIVE

CURRENT

REF

GND

RESET

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Page 14

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Detailed Description

The MAX17552/MAX17552A high-efficiency, high-voltage, synchronous step-down DC-DC converters with integrated MOSFETs operate over a 4V to 60V input voltage range. The converter can deliver output current up to 100mA at output voltages of 0.8V to 0.9 x VIN. The output voltage is accurate to within ±1.75% over -40°C to +125°C. The converter consumes only 22µA of supply current in PFM mode while regulating the output voltage at no load.

The devices use an internally compensated, peakcurrent-mode control architecture (see the Block

Diagram). On the rising edge of the internal clock, the

high-side pMOSFET turns on. An internal error amplifier compares the feedback voltage to a fixed internal reference voltage and generates an error voltage. The error voltage is compared to a sum of the current-sense voltage and a slope-compensation voltage by a PWM comparator to set the “on-time.” During the on-time of the pMOSFET, the inductor current ramps up. For the remainder of the switching period (off-time), the pMOSFET is kept off and the low-side nMOSFET turns on. During the off-time, the inductor releases the stored energy as the inductor current ramps down, providing current to the output. Under overload conditions, cycle-by-cycle current-limit feature limits inductor peak current by turning off the highside pMOSFET and turning on the low-side nMOSFET.

Mode Selection (MODE)

The devices feature a MODE pin for selecting either forced-PWM or PFM mode of operation. If the MODE pin is left unconnected, the devices operate in PFM mode at light loads. If the MODE pin is grounded, the devices operate in a constant-frequency forced-PWM mode at all loads. Mode of operation can be changed on-the-fly during normal operation of the device.

In PWM mode, the inductor current is allowed to go negative. PWM operation is useful in frequency-sensitive applications and provides fixed switching frequency at all loads. However, the PWM mode of operation gives lower efficiency at light loads compared to PFM mode of operation.

PFM mode disables negative inductor current and additionally skips pulses at light loads for high efficiency. In PFM mode, the inductor current is forced to a fixed peak of 72mA (typ) (I rises to 102% (typ) of the nominal voltage. Once the output reaches 102% (typ) of the nominal voltage, both high-side and low-side FETs are turned off and the device

) every clock cycle until the output

PFM

enters hibernate operation until the load discharges the output to 101% (typ) of the nominal voltage. Most of the internal blocks are turned off in hibernate operation to save quiescent current. After the output falls below 101% (typ) of the nominal voltage, the devices come out of hibernate operation, turns on all internal blocks, and again commences the process of delivering pulses of energy to the output until it reaches 102% (typ) of the nominal output voltage. The devices naturally exit PFM mode when the load current increases to a magnitude of approximately:

- (ΔI/2)

PFM

where ΔI is the peak-peak ripple current in the output

inductor. The part enters PFM mode again if the load

current reduces to approximately (ΔI/2). See the Inductor

Selection section for details. The advantage of the PFM

mode is higher efficiency at light loads because of lower current drawn from the supply.

Enable Input (EN/UVLO) and Soft-Start (SS)

When EN/UVLO voltage increases above 1.25V (typ), the devices initiate a soft-start sequence and the duration of the soft-start depends on the status of the SS pin voltage at the time of power-up. If the SS pin is not connected, the devices use a fixed 5ms internal soft-start to ramp up the internal error-amplifier reference. If a capacitor is

connected from SS to GND, a 5μA current source charges

the capacitor and ramps up the SS pin voltage. The SS pin voltage is used as reference for the internal error amplifier. Such a reference ramp up allows the output voltage to increase monotonically from zero to the final set value independent of the load current.

EN/UVLO can be used as an input voltage UVLOadjustment input. An external voltage-divider between IN and EN/UVLO to GND adjusts the input voltage at which the device turns on or turns off. See the Setting

the Input Undervoltage-Lockout Level section for details.

If input UVLO programming is not desired, connect EN/ UVLO to IN (see the Electrical Characteristics table for EN/UVLO rising and falling-threshold voltages). Driving EN/UVLO low disables both power MOSFETs, as well as other internal circuitry, and reduces IN quiescent current to below 1.2μA. The SS capacitor is discharged with an internal pulldown resistor when EN/UVLO is low. If the EN/UVLO pin is driven from an external signal source, a series resistance of minimum 1kW is recommended to be placed between the signal source output and the EN/ UVLO pin, to reduce voltage ringing on the line.

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Page 15

42000

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Switching Frequency (RT/SYNC)

Switching frequency of the devices can be programmed from 100kHz to 2.2MHz by using a resistor connected from RT/SYNC to GND. The switching frequency (fSW) is related to the resistor connected at the RT/SYNC pin (RT) by the following equation, where RT is in kΩ and fSW is in kHz:

Rf=

The switching frequency in ranges of 130kHz to 160kHz and 230kHz to 280kHz are not allowed for user programming to ensure proper configuration of the internal adaptive-loop compensation scheme.

External Synchronization

The RT/SYNC pin can be used to synchronize the device’s internal oscillator to an external system clock. The external clock should be coupled to the RT/SYNC pin through a 47pF capacitor, as shown in Figure 1. The external clock logic high level should be higher than 3V, logic low level lower than 0.5V and the duty cycle of the external clock should be in the range of 10% to 70%. External clock synchronization is allowed only in PWM mode of operation (MODE pin connected to GND). The RT resistor should be selected to set the switching frequency 10% lower than the external clock frequency.

The external clock should be applied at least 500μs

after enabling the device, for proper configuration of the internal loop compensation.

MAX17552/

MAX17552A

RT/SYNC

47pF

CLOCK

SOURCE

LOGIC-HIGH

LOGIC-LOW

DUTY

Figure 1. Synchronization to an External Clock

External Bias (V

The devices provide a V blocks from a low-voltage supply. When the V

OUT

)

pin to power the internal

OUT

pin voltage exceeds 3.1V, the devices draw switching and quiescent current from this pin to improve the converter’s efficiency. In applications with an output voltage setting from 3.3V to 5V, V

should be decoupled to GND

OUT

with a ceramic capacitor, and should be connected to the positive terminal of the output capacitor with a resistor (R4, C1) as shown in the typical application circuits. In the absence of R4 and C1, the absolute maximum rating of V

(-0.3V) can be exceeded under short-circuit

OUT

conditions, due to oscillations between the ceramic output capacitor and the inductance of the short-circuit path. In general, parasitic board or wiring inductance should be minimized and the output voltage waveform under short circuit operation should be verified to ensure that the absolute maximum rating of V

is not exceeded. For

OUT

applications with an output voltage setting less than 3.3V or greater than 5V, V

should be connected to GND.

OUT

Reset Output (RESET)

The devices include an open-drain RESET output to monitor output voltage. RESET should be pulled up with an external resistor to the desired external power supply. RESET goes high impedance 2ms after the output rises above 95% of its nominal set value and pulls low when the output voltage falls below 92% of the set nominal output voltage.

Startup Into a Prebiased Output

The devices support monotonic startup into a prebiased output. When the device starts into a prebiased output, both the high-side and low-side switches are turned off so that the converter does not sink current from the output. High-side and low-side switches do not start switching until the PWM comparator commands the first PWM pulse, at which point switching commences. The output voltage is then smoothly ramped up to the target value in alignment with the internal reference. Such a feature is useful in applications where digital integrated circuits with multiple rails are powered.

Operating Input Voltage Range

The maximum operating input voltage is determined by the minimum controllable on-time, and the minimum operating input voltage is determined by the maximum duty cycle and circuit voltage drops. The minimum and maximum operating input voltages for a given output voltage should be calculated as follows:

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Page 16

= +×

  

10000 x V

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

V (I (R 2.6))

+× +

V (I 2.5)

INMIN OUT

where V the maximum load current, R the inductor, fSW is the switching frequency (max), D is the maximum duty cycle (0.9), and t

OUT OUT DCR

MAX

INMAX

is the steady-state output voltage, I

OUT

ONMIN SW

is the DC resistance of

DCR

ONMIN

OUT

MAX

is the worst-

case minimum controllable switch on-time (128ns)

Overcurrent Protection

The MAX17552 implements a hysteretic cycle-by-cycle peak-current limit protection scheme to protect the inductor and internal FETs under output short circuit conditions. When the inductor peak current exceeds 0.21A (typ), high side switch is turned off and low side switch is turned on to discharge the inductor current. Subsequent clock pulses do not turn on the high-side switch until inductor current discharges to 0.15A (typ). This operation continues until overload/short circuit is removed on the output. Since the inductor current is bounded between two limits, inductor current runaway never happens in this scheme. Additionally, hysteretic negative peak current limit controls the low-side switch negative current when it exceeds 0.1A (typ).

The MAX17552A implements a HICCUP-type overload protection scheme to protect the inductor and internal FETs under output short-circuit conditions. When the inductor peak current exceeds 0.21A (typ) 16 consecutive times, the part enters HICCUP mode. In this mode, the part is initially operated with hysteretic cycle-by-cycle peak-current limit that continues for a time period equal to twice the soft-start time. The part is then turned off for a fixed 51ms hiccup timeout period. This sequence of hysteretic inductor current waveforms, followed by a hiccup timeout period, continues until the short/overload on the output is removed. Since the inductor current is bound between two limits, inductor current runway never happens.

Thermal-Overload Protection

Thermal-overload protection limits the total power dissipation in the IC. When the junction temperature exceeds +160°C, an on-chip thermal sensor shuts down the device, turns off the internal power MOSFETs, allowing the device to cool down. The device turns on after the junction temperature cools by 20°C.

Applications Information

Inductor Selection

A low-loss inductor having the lowest possible DC resistance that fits in the allotted dimensions should be selected. Calculate the required inductance from the equation:

L =

where L is inductance in μH, V

and fSW is the switching frequency in kHz. Calculate the

peak-peak ripple current (ΔI) in the output inductor from

the equation:

1000 V 1

××

OUT

∆=

where L is inductance in μH, V

is input voltage and fSW is the switching frequency in kHz.

The saturation current rating of the inductor must exceed the maximum current-limit value (I ration current rating should be the maximum of either

0.235A or the value from the equation:

I 0.15

= +

SAT

where L is inductance in H, V voltage and t

ON-MIN

is worst case minimum on time

(128ns).

Once the L value is known, the next step is to select the right core material. Ferrite and powdered iron are commonly available core materials. Ferrite cores have low core losses and are preferred for high-efficiency designs. Powdered iron cores have more core losses and are relatively cheaper than ferrite cores.

Input Capacitor Selection

Small ceramic input capacitors are recommended for the IC. The input capacitor reduces peak current drawn from the power source and reduces noise and voltage ripple on the input caused by the switching circuitry. A minimum

of 1μF, X7R-grade capacitor in a package larger than 0805

is recommended for the input capacitor of the IC to keep the input-voltage ripple under 2% of the minimum input voltage, and to meet the maximum ripple-current requirements.

OUT

is output voltage

OUT

−

is output voltage, VIN

OUT

PEAK-LIMIT

INMAX ON MIN

−

is maximum input

INMAX

). The satu-

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Page 17

tSS> 0.05 x C

x V

SS SS

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Output Capacitor Selection

Small ceramic X7R-grade output capacitors are recommended for the devices. The output capacitor has two functions. It stores sufficient energy to support the output voltage under load transient conditions and stabilizes the device’s internal control loop. Usually the output capacitor is sized to support a step load of 50% of the maximum output current in the application, such that the outputvoltage deviation is less than 3%. Calculate the minimum required output capacitance from the following equations:

Frequency

Range

(kHz)

100 to 130

160 to 230

280 to 2200

Minimum Output

Capacitance

(μF)

OUT

It should be noted that dielectric materials used in ceramic capacitors exhibit capacitance loss due to DC bias levels and should be appropriately derated to ensure the required output capacitance is obtained in the application.

Soft-Start Capacitor Selection

The devices offer a 5.1ms internal soft-start when the SS pin is left unconnected. When adjustable soft-start

time is required, connect a capacitor from SS to GND to program the soft-start time. The minimum soft-start time is related to the output capacitance (C voltage(V

) by the following equation.

OUT

where tSS is in milliseconds and C

) and the output

OUT

is in µF.

OUT

Soft-start time (tSS) is related to the capacitor connected at SS (CSS) by the following equation:

C 6.25 t= ×

where tSS is in milliseconds and CSS is in nanofarads.

Setting the Input Undervoltage-Lockout Level

The devices offer an adjustable input undervoltagelockout level. Set the voltage at which the device turns on with a resistive voltage-divider connected from IN to GND (see Figure 2). Connect the center node of the divider to EN/UVLO.

Choose R1 to be 3.3MΩ max and then calculate R2 as

follows:

R1 1.25

(V - 1.25)

INU

where V to turn on. If the EN/UVLO pin is driven from an external signal source, a series resistance of minimum 1kΩ is recommended to be placed between the signal source output and the EN/UVLO pin to reduce voltage ringing on the line.

is the voltage at which the device is required

INU

Figure 2. Adjustable EN/UVLO Network

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MAX17552/

MAX17552A

EN/UVLO

Figure 3. Setting the Output Voltage

MAX17552/

MAX17552A

GND

OUT

Maxim Integrated

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Page 18

 



=××

P VI

( )

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

4.7Ω

Figure 4. Transient Protection

µF

MAX17552/

MAX17552A

GND

C 1

Adjusting the Output Voltage

The output voltage can be programmed from 0.8V to 0.9V x VIN. Set the output voltage by connecting a resistordivider from output to FB to GND (see Figure 3). Choose

R2 in the range of 25kΩ to 100kΩ and calculate R1 with

the following equation:

OUT

= ×

R1 R 2 1

0.8

−

Transient Protection

In applications where fast line transients or oscillations with a slew rate in excess of 15V/µs are expected during power-up or steady-state operation, the MAX17552/ MAX17552A should be protected with a series resistor that forms a lowpass filter with the input ceramic capacitor (Figure 4). These transients can occur in conditions such as hot-plugging from a low-impedance source or due to inductive load switching and surges on the supply lines.

Power Dissipation

At a particular operating condition, the power losses that lead to temperature rise of the device are estimated as follows:

P P -1 - (I R )

LOSS OUT OUT DCR

where P

OUT

  

OUT OUT OUT

is the output power, η is the efficiency of

power conversion, and R







= ×

is the DC resistance of the

DCR

output inductor. See the Typical Operating Characteristics for the power-conversion efficiency or measure the efficiency to determine the total power dissipation.

The junction temperature (TJ) of the device can be estimated at any ambient temperature (TA) from the following equation:

TT P= +θ ×

J A JA LOSS

where θJA is the junction-to-ambient thermal impedance

of the package.

Junction temperature greater than +125°C degrades operating lifetimes.

PCB Layout Guidelines

Careful PCB layout (Figure 5) is critical to achieve clean and stable operation. The switching power stage requires particular attention. Follow these guidelines for good PCB layout:

● Place the input ceramic capacitor as close as possible

to VIN and GND pins

● Minimize the area formed by the LX pin and inductor

connection to reduce the radiated EMI

● Ensure that all feedback connections are short and

direct

● Route high-speed switching node (LX) away from the

signal pins

For a sample PCB layout that ensures the first-pass success, refer to the MAX17552/MAX17552A evaluation kit data sheet.

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Page 19

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

GND PLANE

PLANE

GND

MODE

RESET

OUT

EN/UVLO

MODE

RT/SYNC

MAX17552/

MAX17552A

EN/UVLO

RT/SYNC

GND

VOUT

RESET

VOUT

OUT

GND PLANE

OUT

PLANE

OUT

Figure 5. Layout Guidelines

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Vias to Bottom-Side Ground Plane

Vias to V

OUT

Vias to RESET

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Page 20

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Typical Application Circuits

0.22

220

22.1

6V TO 60V

1µF

191k

Ω

SWITCHING FREQUENCY = 220kHz L1 COILCRAFT LPS5030-224M

MURATA 10µF/X7R/6.3V/1206 (GRM31CR70J106K)

OUT

MURATA 1µF/X7R/100V/1206 (GRM31CR72A105K)

MAX17552/

MAX17552A

EN/UVLO

MODE

RT/SYNC

GND

OUT

RESET

Figure 6. High-Efficiency 5V, 100mA Regulator

6V TO 60V

1µF

69.8k

49.9k

Ω

C 10µF

Ω

OUT

Ω

261k

5V, 100mA

Ω

EN/UVLO

MODE

RT/SYNC

OUT

MAX17552/

MAX17552A

4V TO 60V

1µF

191k

Ω

SWITCHING FREQUENCY = 220kHz L1 COILCRAFT LPS5030-154M

MURATA 10µF/X7R/6.3V/1206 (GRM31CR70J106K)

OUT

MURATA 1µF/X7R/100V/1206 (GRM31CR72A105K)

MAX17552/

MAX17552A

EN/UVLO

MODE

RT/SYNC

GND

OUT

RESET

Figure 7. High-Efficiency 3.3V, 100mA Regulator

GND

OUT

RESET

0.22

100

OUT

10µF

22.1

49.9k

Ω

261k

Ω

5V, 100mA

Ω

OUT

0.22

150

OUT

10µF

Ω

22.1

49.9k

158k

Ω

3.3V, 100mA

Ω

OUT

SWITCHING FREQUENCY = 600kHz L1 COILCRAFT LPS3015-104M C

OUT

Figure 8. Small Footprint 5V, 100mA Regulator

www.maximintegrated.com

MURATA 10µF/X7R/6.3V/0805 (GRM21BR70J106K)

MURATA 1µF/X7R/100V/1206 (GRM31CR72A105K)

Maxim Integrated

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Page 21

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Typical Application Circuits (continued)

4V TO 45V

1µF

69.8k

Ω

SWITCHING FREQUENCY = 600kHz L1 COILCRAFT LPS3015-683M

MURATA 10µF/X7R/6.3V/0805 (GRM21BR70J106K)

OUT

MURATA 1µF/X7R/100V/1206 (GRM31CR72A105K)

MAX17552/

MAX17552A

EN/UVLO

MODE

RT/SYNC

GND

OUT

RESET

0.22

15V TO 60V

1µF

158k

OUT

3.3V, 100mA

Ω

OUT

10µF

Ω

22.1

49.9k

Ω

4V TO 24V

1µF

69.8k

Ω

SWITCHING FREQUENCY = 600kHz L1 COILCRAFT LPS3015-333M

MURATA 10µF/X7R/6.3V/1206 (GRM31CR70J106K)

OUT

MURATA 1µF/X7R/100V/1206 (GRM31CR72A105K)

MAX17552/

MAX17552A

EN/UVLO

MODE

RT/SYNC

GND

OUT

RESET

OUT

10µF

R2 100k

127k

Ω

1.8V, 100mA

Ω

OUT

Figure 10. Small Footprint 1.8V, 100mA RegulatorFigure 9. Small Footprint 3.3V, 100mA Regulator

MAX17552/

MAX17552A

EN/UVLO

GND

220

10µF

OUT

12V, 100mA

MODE

RT/SYNC

69.8k

Ω

SWITCHING FREQUENCY = 600kHz L1 COILCRAFT LPS5030-224M

MURATA 10µF/X7R/16V/1206 (GRM31CR71C106K)

OUT

MURATA 1µF/X7R/100V/1206 (GRM31CR72A105K)

Figure 11. Small Footprint 12V, 100mA Step-Down Regulator

www.maximintegrated.com

OUT

RESET

Ω

24.9k

Ω

348k

Maxim Integrated

│

Page 22

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Ordering Information

PART TEMP RANGE PIN-PACKAGE

MAX17552ATB+ -40°C to +125°C 10 TDFN-EP* MAX17552AUB+ -40°C to +125°C 10 μMAX

MAX17552AATB+ -40°C to +125°C 10 TDFN-EP* MAX17552AAUB+ -40°C to +125°C 10 μMAX

+Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad.

Chip Information

PROCESS: BiCMOS

www.maximintegrated.com

Maxim Integrated

│

Page 23

MAX17552/MAX17552A 60V, 100mA, Ultra-Small, High-E󰀩ciency

Synchronous Step-Down DC-DC Converter

with 22µA No-Load Supply Current

Revision History

REVISION

NUMBER

0 2/14 Initial release —

1 6/14 Added statement regarding EN/UVLO connection 11

2 2/15 Updating to include MAX17552A 1-20

3 6/15

4 9/17

5 8/18 Updated the Mode Selection (MODE) section. 14

REVISION

DATE

DESCRIPTION

Included small solution-size TOCs in Typical Operating Characteristics section and updated Typical Application Circuit diagrams

Updated Features and Benets, Mode Selection (MODE), Setting the Input

Undervoltage-Lockout Level, and Power Dissipation sections. Updated the Electrical Characteristics table global characteristics. Inserted new Note 1 and updated Absolute Maximum Ratings, and added TOC50 and TOC51.

PAGES

CHANGED

2, 6–10,

19, 20

1, 3–5,

11, 14, 17–18

For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.

Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses

are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.

Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.

2018 Maxim Integrated Products, Inc.

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