MAX16922AUPB/V+T - Maxim Integrated

General Description

The MAX16922 power-management integrated circuit

(PMIC) is designed for medium power-level automotive

applications and integrates multiple supplies in a small

footprint. The device includes one high-voltage step-

down converter (OUT1) and three low-voltage cascaded

DC-DC converters (OUT2, OUT3, OUT4). OUT1 and

OUT2 are step-down DC-DC converters, and OUT3/

OUT4 are linear regulators. The device also includes

a reset output (RESET) and a high-voltage-compatible

enable input (EN).

The 1.2A output high-efficiency, step-down DC-DC con-

verter (OUT1) operates from a voltage up to 28V con-

tinuous and is protected from load-dump transients up to

45V. The 600mA output high-efficiency step-down DC-DC

converter (OUT2) runs from a voltage up to 5.5V. The two

300mA LDO linear regulators offer low dropout of only

130mV (typ). The power-good RESET output provides

voltage monitoring for OUT1 and OUT2.

OUT1 and OUT2 use fast 2.2MHz PWM switching and

small external components. The high-voltage converter

(OUT1) enters skip mode automatically under light loads

to prevent an overvoltage condition from occurring at the

output. The low-voltage synchronous DC-DC converter

(OUT2) can operate in forced-PWM mode to prevent any

AM band interference or high-efficiency auto-PWM mode.

The MAX16922 includes overtemperature shutdown and

overcurrent limiting. The device is designed to operate

from -40°C to +125°C ambient temperature.

Benets and Features

●1.2A High-Efficiency 2.2MHz DC-DC Converter

• 3.7V to 28V Operating Supply Voltage

• 45V Load-Dump Protection

• Output Voltage: 3.0V to 5.5V

●600mA High-Efficiency 2.2MHz DC-DC Converter

• 2.7V to 5.5V Supply Voltage

• Output Voltage: 1.0V to 3.9V

• 180° Out-of-Phase Operation

• Forced-PWM and Auto-PWM Modes

●LDO Linear Regulators

• OUT3: 1.0V to 4.15V at 300mA

• OUT4: 1.0V to 4.15V at 300mA

• Separate Inputs for Increased Efficiency

●Enable Input

●RESET Output Monitoring on OUT1 and OUT2

●Overtemperature and Short-Circuit Protection

●Available in

5mm x 5mm x 0.8mm, 20-Pin TQFN-EP

4.5mm x 6.5mm, 20-Pin TSSOP-EP

19-5039; Rev 10; 2/16

Ordering Information appears at end of data sheet.

MAX16922

PV1

4.7µF

1µF

0.1µF

10µF

VPV1

PV3

PWM

4.7µF

VOUT1

OUT3

GND1

GND3

4.7µF

VOUT3

PV4 OUTS1

4.7µF

VOUT2

VOUT1

OUT4

GND2

20kΩ

RESET

GND

4.7µF

VOUT4

LSUP

4.7µH

LX1 VOUT1

BST

PV2

10µF

PGND2

2.2µH

LX2 VOUT2

OUTS2

4.7µF

MAX16922 2.2MHz, Dual, Step-Down DC-DC

Converters, Dual LDOs, and RESET

Typical Operating Circuit

EVALUATION KIT AVAILABLE

PV1, EN to GND .....................................................-0.3V to +45V

LX1 to GND.................................................-0.5V to (PV1 + 0.3V)

LX2 to GND.................................................-0.5V to (PV2 + 0.3V)

BST to LX1.............................................................-0.3V to +6.0V

PV2, PV3, PV4, OUTS1, PWM, RESET to GND_....-0.3V to +6.0V

OUTS2 .......................................................-0.3V to (PV2 + 0.3V)

OUT3 .........................................................-0.3V to (PV3 + 0.3V)

OUT4 .........................................................-0.3V to (PV4 + 0.3V)

LX1 RMS Current .................................................................2.0A

LX2 RMS Current .................................................................1.2A

PGND2 to GND_....................................................-0.3V to +0.3V

LSUP to GND............................................................-0.3V to +6V

OUTS_, OUT_ Output Short-Circuit Duration .............Continuous

Continuous Power Dissipation (TA = +70°C)

TQFN (derate 31.3 mW/°C above +70°C)..................2500mW

TSSOP (derate 26.5 mW/°C above +70°C).................... 2122mW

ESDHB (all pins)...................................................................±2kV

ESDMM (all pins)................................................................±200V

ESDCDM (corner pins).......................................................±750V

ESDCDM (other pins).........................................................±500V

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

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

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

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

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

TQFN

Junction-to-Ambient Thermal Resistance (θJA)...........30°C/W

Junction-to-Case Thermal Resistance (θJC)..................2°C/W

TSSOP

Junction-to-Ambient Thermal Resistance (θJA)........37.7°C/W

Junction-to-Case Thermal Resistance (θJC)..................2°C/W

(Note 1)

(VPV1 = 13.5V, VPV2 = VPV3 = VOUT1, VPV4 = VOUT2; TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA

= +25°C under normal conditions, unless otherwise noted.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

OUT1—SYNCHRONOUS STEP-DOWN DC-DC CONVERTER

Supply-Voltage Range VPV1

(Note 3) 3.7 28 V

Operation < 500ms 45

PV1 Undervoltage Lockout VUVLO,R PV1 rising 3.7 4.0 V

VUVLO,F PV1 falling 2.85 3.3

BST Refresh Load Enable VBRLE PV1 falling (option enabled) 6.45 V

BST Refresh Load Hysteresis 0.65 V

LSUP Regulator Voltage VLSUP 6V ≤ VPV1 ≤ 28V 4.75 5.0 5.45 V

Supply Current IPV1 EN = low 14 µA

PWM Switching Frequency fSW Internally generated 2.0 2.2 2.4 MHz

Voltage Accuracy VOUT1

Duty cycle = 20% to 90%;

ILOAD = 300mA to 1.2A -3 +3 %

SKIP mode (Note 4) -2 +4

DMOS On-Resistance VPV1 = 4V, VBST = 9V, ILX1 = 0.2A 300 700 mΩ

Current-Limit Threshold 1.4 1.75 2.1 A

Soft-Start Ramp Time 2.2 ms

MAX16922 2.2MHz, Dual, Step-Down DC-DC

Converters, Dual LDOs, and RESET

www.maximintegrated.com Maxim Integrated

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Note 1: 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.

Absolute Maximum Ratings

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.

Package Thermal Characteristics

Electrical Characteristics

(VPV1 = 13.5V, VPV2 = VPV3 = VOUT1, VPV4 = VOUT2; TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA

= +25°C under normal conditions, unless otherwise noted.) (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Maximum Output Current IOUT1 (VOUT1 + 1.0V) ≤ VPV1 ≤ 28V 1.2 A

LX1 Leakage Current VPV1 = 12V, LX1 = GND or VPV1;

TA = -40°C to +85°C ±1 µA

Maximum Duty Cycle DCMAX 94 %

Minimum Duty Cycle DCMIN fSW = 2.2MHz 20 %

OUTS1 Discharge Resistance EN = low (or optionally EN = high and

VPV1 < 5.7V) 70 Ω

OUT2—SYNCHRONOUS STEP-DOWN DC-DC CONVERTER

Supply-Voltage Range VPV2 Fully operational 2.7 5.5 V

PWM Switching Frequency fSW Internally generated 2.0 2.2 2.4 MHz

Voltage Accuracy VOUT2

Duty cycle = 20% to 90%;

ILOAD = 1mA to 600mA, PWM = high -3 +3 %

SKIP mode (Note 4) -2 +4 %

pMOS On-Resistance VPV2 = 5.0V, ILX2 = 0.2A 150 250 mΩ

nMOS On-Resistance VPV2 = 5.0V, ILX2 = 0.2A 200 350 mΩ

pMOS Current-Limit Threshold 0.75 0.9 1.05 A

nMOS Zero-Crossing Threshold 50 mA

Soft-Start Ramp Time 1.5 ms

Maximum Output Current IOUT2 VOUT2 + 0.5V ≤ VPV2 ≤ 5.5V 600 mA

LX2 Leakage Current VPV2 = 6V, LX2 = PGND2 or VPV2;

TA = -40°C to +85°C ±1 µA

Duty-Cycle Range Forced-PWM mode only, minimum duty

cycle in skip mode is 0% (Note 4) 15 100 %

OUTS2 Discharge Resistance VEN = 0V 70 Ω

OUT3—LDO REGULATOR

Input Voltage VPV3 1.7 5.5 V

Voltage Accuracy VOUT3 VOUT3 + 0.4V ≤ VPV3 ≤ 5.5V, ILOAD = 1mA -2 +2 %

Load Regulation ILOAD = 0 to 300mA -0.2 %

Dropout Voltage VPV3 = 1.8V, ILOAD = 250mA (Note 4) 130 320 mV

Current Limit 450 mA

Power-Supply Rejection Ratio IOUT3 = 30mA, f = 1kHz 57 dB

Shutdown Output Resistance EN = low 1 kΩ

OUT4—LDO REGULATOR

Input Voltage VPV4 1.7 5.5 V

Voltage Accuracy VOUT4 (VOUT4 + 0.4V) ≤ VPV4 ≤ 5.5V, ILOAD = 1mA -2 +2 %

Load Regulation ILOAD = 0 to 300mA -0.2 %

Dropout Voltage VPV4 = 1.8V, ILOAD = 250mA (Note 4) 130 320 mV

Current Limit 450 mA

MAX16922 2.2MHz, Dual, Step-Down DC-DC

Converters, Dual LDOs, and RESET

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Electrical Characteristics (continued)

(VPV1 = 13.5V, VPV2 = VPV3 = VOUT1, VPV4 = VOUT2; TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA

= +25°C under normal conditions, unless otherwise noted.) (Note 2)

Note 2: All units are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design.

Note 3: Once PVI exceeds undervoltage-lockout rising threshold 4.0V and the device is in regulation.

Note 4: Guaranteed by design; not product tested.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Power-Supply Rejection Ratio IOUT4 = 30mA, f = 1kHz 57 dB

Shutdown Output Resistance EN = low 1 kΩ

THERMAL OVERLOAD

Thermal-Shutdown Temperature (Note 4) 150 175 °C

Thermal-Shutdown Hysteresis 15 °C

RESET

OUT1 OV Threshold 110 %

OUT1 Reset Threshold Reset option 1 (see the Selector Guide) 85 90 95 %

Reset option 2 (see the Selector Guide) 75 80 85

OUT2 Reset Threshold Percentage of nominal output 85 90 95 %

Reset Timeout Period

Reset timeout option 1 (see the Selector

Guide)14.9

Reset timeout option 2 (see the Selector

Guide)1.9

Output-High Leakage Current 1 µA

Output Low Level Sinking -3mA 0.4 V

UV Propagation Time 28 µs

EN LOGIC INPUT

EN Threshold Voltage EN rising 1.4 1.8 2.2 V

EN Threshold Hysteresis 0.4 V

Input Current VEN = 5V 0.5 µA

PWM LOGIC INPUT

Input High Level PWM rising 1.8 V

Input Low Level PWM falling 0.4 V

Logic-Input Current 0 ≤ VPWM ≤ 5.5V 1 µA

MAX16922 2.2MHz, Dual, Step-Down DC-DC

Converters, Dual LDOs, and RESET

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Electrical Characteristics (continued)

(VPV1 = 13.5V, VPV2 = VPV3 = VOUT1, VPV4 = VOUT2; TA = +25°C, unless otherwise specied.)

OUT1 EFFICIENCY vs. LOAD CURRENT

MAX16922 toc02

LOAD CURRENT (A)

EFFICIENCY (%)

1.11.00.8 0.90.3 0.4 0.5 0.6 0.70.2

100

TA = +125°C

PV1 = 13.5V

TA = +25°C

TA = -40°C

0.1 1.2

OUT2 EFFICIENCY vs. LOAD CURRENT

MAX16922 toc03

LOAD CURRENT (A)

EFFICIENCY (%)

0.50.40.30.2

100

0.1 0.6

PV2 = 5V

OUT2 = 2.7V

TA = +125°C TA = +25°C

SUPPLY CURRENT vs. TEMPERATURE

MAX16922 toc04

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

11095-25 -10 5 35 50 6520 80

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.0

-40 125

NO LOAD

PWM = GND

NORMALIZED OUT1 VOLTAGE

vs. LOAD CURRENT

MAX16922 toc05

IPV1 (A)

NORMALIZED OUT1 VOLTAGE (%)

1.11.00.1 0.2 0.3 0.5 0.6 0.7 0.80.4 0.9

-1.5

-1.0

-0.5

0.5

1.0

1.5

2.0

-2.0

0 1.2

OUT1 VOLTAGE vs. VPV1

MAX16922 toc06

VPV1 (V)

OUT1 VOLTAGE (V)

15129

4.85

4.90

4.95

5.00

5.05

5.10

5.15

5.20

4.80

6 18

IOUT1 = 1A

MAX16922 toc07

POWER-UP ENABLE TURNING ON

10V/div

OUT1

5V/div

OUT3

2V/div

OUT2

2V/div

OUT4

1V/div

1ms/div

OUT1 EFFICIENCY vs. LOAD CURRENT

MAX16922 toc01

LOAD CURRENT (A)

EFFICIENCY (%)

1.11.00.8 0.90.3 0.4 0.5 0.6 0.70.2

100

PV1 = 18V

PV1 = 13.5V

PV1 = 8V

0.1 1.2

POWER-UP/DOWN AT

THERMAL SHUTDOWN

RESET

5V/div

OUT1

5V/div

OUT2

2V/div

OUT3

2V/div

OUT4

1V/div

2ms/div

MAX16922 toc08

Maxim Integrated

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MAX16922 2.2MHz, Dual, Step-Down DC-DC

Converters, Dual LDOs, and RESET

Typical Operating Characteristics

(VPV1 = 13.5V, VPV2 = VPV3 = VOUT1, VPV4 = VOUT2; TA = +25°C, unless otherwise specied.)

SWITCHING FREQUENCY

vs. LOAD CURRENT

MAX16922 toc09

LOAD CURRENT (mA)

SWITCHING FREQUENCY (MHz)

1000800600400200

0.4

0.8

1.2

1.6

2.0

0 1200

DROPOUT VOLTAGE

vs. LOAD CURRENT

MAX16922 toc10

LOAD CURRENT (A)

DROPOUT VOLTAGE (V)

1.11.00.8 0.90.2 0.3 0.4 0.5 0.6 0.70.1

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

0 1.2

OUT2

OUT1

OUT3

OUT1 DROPOUT VOLTAGE

vs. TEMPERATURE

MAX16922 toc11

TEMPERATURE (°C)

DROPOUT VOLTAGE (V)

1109580655035205-10-25

0.8

0.9

1.0

1.1

1.2

1.3

1.4

0.7

-40 125

IOUT1 = 1.2A

OUT2 DROPOUT VOLTAGE

vs. TEMPERATURE

MAX16922 toc12

TEMPERATURE (°C)

DROPOUT VOLTAGE (V)

110 1259580655035205-10-25

0.1

0.2

0.3

0.4

0.5

0.6

0.7

-40

IOUT2 = 600mA

OUT1 LOAD TRANSITION

IOUT1

500mA/div

VOUT1

AC-COUPLED

50mV/div

20ms/div

MAX16922 toc13

OUT2 LOAD TRANSIENT

IOUT2

200mA/div

VOUT2

AC-COUPLED

20mV/div

20ms/div

MAX16922 toc14

OUT1 LINE TRANSIENT

4ms/div

MAX16922 toc15

PV1

5V/div

OUT1

AC-COUPLED

20mV/div

Maxim Integrated

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MAX16922 2.2MHz, Dual, Step-Down DC-DC

Converters, Dual LDOs, and RESET

Typical Operating Characteristics (continued)

(VPV1 = 13.5V, VPV2 = VPV3 = VOUT1, VPV4 = VOUT2; TA = +25°C, unless otherwise specied.)

SWITCHING FREQUENCY

vs. TEMPERATURE

MAX16922 toc16

TEMPERATURE (°C)

SWITCHING FREQUENCY (MHz)

1109565 80-10 5 20 35 50-25

2.12

2.14

2.16

2.18

2.20

2.22

2.24

2.26

2.28

2.30 PWM = OUT1

2.10

-40 125

POWER-SUPPLY REJECTION RATIO

vs. FREQUENCY

MAX16922 toc17

FREQUENCY (Hz)

PSRR (dB)

10k1k100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-100

10 100k

OUT3

OUT4

LOAD CURRENT = 100mA

100mVP-P RIPPLE

OUT3 OUTPUT-NOISE DENSITY

vs. FREQUENCY

MAX16922 toc18

FREQUENCY (Hz)

OUTPUT-NOISE DENSITY (nV/ Hz)

10k1k100

400

800

1200

1600

2000

2400

2800

3200

3600

4000

10 100k

RL = 100Ω

OUT4 OUTPUT-NOISE DENSITY

vs. FREQUENCY

MAX16922 toc19

FREQUENCY (Hz)

OUTPUT-NOISE DENSITY (nV/ Hz)

10k1k100

200

400

600

800

1000

1200

1400

1600

1800

2000

10 100k

RL = 100Ω

Maxim Integrated

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MAX16922 2.2MHz, Dual, Step-Down DC-DC

Converters, Dual LDOs, and RESET

Typical Operating Characteristics (continued)

PWM

RESET

GND1

OUT3

PV4

OUT4

PV3

PGND2

LX2

LX1

PV2

PV1

OUTS2

OUTS1

BST

LSUP

PWM

GND2

STEP-DOWN

PWM

OUT2

1.0V TO 3.9V

600mA

STEP-DOWN

PWM

OUT1

3.0V TO 5.5V

1.2A

LINEAR

REGULATOR

POR

GENERATION

LDO REG 1: 300mA

1.0V TO 4.15V

MODE

SELECT

10µF

2.2µH

4.7µH

4.7µF

1µF

VOUT2

10µF

VOUT1

VPV1

VOUT1

20kΩ

100kΩ

4.7µF

LDO REG 2: 300mA

VOUT1

VOUT2

VOUT4

MAX16922

MAX16922 2.2MHz, Dual, Step-Down DC-DC

Converters, Dual LDOs, and RESET

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Functional Diagram

PIN NAME FUNCTION

TQFN TSSOP

1 3 BST Bootstrap Capacitor Input. Connect a 0.1µF ceramic capacitor from BST to LX1.

2 4 PV1 OUT1 Supply Input. Connect a 4.7µF or larger ceramic capacitor from PV1 to PGND.

3 5 LX1

Inductor Connection for OUT1. Connect a 4.7µH inductor between LX1 and OUTS1, and a

Schottky diode between LX1 (cathode) and the power-ground plane (anode) as shown in the

Functional Diagram.

4 6 GND3 Ground. Connect GND, GND1, GND2, and GND3 together.

5 7 OUTS1

OUT1 Voltage-Sensing Input. Connect OUTS1 directly to the OUT1 output voltage and

bypass to power-ground plane with a minimum total capacitance of 15µF. The total

capacitance can include input bypass capacitors cascaded from OUT1, discharged by a

70Ω resistance between OUTS1 and GND3 when disabled.

6 8 PWM

PWM Control Input. Connect PWM to OUTS1 to force LX2 to switch every cycle. Connect

PWM to high for forced-PWM operation on OUT2. Connect low for auto-PWM operation to

improve efciency at light loads.

7 9 GND Ground. Connect GND, GND1, GND2, and GND3 together.

MAX16922

PV2

PV3

OUT3

GND2

OUT4

OUTS1

GND3

LX1

PV1

BST

20 +

GND1

RESET

LSUP

PV4

PWM

GND

OUTS2

PGND2

LX2

TQFN

TOP VIEW

MAX16922 16

GND2

OUT4

PV4

LSUP

LX1

PV1

BST

GND1

PGND2

LX2

PV2

PV3

OUT3

OUTS2

GND

PWM

OUTS1

GND3

TSSOP

RESET

TOP VIEW

MAX16922 2.2MHz, Dual, Step-Down DC-DC

Converters, Dual LDOs, and RESET

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Pin Description

Pin Congurations

PIN NAME FUNCTION

TQFN TSSOP

8 10 OUTS2

OUT2 Voltage Sense Input. Connect OUTS2 directly to the OUT2 output voltage and bypass

to PGND2 with a minimum total capacitance of 10µF. The total capacitance can include input

bypass capacitors cascaded from OUT2, discharged by a 70Ω resistance between OUTS2

and PGND2 when disabled.

911 PGND2 Power Ground for BUCK 2. Connect PGND2 and GND_ together near the device.

10 12 LX2 Inductor Connection for OUT2. Connect a 2.2µH inductor between LX2 and OUT2 as shown

in the Functional Diagram.

11 13 PV2 OUT2 Supply Input. Connect a 4.7µF or larger ceramic capacitor from PV2 to ground.

12 14 PV3 Linear-Regulator Power Input for OUT3. Bypass PV3 to GND with a minimum 2.2µF ceramic

capacitor.

13 15 OUT3 Linear-Regulator 1 Output. Bypass OUT3 to GND with a minimum 2.2µF ceramic capacitor

internally discharged by a 1kΩ resistance when disabled.

14 16 GND2 Ground. Connect GND, GND1, GND2, and GND3 together.

15 17 OUT4 Linear-Regulator 2 Output. Bypass OUT4 to GND with a minimum 2.2µF ceramic capacitor.

Internally discharged by a 1kΩ resistance when disabled.

16 18 PV4 Linear-Regulator Power Input for OUT4. Bypass PV4 to GND with a minimum 2.2µF ceramic

capacitor.

17 19 LSUP 5V Logic Supply to Provide Power to Internal Circuitry. Bypass LSUP to GND1 with a 1µF

ceramic capacitor.

18 20 RESET Open-Drain Reset Output for the Input Monitoring OUT1 and OUT2. External pullup

required.

19 1 GND1 Ground. Connect GND, GND1, GND2, and GND3 together.

20 2 EN Active-High Enable Input. Connect EN to PV1 or a logic-high voltage to turn on all

regulators. Pull EN input low to place the regulators in shutdown.

— — EP

Exposed Pad. Connect the exposed pad to ground. Connecting the exposed pad to ground

does not remove the requirement for proper ground connections to PGND2 and GND_. The

exposed pad is attached with epoxy to the substrate of the die, making it an excellent path to

remove heat from the device.

MAX16922 2.2MHz, Dual, Step-Down DC-DC

Converters, Dual LDOs, and RESET

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Pin Description (continued)

Detailed Description

The MAX16922 PMIC is designed for medium power

level automotive applications requiring multiple supplies

in a small footprint. As shown in the Typical Applications

Circuit, the MAX16922 integrates one high-voltage power

supply and three low-voltage cascaded power supplies.

OUT1 and OUT2 are step-down DC-DC converters,

and OUT3 and OUT4 are linear regulators. The device

also includes a reset output (RESET) and a high-voltage

compatible enable input (EN). The operating input voltage

range is from 3.5V to 28V and tolerant of transient volt-

ages up to 45V.

OUT1 Step-Down DC-DC Regulator

Step-Down Regulator Architecture

OUT1 is a high-input voltage, high-efficiency 2.2MHz

PWM current-mode step-down DC-DC converter that

delivers up to 1.2A. OUT1 has an internal high-side

n-channel switch and uses a low forward-drop free-

wheeling diode for rectification. Under normal operating

conditions, OUT1 is fixed frequency to prevent unwanted

AM radio interference. However, under light loads and

high-input voltage, the step-down regulator skips cycles to

maintain regulation. The output voltage is factory select-

able from 3.0V to 5.5V in 50mV increments.

Soft-Start

When initially powered up or enabled with EN, the OUT1

step-down regulator soft-starts by gradually ramping up

the output voltage for approximately 2.2ms. This reduces

inrush current during startup. During soft-start the full

output current is available. Before a soft-start sequence

begins, the outputs of both DC-DC regulators discharge

below 1.25V through an internal resistor. See the start-

up waveforms in the Typical Operating Characteristics

section.

Current Limit

The MAX16922 limits the peak inductor current sourced

by the n-channel MOSFET. When the peak current limit is

reached, the internal n-channel MOSFET turns off for the

remainder of the cycle. If the current limit is exceeded for

16 consecutive cycles and the output voltage is less than

1.25V, the n-channel MOSFET is turned off for 256 clock

cycles to allow the inductor current to discharge and then

initiate a soft-start sequence for all four outputs.

Dropout

The high-voltage, step-down converter (OUT1) of the

MAX16922 is designed to operate near 100% duty cycle.

When the input voltage is close to the output voltage, the

device tries to maintain the high-side switch on with 100%

duty cycle. However, to maintain proper gate charge, the

high-side switch must be turned off periodically so the

LX pin can go to ground and charge the BST capacitor.

As the input voltage approaches the output voltage, the

effective duty cycle of the n-channel MOSFET approaches

94%. Every 4th cycle is limited to a maximum duty cycle

of 75% (recharge period is approximately 112ns), while

the remaining cycles can go to 100% duty cycle. As a

result, when the MAX16922 is in dropout, the switching

frequency is reduced by a factor of 4.

During dropout conditions under light load, the load

current may not be sufficient to enable the LX pin to reach

ground during the recharge period. To ensure the LX pin

is pulled to ground and proper BST capacitor recharge

occurs, an internal load is applied to OUTS1 when PV1

falls below approximately 6.5V. This load is approxi-

mately 70Ω and is connected between OUTS1 and GND3

through an internal switch.

OUT2 Step-Down DC-DC Regulator

Step-Down Regulator Architecture

OUT2 is a low-input voltage, high-efficiency 2.2MHz PWM

current-mode step-down DC-DC converter that outputs

up to 600mA. OUT2 has an internal high-side p-channel

switch, and low-side n-channel switch for synchronous

rectification. The DC-DC regulator supports auto-PWM

operation so that under light loads the device automatically

enters high-efficiency skip mode. The auto-PWM mode

can be disabled by connecting the PWM input to OUTS1.

The output voltage is factory selectable from 1.0V to 3.9V

in 50mV increments.

Soft-Start

OUT2 enters soft-start when OUT1 finishes its soft-start

sequence to prevent high startup current from exceed-

ing the maximum capability of OUT1. The step-down

regulator executes a soft-start by gradually ramping up

the output voltage for approximately 1.5ms. This reduces

inrush current during startup. During soft-start, the full

output current is available. The soft-start sequence on

OUT2 begins after the soft-start sequence is completed

on OUT1. See the startup waveforms in the Typical

Operating Characteristics section.

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Current Limit

The MAX16922 limits the peak inductor current sourced

by the p-channel MOSFET. When the peak current limit is

reached, the internal p-channel MOSFET turns off for the

remainder of the cycle. If the current limit is exceeded for

16 consecutive cycles, and the output voltage is less than

1.25V, the p-channel MOSFET is turned off and enters

output discharge mode for 256 clock cycles, allowing the

inductor current and output voltage to discharge. Once

completed, a soft-start sequence is initiated on OUT2.

Dropout

As the input voltage approaches the output voltage, the

duty cycle of the p-channel MOSFET reaches 100%. In

this state, the p-channel MOSFET is turned on constantly

(not switching), and the dropout voltage is the voltage

drop due to the output current across the on-resistance of

the internal p-channel MOSFET (RPCH) and the inductor’s

DC resistance (RL):

VDO = ILOAD (RPCH + RL)

PWM

The MAX16922 operates in either auto-PWM or forced-

PWM modes. At light load, auto-PWM switches only

as needed to supply the load to improve light-load

efficiency of the step-down converter. At higher load

currents (~160mA), the step-down converter transitions to

fixed 2.2MHz switching frequency. Forced PWM always

operates with a constant 2.2MHz switching frequency

regardless of the load. Connect PWM high for forced-

PWM applications or low for auto-PWM applications.

LDO Linear Regulators

The MAX16922 contains two low-dropout linear regula-

tors (LDOs), OUT3 and OUT4. The LDO output voltages

are factory preset, and each LDO supplies loads up to

300mA. The LDOs include an internal reference, error

amplifier, p-channel pass transistor, and internal voltage-

dividers. Each error amplifier compares the reference

voltage to the output voltage (divided by the internal

voltage-divider) and amplifies the difference. If the divided

feedback voltage is lower than the reference voltage, the

pass-transistor gate is pulled lower, allowing more current

to pass to the outputs and increasing the output voltage.

If the divided feedback voltage is too high, the pass-

transistor gate is pulled up, allowing less current to pass

to the output. Each output voltage is factory selectable

from 1.0V to 4.15V in 50mV increments. If not using one

of the LDO outputs, then tie the associated input power

pin (PV_) to ground.

Input Supply and Undervoltage Lockout

An undervoltage-lockout circuit turns off the LDO

regulators when the input supply voltage is too low to

guarantee proper operation. When PV3 falls below 1.25V

(typ), OUT3 powers down. When PV4 falls below 1.5V

(typ), OUT4 powers down.

Soft-Start

OUT3 enters soft-start when PV3 exceeds 1.25V, and

OUT4 enters soft-start when PV4 exceeds 1.5V. This

staggers the surge current during startup to prevent

excess current draw from OUT1 or OUT2 that could

trigger an overcurrent shutdown. The soft-start time for

each LDO is 0.1ms (typ). See the startup waveforms in

the Typical Operating Characteristics section.

Current Limit

The OUT3 and OUT4 output current is limited to 450mA

(typ). If the output current exceeds the current limit, the

corresponding LDO output voltage drops out of regulation.

Excess power dissipation in the device can cause the

device to turn off due to thermal shutdown.

Dropout

The dropout voltage for the linear regulators is 320mV

(max) at 250mA load. To avoid dropout, make sure the

input supply voltage corresponding to OUT3 and OUT4

is greater than the corresponding output voltage plus the

dropout voltage based on the application output current

requirements.

LSUP Linear Regulator

LSUP is the output of a 5V linear regulator that powers

MAX16922 internal circuitry. LSUP is internally powered

from PV1 and automatically powers up when EN is high

and PV1 exceeds approximately 3.7V. LSUP automati-

cally powers down when EN is taken low. Bypass LSUP

to GND with a 1μF ceramic capacitor. LSUP remains on

even during a thermal fault.

Thermal-Overload Protection

Thermal-overload protection limits the total power

dissipation in the MAX16922. Thermal-protection

circuits monitor the die temperature. If the die tempera-

ture exceeds +175°C, the device shuts down, allowing it

to cool. Once the device has cooled by 15°C, the device

is enabled again. This results in a pulsed output during

continuous thermal-overload conditions. The thermal-

overload protection protects the MAX16922 in the event

of fault conditions. For continuous operation, do not

exceed the absolute maximum junction temperature of

+150°C. See the Thermal Considerationssection for more

information.

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Applications Information

Power-On Sequence

When the EN input is pulled high and PV1 is greater

than 3.7V (typ), the 5V LSUP linear regulator turns on.

Once LSUP exceeds 2.5V, the internal reference and

bias are enabled. When the internal bias has stabilized

OUT1, soft-start is initiated. After completion of soft-start

on OUT1 (2.8ms typ), OUT2 soft-start is initiated. OUT3

soft-start is enabled when PV3 is greater than or equal to

1.25V (typ), and OUT4 soft-start is enabled when PV4 is

greater than or equal to 1.5V (typ).

Care must be taken when driving the EN pin. Digital input

signals deliver a fast edge that is properly detected by the

MAX16922. If driving the EN pin with an analog voltage

that has a slew rate of less than 1V/ms or a voltage-

divider from PV1, then the input voltage on PV1 must

always be less than 6V when the voltage at EN is near the

turn-off threshold of 1.6V. If this cannot be guaranteed,

then a 1kΩ resistor or 5.6V zener diode must be placed

in parallel with the LSUP output capacitor to prevent

possible damage to the device.

Power-Down and Restart Sequence

The MAX16922 can be shut down by thermal shut-

down, enable low (EN), LSUP regulator undervoltage,

or when PV1 falls below 3.0V (typ). When a shutdown

occurs, all outputs discharge through an internal resistor

connected between each output and ground. When

enable is high, the die temperature is okay, the LSUP

linear regulator is greater than 2.5V (typ), and OUT1 is

less than 1.25V (typ); a complete soft-start power-on

sequence is reinitiated.

Inductor Selection

The OUT1 step-down converter operates with a 4.7μH

inductor and the OUT2 step-down converter operates

with a 2.2μH inductor. The inductor’s DC current

rating must be high enough to account for peak ripple

current and load transients. The step-down converter’s

architecture has minimal current overshoot during startup

and load transients. In most cases, an inductor capable of

1.3 times the maximum load current is acceptable.

For optimum performance choose an inductor with

DC-series resistance in the 50mΩ to 150mΩ range. For

higher efficiency at heavy loads (above 400mA) and

minimal load regulation, the inductor resistance should be

kept as small as possible. For light-load applications (up

to 200mA), higher resistance is acceptable with very little

impact on performance.

MAX16922

PV1

4.7µF220µF

0.1µF

1µF

0.1µF

10µF

PV3

PWM

4.7µF

VOUT1

OUT3

GND1

GND3

4.7µF

PV4 OUTS1

4.7µF

VOUT2

VOUT1

OUT4

GND2

20kΩ

RESET

GND

4.7µF

LSUP

4.7µH

LX1 VOUT1

BST

PV2

10µF

PGND2

2.2µH

LX2 VOUT2

OUTS2

4.7µF

VBAT

MAX16922 2.2MHz, Dual, Step-Down DC-DC

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Typical Applications Circuit

Capacitor Selection

Input Capacitors

The input capacitor, CIN1, reduces the current peaks

drawn from the supply and reduces switching noise in

the MAX16922. The impedance of CIN1 at the switching

frequency should be kept very low. Ceramic capacitors

with X5R or X7R dielectrics are recommended due to their

small size, low ESR, and small temperature coefficients.

Use a 4.7μF ceramic capacitor or an equivalent amount of

multiple capacitors in parallel between PV1 and ground.

Connect CIN1 as close to the device as possible to mini-

mize the impact of PCB trace inductance.

Connect a minimum 4.7μF ceramic capacitor between

PV2 to ground, and a 2.2μF ceramic capacitor between

PV3 to ground and PV4 to ground. Since PV2 is cascaded

from OUT1, the input capacitor connected to PV2 can be

used as part of the total output capacitance for OUT1.

Step-Down Output Capacitors

The step-down output capacitors are required to keep the

output-voltage ripple small and to ensure regulation loop

stability. These capacitors must have low impedance at

the switching frequency. Surface-mount ceramic capaci-

tors are recommended due to their small size and low

ESR. The capacitor should maintain its capacitance over-

temperature and DC bias. Ceramic capacitors with X5R or

X7R temperature characteristics generally perform well.

The output capacitance can be very low. Place a minimum

of 15μF ceramic capacitance from OUTS1 to ground and

a minimum of 10μF from OUTS2 to ground. When the

OUT2 output voltage selection is below 2.35V, the output

capacitance should be increased to prevent instability. For

optimum loadtransient performance and very low output

ripple, the output capacitance can be increased. The

maximum output capacitance should not exceed 3.8mF

for OUT1 and 2.0mF for OUT2.

LDO Output Capacitors and Stability

Connect a 4.7μF ceramic capacitor between OUT3 and

GND, and a second 4.7μF ceramic capacitor from OUT4

to GND. When the input voltage of an LDO is greater than

2.35V, the output capacitor can be decreased to 2.2μF.

The equivalent series resistance (ESR) of the LDO output

capacitors affects stability and output noise. Use output

capacitors with an ESR of 0.1Ω or less to ensure stable

operation and optimum transient response. Connect

these capacitors as close as possible to the device to

minimize PCB trace inductance.

Thermal Considerations

The maximum package power dissipation of the

MAX16922 in the 20-pin thin QFN package is 2500mW.

The power dissipated by the MAX16922 should not

exceed this rating. The total device power dissipation is

the sum of the power dissipation of the four regulators:

PD = PD1 + PD2 + PD3 + PD4

Estimate the OUT1 and OUT2 power dissipations as

follows:

D1 OUT1 OUT1

D2 OUT2 OUT2

PI V

−η

=××

−η

=××

where η is the efficiency (see the Typical Operating

Characteristics section).

Calculate the OUT3 and OUT4 power dissipations as

follows:

PD3 = IOUT3 x (VPV3 - VOUT3)

PD4 = IOUT4 x (VPV4 - VOUT4)

The maximum junction temperature of the MAX16922 is

+150°C. The junction-to-case thermal resistance (θJC) of

the MAX16922 is 2.7°C/W.

When mounted on a single-layer PCB, the junction

to ambient thermal resistance (θJA) is approximately

48°C/W. Mounted on a multilayer PCB, θJA is approxi-

mately 32°C/W. Calculate the junction temperature of the

MAX16922 as follows:

TJ = TA x PD x θJA

where TA is the maximum ambient temperature. Make

sure the calculated value of TJ does not exceed the

+150°C maximum.

MAX16922 2.2MHz, Dual, Step-Down DC-DC

Converters, Dual LDOs, and RESET

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PCB Layout

High-switching frequencies and relatively large peak

currents make PCB layout a very important aspect of

design. Good design minimizes excessive EMI on the

feedback paths and voltage gradients in the ground

plane, both of which can result in instability or regulation

errors. Connect the input capacitors as close as possible

to the PV_ and ground. Connect the inductor and output

capacitors as close as possible to the device and keep

the traces short, direct, and wide to minimize the current

loop area.

The OUTS_ feedback connections are sensitive to

inductor magnetic field interference so route these traces

away from the inductors and noisy traces such as LX_.

Connect GND_ and PGND2 to the ground plane. Connect

the exposed paddle to the ground plane with multiple vias

to help conduct heat away from the device.

Refer to the MAX16922 evaluation kit for a PCB layout

example.

MAX16922 2.2MHz, Dual, Step-Down DC-DC

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*Other standard versions may be available. Contact factory for availability.

**Future product—contact factory for availability.

PART

NUMBER

SUFFIX*

OUT1

VOLTAGE

(V)

OUT2

VOLTAGE

(V)

OUT3

VOLTAGE

(V)

OUT4

VOLTAGE

(V)

OUT1 RESET

THRESHOLD

(%)

RESET

TIMEOUT

(ms)

BST

REFRESH

LOAD

ENABLE

A 5.00 2.70 3.30 1.00 90 14.9 On

B 5.00 1.20 1.80 3.30 90 14.9 On

C 5.00 3.30 1.20 3.00 90 14.9 On

D 3.6 1.20 3.30 3.30 90 14.9 Off

E 5.00 3.30 2.50 1.80 90 14.9 On

F 5.00 1.20 3.15 3.00 90 14.9 On

G 3.30 Off 2.80 1.80 90 14.9 On

H 3.30 1.20 2.50 1.80 90 14.9 Off

I 3.30 1.20 2.85 1.80 90 14.9 Off

J 3.80 3.30 2.50 1.20 90 14.9 Off

K 3.30 2.20 1.60 1.80 90 14.9 On

L 5.00 3.30 1.80 1.25 90 14.9 On

M** 3.30 1.50 2.80 1.8 90 14.9 On

N** 3.30 1.10 2.50 1.80 90 14.9 Off

O** 3.30 1.20 1.80 2.70 90 14.9 On

LEAD FREE

AEC Q100 QUALIFIED

OUTPUT VOLTAGES RESET THRESHOLD, RESET TIMEOUT

-40°C TO +125°C OPERATION, TQFN, 20 PINS

MAX16922 ATP x /V +

LEAD FREE

AEC Q100 QUALIFIED

OUTPUT VOLTAGES RESET THRESHOLD, RESET TIMEOUT

-40°C TO +125°C OPERATION, TSSOP, 20 PINS

MAX16922 AUP x /V +

MAX16922 2.2MHz, Dual, Step-Down DC-DC

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Selector Guide

*Insert the desired suffix letters (from the Selector Guide) into

the blank “_” to complete the part number.

+Denotes a lead(Pb)-free/RoHS-compliant package.

/V denotes an automotive qualified part.

**EP = Exposed pad.

PACKAGE

TYPE

PACKAGE

CODE

OUTLINE

NO.

LAND

PATTERN NO.

20 TQFN-EP T2055+4 21-0140 90-0009

20 TSSOP-EP U20E+1 21-0108 90-0114

PART TEMP RANGE PIN-PACKAGE

MAX16922ATP_/V+* -40°C to +125°C 20 TQFN-EP**

MAX16922AUP_/V+* -40°C to +125°C 20 TSSOP-EP**

MAX16922 2.2MHz, Dual, Step-Down DC-DC

Converters, Dual LDOs, and RESET

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Package Information

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.

Chip Information

PROCESS: BiCMOS

Ordering Information

REVISION

NUMBER

REVISION

DATE DESCRIPTION PAGES

CHANGED

0 10/09 Initial release —

1 5/10 Updated Absolute Maximum Ratings, Electrical Characteristics, Typical Operating

Characteristics, Dropout, and Power-On Sequence sections

1, 2, 4, 6, 11,

2 10/10 Added a new voltage trim option (I) to the Selector Guide 15

311/10 Added a new voltage trim option (J) to the Selector Guide 15

4 4/11 Added a new voltage trim option (K) to the Selector Guide 15

5 1/12 Updated the Functional Diagram to eliminate the PWM signal on OUT1 and changed

PV2 polarized capacitor to an unpolarized capacitor 8

66/13 Added a new variant to the Selector Guide 15

77/14 Updated Package Thermal Characteristics section for TQFN package 2

86/15 Added a new variant (M) to Selector Guide 15

911/15 Added a new variant (N) to Selector Guide 15

10 2/16 Moved Ordering Information to end of data sheet and added a new variant ()) to

Selector Guide 1, 15

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.

│

MAX16922 2.2MHz, Dual, Step-Down DC-DC

Converters, Dual LDOs, and RESET

Revision History

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MAX16922ATPA/V+ MAX16922ATPB/V+ MAX16922ATPC/V+ MAX16922ATPD/V+ MAX16922ATPE/V+

MAX16922ATPF/V+ MAX16922ATPG/V+ MAX16922ATPH/V+ MAX16922AUPA/V+ MAX16922AUPB/V+

MAX16922AUPC/V+ MAX16922AUPD/V+ MAX16922AUPE/V+ MAX16922AUPF/V+ MAX16922AUPG/V+

MAX16922AUPH/V+ MAX16922ATPJ/V+ MAX16922ATPJ/V+T MAX16922ATPK/V+ MAX16922ATPK/V+T

MAX16922ATPL/V+ MAX16922ATPL/V+T MAX16922ATPI/V+ MAX16922ATPI/V+T MAX16922ATPA/V+T

MAX16922ATPB/V+T MAX16922ATPC/V+T MAX16922ATPD/V+T MAX16922ATPE/V+T MAX16922ATPF/V+T

MAX16922ATPG/V+T MAX16922ATPH/V+T MAX16922AUPA/V+T MAX16922AUPB/V+T MAX16922AUPC/V+T

MAX16922AUPD/V+T MAX16922AUPE/V+T MAX16922AUPF/V+T MAX16922AUPG/V+T MAX16922AUPH/V+T