MAXIM MAX8744A, MAX8745A Technical data

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.

General Description

The MAX8744A/MAX8745A are dual step-down, switchmode, power-supply (SMPS) controllers with synchronous rectification, intended for main 5V/3.3V power generation in battery-powered systems. Fixed-frequency operation with optimal interleaving minimizes input ripple current from the lowest input voltages up to the 26V maximum input. Optimal 40/60 interleaving allows the input voltage to go down to 8.3V before duty-cycle overlap occurs, compared to 180° out-of-phase regulators where the duty-cycle overlap occurs when the input drops below 10V.

Output current sensing provides peak current-limit protection, using either an accurate sense resistor or using lossless inductor DCR current sensing. A low-noise mode maintains high light-load efficiency while keeping the switching frequency out of the audible range.

An internal, fixed 5V, 100mA linear regulator powers up the MAX8744A/MAX8745A and their gate drivers, as well as external keep-alive loads. When the main PWM regulator is in regulation, an automatic bootstrap switch bypasses the internal linear regulator, providing current up to 200mA. An additional adjustable linear-regulator driver with an external pnp transistor can be used with a secondary winding to provide a 12V supply, or powered directly from the main outputs to generate lowvoltage outputs as low as 1V.

Independent enable controls and power-good signals allow flexible power sequencing. Voltage soft-start gradually ramps up the output voltage and reduces inrush current, while soft-shutdown gradually ramps the output voltage down, preventing negative voltage dips. The MAX8744A/MAX8745A feature output undervoltage and thermal-fault protection. The MAX8744A also includes output overvoltage-fault protection.

The MAX8744A/MAX8745A are available in a 32-pin, 5mm x 5mm, thin QFN package. The exposed backside pad improves thermal characteristics for demanding linear keep-alive applications.

Applications

Main Power Supplies

2 to 4 Li+ Cell Battery-Powered Devices

Notebook and Subnotebook Computers

PDAs and Mobile Communicators

Features

o Fixed-Frequency, Current-Mode Control o 40/60 Optimal Interleaving o Internal BST Switches o Internal 5V, 100mA Linear Regulator o Auxiliary Linear-Regulator Driver (12V or

Adjustable Down to 1V)

o Dual Mode™ Feedback—3.3V/5V Fixed or

Adjustable Output Voltages

o 200kHz/300kHz/500kHz Switching Frequency o Undervoltage and Thermal-Fault Protection o Overvoltage-Fault Protection (MAX8744A Only) o 6V to 26V Input Range o 2V ±0.75% Reference Output o Independent Enable Inputs and Power-Good

Outputs

o Soft-Start and Soft-Shutdown (Voltage Ramp) o 8μA (typ) Shutdown Current

MAX8744A/MAX8745A

High-Efficiency, Quad Output, Main Power-

Supply Controllers for Notebook Computers

________________________________________________________________

Maxim Integrated Products

19-0839; Rev 0; 6/07

Denotes a lead-free package.

Future product—contact factory for availability.

MAX8744A MAX8745A

THIN QFN

5mm x 5mm

TOP VIEW

DRVA

SHDN

ON3

ON5

REF

ONA

DL3

LDO5

LX3

PGND

DL5

CSL3

4567

2324 22 20 19 18

CSH3

FB3

PGOOD5

CSL5

CSH5

FB5

ILIM

PGOODA

FBA

SKIP

OUTA

FSEL

PGOOD3

BST5

BST3

DH5

GND

LX5

DH3

Pin Configuration

Ordering Information

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

EVALUATION KIT

AVAILABLE

PART TEMP RANGE

MAX8744AETJ+ -40°C to +85°C

MAX8745AETJ+* -40°C to +85°C

PINPACKAGE

32 Thin QFN (5mm x 5mm)

PKG

CODE

T3255-4

MAX8744A/MAX8745A

High-Efficiency, Quad Output, Main PowerSupply Controllers for Notebook Computers

2 _______________________________________________________________________________________

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.

IN, SHDN, DRVA, OUTA to GND............................-0.3V to +28V

LDO5, ON3, ON5, ONA to GND ..............................-0.3V to +6V

PGOODA, PGOOD3, PGOOD5 to GND...................-0.3V to +6V

CSL3, CSH3, CSL5, CSH5 to GND ..........................-0.3V to +6V

REF, FB3, FB5, FBA to GND...................-0.3V to (V

LDO5

+ 0.3V)

SKIP, FSEL, ILIM to GND........................-0.3V to (V

LDO5

+ 0.3V)

DL3, DL5 to PGND..................................-0.3V to (V

LDO5

+ 0.3V)

BST3, BST5 to PGND .............................................-0.3V to +34V

BST3 to LX3..............................................................-0.3V to +6V

DH3 to LX3 ..............................................-0.3V to (V

BST3

+ 0.3V)

BST5 to LX5..............................................................-0.3V to +6V

DH5 to LX5 ..............................................-0.3V to (V

BST5

+ 0.3V)

GND to PGND .......................................................-0.3V to +0.3V

BST3, BST5 to LDO5 .............................................-0.3V to +0.3V

LDO Short Circuit to GND ..........................................Momentary

REF Short Circuit to GND ...........................................Momentary

DRVA Current (Sinking) ......................................................30mA

OUTA Shunt Current ...........................................................30mA

Continuous Power Dissipation (T

= +70°C)

Multilayer PCB

32-Pin, 5mm x 5mm TQFN

(derated 34.5mW/°C above +70°C) .........................2459mW

Operating Temperature Range ...........................-40°C to +85°C

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

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

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

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, VIN= 12V, both SMPS enabled, FSEL = REF, SKIP = GND, ILIM = LDO5, FBA = LDO5, I

REF

= I

LDO5

= I

OUTA

no load, T

= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

INPUT SUPPLIES (Note 1)

VIN Input Voltage Range V

VIN Operating Supply Current I

VIN Standby Supply Current I

VIN Shutdown Supply Current I

Quiescent Power Consumption P

MAIN SMPS CONTROLLERS

3.3V Output Voltage in Fixed Mode

5V Output Voltage in Fixed Mode V

Feedback Voltage in Adjustable Mode (Note 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

IN(STBY)

IN(SHDN)VIN

OUT3

OUT5

FB_

LDO5 in regulation 5.4 26.0

IN = LDO5, V

LDO5 switched over to CSL5, either SMPS on

VIN = 6V to 26V, both SMPS off, includes I

SHDN

= 6V to 26V 8 20 µA

Both S M P S on, FB3 = FB5 = LD O5, SKIP = GN D , V

= 15V ,

OU T A

+ P

C S L 3

VIN = 6V to 26V, SKIP = FB3 = LDO5, 0 < V

CSH3

VIN = 6V to 26V, SKIP = FB5 = LDO5, 0 < V

CSH5

VIN = 6V to 26V, FB3 or FB5 duty factor = 20% to 80%

VIN = 6V to 26V, FB3 or FB5 duty factor = 50%

< 4.4V 4.5 5.5

CSL5

20 36 µA

65 120 µA

+ P

- V

C S L 3

C S L 5

CSL3

CSL5

= 3.5V , V

+ P

OU T A

< 50mV (Note 2)

C S L 5

= 5.3V ,

3.5 4.5 mW

3.265 3.315 3.365 V

4.94 5.015 5.09 V

1.980 2.010 2.040

1.990 2.010 2.030

MAX8744A/MAX8745A

High-Efficiency, Quad Output, Main Power-

Supply Controllers for Notebook Computers

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= 12V, both SMPS enabled, FSEL = REF, SKIP = GND, ILIM = LDO5, FBA = LDO5, I

REF

= I

LDO5

= I

OUTA

no load, T

= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

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

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Output Voltage Adjust Range Either SMPS 2.0 5.5 V

FB3, FB5 Dual Mode Threshold 3.0

Feedback Input Leakage Current V

DC Load Regulation

= V

FB3

= 2.1V -0.1 +0.1 µA

FB5

Either SMPS, SKIP = LDO5,

- V

0 < V

CSH_

CSL_

< 50mV

Line Regulation Error Either SMPS, 6V < VIN < 26V 0.03 %/V

FSEL = GND 170 200 230

Operating Frequency (Note 1) f

OSC

FSEL = REF 270 300 330

FSEL = LDO5 425 500 575

Maximum Duty Factor D

Minimum On-Time t

MAX

ONMIN

(Note 1) 97.5 99 %

SMPS3-to-SMPS5 Phase Shift SMPS5 starts after SMPS3

CURRENT LIMIT

ILIM Adjustment Range 0.5 V

Current-Sense Input Leakage Current

Current-Limit Threshold (Fixed) V

Current-Limit Threshold (Adjustable)

Current-Limit Threshold (Negative)

Current-Limit Threshold (Zero Crossing)

LIMIT

NEG

CSH3 = CSH5 = GND or LDO5 -1 +1 µA

CSH

_ - V

_, ILIM = LDO5 45 50 55 mV

CSL

= 2.00V 185 200 215

CSL

_, SKIP = ILIM = LDO5 -67 -60 -53 mV

CSL

_, SKIP = LDO5, adjustable

CSL

ILIM

= 1.00V 94 100 106

ILIM

mode, percent of current limit

_ - V

CSH

ILIM = LDO5

_, SKIP = GND,

CSL

036mV

ILIM = LDO5 6 10 14 mV

Idle Mode™ Threshold V

IDLE

_ - V

CSH

SKIP = GND

CSL

With respect to current-limit threshold (V

LIMIT

)

ILIM = LDO5 2.5 5 7.5 mV

Idle Mode Threshold (Low Audible-Noise Mode)

IDLE

_ - V

CSH

SKIP = REF

CSL

With respect to current-limit threshold (V

LIMIT

)

ILIM Leakage Current ILIM = GND or REF -1 +1 µA

LOO5

- 1.0

LOO5

- 0.4

-0.1 %

100 ns

40 %

144 Deg

REF

-120 %

20 %

10 %

kHz

MAX8744A/MAX8745A

High-Efficiency, Quad Output, Main PowerSupply Controllers for Notebook Computers

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= 12V, both SMPS enabled, FSEL = REF, SKIP = GND, ILIM = LDO5, FBA = LDO5, I

REF

= I

LDO5

= I

OUTA

no load, T

= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Soft-Start Ramp Time t

Soft-Stop Ramp Time t

SSTART

SSTOP

Measured from the rising edge of ON_ to full scale

Measured from the falling edge of ON_ to full scale

INTERNAL FIXED LINEAR REGULATORS

LDO5 Output Voltage V

LDO5

ON5 = GND, 6V < VIN < 26V, 0 < I

LDO5

< 100mA

LDO5 Undervoltage-Lockout Fault Rising edge, hysteresis = 1%

Short-Circuit Current (Switched Over to CSL5)

LDO5 = GND, V

> 4.7V 200 425 mA

CSL5

4.85 4.95 5.10 V

3.7 4.0 4.1 V

AUXILIARY LINEAR REGULATOR

DRVA Voltage Range V

DRVA Drive Current

FBA Regulation Threshold V

FBA Load Regulation V

DRVA

FBA

= 1.05V, V

FBA

= 0.965V, V

FBA

DRVA

DRA

= 5V, I

= 5V 0.4

DRVA

= 5V 10

DRVA

= 1mA (sink) 0.98 1.00 1.02 V

DRVA

= 0.5mA to 5mA -1.2 -2.2 %

DRVA

0.5 26.0 V

OUTA Shunt Trip Level Rising edge 25 26 27 V

FBA Leakage Current V

Secondary Feedback Regulation Threshold

= 1.035V -0.1 +0.1 µA

FBA

- V

DRVA

OUTA

DL5 Pulse Width

OUTA Leakage Current I

OUTA

DRVA

= V

= 25V 50 µA

OUTA

REFERENCE (REF)

Reference Voltage V

Reference Load-Regulation Error ΔV

REF Lockout Voltage V

REF(UVLO

REF

LDO5 in regulation, I

= -5µA to +50µA -10 +10 mV

REF

= 0 1.985 2.00 2.015 V

REF

Rising edge 1.8 V

FAULT DETECTION

Output Overvoltage Trip Threshold (MAX8744A Only)

Outp ut Over vol tag e Faul t P r op ag ati on D elay (M AX 8744A Only)

OVP

With respect to error-comparator threshold

81114%

50mV overdrive 10 µs

2ms

4ms

OSC

µs

MAX8744A/MAX8745A

High-Efficiency, Quad Output, Main Power-

Supply Controllers for Notebook Computers

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= 12V, both SMPS enabled, FSEL = REF, SKIP = GND, ILIM = LDO5, FBA = LDO5, I

REF

= I

LDO5

= I

OUTA

no load, T

= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

)

Output Undervoltage Protection Trip Threshold

Output Undevoltage Fault Propagation Delay

Output Undervoltage Protection Blanking Time

PGOOD_ Lower Trip Threshold

PGOOD_ Propagation Delay t

PGOOD_ Output Low Voltage I

PGOOD_ Leakage Current I

Thermal-Shutdown Threshold t

GATE DRIVERS

DH_ Gate-Driver On-Resistance R

DL_ Gate-Driver On-Resistance R

DH_ Gate-Driver Source/Sink Current

DL_ Gate-Driver Source Current

DL_ Gate-Driver Sink Current I

Dead Time t

Internal BST_ Switch On-Resistance

BST_ Leakage Current V

INPUTS AND OUTPUTS

SHDN Input Trip Level

ONA Logic Input Voltage Hysteresis = 600mV (typ)

ON3, ON5 Input Voltage

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

With respect to error-comparator threshold

UVP

BLANK

PGOOD

SHDN

DL (SINK

DEAD

BST

50mV overdrive 10 µs

From rising edge of ON_ with respect to f

With respect to error-comparator threshold, hysteresis = 1% (typ)

Falling edge, 50mV overdrive 10

Rising edge, 50mV overdrive 1

= 1mA 0.4 V

SINK

_ High state, PGOOD_ forced to 5.5V 1 µA

Hysteresis = 15°C +160 °C

BST_ – LX_ forced to 5V 1.3 5 Ω

DL_, high state 1.7 5

DL_, low state 0.6 3

DH_ forced to 2.5V, BST_ – LX_ forced to 5V

DL_ forced to 2.5V 1.7 A

DL_ forced to 2.5V 3.3 A

DH_low to DL_high 15 45

DL_low to DH_high 15 44

= 10mA 5 Ω

BST

_ = 26V 2 20 µA

BST

Rising trip level 1.1 1.6 2.2

Falling trip level 0.96 1 1.04

High 2.4

Low 0.8

SMPS off level/clear fault level 0.8

Delay start level 1.9 2.1

SMPS on level 2.4

65 70 75 %

5000 6144 7000 1/f

-12 -10 -8 %

OSC

µs

MAX8744A/MAX8745A

High-Efficiency, Quad Output, Main PowerSupply Controllers for Notebook Computers

6 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, VIN= 12V, both SMPS enabled, FSEL = REF, SKIP = GND, ILIM = LDO5, FBA = LDO5, I

REF

= I

LDO5

= I

OUTA

no load, T

= -40°C to +85°C, unless otherwise noted.) (Note 3)

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= 12V, both SMPS enabled, FSEL = REF, SKIP = GND, ILIM = LDO5, FBA = LDO5, I

REF

= I

LDO5

= I

OUTA

no load, T

= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

LDO5

- 0.4

Tri-Level Input Logic SKIP, FSEL

High

REF 1.65 2.35

GND 0.5

Input Leakage Current

SKIP, FSEL forced to GND or LDO5 -1 +1 SHDN forced to GND or 26V -1 +1

INPUT SUPPLIES (Note 1)

VIN Input Voltage Range VIN

VIN Operating Supply Current I

VIN Standby Supply Current I

VIN Shutdown Supply Current I

Quiescent Power Consumption P

MAIN SMPS CONTROLLERS

3.3V Output Voltage in Fixed Mode

5V Output Voltage in Fixed Mode V

Feedback Voltage in Adjustable Mode

Output Voltage Adjust Range

FB3, FB5 Dual Mode Threshold

Operating Frequency (Note 1) f

Maximum Duty Factor D

PARAMETER SYMBOL CONDITIONS MIN MAX UNITS

LDO5 in regulat ion 5.4 26.0

IN = LDO5, V

LDO5 switched over to CSL5, either SMPS on 40 μA

IN(STBY)

IN(SHDN) VIN

VIN = 6V to 26V, both SMPS off, includes I

SHDN

= 6V to 26V 20 μA

< 4.4V 4.5 5.5

CSL5

Both SMPS on, FB3 = FB5 = LDO5; SKIP = GND, V

OUTA

+ P

OUT3

OUT5

VIN = 6V to 26V, SKIP = FB3 = LDO5, 0 < V

VIN = 6V to 26V, SKIP = FB5 = LDO5, 0 < V

VIN = 6V to 26V, FB3 or FB5

FB_

duty factor = 20% to 80% (Note 2)

Either SMPS 2.0 5.5 V

CSL3

= 15V,

CSL3

- V

CSH3

- V

CSH5

= 3.5V, V

+ P

CSL5

< 50mV (Note 2)

CSL3

< 50mV (Note 2)

CSL5

= 5.3V,

OUTA

3.255 3.375 V

4.925 5.105 V

1.974 2.046 V

FSEL = GND 170 230

OSC

FSEL = REF 270 330

FSEL = LDO5 425 575

97 %

MAX

120 μA

4.5 mW

LDO5

0.4

µA

kHz

MAX8744A/MAX8745A

High-Efficiency, Quad Output, Main Power-

Supply Controllers for Notebook Computers

_______________________________________________________________________________________ 7

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= 12V, both SMPS enabled, FSEL = REF, SKIP = GND, ILIM = LDO5, FBA = LDO5, I

REF

= I

LDO5

= I

OUTA

no load, T

= -40°C to +85°C, unless otherwise noted.) (Note 3)

CURRENT LIMIT

ILIM Adjustment Range

Current-Limit Threshold (Fixed) V

Current-Limit Thresho ld (Adjustable)

PARAMETER SYMBOL CONDITIONS MIN MAX UNITS

0.5 V

LIMIT VCSH

_ - V

_, ILIM = LDO5 44 56 mV

CSL

= 2.00V 185 215

CSL

ILIM

= 1.00V 93 107

ILIM

INTERNAL FIXED LINEAR REGULATORS

LDO5 Output Voltage V

LDO5 Undervoltage-Lockout Fault Threshold

LDO5 Bootstrap Switch

LDO5

ON5 = GND, 6V < VIN < 26V,

Risi ng edge, hysteresi s = 1% (typ) 3.7 4.1 V

Risi ng edge of CSL5, hysteres is = 1% (typ) 4.30 4.75 V

4.85 5.10 V

Short-Circuit Current LDO5 = GND, ON5 = GND 450 mA

Short-Circuit Current (Switched over to CSL5)

AUXILIARY LINEAR REGULATOR

DRVA Voltage Range V

DRVA

DRVA Dri ve Current

FBA Regulation Threshold V

LDO5 = GND, V

0.5 26.0 V

= 1.05V, V

FBA

= 0.965V, V

FBA

DRVA

= 5V, I

> 4.7V 200 mA

CSL5

= 5V 0.4

DRVA

= 5V 10

DRVA

= 1mA (sink) 0.98 1.02 V

DRVA

OUTA Shunt Trip Level 25 27 V

REFERENCE (REF)

Reference Voltage V

LDO5 in regulation, I

REF

= 0 1.980 2.020 V

REF

MAX8744A/MAX8745A

High-Efficiency, Quad Output, Main PowerSupply Controllers for Notebook Computers

8 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VIN= 12V, both SMPS enabled, FSEL = REF, SKIP = GND, ILIM = LDO5, FBA = LDO5, I

REF

= I

LDO5

= I

OUTA

no load, T

= -40°C to +85°C, unless otherwise noted.) (Note 3)

Note 1: The MAX8744A/MAX8745A cannot operate over all combinations of frequency, input voltage (VIN), and output voltage. For

large input-to-output differentials and high switching-frequency settings, the required on-time may be too short to maintain the regulation specifications. Under these conditions, a lower operating frequency must be selected. The minimum on-time must be greater than 150ns, regardless of the selected switching frequency. On-time and off-time specifications are measured from 50% point to 50% point at the DH_ pin with LX_ = GND, V

BST_

= 5V, and a 250pF capacitor connected from

DH_ to LX_. Actual in-circuit times may differ due to MOSFET switching speeds.

Note 2: When the inductor is in continuous conduction, the output voltage has a DC-regulation level lower than the error-comparator

threshold by 50% of the ripple. In discontinuous conduction (SKIP = GND, light load), the output voltage has a DC regulation level higher than the trip level by approximately 1.1% due to slope compensation.

Note 3: Specifications from -40°C to +85°C are guaranteed by design, not production tested.

FAULT DETECTION

Output Overvoltage Trip Threshold (MAX8744A Only)

Output Undervoltage Protection

PGOOD_ Lower Trip Threshold

PGOOD_ Output Low Voltage I

GATE DRIVERS

DH_ Gate-Driver On-Resistance R

DL_ Gate-Driver On-Resistance R

INPUTS AND OUTPUTS

SHDN Input Trip Level

ONA Logic Input Voltage Hysteresis = 600mV

Tri-Level Input Logic SKIP, FSEL

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

With respect to error comparator threshold 8 14 %

With respect to error comparator threshold 65 75 %

With respect to error comparator threshold, hysteresis = 1%

= 1mA 0.4 V

SINK

BST_ – LX_ forced to 5V 5 Ω

DL_, high state 5

DL_, low state 3

Rising trip level 1.0 2.3

Falling trip level 0.96 1.04

High 2.4

Low 0.8

SMPS off level/clear fault level 0.8

Delay start level 1.9 2.1ON3, ON5 Input Voltage

SMPS on level 2.4

High V

REF 1.65 2.35

GND 0.5

-12 -8 %

LDO5

- 0.4

MAX8744A/MAX8745A

High-Efficiency, Quad Output, Main Power-

Supply Controllers for Notebook Computers

_______________________________________________________________________________________

Typical Operating Characteristics

(Circuit of Figure 1, VIN= 12V, SKIP = GND, FSEL = REF, TA= +25°C, unless otherwise noted.)

5V OUTPUT EFFICIENCY

vs. LOAD CURRENT

100

EFFICIENCY (%)

0.001 0.01 0.1 1 10

20V

LOAD CURRENT (A)

3.3V OUTPUT EFFICIENCY vs. LOAD CURRENT

100

12V

SKIP MODE PWM MODE

12V

20V

MAX8744A toc01

MAX8744A toc04

100

EFFICIENCY (%)

100

5V OUTPUT EFFICIENCY

vs. LOAD CURRENT

SKIP MODE

LOW-NOISE

MODE

0.001 0.01 0.1 1 10 LOAD CURRENT (A)

PWM MODE

3.3V OUTPUT EFFICIENCY vs. LOAD CURRENT

SKIP MODE

MAX8744A toc02

OUTPUT VOLTAGE (V)

MAX8744A toc05

5V OUTPUT VOLTAGE

vs. LOAD CURRENT

5.10 SKIP MODE

5.05

5.00

PWM MODE

4.95

4.90

0.0 1.0 2.0 3.0 4.0 5.0

LOW-NOISE MODE

LOAD CURRENT (A)

3.3V OUTPUT VOLTAGE vs. LOAD CURRENT

3.39

SKIP MODE

3.36

LOW-NOISE MODE

3.33

MAX8744A toc03

MAX8744A toc06

EFFICIENCY (%)

0.001 0.01 0.1 1 10 LOAD CURRENT (A)

OUTPUT VOLTAGE DEVIATION

vs. INPUT VOLTAGE

-1

OUTPUT VOLTAGE DEVIATION (%)

-2

-3 0 4 8 12 16 20

3.3V OUTPUT

5.0V OUTPUT

INPUT VOLTAGE (V)

SKIP MODE PWM MODE

EFFICIENCY (%)

100

MAX8744A toc07

SUPPLY CURRENT (mA)

LOW-NOISE

MODE

0.001 0.01 0.1 1 10 LOAD CURRENT (A)

PWM MODE

NO-LOAD INPUT SUPPLY CURRENT

vs. INPUT VOLTAGE

PWM MODE

LOW-NOISE MODE

SKIP MODE

0 4 8 12 16 20

INPUT VOLTAGE (V)

3.30 PWM MODE

OUTPUT VOLTAGE (V)

3.27

3.24

012345

LOAD CURRENT (A)

STANDBY AND SHUTDOWN INPUT CURRENT

vs. INPUT VOLTAGE

100

MAX8744A toc08

STANDBY (ONx = GND)

SUPPLY CURRENT (μA)

0 4 8 12 16 20

INPUT VOLTAGE (V)

SHUTDOWN

(SHDN = GND)

MAX8744A toc09

MAX8744A/MAX8745A

High-Efficiency, Quad Output, Main PowerSupply Controllers for Notebook Computers

10 ______________________________________________________________________________________

Typical Operating Characteristics (continued)

(Circuit of Figure 1, VIN= 12V, SKIP = GND, FSEL = REF, TA= +25°C, unless otherwise noted.)

3.3V IDLE MODE CURRENT vs. INPUT VOLTAGE

SKIP MODE SKIP = GND

IDLE MODE CURRENT (A)

0 4 8 12 16 20

LOW-NOISE MODE

SKIP = REF

INPUT VOLTAGE (V)

1000

FORCED-PWM

MAX8744A toc10

100

LOW-NOISE SKIP

SWITCHING FREQUENCY (kHz)

0.001 10

LDO5 OUTPUT VOLTAGE

5.0

vs. LOAD CURRENT

4.9

4.8

4.7

OUTPUT VOLTAGE (V)

4.6

4.5 0 20406080100

LOAD CURRENT (mA)

12.2

MAX8744A toc13

12.1

12.0

OUTPUT VOLTAGE (V)

11.9 0 50 100 150

3.3V SWITCHING FREQUENCY vs. LOAD CURRENT

PULSE SKIPPING

10.10.01

LOAD CURRENT (A)

OUTA OUTPUT VOLTAGE

vs. LOAD CURRENT

LOAD CURRENT (mA)

MAX8744A toc11

SAMPLE PERCENTAGE (%)

-10 -6 -2 2 6 10

12V

MAX8744A toc14

REFERENCE OFFSET VOLTAGE

DISTRIBUTION

+85°C +25°C

2V REF OFFSET VOLTAGE (mV)

SAMPLE SIZE = 125

LDO5 POWER-UP

1ms/div

A. INPUT SUPPLY, 5V/div B. REF, 2V/div SHDN = IN

C. LDO5, 5V/div D. PGOOD5, 5V/div

MAX8744A toc12

MAX8744A toc15

MAX8744A/MAX8745A

High-Efficiency, Quad Output, Main Power-

Supply Controllers for Notebook Computers

______________________________________________________________________________________

Typical Operating Characteristics (continued)

(Circuit of Figure 1, VIN= 12V, SKIP = GND, FSEL = REF, TA= +25°C, unless otherwise noted.)

SOFT-START WAVEFORM

MAX8744A toc16

400μs/div

3.3V 0

12V

A. ON3 AND ON5, 5V/div B. 5V OUTPUT (V

OUT5

), 5V/div

C. PGOOD5, 5V/div

D. AUX LDO OUTPUT (V

OUTA

), 10V/div E. L5 INDUCTOR CURRENT, 5A/div

SMPS DELAYED STARTUP SEQUENCE

(ON3 = REF)

MAX8744A toc17

1ms/div

3.3V 0

3.3V

A. ON5, 5V/div B. 5V OUTPUT (V

OUT5

), 5V/div C. PGOOD5, 5V/div ON3 = REF

D. 3.3V OUTPUT (V

OUT3

), 5V/div E. PGOOD3, 5V/div

SMPS DELAYED STARTUP SEQUENCE

(ON5 = REF)

MAX8744A toc18

1ms/div

3.3V 0

3.3V

A. ON3, 5V/div B. 5V OUTPUT (V

OUT5

), 5V/div C. PGOOD5, 5V/div ON5 = REF

D. 3.3V OUTPUT (V

OUT3

), 5V/div E. PGOOD3, 5V/div

SMPS SHUTDOWN WAVEFORM

MAX8744A toc19

1ms/div

3.3V

A. SHDN, 5V/div B. 5V OUTPUT (V

OUT5

), 5V/div C. PGOOD5, 5V/div NO LOAD

D. 3.3V OUTPUT (V

OUT3

), 5V/div E. PGOOD3, 5V/div

OUT5 LOAD TRANSIENT

MAX8744A toc20

20μs/div

5.1V

12V

5.0V

4.9V

A. I

OUT5

= 1A TO 5A, 5A/div

B. V

OUT5

, 50mV/div

C. INDUCTOR CURRENT, 5A/div D. LX5, 10V/div

OUT3 LOAD TRANSIENT

MAX8744A toc21

20μs/div

3.35V

12V

3.30V

3.25V

A. I

OUT3

= 1A TO 3A, 5A/div

B. V

OUT3

, 50mV/div

C. INDUCTOR CURRENT, 5A/div D. LX3, 10V/div

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