Rainbow-electronics MAX17008 Manual de usuario descargar pdf

General Description

The MAX17007A/MAX17008 are dual Quick-PWM™

step-down controllers intended for general power gen-

eration in battery-powered systems. The two switched-

mode power supplies (SMPSs) can also be combined to

operate in a two-phase single-output mode. Constant

on-time Quick-PWM operation provides fast response to

load transients and handles wide input/output (I/O) volt-

age ratios with ease, while maintaining a relatively con-

stant switching frequency. The switching frequency can

be individually adjusted between 200kHz and 600kHz

with external resistors. Differential output current sens-

ing allows output sense-resistor sensing for an accurate

current limit, or lossless inductor direct-current resis-

tance (DCR) current sensing for lower power dissipation

while maintaining 0.7% output accuracy. Overvoltage

(MAX17007A only), undervoltage protection, and accu-

rate user-selectable current limits (15mV, 30mV, 45mV,

and 60mV) ensure robust operations.

The SMPS outputs can operate in skip mode or in ultra-

sonic mode for improved light-load efficiency. The ultra-

sonic mode eliminates audible noises by maintaining a

minimum switching frequency of 25kHz in pulse-

skipping mode.

The output voltage of SMPS1 can be dynamically

adjusted by changing the voltage at the REFIN1 pin.

The device includes a 0.5% accurate reference output

that can be used to set the REFIN1 voltage. An external

5V bias supply is required to power the internal circuitry

and its gate drivers.

Independent on/off controls with well-defined logic thresh-

olds and independent open-drain power-good outputs

provide flexible system configurations. To prevent current

surges at startup, the internal voltage target is slowly

ramped up from zero to the final target with a slew rate of

1.3mV/μs for SMPS1 at CSL1 and 0.65mV/μs for SMPS2

at FB2. To prevent the output from ringing off below

ground in shutdown, the internal voltage target is ramped

down from its previous value to zero with the same

respective slew rates. Integrated bootstrap switches

eliminate the need for external bootstrap diodes.

The MAX17007A/MAX17008 are available in a space-

saving, 28-pin, 4mm x 4mm, thin QFN package with an

exposed backside pad.

Applications

Features

o Dual Quick-PWM with Fast Transient Response

o Automatic Dynamic REFIN1 Detection and

PGOOD1/Fault Blanking

o Fixed and Adjustable Output Voltages

±0.7% Output Accuracy Over Line and Load

OUT1: 0 to 2V Dynamic Output or Preset 1.05V

OUT2: 0.7V to 2V Range or Preset 1.5V

o Resistor-Programmable Switching Frequency

o Integrated BST Switches

o Differential Current-Sense Inputs

Low-Cost DCR Sensing or Accurate Current-

Sense Resistors

Internally Coupled Current-Sense Compensation

o Combinable Mode Supports High-Current

Dynamic Output Voltages

o Selectable Forced-PWM, Pulse Skip, or Ultrasonic

Mode Operation

o 26V Maximum Input Voltage Rating

o Independent Enable Inputs

o Independent Power-Good Outputs

o Overvoltage Protection (MAX17007A Only)

o Undervoltage/Thermal Protection

o Voltage Soft-Start and Soft-Shutdown

MAX17007A/MAX17008

Dual and Combinable QPWM Graphics

Core Controllers for Notebook Computers

________________________________________________________________

Maxim Integrated Products

MAX17007A

MAX17008

THIN QFN

(4mm x 4mm)

1422

1323

1224

1125

1026

927

828

LX1

DH1

PGOOD1

EN1

CSH1

TOP VIEW

*EP

*EP = EXPOSED PAD.

CSL1

REFIN1

LX2

DH2

PGOOD2

EN2

CSH2

CSL2

FB2

BST2

PGND

DL2

DL1

GND

BST1

REF

ILIM1

(CCI) ILIM2

SKIP

TON1

TON2

Pin Configuration

Ordering Information

19-3200; Rev 2; 10/08

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

EVALUATION KIT

AVAILABLE

Denotes a lead-free/RoHS-compliant package.

EP = Exposed pad.

PART TEMP RANGE PIN-PACKAGE

MAX17007AGTI+ -40°C to +105°C 28 Thin QFN-EP*

MAX17008GTI+ -40°C to +105°C 28 Thin QFN-EP*

Notebook Computers

Low-Power I/O Supplies

GPU Core Supplies

2 to 4 Li+ Cells Battery-

Powered Devices

Quick-PWM is a trademark of Maxim Integrated Products, Inc.

1 2 3 4 5 6 ... 35 36

Indice de contenidos

Pagina 1 - MAX17007A/MAX17008

General DescriptionThe MAX17007A/MAX17008 are dual Quick-PWM™step-down controllers intended for general power gen-eration in battery-powered systems.

Pagina 2

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers10 _________________________________________________________

Pagina 3

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers____________________________________________________________

Pagina 4

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers12 _________________________________________________________

Pagina 5

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers____________________________________________________________

Pagina 6

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers14 _________________________________________________________

Pagina 7

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers____________________________________________________________

Pagina 8

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers16 _________________________________________________________

Pagina 9

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers____________________________________________________________

Pagina 10

+5V Bias Supply (VCC, VDD)The MAX17007A/MAX17008 require an external 5V biassupply in addition to the battery. Typically, this 5V biassupply is the no

Pagina 11

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers____________________________________________________________

Pagina 12

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers2 __________________________________________________________

Pagina 13

MAX17007A/MAX17008Switching FrequencyThe MAX17007A/MAX17008 feature independent resis-tor-programmable switching frequencies for eachSMPS, providing f

Pagina 14

Soft-StartSoft-start begins when EN is driven high and REF is inregulation. During soft-start, the output is ramped upfrom 0V to the final set voltage

Pagina 15

MAX17007A/MAX17008When SKIP is pulled to GND, the MAX17007A/MAX17008remain in pulse-skipping mode. Since the output is notable to sink current, the ti

Pagina 16

Valley Current-Limit ProtectionThe current-limit circuit employs a unique “valley” cur-rent-sensing algorithm that senses the inductor currentacross t

Pagina 17

MAX17007A/MAX17008Output VoltageThe MAX17007A/MAX17008 feature preset andadjustable output voltages for both SMPSs, and dynam-ic output voltages for S

Pagina 18

Additional load current can slow down the output volt-age change during a positive REFIN1 voltage change,and can speed up the output voltage change du

Pagina 19

MAX17007A/MAX17008Internal IntegrationAn integrator amplifier forces the DC average of the FBvoltage to equal the target voltage. This internal amplif

Pagina 20

Undervoltage Protection (UVP)When the feedback voltage drops below the undervolt-age threshold, the controller immediately pulls PGOODlow and triggers

Pagina 21

MAX17007A/MAX17008Quick-PWM Design ProcedureFirmly establish the input voltage range and maximumload current before choosing a switching frequencyand

Pagina 22

Setting the Valley Current LimitThe minimum current-limit threshold must be highenough to support the maximum load current when thecurrent limit is at

Pagina 23

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers____________________________________________________________

Pagina 24

MAX17007A/MAX17008Output Capacitor SelectionThe output filter capacitor must have low enough effec-tive series resistance (ESR) to meet output ripple

Pagina 25

When only using ceramic output capacitors, outputovershoot (VSOAR) typically determines the minimumoutput capacitance requirement. Their relatively lo

Pagina 26

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers32 _________________________________________________________

Pagina 27

In a single-phase configuration, the absolute point ofdropout is when the inductor current ramps down dur-ing the minimum off-time (ΔIDOWN) as much as

Pagina 28

MAX17007A/MAX170083) Group the gate-drive components (BST capacitors,VDDbypass capacitor) together near the controller IC.4) Make the DC-DC controller

Pagina 29

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers____________________________________________________________

Pagina 30

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook ComputersMaxim cannot assume responsibility for use of any circuitry

Pagina 31 - Power-MOSFET Selection

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers4 __________________________________________________________

Pagina 32

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers____________________________________________________________

Pagina 33

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers6 __________________________________________________________

Pagina 34 - Figure 15. PCB Layout Example

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers____________________________________________________________

Pagina 35

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers8 __________________________________________________________

Pagina 36

MAX17007A/MAX17008Dual and Combinable QPWM GraphicsCore Controllers for Notebook Computers____________________________________________________________

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