Datasheet

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General Description

The MAX8702/MAX8703 dual-phase noninverting

MOSFET drivers are designed to work with PWM con-

troller ICs, such as the MAX8705/MAX8707, in note-

book CPU core and other multiphase regulators.

Applications can either step down directly from the bat-

tery voltage to create the core voltage, or step down

from a low-voltage system supply. The single-stage con-

version method allows the highest possible efficiency,

while the 2-stage conversion at higher switching frequen-

cy provides the minimum possible physical size.

Each MOSFET driver is capable of driving 3nF capaci-

tive loads with only 19ns propagation delay and 8ns

typical rise and fall times. Larger capacitive loads are

allowable but result in longer propagation and transition

times. Adaptive dead-time control helps prevent shoot-

through currents and maximizes converter efficiency.

The MAX8702/MAX8703 feature zero-crossing com-

parators on each channel. When enabled, these com-

parators permit the drivers to be used in pulse-skipping

operation, thereby saving power at light loads. A sepa-

rate shutdown control is also included that disables all

functions, drops quiescent current to 2µA, and sets DH

low and DL high.

The MAX8702 integrates a resistor-programmable tem-

perature sensor. An open-drain output (DRHOT) signals

to the system when the local die temperature exceeds

the set temperature. The MAX8702/MAX8703 are avail-

able in a thermally-enhanced 20-pin thin QFN package.

Applications

Multiphase High-Current Power Supplies

2- to 4-Cell Li+ Battery to CPU Core Supplies

Notebook and Desktop Computers

Servers and Workstations

Features

♦ Dual-Phase MOSFET Driver

♦ 0.35Ω (typ) On-Resistance and 5A (typ)

Drive Current

♦ Drives Large Synchronous-Rectifier MOSFETs

♦ Integrated Temperature Sensor (MAX8702 Only)

Resistor Programmable

Open-Drain Driver Hot Indicator (DRHOT)

♦ Adaptive Dead Time Prevents Shoot-Through

♦ Selectable Pulse-Skipping Mode

♦ 4.5V to 28V Input Voltage Range

♦ Thermally Enhanced Low-Profile Thin QFN Package

MAX8702/MAX8703

Dual-Phase MOSFET Drivers

with Temperature Sensor

________________________________________________________________ Maxim Integrated Products 1

MAX8702

+5V

TSET

AGND

OUT

4.5V TO 28V

BST1

DH1

LX1

DL1

PGND1

DRHOT

SHDN

+5V

OUT

4.5V TO 28V

+5V

BST2

DH2

LX2

DL2

PGND2

SKIP

PWM1

PWM2

Minimal Operating Circuit

Ordering Information

19-3357; Rev 0; 8/04

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

PART

TEMP RANGE

PIN-

PACKAGE

D ESC R IPT IO N

MAX8702ETP

-40°C to +100°C

20 Thi n Q FN

4m m x 4m m

Dual-Phase

Driver with

Temp. Sensor

MAX8703ETP

-40°C to +100°C

20 Thi n Q FN

4m m x 4m m

Dual-Phase

Driver without

Temp. Sensor

Pin Configuration appears at end of data sheet.

Summary of content (14 pages)

PAGE 1
9-3357; Rev 0; 8/04 Dual-Phase MOSFET Drivers with Temperature Sensor The MAX8702/MAX8703 dual-phase noninverting MOSFET drivers are designed to work with PWM controller ICs, such as the MAX8705/MAX8707, in notebook CPU core and other multiphase regulators. Applications can either step down directly from the battery voltage to create the core voltage, or step down from a low-voltage system supply.
PAGE 2
MAX8702/MAX8703 Dual-Phase MOSFET Drivers with Temperature Sensor ABSOLUTE MAXIMUM RATINGS VCC to AGND............................................................-0.3V to +6V VDD to AGND............................................................-0.3V to +6V PGND_ to AGND ...................................................-0.3V to +0.3V SKIP, SHDN, DRHOT, TSET to AGND......................-0.3V to +6V PWM_ to AGND ........................................................-0.3V to +6V DL_ to PGND_ ...........
PAGE 3
Dual-Phase MOSFET Drivers with Temperature Sensor (Circuit of Figure 2. VCC = VDD = VSHDN = VSKIP = 5V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) PARAMETER SYMBOL Thermal-Shutdown Threshold CONDITIONS MIN 10°C hysteresis TYP MAX +160 UNITS °C LOGIC CONTROL SIGNALS Logic Input High Voltage SHDN, SKIP, PWM1, PWM2 Logic Input Low Voltage SHDN, SKIP, PWM1, PWM2 Logic Input Current SHDN, SKIP, PWM1, PWM2 2.4 V -1 0.
PAGE 4
PWM_ 90% 90% DH_ 10% 10% tF_DL tPWM-DL DL_ tDL-DH tPWM-DH tR_DH tF_DH tR_DL tDH-DL 90% 90% 10% 10% Figure 1. Timing Definitions Used in the Electrical Characteristics Typical Operating Characteristics (Circuit of Figure 2. VIN = 12V, VDD = VCC = VSHDN = VSKIP = 5V, TA = +25°C unless otherwise noted.) POWER DISSIPATION vs. FREQUENCY (SINGLE PHASE, BOTH DRIVERS SWITCHING) 250 200 CDL = 3nF, CDH = 3nF 150 100 CDL = 3nF, CDH = 1.5nF 50 POWER DISSIPATION vs.
PAGE 5
Dual-Phase MOSFET Drivers with Temperature Sensor DH/DL RISE/FALL TIMES vs. TEMPERATURE PROPAGATION DELAY vs. TEMPERATURE 15 10 DL RISE 5 DL FALL 40 60 PWM FALL TO DH FALL 30 20 PWM RISE TO DL FALL CDH = CDL = 3nF CDH = CDL = 3nF 20 DL FALL TO DH RISE 40 10 0 0 0 MAX8702 toc06 DH FALL PROPAGATION DELAY (ns) RISE/FALL TIME (ns) DH RISE 50 MAX8702 toc05 20 80 100 0 120 30 60 90 120 TEMPERATURE (°C) TEMPERATURE (°C) RTSET vs.
PAGE 6
MAX8702/MAX8703 Dual-Phase MOSFET Drivers with Temperature Sensor Pin Description PIN NAME FUNCTION MAX8702 MAX8703 1 1 PWM1 Phase 1 PWM Logic Input. DH1 is high when PWM1 is high; DL1 is high when PWM1 is low. 2 2 PWM2 Phase 2 PWM Logic Input. DH2 is high when PWM2 is high; DL2 is high when PWM2 is low. 3 3 AGND Analog Ground. The AGND and PGND_ pins must be connected externally at one point close to the IC. Connect the device’s exposed backside pad to AGND.
PAGE 7
Dual-Phase MOSFET Drivers with Temperature Sensor The typical operating circuit of the MAX8702 (Figure 2) shows the power-stage and gate-driver circuitry of a dualphase CPU core supply operating at 300kHz, with each phase capable of supplying 20A of load current. Table 1 lists recommended component options, and Table 2 lists the component suppliers’ contact information.
PAGE 8
MAX8702/MAX8703 Dual-Phase MOSFET Drivers with Temperature Sensor efficiency while allowing operation with a variety of MOSFETs and PWM controllers. A UVLO circuit allows proper power-on sequencing. The PWM control inputs are both TTL and CMOS compatible. The MAX8702 integrates a resistor-programmable temperature sensor. An open-drain output (DRHOT) signals to the system when the die temperature of the driver exceeds the set temperature. See the Temperature Sensor section.
PAGE 9
Dual-Phase MOSFET Drivers with Temperature Sensor CBST = 2 x 24nC = 0.24µF 200mV Selecting the closest standard value, this example requires a 0.22µF ceramic capacitor. 5V Bias Supply (VCC and VDD) VDD provides the supply voltages for the low-side drivers (DL). The decoupling capacitor at V DD also charges the BST capacitors during the time period when DL is high. Therefore, the VDD capacitor should be large enough to minimize the ripple voltage during switching transitions.
PAGE 10
MAX8702/MAX8703 Dual-Phase MOSFET Drivers with Temperature Sensor A 10°C hysteresis keeps the output from oscillating when the temperature is close to the threshold. The thermal trip point is programmable up to +160°C through an external resistor between TSET and AGND. Use the following equation to determine the value of the resistor: RTSET = (85,210 / T) – (745,200 / T2) – 195 where RTSET is the value of the set-point resistor in kΩ and T is the trip-point temperature in Kelvin.
PAGE 11
Dual-Phase MOSFET Drivers with Temperature Sensor IC Power Dissipation and Thermal Considerations Power dissipation in the IC package comes mainly from driving the MOSFETs. Therefore, it is a function of both switching frequency and the total gate charge of the selected MOSFETs. The total power dissipation when both drivers are switching is given by: PD(IC) = IBIAS x 5V where IBIAS is the bias current of the 5V supply calculated in the 5V Bias Supply (VDD and VCC) section .
PAGE 12
Dual-Phase MOSFET Drivers with Temperature Sensor SHDN SKIP BST1 DH1 LX1 19 18 17 16 TOP VIEW 20 1 15 PGND1 PWM2 2 14 DL1 AGND 3 13 VDD TSET* 4 12 DL2 DRHOT* 5 11 PGND2 7 8 9 10 VCC DH2 LX2 I.C.* 6 MAX8702 MAX8703 Chip Information TRANSISTOR COUNT: 1100 PROCESS: BiCMOS PWM1 BST2 MAX8702/MAX8703 Pin Configuration THIN QFN (4mm x 4mm) *THESE PINS ARE N.C.
PAGE 13
Dual-Phase MOSFET Drivers with Temperature Sensor 24L QFN THIN.EPS PACKAGE OUTLINE 12, 16, 20, 24L THIN QFN, 4x4x0.8mm 21-0139 C 1 2 ______________________________________________________________________________________ 13 MAX8702/MAX8703 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.
PAGE 14
MAX8702/MAX8703 Dual-Phase MOSFET Drivers with Temperature Sensor Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) PACKAGE OUTLINE 12, 16, 20, 24L THIN QFN, 4x4x0.8mm 21-0139 C 2 2 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.