Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - power supply controllers/monitors 25 µA QSOP 28

General Description

The MAX8732A/MAX8733A/MAX8734A dual step-down,

switch-mode power-supply (SMPS) controllers generate

logic-supply voltages in battery-powered systems. The

MAX8732A/MAX8733A/MAX8734A include two pulse-

width modulation (PWM) controllers, adjustable from 2V to

5.5V or fixed at 5V and 3.3V. These devices feature two

linear regulators providing 5V and 3.3V always-on out-

puts. Each linear regulator provides up to 100mA output

current with automatic linear-regulator bootstrapping to

the main SMPS outputs. The MAX8732A/MAX8733A/

MAX8734A include on-board power-up sequencing, a

power-good (PGOOD) output, digital soft-start, and inter-

nal soft-stop output discharge that prevents negative volt-

ages on shutdown. Additionally, the outputs are high

impedance when V

falls below its UVLO set point while

the outputs are enabled.

Maxim’s proprietary Quick-PWM™ quick-response, con-

stant on-time PWM control scheme operates without

sense resistors and provides 100ns response to load tran-

sients while maintaining a relatively constant switching fre-

quency. The unique ultrasonic pulse-skipping mode

maintains the switching frequency above 25kHz, which

eliminates noise in audio applications. Other features

include pulse skipping, which maximizes efficiency in

light-load applications, and fixed-frequency PWM mode,

which reduces RF interference in sensitive applications.

The MAX8732A features a 200kHz/5V and 300kHz/3.3V

SMPS for highest efficiency, while the MAX8733A fea-

tures a 400kHz/5V and 500kHz/3.3V SMPS for “thin and

light” applications. The MAX8734A provides a pin-

selectable switching frequency, allowing either 200kHz/

300kHz or 400kHz/500kHz operation of the 5V/3.3V

SMPSs, respectively. The MAX8732A/MAX8733A/

MAX8734A are available in 28-pin QSOP packages and

operate over the extended temperature range

(-40°C to +85°C).

The MAX8732A/MAX8733A/MAX8734A are pin-for-pin

upgrades to the MAX1777/MAX1977/MAX1999.

The MAX1999 evaluation kit (EV kit) can be used to

evaluate the MAX8732A/MAX8733A/MAX8734A.

Applications

Notebook and Subnotebook Computers

PDAs and Mobile Communication Devices

3- and 4-Cell Li+ Battery-Powered Devices

Features

♦ No Current-Sense Resistor Needed (MAX8734A)

♦ Accurate Current Sense with Current-Sense

Resistor (MAX8732A/MAX8733A)

♦ 1.5% Output Voltage Accuracy

♦ 3.3V and 5V 100mA Bootstrapped Linear

Regulators

♦ Internal Soft-Start and Soft-Stop Output

Discharge

♦ Quick-PWM with 100ns Load Step Response

♦ 3.3V and 5V Fixed or Adjustable Outputs

(Dual Mode™)

♦ 4.5V to 24V Input Voltage Range

♦ Enhanced Ultrasonic Pulse-Skipping Mode

(25kHz min)

♦ Power-Good (PGOOD) Signal

♦ Overvoltage Protection Enable/Disable

MAX8732A/MAX8733A/MAX8734A

High-Efficiency, Quad-Output, Main Power-

Supply Controllers for Notebook Computers

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-3711; Rev 0; 5/05

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-

PA CKA GE

5V/3.3V

SWITCHING

FREQUENCY

(kHz)

MAX8732AEEI+ -40°C to +85°C 28 QSOP

200/300

MAX8732AEEI -40°C to +85°C 28 QSOP

200/300

MAX8733AEEI+ -40°C to +85°C 28 QSOP

400/500

MAX8733AEEI -40°C to +85°C 28 QSOP

400/500

Quick-PWM and Dual Mode are trademarks of Maxim

Integrated Products, Inc.

Ordering Information continued at end of data sheet.

+Denotes lead-free package.

BST3

LX3

DH3

LDO3

DL3

GND

LX5

OUT3

OUT5

V+

DL5

LDO5

DH5

BST5

TON

ILIM5

FB5

REF

FB3

ILIM3

ON5

ON3

PGOOD

N.C.

QSOP

TOP VIEW

MAX8734A

SHDN

PRO

SKIP

Pin Configurations

Pin Configurations continued at end of data sheet.

Summary of content (33 pages)

PAGE 1
9-3711; Rev 0; 5/05 High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers The MAX8732A/MAX8733A/MAX8734A dual step-down, switch-mode power-supply (SMPS) controllers generate logic-supply voltages in battery-powered systems. The MAX8732A/MAX8733A/MAX8734A include two pulsewidth modulation (PWM) controllers, adjustable from 2V to 5.5V or fixed at 5V and 3.3V. These devices feature two linear regulators providing 5V and 3.3V always-on outputs.
PAGE 2
MAX8732A/MAX8733A/MAX8734A High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers ABSOLUTE MAXIMUM RATINGS V+, SHDN to GND ..................................................-0.3V to +25V BST_ to GND ..........................................................-0.3V to +30V LX_ to BST_ ..............................................................-6V to +0.3V CS_ to GND (MAX8732A/MAX8733A only) .................
PAGE 3
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers (Circuit of Figure 1 and Figure 2, no load on LDO5, LDO3, OUT3, OUT5, and REF, V+ = 12V, ON3 = ON5 = VCC, V SHDN = 5V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Operating Frequency CONDITIONS MAX8732A or MAX8734A (VTON = 5V), SKIP = VCC 3.3V SMPS 300 MAX8733A or MAX8734A (VTON = 0), SKIP = VCC 5V SMPS 400 3.3V SMPS 500 MAX 25 36 VOUT5 = 5.05V 1.895 2.105 2.
PAGE 4
MAX8732A/MAX8733A/MAX8734A High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 1 and Figure 2, no load on LDO5, LDO3, OUT3, OUT5, and REF, V+ = 12V, ON3 = ON5 = VCC, V SHDN = 5V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.
PAGE 5
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers (Circuit of Figure 1 and Figure 2, no load on LDO5, LDO3, OUT3, OUT5, and REF, V+ = 12V, ON3 = ON5 = VCC, V SHDN = 5V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS MIN OUT3, OUT5 Discharge-Mode On-Resistance OUT3, OUT5 Discharge-Mode Synchronous Rectifier Turn-On Level 0.2 TYP MAX UNITS 12 40 Ω 0.3 0.
PAGE 6
MAX8732A/MAX8733A/MAX8734A High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 1 and Figure 2, no load on LDO5, LDO3, OUT3, OUT5, and REF, V+ = 12.0.V, ON3 = ON5 = VCC, V SHDN = 5V, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER CONDITIONS MIN TYP MAX UNITS 4.69 V 3.
PAGE 7
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers (Circuit of Figure 1 and Figure 2, no load on LDO5, LDO3, OUT3, OUT5, and REF, V+ = 12.0.V, ON3 = ON5 = VCC, V SHDN = 5V, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER CONDITIONS MIN Clear fault level/SMPS off level ON3, ON5 Input Voltage Input Leakage Current DH_ Gate-Driver On-Resistance DL_ Gate-Driver On-Resistance MAX 1.7 SMPS on level 2.4 V PRO or VTON = 0 or 5V -1 2.
PAGE 8
Typical Operating Characteristics (Circuit of Figure 1 and Figure 2, no load on LDO5, LDO3, OUT3, OUT5, and REF, V+ = 12V, ON3 = ON5 = VCC, SHDN = V+, RCS = 7mΩ, VILIM_ = 0.5V, TA = +25°C, unless otherwise noted.) MAX8732A MAX8732A MAX8732A 5V OUTPUT EFFICIENCY 5V OUTPUT EFFICIENCY 5V OUTPUT EFFICIENCY vs. LOAD CURRENT vs. LOAD CURRENT vs. LOAD CURRENT 40 30 PWM MODE 60 50 ULTRASONIC MODE 40 20 VIN = 7V ON5 = VCC ON3 = GND 10 1 10 0.01 LOAD CURRENT (A) MAX8733A 3.3V OUTPUT EFFICIENCY vs.
PAGE 9
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers 160 120 ULTRASONIC MODE 40 0.01 0.1 1 500 0.01 0.1 1 0 0.1 PWM MODE 450 10 350 300 250 200 150 0.001 0.01 0.1 1 1 0 0.001 10 450 10 350 PWM MODE 300 250 200 150 100 ULTRASONIC MODE 50 PFM MODE 0.01 VIN = 24V 400 ULTRASONIC MODE 50 PFM MODE 0.01 VIN = 7V 400 100 ULTRASONIC MODE 50 0.1 PFM MODE 0 1 0.001 10 0.01 0.1 1 LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A) MAX8733A 3.
PAGE 10
Typical Operating Characteristics (continued) (Circuit of Figure 1 and Figure 2, no load on LDO5, LDO3, OUT3, OUT5, and REF, V+ = 12V, ON3 = ON5 = VCC, SHDN = V+, RCS = 7mΩ, VILIM_ = 0.5V, TA = +25°C, unless otherwise noted.) LDO5 REGULATOR OUTPUT VOLTAGE vs. OUTPUT CURRENT LDO3 REGULATOR OUTPUT VOLTAGE vs. OUTPUT CURRENT 4.97 4.96 4.95 2.005 3.346 3.344 3.342 3.340 2.004 2.003 2.002 2.001 2.000 3.338 1.999 3.336 1.998 3.334 1.997 3.332 1.996 3.
PAGE 11
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers (Circuit of Figure 1 and Figure 2, no load on LDO5, LDO3, OUT3, OUT5, and REF, V+ = 12V, ON3 = ON5 = VCC, SHDN = V+, RCS = 7mΩ, VILIM_ = 0.5V, TA = +25°C, unless otherwise noted.) VOUT, ACCOUPLED 100mV/div 4A VOUT, ACCOUPLED 100mV/div 3.3V 4A INDUCTOR CURRENT 2A/div 1A MAX8732A/3A/4A toc30 MAX8732A/3A/4A toc29 MAX8732A/3A/4A toc28 5V MAX8733A/MAX8734A (TON = GND) 3.
PAGE 12
MAX8732A/MAX8733A/MAX8734A High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers Pin Description PIN MAX8732A MAX8734A MAX8733A 12 1 — — 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 NAME FUNCTION 3.3V SMPS Current-Sense Input. Connect CS3 to a current-sensing resistor from the source of the synchronous rectifier to GND. The voltage at ILIM3 determines the current-limit threshold (see the Current-Limit Circuit (ILIM_) section). N.C.
PAGE 13
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers PIN MAX8732A MAX8734A MAX8733A NAME 13 — CS5 — 13 TON 14 14 BST5 15 15 LX5 16 16 DH5 17 17 VCC 18 18 LDO5 19 19 DL5 20 20 V+ 21 21 OUT5 22 22 OUT3 23 24 23 24 GND DL3 25 25 LDO3 26 26 DH3 27 27 LX3 28 28 BST3 FUNCTION 5V SMPS Current-Sense Input. Connect CS5 to a current-sensing resistor from the source of the synchronous rectifier to GND.
PAGE 14
MAX8732A/MAX8733A/MAX8734A High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers Typical Application Circuits Table 1. Component Suppliers The typical application circuits (Figures 1 and 2) generate the 5V/5A and 3.3V/5A main supplies in a notebook computer. The input supply range is 7V to 24V. Table 1 lists component suppliers.
PAGE 15
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers MAX8732A/MAX8733A/MAX8734A VIN 7V TO 24V 5V ALWAYS ON 1µF 50Ω 4.7µF VCC LDO5 ILIM3 1µF VCC 1/2 D1 ILIM5 V+ 0.1µF 10µF BST5 BST3 DH5 DH3 10Ω MAX8734A N3 FDS6612A 0.1µF 0.1µF L5 LX5 L3 LX3 470pF* C5 10µF 10Ω N1 FDS6612A 5V 10µF CMPSH-3A 1/2 D1 TON D3 EP10QY03 N2 IRF7811AV DL5 DL3 OUT5 OUT3 FB5 470pF* SEE TABLE N4 IRF7811AV 3.
PAGE 16
MAX8732A/MAX8733A/MAX8734A High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers MAX8733A is optimized for “thin and light” applications with a 5V/400kHz SMPS and a 3.3V/500kHz SMPS. The MAX8734A provides a pin-selectable switching frequency, allowing either 200kHz/300kHz or 400kHz/500kHz operation of the 5V/3.3V SMPSs, respectively.
PAGE 17
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers block controls the power-up timing of the main PWMs and monitors the outputs for undervoltage faults. The MAX8732A/MAX8733A/MAX8734A include 5V and 3.3V linear regulators. Bias generator blocks include the 5V (LDO5) linear regulator, 2V precision reference, and automatic bootstrap switchover circuit.
PAGE 18
MAX8732A/MAX8733A/MAX8734A High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers These internal blocks are not powered directly from the battery. Instead, the 5V (LDO5) linear regulator steps down the battery voltage to supply both internal circuitry and the gate drivers. The synchronous-switch gate drivers are directly powered from LDO5, while the highside switch gate drivers are indirectly powered from LDO5 through an external diode-capacitor boost circuit.
PAGE 19
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers ILOAD(SKIP) = K × VOUT _  V + − VOUT _    2×L V+   where K is the on-time scale factor (see the On-Time One-Shot (tON) section). The load-current level at which PFM/PWM crossover occurs, ILOAD(SKIP), is equal to 1/2 the peak-to-peak ripple current, which is a function of the inductor value (Figure 5). For example, in the MAX8732A Typical Application Circuit with VOUT2 = 5V, V+ = 12V, L = 7.
PAGE 20
Reference and Linear Regulators (REF, LDO5, and LDO3) The 2V reference (REF) is accurate to ±1% over temperature, making REF useful as a precision system reference. Bypass REF to GND with a 0.22µF (min) capacitor. REF can supply up to 100µA for external loads. However, if extremely accurate specifications for both the main output voltages and REF are essential, avoid loading REF. Loading REF reduces the LDO5, LDO3, OUT5, and OUT3 output voltages slightly because of the reference load-regulation error.
PAGE 21
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers A negative current limit prevents excessive reverse inductor currents when VOUT sinks current. The negative current-limit threshold is set to approximately 120% of the positive current limit and therefore tracks the positive current limit when ILIM_ is adjusted. The current-limit threshold is adjusted with an external voltage-divider at ILIM_. The current-limit threshold adjustment range is from 50mV to 300mV.
PAGE 22
MAX8732A/MAX8733A/MAX8734A High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers high-side MOSFETs at the expense of efficiency, without degrading the turn-off time (Figure 10). Adaptive dead-time circuits monitor the DL_ and DH_ drivers and prevent either FET from turning on until the other is fully off. This algorithm allows operation without shoot-through with a wide range of MOSFETs, minimizing delays and maintaining efficiency.
PAGE 23
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers MODE CONDITION COMMENT LDO5 < UVLO threshold Transitions to discharge mode after a V+ POR and after REF becomes valid. LDO5, LDO3, and REF remain active. DL_ is active if PRO is low. SHDN = high, ON3 or ON5 enabled Normal operation. Overvoltage Protection Either output > 111% of nominal level, PRO = low DL_ is forced high. LDO3, LDO5 active. Exited by a V+ POR or by toggling SHDN, ON3, or ON5.
PAGE 24
MAX8732A/MAX8733A/MAX8734A High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers Power-Up Sequencing and On/Off Controls (ON3, ON5) ON3 and ON5 control SMPS power-up sequencing. ON3 or ON5 rising above 2.4V enables the respective outputs. ON3 or ON5 falling below 1.6V disables the respective outputs. Connecting ON3 or ON5 to REF forces the respective outputs off while the other output is below regulation and starts after that output regulates.
PAGE 25
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers The MAX8732A/MAX8733A/MAX8734As’ pulse-skipping algorithm (SKIP = GND) initiates skip mode at the critical conduction point, so the inductor’s operating point also determines the load current at which PWM/PFM switchover occurs. The optimum point is usually found between 20% and 50% ripple current.
PAGE 26
MAX8732A/MAX8733A/MAX8734A High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers RESR ≤ VP−P LIR × ILOAD(MAX) where VP-P is the peak-to-peak output voltage ripple. The actual capacitance value required relates to the physical size needed to achieve low ESR, as well as to the chemistry of the capacitor technology.
PAGE 27
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers (   VOUT _ V + − VOUT _ IRMS ≈ ILOAD  V+   )     When V+ = 2 x VOUT_(D = 50%), IRMS has a maximum current of ILOAD / 2. The ESR of the input capacitor is important for determining capacitor power dissipation. All the power (IRMS2 x ESR) heats up the capacitor and reduces efficiency. Nontantalum chemistries (ceramic or OS-CON) are preferred due to their low ESR and resilience to power-up surge currents.
PAGE 28
MAX8732A/MAX8733A/MAX8734A High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers Rectifier Selection Current circulates from ground to the junction of both MOSFETs and the inductor when the high-side switch is off. As a consequence, the polarity of the switching node is negative with respect to ground. This voltage is approximately -0.7V (a diode drop) at both transition edges while both switches are off (dead time). The drop is IL x RDS(ON) when the low-side switch conducts.
PAGE 29
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers V + (MIN) = (5V + 0.1V) LPRIMARY =  0.35µs × 1.5  1−   2.25µs   + 0.1V − 0.1V = 6.65V Calculating with h = 1 yields: V + (MIN) = (5V + 0.1V)  0.35µs × 1 1−    2.25µs  + 0.1V − 0.1V = 6.04 V Therefore, V+ must be greater than 6.65V. A practical input voltage with reasonable output capacitance would be 7.5V.
PAGE 30
USE PGND PLANE TO: USE AGND PLANE TO: - BYPASS LDO_ - BYPASS VCC AND REF - TERMINATE EXTERNAL FB - CONNECT PGND TO THE TOPSIDE STAR GROUND DIVIDER (IF USED) OUT5 VIA BETWEEN POWER - TERMINATE RILIM AND ANALOG GROUND (IF USED) AGND VIA TO OUT5 - PIN-STRAP CONTROL INPUTS PGND L1 C3 C4 VIA TO OUT3 C1 N4 C2 N3 VIAS TO GROUND VIA TO LX5 OUT3 N2 D2 ANALOG GROUND PLANE ON INNER LAYER VIA TO PGND GROUND D1 MAX8732A/MAX8733A/MAX8734A High-Efficiency, Quad-Output, Main PowerSupply Controllers for Not
PAGE 31
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers very close to the device. Connect the AGND and PGND planes together at the GND pin of the device. Layout Procedure 5) On the board’s top side (power planes), make a star ground to minimize crosstalk between the two sides. The top-side star ground is a star connection of the input capacitors and synchronous rectifiers.
PAGE 32
MAX8732A/MAX8733A/MAX8734A High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers Ordering Information (continued) PART PINTEMP RANGE PACKAGE MAX8734AEEI+ -40°C to +85°C 28 QSOP MAX8734AEEI -40°C to +85°C 28 QSOP +Denotes lead free package.
PAGE 33
High-Efficiency, Quad-Output, Main PowerSupply Controllers for Notebook Computers QSOP.EPS PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH 21-0055 E 1 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.