Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - power supply controllers/monitors 15 µA TQFN 32 EP (5x5)

General Description

The MAX1533/MAX1537 are dual step-down, switch-

mode power-supply (SMPS) controllers with synchro-

nous rectification, intended for main 5V/3.3V power

generation in battery-powered systems. Fixed-frequen-

cy 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 regula-

tors where the duty-cycle overlap occurs when the

input drops below 10V. Output current sensing pro-

vides accurate current limit using a sense resistor.

Alternatively, power dissipation can be reduced using

lossless inductor current sensing.

Internal 5V and 3.3V linear regulators power the

MAX1533/MAX1537 and their gate drivers, as well as

external keep-alive loads, up to a total of 100mA. When

the main PWM regulators are in regulation, automatic

bootstrap switches bypass the internal linear regulators,

providing currents up to 200mA from each linear output.

An additional 5V to 23V adjustable internal 150mA linear

regulator is typically used with a secondary winding to

provide a 12V supply.

The MAX1533/MAX1537 include on-board power-up

sequencing, a power-good (PGOOD) output, digital

soft-start, and internal soft-shutdown output discharge

that prevents negative voltages on shutdown. The

MAX1533 is available in a 32-pin 5mm x 5mm thin QFN

package, and the MAX1537 is available in a 36-pin

6mm x 6mm thin QFN package. The exposed backside

pad improves thermal characteristics for demanding

linear keep-alive applications.

Applications

2 to 4 Li+ Cells Battery-Powered Devices

Notebook and Subnotebook Computers

PDAs and Mobile Communicators

Features

♦ Fixed-Frequency, Current-Mode Control

♦ 40/60 Optimal Interleaving

♦ Accurate Differential Current-Sense Inputs

♦ Internal 5V and 3.3V Linear Regulators with

100mA Load Capability

♦ Auxiliary 12V or Adjustable 150mA Linear

Regulator (MAX1537 Only)

♦ Dual-Mode™ Feedback—3.3V/5V Fixed or

Adjustable Output (Dual Mode) Voltages

♦ 200kHz/300kHz/500kHz Switching Frequency

♦ Versatile Power-Up Sequencing

♦ Adjustable Overvoltage and Undervoltage

Protection

♦ 6V to 26V Input Range

♦ 2V ±0.75% Reference Output

♦ Power-Good Output

♦ Soft-Shutdown

♦ 5µA (typ) Shutdown Current

MAX1533/MAX1537

High-Efficiency, 5x Output, Main Power-Supply

Controllers for Notebook Computers

________________________________________________________________ Maxim Integrated Products 1

32 31 30 29 28 27 26

9 101112131415

MAX1533

THIN QFN

5mm x 5mm

TOP VIEW

ON3

ON5

FSEL

ILIM3

ILIM5

REF

GND

SHDN

DH5

BST5

LX5

CSH5

CSL5

FB5

LDO5

DL5

PGND

DL3

LDO3

FB3

CSL3

OVP

LX3

CSH3

BST3

DH3

UVP

PGOOD

PGDLY

SKIP

Pin Configurations

Ordering Information

PART

TEMP RANGE

PIN-PACKAGE

MAX1533ETJ

-40°C to +85°C

32 Thin QFN 5mm x 5mm

MAX1533ETJ+

-40°C to +85°C

32 Thin QFN 5mm x 5mm

MAX1537ETX

-40°C to +85°C

36 Thin QFN 6mm x 6mm

MAX1537ETX+

-40°C to +85°C

36 Thin QFN 6mm x 6mm

19-3501; Rev 0; 11/04

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.

EVALUATION KIT

AVAILABLE

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

Pin Configurations continued at end of data sheet.

+Denotes lead-free package.

Summary of content (38 pages)

PAGE 1
KIT ATION EVALU E L B A IL AVA 19-3501; Rev 0; 11/04 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers Features The MAX1533/MAX1537 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.
PAGE 2
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers ABSOLUTE MAXIMUM RATINGS IN, SHDN, INA, LDOA to GND ...............................-0.3V to +30V GND to PGND .......................................................-0.3V to +0.3V LDO5, LDO3, VCC to GND .......................................-0.3V to +6V ILIM3, ILIM5, PGDLY to GND...................................-0.3V to +6V CSL3, CSH3, CSL5, CSH5 to GND ..........................-0.
PAGE 3
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers (Circuit of Figure 1, VIN = 12V, both SMPS enabled, VCC = 5V, FSEL = REF, SKIP = GND, VILIM_ = VLDO5, VINA = 15V, VLDOA = 12V, ILDO5 = ILDO3 = ILDOA = no load, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.
PAGE 4
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 1, VIN = 12V, both SMPS enabled, VCC = 5V, FSEL = REF, SKIP = GND, VILIM_ = VLDO5, VINA = 15V, VLDOA = 12V, ILDO5 = ILDO3 = ILDOA = no load, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER MIN TYP MAX UNITS Standby mode, 6V < VIN < 26V, 0 < ILOAD < 100mA 3.20 3.35 3.
PAGE 5
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers (Circuit of Figure 1, VIN = 12V, both SMPS enabled, VCC = 5V, FSEL = REF, SKIP = GND, VILIM_ = VLDO5, VINA = 15V, VLDOA = 12V, ILDO5 = ILDO3 = ILDOA = no load, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.
PAGE 6
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 1, VIN = 12V, both SMPS enabled, VCC = 5V, FSEL = REF, SKIP = GND, VILIM_ = VLDO5, VINA = 15V, VLDOA = 12V, ILDO5 = ILDO3 = ILDOA = no load, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS High FSEL Three-Level Input Logic MIN TYP REF 1.
PAGE 7
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers (Circuit of Figure 1, VIN = 12V, both SMPS enabled, VCC = 5V, FSEL = REF, SKIP = GND, VILIM_ = VLDO5, VINA = 15V, VLDOA = 12V, ILDO5 = ILDO3 = ILDOA = no load, TA = -40°C to +85°C, unless otherwise noted.
PAGE 8
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 1, VIN = 12V, both SMPS enabled, VCC = 5V, FSEL = REF, SKIP = GND, VILIM_ = VLDO5, VINA = 15V, VLDOA = 12V, ILDO5 = ILDO3 = ILDOA = no load, TA = -40°C to +85°C, unless otherwise noted.
PAGE 9
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers (MAX1537 circuit of Figure 1, VIN = 12V, LDO5 = VCC = 5V, SKIP = GND, FSEL = REF, TA = +25°C, unless otherwise noted.) VIN = 7V 70 VIN = 12V VIN = 20V 60 0.01 0.1 MAX1533/37 toc02 4.96 10 5.04 5.00 4.96 4.92 SKIP = GND SKIP = VCC 4.88 0 1 2 3 4 5 6 5 10 15 20 25 LOAD CURRENT (A) INPUT VOLTAGE (V) PWM3 EFFICIENCY vs. LOAD CURRENT (VOUT3 = 3.3V) 3.3V OUTPUT VOLTAGE (OUT3) vs. LOAD CURRENT 3.
PAGE 10
Typical Operating Characteristics (continued) (MAX1537 circuit of Figure 1, VIN = 12V, LDO5 = VCC = 5V, SKIP = GND, FSEL = REF, TA = +25°C, unless otherwise noted.) 2.0 1.5 1.0 LDO DEVIATION VOLTAGE (mV) 2.5 50 MAX1533 toc11 DUTY CYCLE LIMITED 2.01 REF VOLTAGE (V) PEAK CURRENT (A) 2.02 MAX1533/37 toc10 3.5 3.0 LINEAR-REGULATOR LOAD REGULATION 2.0V REFERENCE LOAD REGULATION 2.00 1.99 0.5 MAX1533/37 toc12 IDLE-MODE CURRENT vs.
PAGE 11
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers (MAX1537 circuit of Figure 1, VIN = 12V, LDO5 = VCC = 5V, SKIP = GND, FSEL = REF, TA = +25°C, unless otherwise noted.) DELAYED STARTUP WAVEFORM (LIGHT LOAD) STARTUP WAVEFORM (HEAVY LOAD) 3.3V A 0 5V SHUTDOWN WAVEFORM (NO LOAD) MAX1533/37 toc17 MAX1533/37 toc16 3.3V 0 MAX1533/37 toc18 A 4V B 0 5V 0 2.5A 0 C 0 3.3V 0 5V D B 2V 0 3.3V C 0 E 0 E F 0 2ms/div A. SHDN, 5V/div D. 3.3V OUTPUT, 5V/div B.
PAGE 12
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers Typical Operating Characteristics (continued) (MAX1537 circuit of Figure 1, VIN = 12V, LDO5 = VCC = 5V, SKIP = GND, FSEL = REF, TA = +25°C, unless otherwise noted.) OUTPUT OVERLOAD (UVP ENABLED) 3.3V OUTPUT LOAD TRANSIENT (PULSE SKIPPING) 4A 5V A 0 MAX1533/37 toc24 A 0 3.3V 3.
PAGE 13
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers PIN MAX1533 MAX1537 — 1 1 2 NAME FUNCTION ADJA Auxiliary Feedback Input. Connect a resistive voltage-divider from LDOA to analog ground to adjust the auxiliary linear-regulator output voltage. ADJA regulates at 2V. Connect ADJA to GND for nominal 12V output using internal feedback. ON5 5V SMPS Enable Input.
PAGE 14
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers Pin Description (continued) PIN MAX1533 14 MAX1537 NAME FUNCTION Open-Drain Power-Good Output. PGOOD is low if either output is more than 10% (typ) below the normal regulation point, during soft-start, and in shutdown. PGOOD is delayed on the rising edge by the PGDLY one-shot timer. PGOOD becomes high impedance when both SMPS outputs are in regulation.
PAGE 15
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers PIN NAME FUNCTION MAX1533 MAX1537 25 27 CSL5 Negative Current-Sense Input for 5V SMPS. Connect to the negative terminal of the current-sense element. Figure 9 describes two different current-sensing options. CSL5 also serves as the bootstrap input for LDO5. 26 28 CSH5 Positive Current-Sense Input for 5V SMPS. Connect to the positive terminal of the current-sense element.
PAGE 16
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers Table 1. Component Selection for Standard Applications COMPONENT 5A/300kHz 5A/500kHz Input Voltage VIN = 7V to 24V VIN = 7V to 24V (2) 10µF, 25V Taiyo Yuden TMK432BJ106KM (2) 10µF, 25V Taiyo Yuden TMK432BJ106KM COUT5, Output Capacitor 150µF, 6.3V, 40mΩ, low-ESR capacitor Sanyo 6TPB150ML 150µF, 6.
PAGE 17
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers MAX1533/MAX1537 INPUT (VIN) 5V LDO OUTPUT C1 10µF IN LDO5 DBST NH1 DL1 L1 5.8µH DBST DH3 CBST 0.1µF CIN (2) 10µF BST3 MAX1533 MAX1537 C5 22µF NH2 DH5 BST5 SECONDARY OUTPUT CBST 0.1µF LX3 LX5 DL3 DL5 NL1 D1 DL2 T1 1:2 TURNS LP = 6.8µH NL2 PGND GND RCS1 10mΩ 3.3V PWM OUTPUT COUT1 220µF 40mΩ CREF 0.22µF R3 60.
PAGE 18
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers SMPS to LDO Bootstrap Switchover When the 5V main output voltage is above the LDO5 bootstrap-switchover threshold, an internal 0.75Ω (typ) p-channel MOSFET shorts CSL5 to LDO5 while simultaneously shutting down the LDO5 linear regulator. Similarly, when the 3.
PAGE 19
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers MAX1533/MAX1537 LDO3 IN 5V LINEAR REGULATOR 3.
PAGE 20
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers Table 3. Operating Modes MODE INPUTS* SHDN ON5 OUTPUTS ON3 LDO5 LDO3 5V SMPS 3V SMPS Shutdown Mode LOW X X OFF OFF OFF OFF Standby Mode HIGH LOW LOW ON ON OFF OFF Normal Operation HIGH HIGH HIGH ON ON ON ON 3.3V SMPS Active HIGH LOW HIGH ON ON OFF ON 5V SMPS Active HIGH HIGH LOW ON ON ON OFF ON ON Power-up after 3.
PAGE 21
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers (SEE FIGURE 5) CSL REF / 2 SLOPE COMP AGND 0.2 x VLIMIT R Q IDLEMODE CURRENT S DH DRIVER SKIP SOFT-START COUNTER ON DAC CURRENT LIMIT OSC -1.2 x VLIMIT S R Q DL DRIVER LX PGND MAX1537 ONLY 0.
PAGE 22
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers Frequency Selection (FSEL) The FSEL input selects the PWM-mode switching frequency. Table 4 shows the switching frequency based on FSEL connection. High-frequency (500kHz) operation optimizes the application for the smallest component size, trading off efficiency due to higher switching losses. This may be acceptable in ultra-portable devices where the load currents are lower.
PAGE 23
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers MAX1533/MAX1537 TO ERROR AMPLIFIER ADJUSTABLE OUTPUT FB INDUCTOR CURRENT tON(SKIP) ≥ REF (2.0V) IIDLEL VIN - VOUT 12R R ILOAD(SKIP) FIXED OUTPUT FB = GND CSL 0 ON-TIME TIME Figure 4. Pulse-Skipping/Discontinuous Crossover Point Figure 5. Dual-Mode Feedback Decoder Output Voltage DC output accuracy specifications in the Electrical Characteristics table refer to the error-comparator’s threshold.
PAGE 24
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers When adjusting both output voltages, set the 3.3V SMPS lower than the 5V SMPS. LDO5 connects to the 5V output (CSL5) through an internal switch only when CSL5 is above the LDO5 bootstrap threshold (4.56V). Similarly, LDO3 connects to the 3.3V output (CSL3) through an internal switch only when CSL3 is above the LDO3 bootstrap threshold (2.91V).
PAGE 25
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers CBYP MAX1533 MAX1537 LDO5 BST (RBST)* DBST INPUT (VIN) CBST DH NH L LX LDO5 DL NL (CNL)* GND Fault Protection Output Overvoltage Protection (OVP) If the output voltage of either SMPS rises above 111% of its nominal regulation voltage and the OVP protection is enabled (OVP = GND), the controller sets the fault latch, pulls PGOOD low, shuts down both SMPS controllers, and immediately pulls DH_ low and forces DL_ (RBS
PAGE 26
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers high. This turns on the synchronous-rectifier MOSFETs with 100% duty, rapidly discharging the output capacitors and clamping both outputs to ground. However, immediately latching DL_ high typically causes slightly negative output voltages due to the energy stored in the output LC at the instant the OVP occurs.
PAGE 27
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers Auxiliary LDO Detailed Description (MAX1537 Only) The MAX1537 includes an auxiliary linear regulator that delivers up to 150mA of load current. The output (LDOA) can be preset to 12V, ideal for PCMCIA power requirements, and for biasing the gates of load switches in a portable device. In adjustable mode, LDOA can be set to anywhere from 5V to 23V.
PAGE 28
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers • Maximum Load Current. There are two values to consider. The peak load current (ILOAD(MAX)) determines the instantaneous component stresses and filtering requirements and thus drives output-capacitor selection, inductor saturation rating, and the design of the current-limit circuit.
PAGE 29
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers VSEC + VFWD VOUT5 + VRECT + VSENSE where LPRIMARY is the primary inductance, N is the transformer turns ratio, VSEC is the minimum required rectified secondary voltage, VFWD is the forward drop across the secondary rectifier, VOUT5(MIN) is the minimum value of the main output voltage, and VRECT is the on-state voltage drop across the synchronous-rectifier MOSFET.
PAGE 30
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers Alternatively, high-power applications that do not require highly accurate current-limit protection may reduce the overall power dissipation by connecting a series RC circuit across the inductor (Figure 9b) with an equivalent time constant: L = CEQ × REQ RL where RL is the inductor’s series DC resistance. In this configuration, the current-sense resistance equals the inductor’s DC resistance (RSENSE = RL).
PAGE 31
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers VRIPPLE(P − P) = RESR ILOAD(MAX) LIR In idle mode, the inductor current becomes discontinuous, with peak currents set by the idle-mode currentsense threshold (VIDLE = 0.2VLIMIT).
PAGE 32
This offers improved efficiency over a regular 180° outof-phase architecture where the duty cycles begin to overlap below 10V. Figure 10 shows the input-capacitor RMS current vs. input voltage for an application that requires 5V/5A and 3.3V/5A. This shows the improvement of the 40/60 optimal interleaving over 50/50 interleaving and in-phase operation.
PAGE 33
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers For the low-side MOSFET (NL), the worst-case power dissipation always occurs at maximum battery voltage: ⎡ ⎛ V ⎞⎤ 2 PD (NL Re sistive) = ⎢1 - ⎜ OUT ⎟ ⎥(ILOAD ) RDS(ON) ⎢ ⎝ VIN(MAX) ⎠ ⎥⎦ ⎣ The absolute worst case for MOSFET power dissipation occurs under heavy-overload conditions that are greater than ILOAD(MAX) but are not high enough to exceed the current limit and cause the fault latch to trip.
PAGE 34
MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers back-threshold voltage, the controller does not trigger an on-time pulse, effectively skipping a cycle. This allows the controller to maintain regulation above the maximum input voltage, but forces the controller to effectively operate with a lower switching frequency.
PAGE 35
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers MAX1533/MAX1537 CONNECT GND AND PGND TO THE CONTROLLER AT ONE POINT ONLY AS SHOWN CONNECT THE EXPOSED PAD TO ANALOG GND VIA TO POWER GROUND VIA TO REF BYPASS CAPACITOR VIA TO REF PIN VIA TO VCC BYPASS CAPACITOR MAX1533 TOP LAYER MAX1533 BOTTOM LAYER KELVIN-SENSE VIAS UNDER THE SENSE RESISTOR (SEE THE EVALUATION KIT) VIA TO VCC PIN DUAL n-CHANNEL MOSFET INDUCTOR SINGLE n-CHANNEL MOSFETS INDUCTOR DH LX DL COUT CIN
PAGE 36
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers TRANSISTOR COUNT: 6890 PROCESS: BiCMOS CSL5 FB5 ADJA ON5 1 27 2 26 ON3 ONA 3 25 4 24 FSEL ILIM3 5 ILIM5 REF GND 7 21 8 20 PGND DL3 LDO3 FB3 9 19 CSL3 23 16 17 18 OVP CSH3 15 14 11 12 10 22 VCC 13 MAX1537 6 Chip Information 28 29 30 31 SKIP DH5 BST5 LX5 IN CSH5 33 32 INA SHDN 35 34 LDOA 36 TOP VIEW PGDLY PGOOD UVP DH3 BST3 LX3 MAX1533/MAX1537 Pin Configurations (continued) LDO
PAGE 37
High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers b C L 0.10 M C A B D2/2 D/2 k 0.15 C B MARKING QFN THIN.EPS D2 0.15 C A D XXXXX E/2 E2/2 C L (NE-1) X e E E2 k L DETAIL A PIN # 1 I.D. e PIN # 1 I.D. 0.35x45∞ (ND-1) X e DETAIL B e L1 L C L C L L L e e 0.10 C A C 0.08 C A1 A3 PACKAGE OUTLINE, 16, 20, 28, 32L THIN QFN, 5x5x0.8mm 21-0140 -DRAWING NOT TO SCALE- COMMON DIMENSIONS A 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.
PAGE 38
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.) QFN THIN 6x6x0.8.EPS MAX1533/MAX1537 High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers D2 D CL D/2 b D2/2 k E/2 E2/2 (NE-1) X e E CL E2 k e L (ND-1) X e e L CL CL L1 L L e A1 A2 e A PACKAGE OUTLINE 36, 40, 48L THIN QFN, 6x6x0.