Datasheet

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General Description

The MAX1584/MAX1585 provide a complete power-

supply solution for slim digital cameras. They improve

performance, component count, and size compared to

conventional multichannel controllers in 2-cell AA, 1-cell

Li+, and dual-battery designs. On-chip MOSFETs pro-

vide up to 95% efficiency for critical power supplies,

while additional channels operate with external FETs for

optimum design flexibility. This optimizes overall effi-

ciency and cost, while also reducing board space.

The MAX1584/MAX1585 include 5 high-efficiency DC-

DC conversion channels:

• Step-up DC-DC converter with on-chip FETs

• Step-down DC-DC converter with on-chip FETs

• Three PWM DC-DC controllers for CCD, LCD, LED,

or other functions

The step-down DC-DC converter can operate directly

from the battery or from the step-up output, providing

boost-buck capability with a compound efficiency of up

to 90%. Both devices include three PWM DC-DC con-

trollers: the MAX1584 includes two step-up controllers

and one step-down controller, while the MAX1585

includes one step-up controller, one inverting controller,

and one step-down controller. All DC-DC channels

operate at one fixed frequency—settable from 100kHz

to 1MHz—to optimize size, cost, and efficiency. Other

features include soft-start, power-OK outputs, and over-

load protection. The MAX1584/MAX1585 are available

in space-saving, 32-pin thin QFN packages. An evalua-

tion kit is available to expedite designs.

Applications

Digital Cameras

PDAs

Features

♦ Step-Up DC-DC Converter, 95% Efficient

♦ Step-Down DC-DC Converter

Operate from Battery for 95% Efficient

Step-Down

90% Efficient Boost-Buck with Step-Up

♦ Three Auxiliary PWM DC-DC Controllers

♦ No Transformers (MAX1585)

♦ Up to 1MHz Operating Frequency

♦ 1mA Shutdown Mode

♦ Internal Soft-Start Control

♦ Overload Protection

♦ Compact 32-Pin Thin QFN Package (5mm x 5mm)

MAX1584/MAX1585

5-Channel Slim DSC Power Supplies

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

MAX1585

INPUT

0.7V TO 5.5V

ONSU

ONSD

ON1

ON2

ON3

STEP-UP SYSTEM +5V

STEP-DOWN CORE +1.8V

AUX1 LCD, CCD, LED +15V

AUX2 CCD -7.5V

AUX3 LOGIC +3.3V

Typical Operating Circuit

19-2883; Rev 0; 7/03

PART

TEMP RANGE

PIN-

PACKAGE

AUX

FUNCTIONS

MAX1584ETJ

-40°C to +85°C

32 Thin QFN

5mm x 5mm

2 step-up

1 step-down

MAX1585ETJ

-40°C to +85°C

32 Thin QFN

5mm x 5mm

1 step-up

1 step-down

1 inverting

1CC1

FB1

PGSD

LXSD

PVSD

ONSD

CCSD

FBSD

ON1

ON2

ON3

ONSU

REF

FBSU

CCSU

AUX1OK

FB3

CC3

GND

DL1

DL3

DL2

INDL2

24 CC2

FB2

PVSU

LXSU

PGSU

OSC

SCF

SDOK

MAX1584

MAX1585

THIN QFN

5mm x 5mm

Pin Configuration

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.

Summary of content (29 pages)

PAGE 1
9-2883; Rev 0; 7/03 5-Channel Slim DSC Power Supplies The MAX1584/MAX1585 provide a complete powersupply solution for slim digital cameras. They improve performance, component count, and size compared to conventional multichannel controllers in 2-cell AA, 1-cell Li+, and dual-battery designs. On-chip MOSFETs provide up to 95% efficiency for critical power supplies, while additional channels operate with external FETs for optimum design flexibility.
PAGE 2
MAX1584/MAX1585 5-Channel Slim DSC Power Supplies ABSOLUTE MAXIMUM RATINGS PV, PVSU, PVSD, SDOK, AUX1OK, SCF, ON_, FB_ to GND..........................................................................-0.3V to +6V PGND to GND....................................................…-0.3V to +0.3V INDL2, DL1, DL3 to GND.........................-0.3V to (PVSU + 0.3V) DL2 to GND ............................................-0.3V to (INDL2 + 0.3V) PV to PVSU ...........................................................
PAGE 3
5-Channel Slim DSC Power Supplies (VPVSU = VPV = VPVSD = VINDL2 = 3.6V, TA = 0°C to +85°C, unless otherwise noted.) PARAMETER CONDITIONS Step-Up Voltage Adjust Range MIN TYP 3.0 Start Delay of ONSD, ON1, ON2, ON3 after SU in Regulation MAX UNITS 5.5 V OSC cycles 1024 FBSU Regulation Voltage 1.231 1.25 1.269 V FBSU to CCSU Transconductance FBSU = CCSU 80 135 185 µS FBSU Input Leakage Current FBSU = 1.
PAGE 4
MAX1584/MAX1585 5-Channel Slim DSC Power Supplies ELECTRICAL CHARACTERISTICS (continued) (VPVSU = VPV = VPVSD = VINDL2 = 3.6V, TA = 0°C to +85°C, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS 80 85 90 % AUX1, 2, 3 DC-DC CONTROLLERS Maximum Duty Cycle FB_ = 1V FB1 and FB3 Regulation Voltage FB_ = CC_ 1.231 1.25 1.269 V FB2 (MAX1584) Regulation Voltage FB_ = CC_ 1.231 1.25 1.269 V FB2 (MAX1585) (Inverter) Regulation Voltage FB_ = CC_ -0.01 0 +0.
PAGE 5
-Channel Slim DSC Power Supplies (VPVSU = VPV = VPVSD = VINDL2 = 3.6V, TA = -40°C to +85°C, unless otherwise noted.) (Note 8) PARAMETER CONDITIONS MIN MAX UNITS 0.7 5.5 V 5 µA GENERAL Input Voltage Range (Note 2) Shutdown Supply Current into PVSU PVSU = 3.6V Supply Current into PV with Step-Up Enabled ONSU = 3.6V, FBSU = 1.5V (does not include switching losses) 450 µA Supply Current into PV with Step-Up and Step-Down Enabled ONSU = ONSD = 3.6V, FBSU = 1.5V, FBSD = 1.
PAGE 6
MAX1584/MAX1585 5-Channel Slim DSC Power Supplies ELECTRICAL CHARACTERISTICS (continued) (VPVSU = VPV = VPVSD = VINDL2 = 3.6V, TA = -40°C to +85°C, unless otherwise noted.) (Note 8) PARAMETER CONDITIONS FBSD Regulation Voltage MIN MAX UNITS 1.225 1.275 V FBSD to CCSD Transconductance FBSD = CCSD 80 185 µS FBSD Input Leakage Current FBSD = 1.25V -100 +100 nA LXSD Leakage Current VLXSD = 0 to 3.6V, PVSU = 3.
PAGE 7
5-Channel Slim DSC Power Supplies (VPVSU = VPV = VPVSD = VINDL2 = 3.6V, TA = -40°C to +85°C, unless otherwise noted.) (Note 8) Note 5: The step-up current limit in startup refers to the LXSU switch current limit, not an output current limit. Note 6: The idle mode current threshold is the transition point between fixed-frequency PWM operation and idle mode operation (where switching rate varies with load). The specification is given in terms of inductor current.
PAGE 8
Typical Operating Characteristics (continued) (Circuit of Figure 1, TA = +25°C, unless otherwise noted.) MINIMUM STARTUP VOLTAGE vs. LOAD CURRENT (VSU) NO-LOAD INPUT CURRENT vs. INPUT VOLTAGE (SWITCHING) BOOST-BUCK (SU + AUX3) VSU = 5.0V, OUT3 = 3.33V 6 5 4 3 2 3.0 2.5 1.5 1.0 0.5 VSU = 5.0V 1 0 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 200 400 600 800 1000 INPUT VOLTAGE (V) LOAD CURRENT (mA) REFERENCE VOLTAGE vs. TEMPERATURE REFERENCE VOLTAGE vs.
PAGE 9
5-Channel Slim DSC Power Supplies AUX MAXIMUM DUTY CYCLE vs. FREQUENCY WHEN THIS DUTY CYCLE IS EXCEEDED FOR 100,000 CLOCK CYCLES, THE MAX1584/MAX1585 SHUT DOWN 86 MAX1584/85 toc13 MAXIMUM DUTY CYCLE (%) 87 STEP-UP STARTUP RESPONSE MAX1584/85 toc14 88 ONSU 5V/div OUTSU 5V/div IOUTSU 200mA/div 0V 85 0V 84 0A 83 82 IIN 1.0A/div 0A 81 COSC = 330pF VIN = 3.
PAGE 10
5-Channel Slim DSC Power Supplies MAX1584/MAX1585 Pin Description 10 PIN NAME FUNCTION 1 CC1 AUX1 Controller Compensation Node. Connect a series resistor-capacitor from CC1 to GND to compensate the converter control loop. This pin is actively driven to GND in shutdown, overload, and thermal limit. See the AUX Compensation section. 2 FB1 AUX1 Controller Feedback Input. The feedback threshold is 1.25V. This pin is high impedance in shutdown. 3 PGSD Step-Down Power Ground.
PAGE 11
5-Channel Slim DSC Power Supplies PIN NAME 16 AUX1OK 17 SDOK FUNCTION Open-Drain Power-OK Signal for AUX1 Controller. AUX1OK is low when the AUX1 controller has successfully completed soft-start. This pin is high impedance in shutdown, overload, and thermal limit. Open-Drain Power-OK Signal for Step-Down Converter. SDOK is low when the step-down has successfully completed soft-start. This pin is high impedance in shutdown, overload, and thermal limit.
PAGE 12
5-Channel Slim DSC Power Supplies MAX1584/MAX1585 Pin Description (continued) PIN NAME 28 DL3 AUX3 Step-Down Controller Gate-Drive Output. Connect to the gate of a P-channel MOSFET. DL3 swings from GND to PVSU and supplies up to 500mA. DL3 is driven to PVSU in shutdown and thermal limit. 29 DL1 AUX1 Step-Up Controller Gate-Drive Output. Connect to the gate of an N-channel MOSFET. DL1 swings from GND to PVSU and supplies up to 500mA. DL1 is driven to GND in shutdown and thermal limit.
PAGE 13
5-Channel Slim DSC Power Supplies L3 2μH MAX1585 +15V, 80mA +CCD LCD LED INDL2 AUX2 V-MODE INV PWM P1 DL2 D2 -7.5V -CDD BIAS R8 526kΩ C8 4.7μF AUX1 V-MODE STEP-UP PWM N1 AUX3 V-MODE STEP-DOWN PWM REF L4 10μH DL3 D3 FB3 OSC 3.3V 250mA LOGIC C25 47μF 1.25V REF R14 30.1kΩ R15 18.2kΩ 20kΩ TO PVSU R7 90.9kΩ TO PVSU C23 OR VIN 10μF P2 0.1μF R6 1MΩ FB1 FB2 L6 3.6μH R9 93.1kΩ C6 4.7μF D1 DL1 R22 1.2kΩ C20 560pF TO VIN D4 PV MAX1584/MAX1585 VIN 1.5V TO 4.
PAGE 14
MAX1584/MAX1585 5-Channel Slim DSC Power Supplies PVSU INTERNAL POWER-OK NORMAL MODE STARTUP OSCILLATOR 2.35V MAX1584/ MAX1585 ONSU VREF OVER TEMP REFOK SCF 1V FAULT 100,000 IN CLOCK CYCLE FAULT TIMER CLK ONSU FLTALL TO INTERNAL POWER PV OSC 1.
PAGE 15
5-Channel Slim DSC Power Supplies Boost-Buck Operation The step-down input can be powered from the output of the step-up. By cascading these two channels, the step-down output can maintain regulation even as the battery voltage falls below the step-down output voltage. This is especially useful when trying to generate 3.3V from 1-cell Li+ inputs, or 2.5V from 2-cell alkaline or NiMH inputs, or when designing a power supply that must operate from both Li+ and alkaline/NiMH inputs.
PAGE 16
MAX1584/MAX1585 5-Channel Slim DSC Power Supplies FB_ FB2 MAX1584 AUX1 AND AUX2, MAX1585 AUX1 STEP-UP CONTROLLER MAX1585 AUX2 INVERTING CONTROLLER CC_ CC2 R LEVEL SHIFT REFI REF 0.85 REF Q REFI SOFT-START (REFI RAMPS FROM 0V TO REF IN 1024 OSC CYCLES) R LEVEL SHIFT DL_ S Q DL2 S SOFT-START (REFI RAMPS FROM REF TO 0V IN 1024 OSC CYCLES) REF 0.
PAGE 17
5-Channel Slim DSC Power Supplies AUX2 In the MAX1584, AUX2 is identical to AUX1. In the MAX1585, AUX2 is an inverting controller that generates a regulated negative output voltage, typically for CCD and LCD bias. This is handy in height-limited designs where transformers might not be desired. The AUX2 MOSFET driver (DL2) in the MAX1585 is designed to drive P-channel MOSFETs. DL2 swings from GND to PVSU. See Figure 8 for a typical inverter configuration.
PAGE 18
MAX1584/MAX1585 5-Channel Slim DSC Power Supplies VSU MAX1584 MAX1585 (PARTIAL) ROSC TO VBATT AUX PWM OSC COSC VREF (1.25V) PVSU Q1 DL_ 150ns ONE-SHOT MAX1584 MAX1585 D6 +15V 50mA LCD FB_ NOTE: THIS CIRCUIT CAN OPERATE WITH AUX1 OR AUX2 ON THE MAX1584, AND WITH AUX1 ON THE MAX1585 Figure 4. Oscillator Functional Diagram Figure 5. +15V LCD Bias with Basic Boost Topology end of the soft-start interval.
PAGE 19
5-Channel Slim DSC Power Supplies Design Procedure Setting the Switching Frequency Choose a switching frequency to optimize external component size or circuit efficiency for the particular application. Typically, switching frequencies between 400kHz and 500kHz offer a good balance between component size and circuit efficiency—higher frequencies generally allow smaller components, and lower frequencies give better conversion efficiency.
PAGE 20
MAX1584/MAX1585 5-Channel Slim DSC Power Supplies IIND(PK) = 1.25 x IOUT / (1 - D) Inductance values smaller than LIDEAL can be used to reduce inductor size; however, if much smaller values are used, inductor current rises and a larger output capacitance might be required to suppress output ripple. Step-Up Compensation The inductor and output capacitor are usually chosen first in consideration of performance, size, and cost.
PAGE 21
5-Channel Slim DSC Power Supplies If CP is calculated to be <10pF, it can be omitted. Step-Down Component Selection Step-Down Inductor The external components required for the step-down are an inductor, input and output filter capacitors, and a compensation RC network. The MAX1585/1585 step-down converter provides best efficiency with continuous inductor current.
PAGE 22
MAX1584/MAX1585 5-Channel Slim DSC Power Supplies Significant MOSFET selection parameters are as follows: • On-resistance (RDS(ON)) • Maximum drain-to-source voltage (VDS(MAX)) • Total gate charge (QG) • Reverse transfer capacitance (CRSS) DL1 and DL3 swing between PVSU and GND. DL2 swings between INDL2 and GND. Use a MOSFET with on-resistance specified at or below the DL_ drive voltage.
PAGE 23
5-Channel Slim DSC Power Supplies Place: 1 / (2π x RC x CC) = 1 / (2π x RLOAD x COUT), so that RC = RLOAD x COUT / CC Or, reduce the inductor value for discontinuous operation. AUX3 Step-Down Compensation It is expected that most AUX3 step-down applications employ continuous inductor current to optimize inductor size and efficiency. To ensure stability, the controlloop gain should cross over (drop below unity gain) at a frequency (fC) much less than that of the switching frequency.
PAGE 24
MAX1584/MAX1585 5-Channel Slim DSC Power Supplies MAX1585 AUX2 Inverter Compensation, Discontinuous Inductor Current If the load current is very low (40mA or less), discontinuous current is preferred for simple loop compensation and freedom from duty-cycle restrictions on the inverter input-output ratio. To ensure discontinuous operation, the inductor must have a sufficiently low inductance to fully discharge on each cycle.
PAGE 25
5-Channel Slim DSC Power Supplies MAX1584/MAX1585 TO VBATT 1μF TO VBATT PVSU 1μF +15V 50mA CCD+ MAX1584 MAX1585 (PARTIAL) DL_ AUX_ PWM WHITE LEDS AUX PWM PVSU Q1 D2 -7.5V 30mA CCD- DL_ FB_ 62Ω (FOR 20mA) MAX1585 (PARTIAL) NOTE: THIS CIRCUIT CAN OPERATE WITH AUX1 OR AUX2 ON THE MAX1584, AND WITH AUX1 ON THE MAX1585. FB_ NOTE: THIS CIRCUIT CAN OPERATE WITH AUX1 OR AUX2 ON THE MAX1584, AND WITH AUX1 ON THE MAX1585. Figure 6. AUX_ Channel Powering a White LED Step-Up Current Source Figure 7.
PAGE 26
MAX1584/MAX1585 5-Channel Slim DSC Power Supplies +15V 20mA TO VBATT MAX1585 (PARTIAL) TO VBATT FB_ AUX_ PWM INDL2 DL2 PVSU AUX2 INVERTING PWM -7.5V 20mA DL_ -7.5V 100mA RTOP FB2 MAX1584/MAX1585 (PARTIAL) RREF IN REF SHDN GND OUT Figure 8. Regulated -7.5V Negative CCD Bias Provided by Conventional Inverter (MAX1585 Only) FB_ +1.25V L1 10μH D2 TO VBATT VOUT+ +15V 20mA C2 1μF 1μF R1 1MΩ Figure 10. +15V and -7.5V CCD Bias Without Transformer from AUX-Driven Boost and Charge Pump.
PAGE 27
5-Channel Slim DSC Power Supplies TO VBATT VOUT PVSU DL IN MAX1584 MAX1585 OSC (PARTIAL) MAX1801 OSC MAX1584 MAX1585 (PARTIAL) PVSU AUX1 PWM FB COMP D6 15V 100mA REF REF GND DL1 DCON FB1 AUX1OK PV PVSU Figure 12. Adding a PWM Channel with an External MAX1801 Slave Controller TO VBATT CURRENTMODE STEP-UP PWM MAX1584/MAX1585 (PARTIAL) AUX3 V-MODE STEP-DOWN PWM LXSU GATED +5V TO CCD VSU +5V L2 TO PVSU PGSU DL3 FBSU 3.3V LOGIC Figure 14.
PAGE 28
MAX1584/MAX1585 5-Channel Slim DSC Power Supplies VSU 3.3V MAX1584 MAX1585 (PARTIAL) PVSU PV PV PVSU VSU +5V MAX1584 MAX1585 (PARTIAL) PVSD 10μF TO VBATT CURRENT-MODE STEP-UP PWM LXSU L2 LXSD CURRENT-MODE STEP-DOWN 4.7μH VSD 0.8V 22μF PGSU FBSD SCF PGSD FBSD R3 100kΩ VFBSD 1.25V R1 56kΩ OK PWR-ON OR FAULT R2 100kΩ Figure 15. SCF controls a PFET load switch to disconnect all 5V loads on fault. This also allows full-load startup. Figure 16. Setting PVSD for Outputs Below 1.
PAGE 29
5-Channel Slim DSC Power Supplies QFN THIN.EPS 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.