Rainbow Electronics MAX1765 User Manual

General Description

The MAX1765 is a high-efficiency, low-noise, step-up
DC-DC converter intended for use in battery-powered
wireless applications. This device operates at a high
1MHz fixed frequency while maintaining an exception­ally low quiescent supply current (200µA). Its small
external components and tiny package make this
device an excellent choice for small hand-held applica­tions that require the longest possible battery life.

The MAX1765 uses a synchronous-rectified pulse­width-modulation (PWM) boost topology to generate

2.5V to 5.5V outputs from a wide range of input
sources, such as one to three alkaline or NiCd/NiMH
cells or a single lithium-ion (Li+) cell. Maxim's propri­etary architecture significantly improves efficiency at
low load currents while automatically transitioning to
fixed-frequency PWM operation at medium to high load
currents to maintain excellent full-load efficiency.
Forced-PWM mode is available for applications that
require constant-frequency operation at all load cur­rents, and the MAX1765 may also be synchronized to
an external clock to protect sensitive frequency bands
in communications equipment.

The MAX1765’s low-dropout (LDO) linear regulator and
DC-DC converter have separate shutdown control. The
linear regulator's 250mΩ pass device maintains excel­lent dropout voltage at currents up to 500mA. The
MAX1765 also features analog soft-start and current­limit functions to permit optimization of efficiency, exter­nal component size, and output voltage ripple.

The MAX1765 comes in a 16-pin QSOP package and a
thermally enhanced 16-pin TSSOP-EP.

____________________________Features

♦ High-Efficiency Step-Up Converter

Up to 93% Efficiency
Adjustable Output from +2.5V to +5.5V
Up to 800mA Output
PWM Synchronous-Rectified Topology
1MHz Operating Frequency (or Sync)

♦ LDO Linear Regulator

500mA LDO Linear Regulator

2.85V Linear Regulator Output or Adjustable
(1.25V to 5V)
Low 125mV Dropout at 500mA

♦ +0.7V to +5.5V Input Range

♦ 0.1µA Logic-Controlled Shutdown

♦ Adjustable Inductor Current Limit and Soft-Start

♦ Thermal Shutdown

♦ 1.5W, 16-Pin TSSOP-EP Package Available

MAX1765

800mA, Low-Noise, Step-Up DC-DC Converter

with 500mA Linear Regulator

________________________________________________________________ Maxim Integrated Products 1

19-1805; Rev 0; 12/00

For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

FBL ONL

TRACK

INL

POUT

LX

PGND

OUTL

TOP VIEW

MAX1765

QSOP/TSSOP-EP

ONB

ISET

REF

OUT

GND

FB

ONA

CLK/SEL

Pin Configuration

Wireless Handsets

PCS Phones

Palmtop Computers

Personal
Communicators

Hand-Held Instruments

Portable Audio Players

Applications

Typical Operating Circuit

Ordering Information

*Exposed pad

PART

PIN-PACKAGE

MAX1765EEE

16 QSOP

MAX1765EUE

16 TSSOP-EP*

TEMP. RANGE

-40°C to +85°C

-40°C to +85°C

(0.7V TO 5.5V)

3.3µH

ONL

LX

ONB

CLK/SEL

TRACK

MAX1765

REF
ILIM

GND PGND

FBL

ONA

POUT

INL

OUT

OUTL

OUT = 3.3V

FB

OUTL = 2.85V

(ADJ 1.25V
TO 5V)

MAX1765

800mA, Low-Noise, Step-Up DC-DC Converter
with 500mA Linear Regulator

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(V

OUT

= V

POUT

= V

INL

= V

ONA

= V

ONL

= 3.6V, CLK/SEL = FBL = ONB = TRACK = PGND = GND, ISET = REF (bypassed with

0.22µF), LX = open, OUTL = open (bypassed with 4.7µF), T

A

= 0°C to +85°C, unless otherwise noted. Typical values are at

T

A

= +25°C.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

ONA, ONB, ONL, TRACK, OUT, INL to GND..............-0.3V, +6V

PGND to GND.....................................................................±0.3V

LX to GND ...............................................-0.3V to (POUT + 0.3V)

OUTL to GND ..............................................-0.3V to (INL + 0.3V)

CLK/SEL, REF, FB, FBL, ISET, POUT

to GND...................................................-0.3V to (OUT + 0.3V)

OUTL Short Circuit .....................................................Continuous

Continuous Power Dissipation (T

A

= +70°C)

16-Pin QSOP (derate 8.3mW/°C above +70°C)...........667mW

16-Pin TSSOP-EP (derate 19mW/°C above +70°C) ....1500mW

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

V

OUTL

+ 0.4

V

OUTL

+ 0.5

V

OUTL

+ 0.6

DC-DC CONVERTER

Input Voltage Range (Note 1) 0.7 5.5 V

INL Voltage Range (Note 1) 2.3 5.5 V

Minimum Startup Voltage I

Temperature Coefficient of
Startup Voltage

FB Regulation Voltage V

FB Input Leakage Current VFB = 1.35V 0.01 100 nA

Output Voltage Adjust Range 2.5 5.5 V

Load Regulation CLK/SEL = OUT, 0 < I

OUT Voltage in Track Mode V

Frequency in Startup Mode f

Startup to Normal Mode
Transition Voltage

ISET Input Leakage Current V

Supply Current in Normal Mode
(Note 3)

Supply Current in Low-Noise
PWM Mode (Note 3)

Supply Current in Shutdown ONA = ONL = GND, ONB = OUT 1 10 µA

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

LX

FB

< 1mA, T

LOAD

< 1mA -2 m V /°C

I

LOAD

CLK/SEL = OUT, 0 < ILX < 0.55A 1.215 1.250 1.275 V

> 2.0V, INL = POUT

OUTL

V

= 1.5V 125 1000 kHz

OUT

Rising edge only (Note 2) 2.00 2.15 2.30 V

= 1.25V 0.01 50 nA

ISET

CLK/SEL = ONL = GND, no load 100 200 µA

C LK/S E L = OU T,
no l oad

= +25°C, Figure 2 0.9 1.1 V

A

< 800mA -1 %

LOAD

VFB = 1.5V 130 200 µA

FB = GN D ( LX sw i tchi ng ) 2.5 mA

V

MAX1765

800mA, Low-Noise, Step-Up DC-DC Converter

with 500mA Linear Regulator

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(V

OUT

= V

POUT

= V

INL

= V

ONA

= V

ONL

= 3.6V, CLK/SEL = FBL = ONB = TRACK = PGND = GND, ISET = REF (bypassed with

0.22µF), LX = open, OUTL = open (bypassed with 4.7µF), T

A

= 0°C to +85°C, unless otherwise noted. Typical values are at

T

A

= +25°C.)

DC-DC SWITCHES

POUT Leakage Current VLX = 0, V

LX Leakage Current V

Switch On-Resistance

N - C hannel C ur r ent Li m i t ( N ote 4) I

P-Channel Turn-Off Current CLK/SEL = GND 10 50 120 mA

REFERENCE

Reference Output Voltage V
Reference Load Regulation -1µA < I

Reference Supply Regulation 2.5V < V

LINEAR REGULATOR

INL Voltage Range (Note 1) 2.3 5.5 V

INL Startup Voltage V

Output Voltage in Internal
Feedback Mode

FBL Dual-Mode Threshold 150 250 350 mV

FBL Regulation Voltage V

FBL Input Leakage Current V

OUTL Adjust Range 1.25 5 V

Short-Circuit Current Limit V

Dropout Resistance V

Load Regulation 1mA < I

Line Regulation

INL Supply Current in Shutdown OUTL = ONA = ONL = GND 0.1 10 µA

INL No-Load Supply Current I

AC Power-Supply Rejection f = 10kHz 65 dB
Thermal Shutdown Hysteresis approximately 10°C 160 °C

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

= 5.5V 0.1 10 µA

OUT

= V

LX

= V

OUT

= 5.5V, ONA = GND 0.1 10 µA

ONB

N-channel 0.17 0.28

P-channel 0.22 0.5

V

LIM

REF

INL

FBL

= 1.25V, CLK/SEL = GND or OUT 1000 1250 1600 mA

ISET

I

= 0 1.230 1.250 1.270 V

REF

< 50µA515mV

REF

< 5.5V 0.2 5 mV

OUT

V

= 2V, rising edge only 2.15 2.30 2.45 V

OUT

FBL = GND, I

FBL = OUTL, I

= 1.5V 0.01 50 nA

FBL

= 1V 550 1300 mA

FBL

= 1V, I

FBL

OUTL

2.5V < (V

OUT

FBL = OUTL

= 0, V

OUTL

= 10mA 2.80 2.85 2.90 V

OUTL

= 10mA, I

OUTL

= 500mA 0.25 0.5 Ω

OUTL

= 0 1.230 1.250 1.270 V

REF

< 500mA, FBL = GND 0.5 1 %

= V

= V

INL

= 5.5V 90 250 µA

INL

POUT

) < 5.5V,

-0.5 0.5 %

Ω

MAX1765

800mA, Low-Noise, Step-Up DC-DC Converter
with 500mA Linear Regulator

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(V

OUT

= V

POUT

= V

INL

= V

ONA

= V

ONL

= 3.6V, CLK/SEL = FBL = ONB = TRACK = PGND = GND, ISET = REF (bypassed with

0.22µF), LX = open, OUTL = open (bypassed with 4.7µF), T

A

= 0°C to +85°C, unless otherwise noted. Typical values are at

TA=+25 °C.)

CONTROL INPUTS

Input Low Level

Input High Level

Input Leakage Current
(CLK/SEL, ONA, ONB,
ONL, TRACK)

Internal Oscillator Frequency CLK/SEL = OUT 0.8 1 1.2 MHz

External Oscillator
Synchronization Range

Oscillator Maximum Duty Cycle 80 86 90 %

Minimum CLK/SEL Pulse 200 ns

M axi m um C LK/S E L Ri se/Fal l Ti m e 100 ns

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

O N A, O NB, O N L
( N ote 5)

CLK/SEL 1.2V < V

TRACK 1.2V < V

O N A, O NB, O N L
( N ote 5)

CLK/SEL 1.2V < V

TRACK 1.2V < V

1.1V < V

1.8V < V

1.1V < V

1.8V < V

< 1.8V 0.2

OUT

< 5.5V 0.4

OUT

< 5.5V

OUT

< 5.5V

INL

V

< 1.8V

OUT

< 5.5V 1.6

OUT

< 5.5V

OUT

< 5.5V

INL

OUT

- 0.2

0.8 ×
V

OUT

0.8 ×

V

INL

0.01 1 µA

0.5 1.2 MHz

0.2 ×
V

OUT

0.2 ×

V

V

INL

V

MAX1765

800mA, Low-Noise, Step-Up DC-DC Converter

with 500mA Linear Regulator

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS

(V

OUT

= V

POUT

= V

INL

= V

ONA

= V

ONL

= 3.6V, CLK/SEL = FBL = ONB = TRACK = PGND = GND, ISET = REF (bypassed with

0.22µF), LX = open, OUTL = open (bypassed with 4.7µF), T

A

= -40°C to +85°C, unless otherwise noted.) (Note 6)

PARAMETER

CONDITIONS

UNITS

DC-DC CONVERTER

FB Regulation Voltage V

FB

CLK/SEL = OUT, 0 < ILX < 0.55A

V

OUT Voltage in Track Mode V

OUTL

> 2.0V, INL = POUT

V

OUTL

V

OUTL

V

Startup to Normal Mode
Transition Voltage

Rising edge only (Note 2)

V

Supply Current in Normal Mode
(Note 3)

CLK/SEL = ONL = GND, no load

µA

Supply Current in
Low-Noise PWM Mode (Note 3

C LK/S E L = OU T, V

FB

= 1.5V , no l oad

µA

Supply Current in Shutdown ONA = ONL = GND, ONB = OUT 10 µA

DC-DC SWITCHES

POUT Leakage Current VLX = 0, V

OUT

= 5.5V 10 µA

LX Leakage Current V

LX

= V

OUT

= V

ONB

= 5.5V, ONA = GND 10 µA

N-channel

Switch On-Resistance

P-channel

Ω

N - C hannel C ur r ent Li m i t ( N ote 4)

I

LIM

V

ISET

= 1.25V, CLK/SEL = GND or OUT

mA

P-Channel Turn-Off Current CLK/SEL = GND 5

mA

REFERENCE

Reference Output Voltage I

REF

= 0

V

LINEAR REGULATOR

Output Voltage in Internal
Feedback Mode

FBL = GND, I

OUTL

= 10mA

V

FBL Input Threshold

mV

FBL Regulation Voltage FBL = OUTL, I

OUTL

= 10mA, I

REF

= 0

V

LDO Startup Voltage V

OUT

= 2V, rising edge only

V

Dropout Resistance V

FBL

= 1V, I

OUTL

= 500mA 0.5 Ω

INL Supply Current in Shutdown

OUTL = ONA = ONL = GND 10 µA

INL No-Load Supply Current I

OUTL

= 0, V

INL

= 5.5V

µA

SYMBOL

MIN TYP MAX

1.210 1.280

+ 0.4

+ 0.6

2.00 2.30

200

200

0.28

0.50

1000 1600

1.225 1.275

120

2.79 2.90

150 350

1.225 1.275

2.15 2.45

250

MAX1765

800mA, Low-Noise, Step-Up DC-DC Converter
with 500mA Linear Regulator

6 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(V

OUT

= V

POUT

= V

INL

= V

ONA

= V

ONL

= 3.6V, CLK/SEL = FBL = ONB = TRACK = PGND = GND, ISET = REF (bypassed with

0.22µF), LX = open, OUTL = open (bypassed with 4.7µF), T

A

= -40°C to +85°C, unless otherwise noted.) (Note 6)

Note 1: Operating voltage. Since the regulator is bootstrapped to the output, once started it will operate down to 0.7V input.
Note 2: The device is in startup mode when V

OUT

is below this value (see Low-Voltage Startup Oscillator section). Do not apply full

load current.

Note 3: Supply current into the OUT and POUT pins. This current correlates directly to the actual battery-supply current, but is

reduced in value according to the step-up ratio and efficiency.

Note 4: Minimum recommended ISET voltage in normal mode is 0.625V.
Note 5: ONA, ONB, ONL have hysteresis of approximately 0.15

✕

V

OUT

.

Note 6: Specifications to -40°C are guaranteed by design and not production tested.

CONTROL INPUTS

Input Low Level

Input High Level

Input Leakage Current
(CLK/SEL, ONA, ONB,
ONL, TRACK)

Internal Oscillator Frequency CLK/SEL = OUT 0.8 1.2 MHz

Oscillator Maximum Duty Cycle 79 90 %

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

O N A, O NB, O N L
( N ote 5)

CLK/SEL 1.2V < V

TRACK 1.2V < V

O N A, O NB, O N L
( N ote 5)

CLK/SEL 1.2V < V

TRACK 1.2V < V

1.1V < V

1.8V < V

1.1V < V

1.8V < V

< 1.8V 0.2

OUT

< 5.5V 0.4

OUT

< 5.5V

OUT

< 5.5V

INL

V

< 1.8V

OUT

< 5.5V 1.6

OUT

< 5.5V

OUT

< 5.5V

INL

OUT

- 0.2

0.8 ×
V

OUT

0.8 ×
V

INL

0.2 ×
V

0.2 ×

V

OUT

INL

1 µA

V

V