Rainbow Electronics MAX1706 User Manual

_______________General Description

The MAX1705/MAX1706 are high-efficiency, low-noise,
step-up DC-DC converters with an auxiliary linear­regulator output. These devices are intended for use in
battery-powered wireless applications. They use a syn­chronous rectifier pulse-width-modulation (PWM) boost
topology to generate 2.5V to 5.5V outputs from battery
inputs, such as 1 to 3 NiCd/NiMH cells or 1 Li-Ion cell.
The MAX1705 has an internal 1A N-channel MOSFET
switch. The MAX1706 has a 0.5A switch. Both devices
also have a built-in low-dropout linear regulator that
delivers up to 200mA.

With an internal synchronous rectifier, the MAX1705/
MAX1706 deliver 5% better efficiency than similar non­synchronous converters. They also feature a pulse­frequency-modulation (PFM) standby mode to improve
efficiency at light loads, and a 1µA shutdown mode. An
efficiency-enhancing track mode reduces the step-up
DC-DC converter output to 300mV above the linear-reg­ulator output.

Both devices come in a 16-pin QSOP package, which
occupies the same space as an 8-pin SO. Other features
include two shutdown-control inputs for push-on/push-off
control, and an uncommitted comparator for use as a volt­age monitor.

________________________Applications

Digital Cordless Phones PCS Phones
Personal Communicators Wireless Handsets
Palmtop Computers Two-Way Pagers
Hand-Held Instruments

____________________________Features

♦ Up to 96% Efficiency
♦ 1.1VINGuaranteed Start-Up
♦ Up to 850mA Output (MAX1705)
♦ Step-Up Output (2.5V to 5.5V adjustable)
♦ Linear Regulator (1.25V to 5.0V adjustable)
♦ PWM/PFM Synchronous-Rectified Topology
♦ 300kHz PWM Mode or Synchronizable
♦ 1µA Shutdown Mode
♦ Voltage Monitor
♦ Pushbutton On/Off Control

MAX1705/MAX1706

1- to 3-Cell, High-Current, Low-Noise,

Step-Up DC-DC Converters with Linear Regulator

________________________________________________________________

Maxim Integrated Products

1

16
15
14
13
12
11
10

9

1
2
3
4
5
6
7
8

LBP POUT

ONA
ONB
LX
PGND
CLK/SEL
LBO
LDO

TOP VIEW

MAX1705
MAX1706

QSOP

LBN
REF

OUT

TRACK

GND

FB

FBLDO

__________________Pin Configuration

LX

POUT

OUT

STEP-UP OUTPUT

FB

CLK/SEL

ONA
ONB

TRACK

INPUT 0.7V TO 5.5V

PGNDGND

LDO

FBLDO

LBP

LBO

LBN
REF

MAX1705
MAX1706

LINEAR
REGULATOR
OUTPUT

LOW-BATTERY

DETECTION

ON/OFF CONTROL

HIGH

EFFICIENCY

LOW

NOISE

__________Typical Operating Circuit

19-1198; Rev 0; 4/97

PART

MAX1705C/D

MAX1705EEE
MAX1706C/D

0°C to +70°C

-40°C to +85°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

Dice*

16 QSOP

Dice*

EVALUATION KIT MANUAL

AVAILABLE

______________Ordering Information

*

Dice are tested at TA= +25°C, DC parameters only.

For free samples & the latest literature: http://www.maxim-ic.com, or phone [phone]

MAX1706EEE -40°C to +85°C

16 QSOP

MAX1705/MAX1706

1- to 3-Cell, High-Current, Low-Noise,
Step-Up DC-DC Converters with Linear Regulator

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(V

OUT

= V

POUT

= V

LBP

= 3.6V, CLK/SEL = FB = LBN = LBO = ONA = ONB = TRACK = GND, REF = open (bypassed with 0.22µF),

LX = open, T

A

= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +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, FBLDO, OUT, POUT to GND...................-0.3V to 6V

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

POUT to OUT......................................................................±0.3V

LX to PGND ............................................-0.3V to (V

POUT

+ 0.3V)

CLK/SEL, REF, FB, TRACK, LDO,

LBN, LBP, LBO to GND.......................-0.3V to (V

OUT

+ 0.3V)

LDO Short Circuit.......................................................Continuous

Continuous Power Dissipation (T

A

= +70°C)

QSOP (derate 8.70mW/°C above +70°C)...................696mW

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

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

Storage Temperature Range.............................-65°C to +160°C

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

CLK/SEL = OUT

-1µA < I

REF

< 50µA

(Note 1)

I

REF

= 0µA

CLK/SEL = GND, VFB= V

FBLDO

= 1.5V,

no load

ONA = GND, ONB = OUT, measure I

OUT

(Note 2)

V

POUT

= V

OUT

= 1.5V

VFB= 1.5V

MAX1705, 0A ≤ ILX≤ 0.5A;
MAX1706, 0A ≤ ILX≤ 0.25A;
CLK/SEL = OUT

TRACK = V

LDO

> 2.3V

CLK/SEL = OUT

CONDITIONS

mV4 15Reference Load Regulation

V1.238 1.250 1.262Reference Output Voltage

µA180 360

I

OUT

Supply Current in
Low-Noise Mode

V1.219 1.233 1.247FB Regulation Voltage

V0.7

Minimum Operating Battery
Voltage

µA100 190I

OUT

Supply Current in
Low-Power Mode

µA1 20I

OUT

Supply Current in Shutdown

V2.00 2.15 2.30

Start-Up to Normal Mode
Transition Voltage

kHz40 150 300f

LX

Frequency in Start-Up Mode

nA0.01 50FB Input Current

V2.5 5.5OUT Adjust Range

%0.65 1.25Load Regulation

V

V

LDO

V

LDO VLDO

+ 0.2 + 0.3 + 0.4

OUT Voltage in Track Mode

UNITSMIN TYP MAXSYMBOLPARAMETER

TA= +25°C, I

LOAD

< 1mA, Figure 2 V0.9 1.1Minimum Start-Up Voltage

2.5V < V

OUT

< 5.5V mV0.2 5Reference Supply Regulation

DC-DC CONVERTER

REFERENCE

VFB= V

FBLDO

= 1.5V, no load

FB = GND (LX switching) 2.1 mA

MAX1705/MAX1706

1- to 3-Cell, High-Current, Low-Noise,

Step-Up DC-DC Converters with Linear Regulator

_______________________________________________________________________________________

3

ELECTRICAL CHARACTERISTICS (continued)

(V

OUT

= V

POUT

= V

LBP

= 3.6V, CLK/SEL = FB = LBN = LBO = ONA = ONB = TRACK = GND, REF = open (bypassed with 0.22µF),

LX = open, T

A

= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

f = 300kHz

V

OUT

= 5.5V, CLK/SEL, TRACK

V

LBO

= V

OUT

= 5V

I

SINK

= 1mA, V

OUT

= 2.5V, LBP = GND,

LBN = OUT

1.2V < V

OUT

< 5.5V, ONA, ONB (Note 3)

V

OUT

= 2.5V, CLK/SEL, TRACK

V

LBN

= VLBP = 1V

V

LBN

= 0.5V and 1.5V (at least one input must

be within this range)

Hysteresis approximately 10°C

LBP falling

1.2V < V

OUT

< 5.5V, ONA, ONB (Note 3)

LBP rising

CONDITIONS

µA1

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

0.8V

OUT

V

0.8V

OUT

Input High Level

0.2V

OUT

V

0.2V

OUT

Input Low Level

dB38AC Power-Supply Rejection

µA1LBO High Leakage

V0.4LBO Output Low Voltage

nA0.01 50LBN, LBP Input Current

V0.5 1.5

LBN, LBP Common-Mode
Input Range

°C155Thermal Shutdown

mV-5 5LBN, LBP Offset
mV16LBN, LBP Hysteresis

UNITSMIN TYP MAXSYMBOLPARAMETER

mA20 70 120

P-Channel Synchronous­Rectifier Turn-Off Current

VLX= 0V, V

ONB

= V

OUT

= 5.5V µA0.1 20POUT Leakage Current

CLK/SEL = GND

CLK/SEL = GND

250 435 550

CLK/SEL = OUT

mA

1000 1280 1550

I

LIM

N-Channel MOSFET
Current Limit

550 750 950

MAX1705

MAX1705
MAX1706

MAX1706 250 435 550

FBLDO = LDO, I

LOAD

= 1mA V1.238 1.250 1.262FBLDO Regulation Voltage

V

FBLDO

= 1.5V nA0.01 50FBLDO Input Current

FBLDO = GND mA220 300 500Short-Circuit Current Limit
V

FBLDO

= 1V, I

LDO

= 200mA

Ω

0.5 1.2Dropout Resistance

10µA < I

LDO

< 200mA, FBLDO = LDO %0.4 1.2Load Regulation

2.5V < V

OUT

< 5.5V, FBLDO = LDO,

I

LDO

= 1mA

%0.1 0.5Line Regulation

P-channel, ILX= 100mA 0.27 0.50

N-channel, ILX= 100mA

Ω

0.23 0.45

Switch On-Resistance

0.16 0.28

CLK/SEL = GND
CLK/SEL = OUT

VLX= 0V, V

ONB

= V

OUT

= 5.5V µA0.1 20LX Leakage Current

V1.25 5.0LDO Adjust Range

CONTROL INPUTS

LOW-BATTERY COMPARATOR

LINEAR REGULATOR

DC-DC SWITCHES

MAX1705/MAX1706

1- to 3-Cell, High-Current, Low-Noise,
Step-Up DC-DC Converters with Linear Regulator

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(V

OUT

= V

POUT

= V

LBP

= 3.6V, CLK/SEL = FB = LBN = LBO = ONA = ONB = TRACK = GND, REF = open (bypassed with 0.22µF),

LX = open, T

A

= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

ELECTRICAL CHARACTERISTICS

(V

OUT

= V

POUT

= V

LBP

= 3.6V, CLK/SEL = FB = LBN = LBO = ONA = ONB = TRACK = GND, REF = open (bypassed with 0.22µF),

LX = open, T

A

= -40°C to +85°C, unless otherwise noted, Note 4.)

PARAMETER SYMBOL MIN TYP MAX UNITS

Minimum CLK/SEL Pulse

Internal Oscillator Frequency 260 300 340 kHz

200 ns

Maximum CLK/SEL
Rise/Fall Time

100 ns

CONDITIONS

CLK/SEL = OUT

Supply Current in
Low-Power Mode

I

OUT

190 µACLK/SEL = 0V, FB = FBLDO = 1.5V, no load

Supply Current in Shutdown I

OUT

20 µA

ONA = 0V, ONB = OUT, measure I

OUT

OUT Voltage in Track Mode

V

LDO

+ V

LDO

+

0.2 0.4

VTRACK = OUT, V

LDO

> 2.3V

250 570MAX1706

MAX1706

CLK/SEL = OUT

CLK/SEL = 0V

MAX1705

CLK/SEL = OUT

CLK/SEL = 0V

0.28

MAX1705

Switch On-Resistance

0.45

Ω

N-channel, ILX= 100mA

550 950

N-Channel MOSFET
Current Limit

I

LIM

1000 1700

mA

CLK/SEL = OUT

250 570

0.50

CLK/SEL = 0V

P-channel, ILX= 100mA

PARAMETER SYMBOL MIN TYP MAX

P-Channel Synchronous­Rectifier Turn-Off Current

UNITSCONDITIONS

20 120 mA

Start-Up to Normal Mode
Transition Voltage

2.0 2.3 V

FB Regulation Voltage 1.215 1.251 VCLK/SEL = OUT

Reference Output Voltage 1.235 1.265 VI

REF

= 0µA

Oscillator Maximum Duty Cycle 80 86 90 %

External Oscillator
Synchronization Range

200 400 kHz

Supply Current in
Low-Noise Mode

I

OUT

360 µA

CLK/SEL = OUT, V

FB

= V

FBLDO

= 1.5V,

no load

DC-DC CONVERTER

REFERENCE

DC-DC CONVERTER

MAX1705/MAX1706

1- to 3-Cell, High-Current, Low-Noise,

Step-Up DC-DC Converters with Linear Regulator

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS (continued)

(V

OUT

= V

POUT

= V

LBP

= 3.6V, CLK/SEL = FB = LBN = LBO = ONA = ONB = TRACK = GND, REF = open (bypassed with 0.22µF),

LX = open, T

A

= -40°C to +85°C, unless otherwise noted, Note 4.)

PARAMETER SYMBOL MIN TYP MAX UNITS

LBN, LBP Common-Mode
Input Range

0.5 1.5 V

CONDITIONS

LBN = 0.5V and 1.5V (at least one input must
be within this range)

LBO High Leakage 1 µALBO = OUT = 5V

Input Low Level

0.15V

OUT

V

1.2V < V

OUT

< 5.5V, ONA, ONB (Note 2)

0.85V

OUT

1.2V < V

OUT

< 5.5V, ONA, ONB (Note 2)

Internal Oscillator Frequency 260 340 kHzCLK/SEL = OUT
External Oscillator

Synchronization Range

200 400 kHz

0.85V

OUT

V

OUT

= 5.5V, CLK/SEL, TRACK

Note 1: Once the output is in regulation, the MAX1705/MAX1706 operate down to a 0.7V input voltage.
Note 2: The device is in start-up mode when V

OUT

is below this value (see

Low-Voltage Start-Up Oscillator

section).

Note 3: ONA and ONB inputs have a hysteresis of approximately 0.15V

OUT

.

Note 4: Specifications to -40°C to are guaranteed by design, not production tested.

Input High Level

V

OUT

= 2.5V, CLK/SEL, TRACK 0.15V

OUT

V

LBN, LBP Offset -5 5 mVLBP falling

FBLDO Regulation Voltage 1.233 1.268 VFBLDO = LDO, I

LOAD

= 1mA

Short-Circuit Current Limit 220 600 mAFBLDO = LDO = GND

FBLDO Input Current 0.01 50 nAV

FBLDO

= 1.5V

Dropout Resistance 1.2 ΩV

FBLDO

= 1V, I

LDO

= 200mA

LINEAR REGULATOR

CONTROL INPUTS

LOW-BATTERY COMPARATOR

MAX1705/MAX1706

1- to 3-Cell, High-Current, Low-Noise,
Step-Up DC-DC Converters with Linear Regulator

6 _______________________________________________________________________________________

__________________________________________Typical Operating Characteristics

(Circuit of Figure 2, TA= +25°C, unless otherwise noted.)

100

0

0.1 10 1001 1000

MAX1705

EFFICIENCY vs. OUTPUT CURRENT

(V

OUT

= 5V)

20

MAX1705/6 TOC02

OUTPUT CURRENT (mA)

EFFICIENCY (%)

40

60

80

90

10

30

50

70

L = 10µH
V

OUT

= 5V

A: V

IN

= 0.9V

C: V

IN

= 2.4V

E: V

IN

= 3.6V
1: PFM MODE
2: PWM MODE

A.1

A.2

C.1

C.2

B.2

B.1

100

0

0.1 10 1001 1000

MAX1705

EFFICIENCY vs. OUTPUT CURRENT

(V

OUT

= 3.3V)

20

MAX1705/6 TOC01

OUTPUT CURRENT (mA)

EFFICIENCY (%)

40

60

80

90

10

30

50

70

L = 10µH
V

OUT

= 3.3V

A: V

IN

= 0.9V
B: V

IN

= 2.7V
1: PFM MODE
2: PWM MODE

B.1

B.2

A.1

A.2

0

0

MAX1705

MAXIMUM OUTPUT CURRENT

vs. INPUT VOLTAGE

200
100

300

MAX1705/6 TOC03

INPUT VOLTAGE (V)

MAXIMUM OUTPUT CURRENT (mA)

3.5

700
600

900
800

400

500

1.0 2.5 4.5

1000

2.0 3.00.5 4.01.5

L = 10µH

PWM MODE

PFM MODE

V

OUT

= 3.3V

V

OUT

= 3.3V

V

OUT

= 5V

V

OUT

= 5V

100

0

0.1 10 1001 1000

MAX1706

EFFICIENCY vs. OUTPUT CURRENT

(V

OUT

= 3.3V)

20

MAX1705/6 TOC04

OUTPUT CURRENT (mA)

EFFICIENCY (%)

40

60

80

90

10

30

50

70

B.2

A.2

A.1

B.1

L = 22µH
V

OUT

= 3.3V

A: V

IN

= 0.9V

B: V

IN

= 2.7V
1: PFM MODE
2: PWM MODE

0.5

0.01

MAX1705

START-UP INPUT VOLTAGE

vs. OUTPUT CURRENT

0.9

0.7

1.1

MAX1705/6 TOC07

OUTPUT CURRENT (mA)

START-UP INPUT VOLTAGE (V)

100

1.7

1.5

2.1

1.9

1.3

0.1 10 1000

2.3

1

NO-LOAD START-UP:

1.0V AT -40°C

0.79 AT +25°C

0.64V AT +85°C
CONSTANT-CURRENT LOAD
V

OUT

= 3.3V
L = 10µH
D1 = MBR0520L

TA = -40°C

TA = +25°C

TA = +85°C

100

0

0.1 10 1001 1000

MAX1706

EFFICIENCY vs. OUTPUT CURRENT

(V

OUT

= 5V)

20

MAX1705/6 TOC05

OUTPUT CURRENT (mA)

EFFICIENCY (%)

40

60

80

90

10

30

50

70

A.1

A.2

C.2

B.2

C.1

B.1

L = 22µH
V

OUT

= 5V

A: V

IN

= 0.9V

B: V

IN

= 2.4V

C: V

IN

= 3.6V
1: PFM MODE
2: PWM MODE

0

0

MAX1706

MAXIMUM OUTPUT CURRENT

vs. INPUT VOLTAGE

200

100

300

MAX1705/6 TOC06

INPUT VOLTAGE (V)

MAXIMUM OUTPUT CURRENT (mA)

3.5

700
600

400

500

1.0 3 4.52.00.5 2.5 41.5

PWM MODE

L = 22µH

PFM MODE

V

OUT

= 5V

V

OUT

= 5V

V

OUT

= 3.3V

V

OUT

= 3.3V

0

0

NO-LOAD SUPPLY CURRENT

vs. INPUT VOLTAGE

2
1

3

MAX1705/6 TOC8

INPUT VOLTAGE (V)

NO-LOAD SUPPLY CURRENT (mA)

4.0

7
6

10

9
8

4

5

1.0 3.0 5.0

12
11

2.0 3.50.5 2.5 4.51.5

PFM MODE

PWM MODE

V

OUT

= 3.3V

L = 10µH

0

0

LINEAR-REGULATOR DROPOUT

VOLTAGE vs. LOAD CURRENT

20

40

MAX1705/6 TOC09

LOAD CURRENT (mA)

DROPOUT VOLTAGE (mV)

160

120

100

60

80

40 120 200

140

80

V

LDO

= 3.3V

V

LDO

= 2.5V

V

LDO

= 5V