19-1198; Rev 1; 8/00
1- to 3-Cell, High-Current, Low-Noise,
Step-Up DC-DC Converters with Linear Regulator
General Description
The MAX1705/MAX1706 are high-efficiency, low-noise,
step-up DC-DC converters with an auxiliary linear-
regulator output. These devices are intended for use in
battery-powered wireless applications. They use a syn-
chronous 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 non-
synchronous converters. They also feature a pulse-
frequency-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-reg-
ulator 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 volt-
age monitor.
♦
Up to 96% Efficiency
♦
1.1V
IN
Guaranteed Startup
♦
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
KIT
ATION
EVALU
BLE
AVAILA
Features
MAX1705/MAX1706
Ordering Information
PART
MAX1705C/D
TEMP RANGE
0°C to +70°C
PIN-PACKAGE
Dice*
16 QSOP
MAX1705EEE
-40°C to +85°C
MAX1706C/D
Dice*
0°C to +70°C
16 QSOP
MAX1706EEE
-40°C to +85°C
*Dice
are tested at T
A
= +25°C, DC parameters only.
________________________Applications
Digital Cordless Phones
Personal Communicators
Palmtop Computers
Handheld Instruments
PCS Phones
Wireless Handsets
Two-Way Pagers
__________Typical Operating Circuit
INPUT 0.7V TO 5.5V
LX
Pin Configuration
TOP VIEW
LBP
LOW-BATTERY
DETECTION
POUT
OUT
STEP-UP OUTPUT
LBP 1
LBN 2
REF 3
TRACK 4
GND 5
OUT 6
FB 7
FBLDO 8
16 POUT
15 ONA
14 ONB
ON/OFF CONTROL
HIGH
EFFICIENCY
LOW
NOISE
LBO
MAX1706
ONA
ONB
CLK/SEL
TRACK
MAX1705
FB
MAX1705
MAX1706
13 LX
12 PGND
11 CLK/SEL
10 LBO
9
LDO
LINEAR
REGULATOR
OUTPUT
LDO
FBLDO
GND PGND
LBN
REF
QSOP
________________________________________________________________
Maxim Integrated Products
1
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.
1- to 3-Cell, High-Current, Low-Noise,
Step-Up DC-DC Converters with Linear Regulator
MAX1705/MAX1706
ABSOLUTE MAXIMUM RATINGS
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, 10s) .................................+300°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.
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 T
A
= +25°C.)
PARAMETER
DC-DC CONVERTER
Minimum Startup Voltage
Minimum Operating Battery
Voltage
FB Regulation Voltage
FB Input Current
OUT Adjust Range
Load Regulation
MAX1705, 0A
≤
I
LX
≤
0.5A;
MAX1706, 0A
≤
I
LX
≤
0.25A;
CLK/SEL = OUT
TRACK = V
LDO
> 2.3V
f
LX
V
POUT
= V
OUT
= 1.5V
(Note 2)
I
OUT
I
OUT
ONA = GND,
ONB
= OUT, measure I
OUT
CLK/SEL = GND, V
FB
= V
FBLDO
= 1.5V,
no load
V
FB
= V
FBLDO
= 1.5V, no load
I
OUT
CLK/SEL = OUT
FB = GND (LX switching)
I
REF
= 0µA
-1µA < I
REF
< 50µA
2.5V < V
OUT
< 5.5V
1.238
2.1
1.250
4
0.2
1.262
15
5
mA
V
mV
mV
V
LDO
+ 0.2
40
2.00
T
A
= +25°C, I
LOAD
< 1mA, Figure 2
(Note 1)
CLK/SEL = OUT
V
FB
= 1.5V
2.5
0.65
V
LDO
+ 0.3
150
2.15
1
100
180
1.219
0.9
0.7
1.233
0.01
1.247
50
5.5
1.25
V
LDO
+ 0.4
300
2.30
20
190
360
1.1
V
V
V
nA
V
%
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
OUT Voltage in Track Mode
Frequency in Startup Mode
Startup to Normal Mode
Transition Voltage
Supply Current in Shutdown
Supply Current in
Low-Power Mode
Supply Current in
Low-Noise Mode
REFERENCE
Reference Output Voltage
Reference Load Regulation
Reference Supply Regulation
V
kHz
V
µA
µA
µA
2
_______________________________________________________________________________________
1- to 3-Cell, High-Current, Low-Noise,
Step-Up DC-DC Converters with Linear Regulator
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 T
A
= +25°C.)
PARAMETER
DC-DC SWITCHES
POUT Leakage Current
LX Leakage Current
Switch On-Resistance
V
LX
= 0V, V
ONB
= V
OUT
= 5.0V
V
LX
= V
ONB
= V
OUT
= 5.0V
n-channel, I
LX
= 100mA
p-channel, I
LX
= 100mA
CLK/SEL = OUT
n-Channel MOSFET
Current Limit
I
LIM
CLK/SEL = GND
p-Channel Synchronous-
Rectifier Turn-Off Current
LINEAR REGULATOR
FBLDO Regulation Voltage
FBLDO Input Current
LDO Adjust Range
Short-Circuit Current Limit
Dropout Resistance
Load Regulation
Line Regulation
AC Power-Supply Rejection
Thermal Shutdown
LOW-BATTERY COMPARATOR
LBN, LBP Offset
LBN, LBP Hysteresis
LBN, LBP Common-Mode
Input Range
LBN, LBP Input Current
LBO Output Low Voltage
LBO High Leakage
CONTROL INPUTS
Input Low Level
Input High Level
Input Leakage Current
(CLK/SEL, ONA,
ONB,
TRACK)
1.2V < V
OUT
< 5.5V, ONA,
ONB
(Note 3)
V
OUT
= 2.5V, CLK/SEL, TRACK
1.2V < V
OUT
< 5.5V, ONA,
ONB
(Note 3)
V
OUT
= 5.5V, CLK/SEL, TRACK
0.8V
OUT
0.8V
OUT
1
0.2V
OUT
0.2V
OUT
V
V
µA
LBP falling
LBP rising
V
LBN
= 0.5V and 1.5V (at least one input must
be within this range)
V
LBN
= V
LBP
= 1V
I
SINK
= 1mA, V
OUT
= 2.5V, LBP = GND,
LBN = OUT
V
LBO
= V
OUT
= 5V
0.5
0.01
-5
16
1.5
50
0.4
1
+5
mV
mV
V
nA
V
µA
FBLDO = GND
V
FBLDO
= 1V, I
LDO
= 200mA
100µA < I
LDO
< 200mA, FBLDO = LDO
2.5V < V
OUT
< 5.5V, FBLDO = LDO,
I
LDO
= 1mA
f = 300kHz
Hysteresis approximately 10°C
FBLDO = LDO, I
LOAD
= 1mA
V
FBLDO
= 1.5V
1.25
220
300
0.5
0.4
0.1
38
155
1.238
1.250
0.01
1.262
50
5.0
500
1.2
1.2
0.5
V
nA
V
mA
Ω
%
%
dB
°C
CLK/SEL = GND
MAX1705
MAX1706
MAX1705
MAX1706
1000
550
250
250
20
CLK/SEL = GND
CLK/SEL = OUT
0.1
0.1
0.23
0.16
0.27
1280
750
435
435
70
20
20
0.45
0.28
0.50
1550
950
550
550
120
mA
mA
Ω
µA
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1705/MAX1706
_______________________________________________________________________________________
3
1- to 3-Cell, High-Current, Low-Noise,
Step-Up DC-DC Converters with Linear Regulator
MAX1705/MAX1706
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 T
A
= +25°C.)
PARAMETER
Internal Oscillator Frequency
External Oscillator
Synchronization Range
Oscillator Maximum Duty Cycle
Minimum CLK/SEL Pulse
Maximum CLK/SEL
Rise/Fall Time
SYMBOL
CONDITIONS
CLK/SEL = OUT
MIN
260
200
80
86
200
100
TYP
300
MAX
340
400
90
UNITS
kHz
kHz
%
ns
ns
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)
noted. (Note 4) LX = open,
T
A
= -40°C to +85°C,
unless otherwise noted. (Note 4)
PARAMETER
DC-DC CONVERTER
FB Regulation Voltage
OUT Voltage in Track Mode
Startup to Normal Mode
Transition Voltage
Supply Current in Shutdown
Supply Current in
Low-Power Mode
Supply Current in
Low-Noise Mode
REFERENCE
Reference Output Voltage
DC-DC CONVERTER
Switch On-Resistance
n-channel, I
LX
= 100mA
p-channel, I
LX
= 100mA
CLK/SEL = OUT
n-Channel MOSFET
Current Limit
I
LIM
CLK/SEL = 0V
p-Channel Synchronous-
Rectifier Turn-Off Current
CLK/SEL = 0V
CLK/SEL = 0V
CLK/SEL = OUT
CLK/SEL = OUT
MAX1705
MAX1706
MAX1705
MAX1706
1000
550
250
250
20
0.45
0.28
0.50
1700
950
570
570
120
mA
mA
Ω
I
REF
= 0µA
1.235
1.265
V
I
OUT
I
OUT
I
OUT
ONA = 0V,
ONB
= OUT, measure I
OUT
CLK/SEL = 0V, FB = FBLDO = 1.5V, no load
CLK/SEL = OUT, V
FB
= V
FBLDO
= 1.5V,
no load
SYMBOL
CONDITIONS
CLK/SEL = OUT
TRACK = OUT, V
LDO
> 2.3V
MIN
1.215
V
LDO
+
0.2
2.0
TYP
MAX
1.251
V
LDO
+
0.4
2.3
20
190
360
UNITS
V
V
V
µA
µA
µA
4
_______________________________________________________________________________________
1- to 3-Cell, High-Current, Low-Noise,
Step-Up DC-DC Converters with Linear Regulator
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
LINEAR REGULATOR
FBLDO Regulation Voltage
FBLDO Input Current
Short-Circuit Current Limit
Dropout Resistance
LOW-BATTERY COMPARATOR
LBN, LBP Offset
LBN, LBP Common-Mode
Input Range
LBO High Leakage
CONTROL INPUTS
Input Low Level
Input High Level
Internal Oscillator Frequency
External Oscillator
Synchronization Range
Note 1:
Note 2:
Note 3:
Note 4:
1.2V < V
OUT
< 5.5V, ONA,
ONB
(Note 2)
V
OUT
= 2.5V, CLK/SEL, TRACK
1.2V < V
OUT
< 5.5V, ONA,
ONB
(Note 2)
V
OUT
= 5.5V, CLK/SEL, TRACK
CLK/SEL = OUT
0.85V
OUT
0.85V
OUT
260
200
340
400
0.15V
OUT
0.15V
OUT
V
V
kHz
kHz
LBP falling
LBN = 0.5V and 1.5V (at least one input must
be within this range)
LBO = OUT = 5V
-5
0.5
+5
1.5
1
mV
V
µA
FBLDO = LDO, I
LOAD
= 1mA
V
FBLDO
= 1.5V
FBLDO = LDO = GND
V
FBLDO
= 1V, I
LDO
= 200mA
220
1.233
0.01
1.268
50
600
1.2
V
nA
mA
Ω
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1705/MAX1706
Once the output is in regulation, the MAX1705/MAX1706 operate down to a 0.7V input voltage.
The device is in startup mode when V
OUT
is below this value (see
Low-Voltage Startup Oscillator
section).
ONA and
ONB
inputs have a hysteresis of approximately 0.15V
OUT
.
Specifications to -40°C to are guaranteed by design, not production tested.
_______________________________________________________________________________________
5
综合技术交流
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
