19-1805; Rev 1; 4/11
800mA, Low-Noise, Step-Up DC-DC Converter
with 500mA Linear Regulator
MAX1765
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 exception-
ally low quiescent supply current (200µA). Its small
external components and tiny package make this
device an excellent choice for small hand-held applica-
tions that require the longest possible battery life.
The MAX1765 uses a synchronous-rectified pulse-
width-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 propri-
etary 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 cur-
rents, 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 excel-
lent dropout voltage at currents up to 500mA. The
MAX1765 also features analog soft-start and current-
limit functions to permit optimization of efficiency, exter-
nal component size, and output voltage ripple.
The MAX1765 comes in a 16-pin QSOP package and a
thermally enhanced 16-pin TSSOP-EP.
____________________________Features
o
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)
o
LDO Linear Regulator
500mA LDO Linear Regulator
2.85V Linear Regulator Output or Adjustable
(1.25V to 5V)
Low 125mV Dropout at 500mA
o
+0.7V to +5.5V Input Range
o
0.1μA Logic-Controlled Shutdown
o
Adjustable Inductor Current Limit and Soft-Start
o
Thermal Shutdown
o
1.5W, 16-Pin TSSOP-EP Package Available
Ordering Information
PART
MAX1765EEE+
MAX1765EUE+
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 QSOP
16 TSSOP-EP*
*EP
= Exposed pad.
+Denotes
a lead(Pb)-free/RoHS-compliant package.
Applications
Wireless Handsets
PCS Phones
Palmtop Computers
Personal
Communicators
Hand-Held Instruments
Portable Audio Players
Typical Operating Circuit
TOP VIEW
(0.7V TO 5.5V)
3.3μH
ONL
LX
ONB
CLK/SEL
TRACK
MAX1765
REF
ILIM
OUTL = 2.85V
(ADJ 1.25V
TO 5V)
ONA
POUT
INL
OUT
REF 3
Pin Configuration
OUT = 3.3V
FBL 1
ISET 2
16 ONL
15 TRACK
14 OUTL
FB
GND 4
FB 5
OUT 6
ONA 7
CLK/SEL 8
MAX1765
13 INL
12 POUT
11 LX
10 PGND
9
ONB
OUTL
GND FBL PGND
QSOP/TSSOP-EP
________________________________________________________________
Maxim Integrated Products
1
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.
800mA, Low-Noise, Step-Up DC-DC Converter
with 500mA Linear Regulator
MAX1765
ABSOLUTE MAXIMUM RATINGS
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
Soldering Temperature (reflow) .......................................+260°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
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.)
PARAMETER
DC-DC CONVERTER
Input Voltage Range
INL Voltage Range
Minimum Startup Voltage
Temperature Coefficient of
Startup Voltage
FB Regulation Voltage
FB Input Leakage Current
Output Voltage Adjust Range
Load Regulation
OUT Voltage in Track Mode
Frequency in Startup Mode
Startup to Normal Mode
Transition Voltage
ISET Input Leakage Current
Supply Current in Normal Mode
(Note 3)
Supply Current in Low-Noise
PWM Mode (Note 3)
Supply Current in Shutdown
f
LX
CLK/SEL = OUT, 0 < I
LOAD
< 800mA
V
OUTL
> 2.0V, INL = POUT
V
OUT
= 1.5V
Rising edge only (Note 2)
V
ISET
= 1.25V
CLK/SEL = ONL = GND, no load
CLK/SEL = OUT,
no load
V
FB
= 1.5V
FB = GND (LX switching)
V
OUTL
+ 0.4
125
2.00
2.15
0.01
100
130
2.5
1
10
V
FB
(Note 1)
(Note 1)
I
LOAD
< 1mA, T
A
= +25°C, Figure 2
I
LOAD
< 1mA
CLK/SEL = OUT, 0 < I
LX
< 0.55A
V
FB
= 1.35V
2.5
-1
V
OUTL
+ 0.5
V
OUTL
+ 0.6
1000
2.30
50
200
200
1.215
0.7
2.3
0.9
-2
1.250
0.01
1.275
100
5.5
5.5
5.5
1.1
V
V
V
mV/°C
V
nA
V
%
V
kHz
V
nA
μA
μA
mA
μA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
ONA = ONL = GND,
ONB
= OUT
2
_______________________________________________________________________________________
800mA, Low-Noise, Step-Up DC-DC Converter
with 500mA Linear Regulator
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.)
PARAMETER
DC-DC SWITCHES
POUT Leakage Current
LX Leakage Current
Switch On-Resistance
N-Channel Current Limit (Note 4)
P-Channel Turn-Off Current
REFERENCE
Reference Output Voltage
Reference Load Regulation
Reference Supply Regulation
LINEAR REGULATOR
INL Voltage Range
INL Startup Voltage
Output Voltage in Internal
Feedback Mode
FBL Dual-Mode Threshold
FBL Regulation Voltage
FBL Input Leakage Current
OUTL Adjust Range
Short-Circuit Current Limit
Dropout Resistance
Load Regulation
Line Regulation
INL Supply Current in Shutdown
INL No-Load Supply Current
AC Power-Supply Rejection
Thermal Shutdown
V
FBL
= 1V
V
FBL
= 1V, I
OUTL
= 500mA
1mA < I
OUTL
< 500mA, FBL = GND
2.5V < (V
OUT
= V
INL
= V
POUT
) < 5.5V,
FBL = OUTL
OUTL = ONA = ONL = GND
I
OUTL
= 0A, V
INL
= 5.5V
f = 10kHz
Hysteresis approximately 10°C
-0.5
0.1
90
65
160
V
FBL
FBL = OUTL, I
OUTL
= 10mA, I
REF
= 0A
V
FBL
= 1.5V
1.25
550
0.25
0.5
V
INL
(Note 1)
V
OUT
= 2V, rising edge only
FBL = GND, I
OUTL
= 10mA
2.15
2.80
150
1.230
2.3
2.30
2.85
250
1.250
0.01
5.5
2.45
2.90
350
1.270
50
5
1300
0.5
1
0.5
10
250
V
V
V
mV
V
nA
V
mA
Ω
%
%
µA
µA
dB
°C
V
REF
I
REF
= 0A
-1µA < I
REF
< 50µA
2.5V < V
OUT
< 5.5V
1.230
1.250
5
0.2
1.270
15
5
V
mV
mV
I
LIM
V
LX
= 0V, V
OUT
= 5.5V
V
LX
= V
OUT
= V
ONB
= 5.5V, ONA = GND
N-channel
P-channel
V
ISET
= 1.25V, CLK/SEL = GND or OUT
CLK/SEL = GND
1000
10
0.1
0.1
0.17
0.22
1250
50
10
10
0.28
0.5
1600
120
µA
µA
Ω
mA
mA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1765
_______________________________________________________________________________________
3
800mA, Low-Noise, Step-Up DC-DC Converter
with 500mA Linear Regulator
MAX1765
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.)
PARAMETER
CONTROL INPUTS
ONA,
ONB,
ONL
(Note 5)
Input Low Level
CLK/SEL
TRACK
ONA,
ONB,
ONL
(Note 5)
Input High Level
CLK/SEL
TRACK
Input Leakage Current
(CLK/SEL, ONA,
ONB,
ONL, TRACK)
Internal Oscillator Frequency
External Oscillator
Synchronization Range
Oscillator Maximum Duty Cycle
Minimum CLK/SEL Pulse
Maximum CLK/SEL Rise/Fall Time
CLK/SEL = OUT
0.8
0.5
80
86
200
100
1.1V < V
OUT
< 1.8V
1.8V < V
OUT
< 5.5V
1.2V < V
OUT
< 5.5V
1.2V < V
INL
< 5.5V
1.1V < V
OUT
< 1.8V
1.8V < V
OUT
< 5.5V
1.2V < V
OUT
< 5.5V
1.2V < V
INL
< 5.5V
V
OUT
- 0.2
1.6
0.8
×
V
OUT
0.8
×
V
INL
0.01
1
1
1.2
1.2
90
μA
MHz
MHz
%
ns
ns
V
0.2
0.4
0.2
×
V
OUT
0.2
×
V
INL
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
4
_______________________________________________________________________________________
800mA, Low-Noise, Step-Up DC-DC Converter
with 500mA Linear Regulator
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
DC-DC CONVERTER
FB Regulation Voltage
OUT Voltage in Track Mode
Startup to Normal Mode
Transition Voltage
Supply Current in Normal Mode
(Note 3)
Supply Current in
Low-Noise PWM Mode (Note 3
Supply Current in Shutdown
DC-DC SWITCHES
POUT Leakage Current
LX Leakage Current
Switch On-Resistance
N-Channel Current Limit (Note 4)
P-Channel Turn-Off Current
REFERENCE
Reference Output Voltage
LINEAR REGULATOR
Output Voltage in Internal
Feedback Mode
FBL Input Threshold
FBL Regulation Voltage
LDO Startup Voltage
Dropout Resistance
INL Supply Current in Shutdown
INL No-Load Supply Current
FBL = OUTL, I
OUTL
= 10mA, I
REF
= 0A
V
OUT
= 2V, rising edge only
V
FBL
= 1V, I
OUTL
= 500mA
OUTL = ONA = ONL = GND
I
OUTL
= 0A, V
INL
= 5.5V
FBL = GND, I
OUTL
= 10mA
2.79
150
1.225
2.15
2.90
350
1.275
2.45
0.5
10
250
V
mV
V
V
Ω
µA
µA
I
REF
= 0A
1.225
1.275
V
I
LIM
V
LX
= 0V, V
OUT
= 5.5V
V
LX
= V
OUT
= V
ONB
= 5.5V, ONA = GND
N-channel
P-channel
V
ISET
= 1.25V, CLK/SEL = GND or OUT
CLK/SEL = GND
1000
5
10
10
0.28
0.50
1600
120
µA
µA
Ω
mA
mA
V
FB
CLK/SEL = OUT, 0 < I
LX
< 0.55A
V
OUTL
> 2.0V, INL = POUT
Rising edge only (Note 2)
CLK/SEL = ONL = GND, no load
CLK/SEL = OUT, V
FB
= 1.5V, no load
ONA = ONL = GND,
ONB
= OUT
1.210
V
OUTL
+ 0.4
2.00
1.280
V
OUTL
+ 0.6
2.30
200
200
10
V
V
V
µA
µA
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX1765
_______________________________________________________________________________________
5
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