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19-1360; Rev 0; 7/98
IT
TION K
VALUA
E
BLE
AVAILA
High-Efficiency, Low-Supply-Current,
Compact, Step-Up DC-DC Converters
General Description
____________________________Features
o
94% Efficient at 200mA Output Current
o
16µA Quiescent Supply Current
o
Internal Synchronous Rectifier (no external diode)
o
0.1µA Logic-Controlled Shutdown
o
LBI/LBO Low-Battery Detector
o
Selectable Current Limit for Reduced Ripple
o
Low-Noise, Anti-Ringing Feature (MAX1676)
o
8-Pin and 10-Pin µMAX Packages
o
Preassembled Evaluation Kit (MAX1676EVKIT)
MAX1674/MAX1675/MAX1676
The MAX1674/MAX1675/MAX1676 compact, high-effi-
ciency, step-up DC-DC converters fit in small µMAX
packages. They feature a built-in synchronous rectifier,
which improves efficiency and reduces size and cost
by eliminating the need for an external Schottky diode.
Quiescent supply current is only 16µA.
The input voltage ranges from 0.7V to V
OUT
, where
V
OUT
can be set from 2V to 5.5V. Start-up is guaran-
teed from 1.1V inputs. The MAX1674/MAX1675/
MAX1676 have a preset, pin-selectable output for 5V or
3.3V. The outputs can also be adjusted to other volt-
ages using two external resistors.
All three devices have a 0.3Ω N-channel MOSFET
power switch. The MAX1674 has a 1A current limit. The
MAX1675 has a 0.5A current limit, which permits the
use of a smaller inductor. The MAX1676 comes in a
10-pin µMAX package and features an adjustable cur-
rent limit and circuitry to reduce inductor ringing.
_______________Ordering Information
PART
MAX1674EUA
MAX1675EUA
MAX1676EUB
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 µMAX
8 µMAX
10 µMAX
________________________Applications
Pagers
Wireless Phones
Medical Devices
Hand-Held Computers
PDAs
RF Tags
1 to 3-Cell Hand-Held Devices
Pin Configurations
TOP VIEW
Typical Operating Circuit
FB
1
INPUT
0.7V TO V
OUT
LBI
LBO
2
3
8
OUT
LX
GND
SHDN
MAX1674
MAX1675
7
6
5
REF
4
ON
OFF
SHDN
LX
OUTPUT
3.3V, 5V, OR
ADJ (2V TO 5.5V)
UP TO 300mA
µMAX
MAX1674
OUT
MAX1675
FB
1
LBI
2
LOW-BATTERY
DETECT IN
LBI
REF
0.1µF
FB
LBO
GND
LOW-BATTERY
DETECT OUT
LBO
3
CLSEL
4
REF
5
10
OUT
9
LX
GND
BATT
SHDN
MAX1676
8
7
6
µMAX
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
High-Efficiency, Low-Supply-Current,
Compact, Step-Up DC-DC Converters
MAX1674/MAX1675/MAX1676
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (OUT to GND) ..............................-0.3V to +6.0V
Switch Voltage (LX to GND) .....................-0.3V to (V
OUT
+ 0.3V)
Battery Voltage (BATT to GND).............................-0.3V to +6.0V
SHDN, LBO
to GND ..............................................-0.3V to +6.0V
LBI, REF, FB, CLSEL to GND ...................-0.3V to (V
OUT
+ 0.3V)
Switch Current (LX) ...............................................-1.5A to +1.5A
Output Current (OUT) ...........................................-1.5A to +1.5A
Continuous Power Dissipation (T
A
= +70°C)
8-Pin µMAX (derate 4.1mW/°C above +70°C) .............330mW
10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +165°C
Lead Temperature (soldering, 10sec) .............................+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
BATT
= 2V, FB = OUT (V
OUT
= 3.3V), R
L
= ˙∞,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Minimum Input Voltage
Operating Voltage
Start-Up Voltage
Start-Up Voltage Tempco
Output Voltage
Output Voltage Range
FB = OUT
(V
OUT
= 3.3V)
Steady-State Output Current
(Note 2)
I
OUT
FB = GND
(V
OUT
= 5V)
Reference Voltage
Reference Voltage Tempco
Reference Voltage Load
Regulation
Reference Voltage Line
Regulation
FB, LBI Input Threshold
Internal NFET, PFET
On-Resistance
LX Switch Current
Limit (NFET)
LX Leakage Current
R
DS(ON)
I
LIM
I
LEAK
I
LX
= 100mA
MAX1674, MAX1676 (CLSEL = OUT)
MAX1675, MAX1676 (CLSEL = GND)
V
LX
= 0, 5.5V; V
OUT
= 5.5V
0.80
0.4
V
REF
TEMPCO
V
REF_LOAD
V
REF_LINE
I
REF
= 0 to 100µA
V
OUT
= 2V to 5.5V
1.274
I
REF
= 0
MAX1674,
MAX1676 (CLSEL = OUT)
MAX1675,
MAX1676 (CLSEL = GND)
MAX1674,
MAX1676 (CLSEL = OUT)
MAX1675,
MAX1676 (CLSEL = GND)
V
OUT
FB = OUT
FB = GND
3.17
4.80
2
300
150
180
90
1.274
420
220
mA
285
130
1.30
0.024
3
0.08
1.30
0.3
1
0.5
0.05
15
2.5
1.326
0.6
1.20
0.65
1
1.326
V
mV/°C
mV
mV/V
V
Ω
A
µA
V
IN
T
A
= +25°C
T
A
= +25°C, R
L
= 3kΩ (Note 1)
1.1
0.9
-2
3.30
5
3.43
5.20
5.5
SYMBOL
CONDITIONS
MIN
TYP
0.7
5.5
1.1
MAX
UNITS
V
V
V
mV/°C
V
V
2
_______________________________________________________________________________________
High-Efficiency, Low-Supply-Current,
Compact, Step-Up DC-DC Converters
ELECTRICAL CHARACTERISTICS (continued)
(V
BATT
= 2V, FB = OUT (V
OUT
= 3.3V), R
L
= ˙∞,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Operating Current into OUT
(Note 3)
Shutdown Current into OUT
Efficiency
LX Switch On-Time
LX Switch Off-Time
FB Input Current
LBI Input Current
CLSEL Input Current
SHDN
Input Current
LBO
Low Output Voltage
LBO
Off Leakage Current
Damping Switch Resistance
SHDN
Input Voltage
CLSEL Input Voltage
V
IL
V
IH
V
IL
V
IH
0.8V
OUT
0.8V
OUT
0.2V
OUT
I
LBO
t
ON
t
OFF
I
FB
I
LBI
I
CLSEL
I
SHDN
SYMBOL
CONDITIONS
V
FB
= 1.4V, V
OUT
= 3.3V
SHDN
= GND
V
OUT
= 3.3V, I
LOAD
= 200mA
V
OUT
= 2V, I
LOAD
= 1mA
V
FB
= 1V, V
OUT
= 3.3V
V
FB
= 1V, V
OUT
= 3.3V
V
FB
= 1.4V
V
LBI
= 1.4V
MAX1676, CLSEL = OUT
V
SHDN
= 0 or V
OUT
V
LBI
= 0, I
SINK
= 1mA
V
LBO
= 5.5V, V
LBI
= 5.5V
MAX1676, V
BATT
= 2V
3
0.8
MIN
TYP
16
0.1
90
85
4
1
0.03
1
1.4
0.07
0.2
0.07
88
7
1.2
50
50
3
50
0.4
1
150
0.2V
OUT
MAX
35
1
UNITS
µA
µA
%
µs
µs
nA
nA
µA
nA
V
µA
Ω
V
V
MAX1674/MAX1675/MAX1676
Note 1:
Start-up voltage operation is guaranteed with the addition of a Schottky MBR0520 external diode between the input and
output.
Note 2:
Steady-state output current indicates that the device maintains output voltage regulation under load. See Figures 5 and 6.
Note 3:
Device is bootstrapped (power to the IC comes from OUT). This correlates directly with the actual battery supply.
ELECTRICAL CHARACTERISTICS
(V
BATT
= 2V, FB = OUT, R
L
=
∞,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 4)
PARAMETER
Output Voltage
Output Voltage Range
Reference Voltage
FB, LBI Thresholds
Internal NFET, PFET
On-Resistance
Operating Current into OUT
(Note 3)
Shutdown Current into OUT
LX Switch On-Time
LX Switch Off-Time
LX Switch Current
Limit (NFET)
t
ON
t
OFF
I
LIM
R
DS(ON)
V
FB
= 1.4V, V
OUT
= 3.3V
SHDN
= GND
V
FB
= 1V, V
OUT
= 3.3V
V
FB
= 1V, V
OUT
= 3.3V
MAX1674, MAX1676 (CLSEL = OUT)
MAX1675, MAX1676 (CLSEL = GND)
2.7
0.75
0.75
0.36
V
REF
I
REF
= 0
SYMBOL
V
OUT
FB = OUT
FB = GND
CONDITIONS
MIN
3.13
4.75
2.20
1.2675
1.2675
MAX
3.47
5.25
5.5
1.3325
1.3325
0.6
40
1
7.0
1.25
1.25
0.69
UNITS
V
V
V
V
Ω
µA
µA
µs
µs
A
_______________________________________________________________________________________
3
High-Efficiency, Low-Supply-Current,
Compact, Step-Up DC-DC Converters
MAX1674/MAX1675/MAX1676
ELECTRICAL CHARACTERISTICS (continued)
(V
BATT
= 2V, FB = OUT, R
L
=
∞,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 4)
PARAMETER
CLSEL Input Current
SHDN
Input Current
LBO
Off Leakage Current
SYMBOL
I
CLSEL
I
SHDN
I
LBO
CONDITIONS
MAX1676, CLSEL = OUT
V
SHDN
= 0 or V
OUT
V
LBO
= 5.5V, V
LBI
= 5.5V
MIN
MAX
3
75
1
UNITS
µA
nA
µA
Note 4:
Specifications to -40°C are guaranteed by design, not production tested.
Typical Operating Characteristics
(L = 22µH, C
IN
= 47µF, C
OUT
= 47µF

0.1µF, C
REF
= 0.1µF, T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
MAX1674 toc01
EFFICIENCY vs. LOAD CURRENT
MAX1674 toc02
EFFICIENCY vs. LOAD CURRENT
90
80
EFFICIENCY (%)
70
60
50
40
30
20
V
IN
= 2.4V
V
IN
= 1.2V
MAX1674 toc03
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
0.1
1
10
V
OUT
= 5V
I
LIMIT
= 500mA
100
V
IN
= 3.6V
V
IN
= 2.4V
V
IN
= 1.2V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
0.1
1
10
LOAD CURRENT (mA)
V
OUT
= 5V
I
LIMIT
= 1A
100
V
IN
= 1.2V
V
IN
= 2.4V
V
IN
= 3.6V
100
10
0
0.01
0.1
1
10
V
OUT
= 3.3V
I
LIMIT
= 500mA
100
1000
1000
1000
LOAD CURRENT (mA)
LOAD CURRENT (mA)
EFFICIENCY vs. LOAD CURRENT
MAX1674 toc04
REFERENCE OUTPUT VOLTAGE
vs. TEMPERATURE
MAX1674 toc05
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
0.1
1
10
LOAD CURRENT (mA)
V
OUT
= 3.3V
I
LIMIT
= 1A
100
V
IN
= 1.2V
V
IN
= 2.4V
1.300
REFERENCE OUTPUT VOLTAGE (V)
1.298
I
REF
= 0
1.296
1.294
I
REF
= 100µA
1.292
1.290
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
1000
4
_______________________________________________________________________________________
High-Efficiency, Low-Supply-Current,
Compact, Step-Up DC-DC Converters
Typical Operating Characteristics (continued)
(L = 22µH, C
IN
= 47µF, C
OUT
= 47µF

0.1µF, C
REF
= 0.1µF, T
A
= +25°C, unless otherwise noted.)
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
MAX1674toc08
MAX1674/MAX1675/MAX1676
NO-LOAD BATTERY CURRENT
vs. INPUT BATTERY VOLTAGE
MAX1674toc07
START-UP VOLTAGE
vs. LOAD CURRENT
1.8
1.6
START-UP VOLTAGE (V)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0.01
0.1
1
10
LOAD CURRENT (mA)
100
WITH 1N5817
WITHOUT DIODE
1.0
0.8
SHUTDOWN CURRENT (µA)
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1.0
1
140
INPUT BATTERY CURRENT (µA)
120
100
80
I
LIMIT
= 0.5A, 5.0V
60
40
20
0
0
I
LIMIT
= 0.5A, 3.3V
I
LIMIT
= 1A, 3.3V
I
LIMIT
= 1A, 5.0V
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
INPUT BATTERY VOLTAGE (V)
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY VOLTAGE (V)
SHUTDOWN THRESHOLD
vs. SUPPLY VOLTAGE
MAX1674TOC10
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE (V
OUT
= 5V)
800
700
600
500
400
300
200
0.5A CURRENT LIMIT
100
0
1A CURRENT LIMIT
MAX1674toc11
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE (V
OUT
= 3.3V)
700
600
1A CURRENT LIMIT
500
400
300
200
100
0
1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
INPUT VOLTAGE (V)
0.5A CURRENT LIMIT
MAX1674toc12
1.4
1.2
SHUTDOWN THRESHOLD (V)
1.0
0.8
0.6
0.4
0.2
0
0
900
MAXIMUM OUTPUT CURRENT (mA)
800
MAXIMUM OUTPUT CURRENT (mA)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
INPUT VOLTAGE (V)
HEAVY-LOAD SWITCHING WAVEFORMS
MAX1674 TOC13
SWITCH RESISTANCE vs. TEMPERATURE
0.40
V
LX
5V/div
I
LX
0.5A/div
0.35
RESISTANCE (Ω)
0.30
0.25
0.20
0.15
0.10
0.2
0.05
0
0
-60 -40
-20
0
20
40
60
80
100
2.0
2.5
N-CHANNEL
I
LIM
(A)
MAX1674toc13.5
LX CURRENT LIMIT
vs. OUTPUT VOLTAGE
MAX1674, MAX1676 (CLSEL = OUT)
MAX1674toc14
0.45
P-CHANNEL
1.2
1.0
0.8
0.6
0.4
MAX1675, MAX1676 (CLSEL = GND)
V
IN
= 2.4V
V
OUT
= 5.0V
1µs/div
V
OUT
AC COUPLED
100mV/div
3.0
3.5
4.0
4.5
5.0
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
_______________________________________________________________________________________
5
MAX167toc09
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