19-1307; Rev 2; 11/02
L
MANUA
ION KIT HEET
AT
EVALU
DATA S
LOWS
FOL
Step-Up/Down DC-DC Converter
in QSOP Package
____________________________Features
o
Step-Up/Down Voltage Conversion
o
1.8V to 11V Input Range
o
3.3V/5V or Adjustable Output Voltage Range
o
Output Current:
300mA at 5V (V
IN
≥
2.5V)
150mA at 5V (V
IN
≥
1.8V)
o
Smaller Inductor than SEPIC and Flybacks
o
Load Disconnects from Input in Shutdown
o
Supply Current from Battery:
85µA (No-Load)
0.1µA (Shutdown)
o
PGI/PGO Low-Battery Comparator
o
16-Pin QSOP Package
(Same Footprint as 8-pin SO)
o
No External FETs Required
o
Thermal and Short-Circuit Protection
________________General Description
The MAX1672 integrates a step-up DC-DC converter with a
linear regulator to provide step-up/down voltage conver-
sion. This device provides a constant output voltage for
inputs that vary above and below the output voltage. It has
a 1.8V to 11V input range and a preset 3.3V or 5V output.
The output can also be set from 1.25V to 5.5V using two
resistors. Typical efficiency is 85%.
The MAX1672’s step-up/linear-regulator configuration per-
mits the use of a single, physically smaller inductor than
can be used with competing SEPIC and flyback configura-
tions. Switch current is also selectable, permitting the use
of smaller inductors in low-current applications. The linear
regulator also acts as a filter to reduce output ripple voltage.
The MAX1672 has a low 85µA quiescent supply current, which
is further reduced to 0.1µA in logic-controlled shutdown. The
output voltage is disconnected from the input in shutdown.
The MAX1672 also has a PGI/PGO low-battery detector.
The MAX1672 comes in a 16-pin QSOP package (same size
as a standard 8-pin SO). For a larger device that delivers more
output current, refer to the MAX710/MAX711. The preassem-
bled MAX1672 evaluation kit is available to speed designs.
MAX1672
________________________Applications
Single-Cell, Lithium-Powered
Portable Devices
3.3V and Other Low-Voltage
Systems
Digital Cameras
2-Cell to 4-Cell AA Alkaline
Hand-Held Equipment
Battery-Powered Devices
with AC Input Adapters
PART
MAX1672C/D
MAX1672EEE
Ordering Information
TEMP RANGE
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
Dice*
16 QSOP
*Dice
are tested at T
A
= +25°C.
Typical Operating Circuit
INPUT
1.8V TO 11V
IN
PGI
LX
PS
LX 1
PGND 2
Pin Configuration
TOP VIEW
16 LX
15 PGND
14 GND
MAX1672
ON
ON
3.3V
0.5A
OFF
OFF
5V
0.8A
ONA
ONB
3/5
ILIM
REF
PGND
GND
OUT
3.3V/5V
OUTPUT
ONB 3
ONA 4
3/5 5
PGI 6
PG0
FB
LOW-BATTERY
DETECTOR
OUTPUT
PGO 7
ILIM 8
MAX1672
13 REF
12 IN
11 PS
10 FB
9
OUT
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.
Step-Up/Down DC-DC Converter
in QSOP Package
MAX1672
ABSOLUTE MAXIMUM RATINGS
IN, PS, LX, OUT,
PGO
to GND ......................... -0.3V to +11.5V
ILIM, ONA,
ONB,
FB, 3/5,
REF, PGI to GND......................................-0.3V to (V
PS
+ 0.3V)
PGND to GND .......................................................-0.3V to +0.3V
OUT Short Circuit to GND ..........................................Continuous
Output Current ..................................................................350mA
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate above +70°C by 8.3mW/°C).......667mW
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
PS
= 6V, C
REF
= 0.1µF, C
OUT
= 4.7µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Input Voltage
Startup Voltage
FB = GND,
I
OUT
= 0mA to
150mA
3/5 = GND
V
PS
= 6.8V
3/5 = PS
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
4.8
4.75
3.17
3.13
1.25
V
IN
= 2V, 3/5 = GND, FB = GND, I
OUT
= 10mA to 150mA
V
IN
= 3V to 5V, 3/5 = GND, I
OUT
= 100mA
ONA = PS or
ONB
= GND, current measured into PS pin,
I
OUT
= 0mA
ONA = GND,
ONB
= PS, current measured into PS pin
I
REF
= 0mA
OUT = FB
Hysteresis = 15mV typical
V
FB
= 1.3V
V
IN
= GND to 11V
V
PS
= 5.5V, I
LX
= 50mA
V
PS
= 2.7V, I
LX
= 50mA
V
LX
= 11V, ONA = GND,
ONB
= PS
ILIM = GND
LX Current Limit
ILIM = PS
Output PFET Resistance
V
PS
= 5.5V, I
OUT
= 50mA
V
PS
= 2.7V, I
OUT
= 50mA
V
PS
= 5.5V
0.35
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
0.35
0.3
0.6
0.5
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
1.21
1.21
1.20
70
1
3
0.6
0.9
0.1
0.5
0.5
0.8
0.8
1.2
2.3
0.1
0.7
50
6
1.3
2.0
1
0.65
0.7
1.0
1.1
2.4
4.6
1
1.4
Ω
µA
A
A
0.003
0.15
85
0.1
1.25
1.25
125
1
1.29
1.29
1.30
3.30
5.00
CONDITIONS
MIN
1.8
0.9
5.2
5.25
3.43
3.47
5.5
V
%/mA
%/V
µA
µA
V
V
mV
nA
µA
Ω
µA
V
TYP
MAX
11.0
UNITS
V
V
Output Voltage
Output Voltage Adjustment
Range
Output Load Regulation
Output Line Regulation
Quiescent Current
Shutdown Quiescent Current
Reference Voltage
FB Voltage
FB Dual-Mode Trip Threshold
FB Input Current
IN Input Current
LX On-Resistance
LX Leakage Current
Output PFET Leakage Current V
OUT
= 0V, ONA = GND,
ONB
= PS
Output PFET Current Limit
2
_______________________________________________________________________________________
Step-Up/Down DC-DC Converter
in QSOP Package
ELECTRICAL CHARACTERISTICS (continued)
(V
PS
= 6V, C
REF
= 0.1µF, C
OUT
= 4.7µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
PGI/PGO COMPARATOR
PGI Input Bias Current
Hysteresis
PGI Threshold Voltage
PGO
Output Leakage
PGO
Output Low Voltage
LOGIC AND CONTROL INPUTS
Input Low Voltage
Input High Voltage
Input Bias Current
ONA,
ONB,
3/5; ILIM
ONA,
ONB,
3/5; ILIM
ONA,
ONB,
3/5, ILIM
1.6
1
100
0.4
V
V
nA
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
V
PGO
= 11V
I
PGO
= 2mA, V
PGI
= 1.2V
1.21
1.19
1.25
0.1
0.1
V
PGI
= 1.3V
CONDITIONS
MIN
TYP
150
20
1
30
1.29
1.31
1
0.4
50
MAX
UNITS
°C
°C
nA
mV
V
µA
V
MAX1672
Note 1:
Specifications to -40°C are guaranteed by design.
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 5V)
MAX1672-01
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 3.3V)
MAX1672-02
EFFICIENCY vs. INPUT VOLTAGE
(I
OUT
= 10mA)
MAX1672-03
100
V
IN
= 5V
V
IN
= 2.7V
80
V
IN
= 3.6V
100
V
IN
= 3.3V
V
IN
= 2.7V
100
90
EFFICIENCY (%)
90
EFFICIENCY (%)
90
EFFICIENCY (%)
V
OUT
= 5V
80
80
70
V
IN
= 1.8V
60
V
IN
= 0.9V
70
V
IN
= 1.8V
60
V
IN
= 0.9V
70
V
OUT
= 3.3V
60
50
0.1
1
10
100
1000
OUTPUT CURRENT (mA)
50
0.1
1
10
100
1000
OUTPUT CURRENT (mA)
50
0
1
2
3
4
5
6
7
8
9
10
INPUT VOLTAGE (V)
_______________________________________________________________________________________
3
Step-Up/Down DC-DC Converter
in QSOP Package
MAX1672
Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
(POWER DISSIPATION LIMIT)
MAX1672-05
MAXIMUM OUTPUT CURRENT vs.
INPUT VOLTAGE (V
OUT
= 5V)
MAX1672-04
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE (V
OUT
= 3.3V)
400
MAXIMUM OUTPUT CURRENT (mA)
MAXIMUM RECOMMENDED
OUTPUT CURRENT
300
ILIM = PS (0.8A)
200
ILIM = GND (0.5A)
400
MAXIMUM OUTPUT CURRENT (mA)
MAXIMUM OUTPUT CURRENT (mA)
MAXIMUM RECOMMENDED
OUTPUT CURRENT
300
300
MAXIMUM RECOMMENDED
OUTPUT CURRENT
V
OUT
= 5V
200
ILIM = PS (0.8A)
ILIM = GND (0.5A)
200
V
OUT
= 3.3V
100
V
OUT
= 5V
T
A
= +25°C
T
A
= +85°C
V
OUT
= 3.3V
7
8
9
10
11
100
100
0
0
1
2
INPUT VOLTAGE (V)
3
4
0
0
1
2
INPUT VOLTAGE (V)
3
4
0
4
5
6
INPUT VOLTAGE (V)
MAXIMUM RECOMMENDED INPUT VOLTAGE
MAX1672-12
12
NO-LOAD BATTERY CURRENT
vs. INPUT VOLTAGE
MAX1672-07
SHUTDOWN CURRENT
vs. INPUT VOLTAGE
MAX1672-08
LINEAR REGULATOR POWER-SUPPLY
REJECTION RATIO vs. FREQUENCY
MAX1672-09
1000
1
70
60
50
PSRR (dB)
SUPPLY CURRENT (µA)
V
OUT
= 5V
100
V
OUT
= 3.3V
SUPPLY CURRENT (µA)
0.1
40
30
20
10
0
1
2
3
4
5
6
7
8
9 10 11
INPUT VOLTAGE (V)
0.01
0
1
2
3
4
5
6
7
8
9 10 11
INPUT VOLTAGE (V)
10
0.01
0.1
1
10
100
1000
FREQUENCY (kHz)
LINE-TRANSIENT RESPONSE
MAX1672-10
LOAD-TRANSIENT RESPONSE
MAX1672-11
OUTPUT RIPPLE (MEDIUM LOAD)
A
A
B
B
B
2ms/div
A: V
OUT
= 5V (100mV/div, AC COUPLED)
B: V
IN
= 2V TO 4V (I
OUT
= 100mA)
2ms/div
A: V
OUT
= 5V (50mV/div, AC COUPLED)
B: I
OUT
= 10mA TO 100mA (V
IN
= 2V)
10µs/div
A: V
OUT
= 5V (20mV/div, AC COUPLED)
B: I
L1
(500mA /div) (V
IN
= 2.7V, I
OUT
= 80mA)
4
_______________________________________________________________________________________
MAX1672-06
400
A
Step-Up/Down DC-DC Converter
in QSOP Package
Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
MAX1672
OUTPUT RIPPLE (HEAVY LOAD)
MAX1672-13
STARTUP DELAY
MAX1672-14
TURN-OFF DELAY
MAX1672-15
A
A
A
B
B
B
10µs/div
A: V
OUT
= 5V (20mV/div, AC COUPLED)
B: I
L1
(500mA/div) (V
IN
= 2.7V, I
OUT
= 250mA)
50µs/div
A: V
OUT
= (2V/div)
B: ONB (2V/div) (V
IN
= 2.7V, R
LOAD
= 50Ω)
200µs/div
A: V
OUT
= (2V/div)
B: ONB (2V/div) (V
IN
= 2.7V, R
LOAD
= 50Ω)
______________________________________________________________Pin Description
PIN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
NAME
LX
PGND
ONB
ONA
3/5
PGI
PGO
ILIM
OUT
FB
PS
IN
REF
GND
PGND
LX
FUNCTION
Inductor Connection to the Drain of the Internal N-Channel Power MOSFET
Power Ground
On Control Input. When
ONB
= low or ONA = high, the IC is on. Connect
ONB
to GND for normal operation
(Table 1).
On Control Input. When ONA = low and
ONB
= high, the IC is off. Connect ONA to PS for normal operation
(Table 1).
Output Voltage Selection Input. Connect to PS for 3.3V output and to GND for 5V output. With V
FB
> 80mV,
the state of the 3/5 pin is ignored (Table 2).
Low-Battery Detector Input (1.25V threshold)
Low-Battery Detector Output (open drain).
PGO
pulls low when V
PGI
is greater than 1.25V.
Inductor-Current-Limit Selection Input. Connect to PS for 0.8A current limit and to GND for 0.5A current limit.
Regulator Output. Drain of internal PFET linear regulator. Bypass with a 4.7µF capacitor to GND.
Feedback Input. For 3.3V or 5V output, connect to GND. For adjustable output, connect to feedback resistor-
divider network. With V
FB
> 70mV, the state of the 3/5 pin is ignored.
Bootstrapped Power Supply. Output of step-up switch-mode regulator and source of internal PFET linear
regulator. The IC is powered from this pin.
Input Voltage Sense Input. Connect to input supply.
Reference Voltage Output. Bypass with a 0.1µF capacitor to GND.
Analog Ground
Power Ground
Inductor Connection to the Drain of the Internal N-Channel Power MOSFET
_______________________________________________________________________________________
5
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