_______________General Description
The MAX1642/MAX1643 are high-efficiency, low-voltage,
step-up DC-DC converters intended for devices pow-
ered by a single alkaline cell. They feature low quies-
cent supply currents and are supplied in the ultra-small
MAX package, which is only 1.1mm high. The guaran-
teed start-up voltage is 0.88V.
Each device consists of an internal 1
, N-channel
MOSFET power switch; a built-in synchronous rectifier
that acts as the catch diode; an oscillator; a reference;
and pulse-frequency-modulation (PFM) control circuitry.
Both devices feature an independent undervoltage
comparator (PFI/PFO). The MAX1642 also includes a
2A logic-controlled shutdown mode. The MAX1643
offers a dedicated low-battery detector (BATTLO) in
lieu of shutdown.
The output voltage for each device is preset to 3.3V
4%, or can be adjusted from +2V to +5.2V using only
two resistors.
________________________Applications
Pagers
Remote Controls
Pointing Devices
Personal Medical Monitors
Single-Cell Battery-Powered Devices
____________________________Features
o
Built-In Synchronous Rectifier
o
0.88V Guaranteed Start-Up
o
Ultra-Small MAX Package: 1.1mm High
o
83% Efficiency
o
4A Quiescent Supply Current into BATT Pin
o
2A Logic-Controlled Shutdown (MAX1642)
o
Two Undervoltage Detectors (MAX1643)
o
2V to 5.2V Output Range
o
20mA Output Current at 1.2V Input
o
Reverse Battery Protection
MAX1642/MAX1643
High-Efficiency, Step-Up
DC-DC Converters for 1V Inputs
________________________________________________________________
Maxim Integrated Products
1
GND
PFO
FB
SHDN
1
2
8
7
OUT
LX
PFI
BATT
MAX1642
MAX
TOP VIEW
3
4
6
5
GND
BATTLO
FB
PFO
1
2
8
7
OUT
LX
PFI
BATT
MAX1643
MAX
3
4
6
5
_________________Pin Configurations
OUT
OUTPUT
3.3V
INPUT
0.88V TO 1.65V
100
H
22
F
22
F
ON
LOW-BATTERY
DETECTOR INPUT
LOW-BATTERY
DETECTOR OUTPUT
OFF
PFO
BATT
LX
MAX1642
SHDN
PFI
GND
FB
__________Typical Operating Circuit
______________Ordering Information
PART
MAX1642
C/D
MAX1642EUA
MAX1643
C/D
0C to +70C
-40C to +85C
0C to +70C
TEMP. RANGE
PIN-PACKAGE
Dice*
8 MAX
Dice*
MAX1643EUA
-40C to +85C
8 MAX
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
19-1183; Rev 0; 6/97
*
Dice are tested at T
A
= +25C.
Note: To order these devices shipped in tape and reel, add a -T
to the part number.
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.
MAX1642/MAX1643
High-Efficiency, Step-Up
DC-DC Converters for 1V Inputs
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
BATT to GND ...........................................................-0.3V to 6.0V
BATT Forward Current ..........................................................0.5A
OUT to GND.............................................................-0.3V to 6.0V
OUT, LX Current.......................................................................1A
LX to GND................................................................-0.3V to 6.0V
SHDN, FB, BATTLO, PFO to GND ...........................-0.3V to 6.0V
PFI to GND ............................................................-0.3V to V
BATT
Reverse Battery Current (T
A
= +25C) (Note 1) ...............220mA
Continuous Power Dissipation
MAX (derate 4.1mW/C above 70C)..........................330mW
Operating Temperature Range
MAX1642EUA/MAX1643EUA ............................-40C to +85C
Junction Temperature ......................................................+150C
Storage Temperature Range .............................-65C to +165C
Lead Temperature (soldering, 10sec) .............................+300C
R
L
= 3k
, T
A
= +25C
V
FB
= 1.3V
I
LOAD
= 20mA
V
BATT
= 1.0V (MAX1642)
0.9V < V
BATT
< 1.5V (t
ON
= K / V
BATT
)
V
OUT
= 3.5V (MAX1642)
I
DIODE
= 100mA, P-channel switch off
V
OUT
= 3.3V
V
FB
< 0.1V
External feedback
External feedback
V
OUT
= 3.5V
V
OUT
= 3.3V
0.9V < V
BATT
< 1.5V, V
OUT
= 3.3V
CONDITIONS
nA
10
FB Input Current
%
80
Efficiency
A
2
3.5
I
SHDN,BATT
Shutdown Current into BATT
A
0.1
1
I
SHDN,OUT
Shutdown Current into OUT
A
4
6.5
I
QBATT
Quiescent Current into BATT
A
11
18
I
QOUT
Quiescent Current into OUT
1
1.5
RATIO
Off-Time Tracking Ratio (Note 3)
mV/C
-2
Start-Up Voltage Tempco
V
0.88
V
0.7
V
BATT(MIN)
Minimum Operating Input Voltage
Start-Up Voltage (Note 2)
V-s
17
25
35
K
On-Time Constant
V
0.8
P-Channel Catch-Diode Voltage
1.5
2.2
P-Channel On-Resistance
V
3.16
3.30
3.44
V
OUT
Output Voltage
V
2.0
5.2
Output Voltage Range
V
1.18
1.225
1.27
V
FB
FB Set Voltage
1
1.5
N-Channel On-Resistance
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
ELECTRICAL CHARACTERISTICS
(V
BATT
= V
SHDN
= 1.3V, I
LOAD
= 0mA, FB = GND,
T
A
= 0C to +85C,
unless otherwise noted. Typical values are at T
A
= +25C.)
Note 1:
The reverse battery current is measured from the
Typical Operating Circuit's input terminal to GND when the battery is con-
nected backward. A reverse current of 220mA will not exceed package dissipation limits but, if left for an extended time
(more than 10 minutes), may degrade performance.
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.
V
1.65
Maximum Operating Input Voltage
Falling PFI, hysteresis = 1%
mV
590
614
632
PFI Trip Voltage
V
PFI
= 0V, V
OUT
= 3.3V, I
SINK
= 1mA
V
PFI
= 650mV
V
0.4
V
OL
PFO, BATTLO Low Output Voltage
nA
10
PFI Input Current
V
OUT
= 3.3V, hysteresis = 2% (MAX1643)
V
PFI
= 650mV, V
PFO
= 6V
V
0.96
1.0
1.04
BATTLO Trip Voltage
A
1
PFO, BATTLO Leakage Current
% of V
BATT
(MAX1642)
% of V
BATT
(MAX1642)
%
80
V
IH
SHDN Input High Voltage
%
20
V
IL
SHDN Input Low Voltage
(MAX1642)
nA
10
SHDN Input Current
MAX1642/MAX1643
High-Efficiency, Step-Up
DC-DC Converters for 1V Inputs
_______________________________________________________________________________________
3
Note 2:
Start-up guaranteed by correlation to measurements of device parameters (i.e., switch on-resistance, on-times, off-times, and
output voltage trip points).
Note 3:
. This guarantees discontinuous conduction.
Note 4:
Specifications to -40C are guaranteed by design, not production tested.
t
=
t
x V
V
- V
x RATIO
OFF
ON
BATT
OUT
BATT
Falling PFI, hysteresis = 1%
V
BATT
= 1.0V (MAX1642)
0.9V < V
BATT
< 1.5V (t
ON
= K / V
BATT
)
V
OUT
= 3.5V (MAX1642)
V
OUT
= 3.3V
V
FB
< 0.1V
External feedback
V
OUT
= 3.5V
V
OUT
= 3.3V
CONDITIONS
mV
550
662
PFI Trip Voltage
A
3.5
I
SHDN,BATT
Shutdown Current into BATT
A
1
I
SHDN,OUT
Shutdown Current into OUT
A
6.5
I
QBATT
Quiescent Current into BATT
A
18
I
QOUT
Quiescent Current into OUT
V-s
12.4
38.2
K
On-Time Constant
2.2
P-Channel On-Resistance
V
2.99
3.56
V
OUT
Output Voltage
V
1.11
1.32
V
FB
FB Set Voltage
1.5
N-Channel On-Resistance
UNITS
MIN
MAX
SYMBOL
PARAMETER
ELECTRICAL CHARACTERISTICS
(V
BATT
= V
SHDN
= 1.3V, I
LOAD
= 0mA, FB = GND,
T
A
= -40C to +85C,
unless otherwise noted.) (Note 4)
Falling V
BATT
, V
OUT
= 3.3V, hysteresis = 2%
(MAX1643)
V
0.93
1.06
BATTLO Trip Voltage
__________________________________________Typical Operating Characteristics
(Circuit of Figure 4, V
BATT
= 1.2V, R1 + R2 = 1M
, T
A
= +25C, unless otherwise noted.)
0
0.01
1
10
0.1
100
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 2.4V)
10
MAX1642/43 TOC01A
OUTPUT CURRENT (mA)
EFFICIENCY (%)
V
IN
= 1.6V
L1 = 100
H
SUMIDA CD54-101
V
IN
= 1.2V
V
IN
= 0.85V
V
IN
= 1.0V
20
30
40
50
60
70
80
90
100
0
0.01
1
10
0.1
100
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 2.4V)
10
MAX1642/43 TOC01B
OUTPUT CURRENT (mA)
EFFICIENCY (%)
V
IN
= 1.6V
L1 = 150
H
TDK NLC565050T-151K
V
IN
= 1.2V
V
IN
= 0.85V
V
IN
= 1.0V
20
30
40
50
60
70
80
90
100
0
0.01
1
10
0.1
100
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 3.3V)
10
MAX1642/43 TOC02A
OUTPUT CURRENT (mA)
EFFICIENCY (%)
V
IN
= 1.6V
L1 = 100
H
SUMIDA CD54-101
V
IN
= 1.2V
V
IN
= 0.85V
V
IN
= 1.0V
20
30
40
50
60
70
80
90
100
MAX1642/MAX1643
High-Efficiency, Step-Up
DC-DC Converters for 1V Inputs
4
_______________________________________________________________________________________
0.6
0
MINIMUM START-UP INPUT VOLTAGE
vs. OUTPUT CURRENT
0.7
0.8
MAX1642/43 TOC07b
OUTPUT CURRENT (mA)
START-UP INPUT VOLTAGE (V)
12
14
1.2
1.1
1.5
1.4
1.3
0.9
1.0
2
4
6
10
16
1.6
8
L1 = 150
H
TDK NLC565050T-151K
V
OUT
= 5V
V
OUT
= 2.4V, 3.3V
0.6
0
MINIMUM START-UP INPUT VOLTAGE
vs. OUTPUT CURRENT
0.7
0.8
MAX1642/43 TOC07a
OUTPUT CURRENT (mA)
START-UP INPUT VOLTAGE (V)
20
1.2
1.1
1.5
1.4
1.3
0.9
1.0
5
15
25
1.6
10
L1 = 100
H
SUMIDA CD54-101
V
OUT
= 5V
V
OUT
= 2.4V, 3.3V
____________________________Typical Operating Characteristics (continued)
(Circuit of Figure 4, V
BATT
= 1.2V, R1 + R2 = 1M
, T
A
= +25C, unless otherwise noted.)
0
0.01
1
10
0.1
100
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 3.3V)
10
MAX1642/43 TOC02B
OUTPUT CURRENT (mA)
EFFICIENCY (%)
V
IN
= 1.6V
L1 = 150
H
TDK NLC565050T-151K
V
IN
= 1.2V
V
IN
= 0.85V
V
IN
= 1.0V
20
30
40
50
60
70
80
90
100
100
90
80
0
0.01
1
10
0.1
100
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 5.0V)
20
10
MAX1642/43 TOC03a
OUTPUT CURRENT (mA)
EFFICIENCY (%)
30
40
50
60
70
V
IN
= 1.6V
V
IN
= 0.85V
V
IN
= 1.0V
L1 = 100
H
SUMIDA CD54-101
V
IN
= 1.2V
100
90
80
0
0.01
1
10
0.1
100
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 5.0V)
20
10
MAX1642/43 TOC03b
OUTPUT CURRENT (mA)
EFFICIENCY (%)
30
40
50
60
70
V
IN
= 1.6V
V
IN
= 0.85V
V
IN
= 1.0V
L1 = 150
H
TDK NLC565050T-151K
V
IN
= 1.2V
10,000
10
0.8
1.0
1.4
1.8
NO-LOAD BATTERY CURRENT
vs. INPUT VOLTAGE
100
1000
MAX1642/43 TOC04
INPUT VOLTAGE (V)
QUIESCENT CURRENT (
m
A)
1.2
1.6
V
OUT
= 5.0V
V
OUT
= 2.5V OR 3.3V
0
-40
NO-LOAD BATTERY CURRENT
vs. TEMPERATURE
20
MAX1642/43 TOC05
TEMPERATURE (C)
QUIESCENT CURRENT (
A)
60
100
120
80
40
60
-20
40
20
80
100
140
0
V
BATT
= 1.2V
V
OUT
= 3.3V
0
-40
BATT AND OUT PIN QUIESCENT CURRENTS
vs. TEMPERATURE
5
MAX1642/43 TOC06
TEMPERATURE (C)
QUIESCENT CURRENT (
A)
60
20
25
10
15
-20
40
20
80
100
30
0
V
BATT
= 1.2V
V
OUT
= 3.6V
I
BATT
I
OUT
MAX1642/MAX1643
High-Efficiency, Step-Up
DC-DC Converters for 1V Inputs
_______________________________________________________________________________________
5
____________________________Typical Operating Characteristics (continued)
(Circuit of Figure 4, V
BATT
= 1.2V, R1 + R2 = 1M
, T
A
= +25C, unless otherwise noted.)
B
LOAD-TRANSIENT RESPONSE
MAX1642/43 TOC10
A
400s/div
V
OUT
= 3.3V, V
BATT
= 1.2V
A: OUT, 20mV/div, 3.3V DC OFFSET
B: LOAD, 2mA to 20mA, 10mA/div
0
0.8
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
MAX1642/43 TOC08b
INPUT VOLTAGE (V)
MAXIMUM OUTPUT CURRENT (mA)
1.4
25
30
5
15
10
20
0.9
1.3
1.2
1.5
1.6
35
1.0
1.1
L1 = 100
H
SUMIDA CD54-101
V
OUT
= 5V
V
OUT
= 3.3V
V
OUT
= 2.4V
0
0.8
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
MAX1642/43 TOC08c
INPUT VOLTAGE (V)
MAXIMUM OUTPUT CURRENT (mA)
1.4
14
12
18
16
4
2
6
10
8
0.9
1.3
1.2
1.5
1.6
20
1.0
1.1
L1 = 150
H
TDK NLC565050T-151K
V
OUT
= 5V
V
OUT
= 3.3V
V
OUT
= 2.4V
C
SWITCHING WAVEFORMS
MAX1642/43 TOC09
B
A
10ms/div
V
OUT
= 3.3V, V
IN
= 1.2V, I
OUT
= 12mA
A: LX, 2V/div, L1 = TDK NLC565050T-151K
B: OUT, 20mV/div, 3.3V DC OFFSET
C: INDUCTOR CURRENT, 100mA/div
B
LINE-TRANSIENT RESPONSE
MAX1642/43 TOC11
A
400s/div
V
OUT
= 3.3V, LOAD = 15mA
A: OUT, 50mV/div, 3.3V DC OFFSET
B: V
BATT
, 1V to 1.5V, 500mV/div
B
C
SHUTDOWN RESPONSE AND
INDUCTOR CURRENT
MAX1642/43 TOC12
A
10ms/div
V
OUT
= 3.3V, V
BATT
= 1.2V, I
OUT
= 5mA
A: OUT, 1V/div
B: INDUCTOR CURRENT, 200mA/div
C: SHDN, 2V/div
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