19-1183; Rev 0; 6/97
ANUAL
N KIT M EET
ATIO
EVALU
TA SH
WS DA
FOLLO
High-Efficiency, Step-Up
DC-DC Converters for 1V Inputs
____________________________Features
o
Built-In Synchronous Rectifier
o
0.88V Guaranteed Start-Up
o
Ultra-Small µMAX Package: 1.1mm High
o
83% Efficiency
o
4µA Quiescent Supply Current into BATT Pin
o
2µA 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
_______________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
µMAX package, which is only 1.1mm high. The guaran-
teed start-up voltage is 0.88V.
Each device consists of an internal 1Ω, 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
2µA 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.
MAX1642/MAX1643
______________Ordering Information
PART
MAX1642C/D
MAX1642EUA
MAX1643C/D
MAX1643EUA
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
Dice*
8 µMAX
Dice*
8 µMAX
________________________Applications
Pagers
Remote Controls
Pointing Devices
Personal Medical Monitors
Single-Cell Battery-Powered Devices
*Dice
are tested at T
A
= +25°C.
Note: To order these devices shipped in tape and reel, add a -T
to the part number.
_________________Pin Configurations
TOP VIEW
BATT
1
8
OUT
LX
GND
FB
__________Typical Operating Circuit
PFI
2
PFO
3
SHDN
4
MAX1642
7
6
5
INPUT
0.88V TO 1.65V
22µF
100µH
LX
OUT
OUTPUT
3.3V
22µF
BATT
1
µMAX
MAX1642
BATT
ON
OFF
SHDN
PFI
GND
PFO
FB
8
OUT
LX
GND
FB
LOW-BATTERY
DETECTOR INPUT
LOW-BATTERY
DETECTOR OUTPUT
PFI
2
BATTLO
3
PFO
4
MAX1643
7
6
5
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, Step-Up
DC-DC Converters for 1V Inputs
MAX1642/MAX1643
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
= +25°C) (Note 1) ...............220mA
Continuous Power Dissipation
µMAX (derate 4.1mW/°C above 70°C)..........................330mW
Operating Temperature Range
MAX1642EUA/MAX1643EUA ............................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +165°C
Lead Temperature (soldering, 10sec) .............................+300°C
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.
ELECTRICAL CHARACTERISTICS
(V
BATT
= V
SHDN
= 1.3V, I
LOAD
= 0mA, FB = GND,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Minimum Operating Input Voltage
Maximum Operating Input Voltage
Start-Up Voltage (Note 2)
Start-Up Voltage Tempco
Output Voltage
Output Voltage Range
FB Set Voltage
N-Channel On-Resistance
P-Channel On-Resistance
P-Channel Catch-Diode Voltage
On-Time Constant
Off-Time Tracking Ratio (Note 3)
Quiescent Current into OUT
Quiescent Current into BATT
Shutdown Current into OUT
Shutdown Current into BATT
Efficiency
FB Input Current
PFI Trip Voltage
PFI Input Current
PFO, BATTLO
Low Output Voltage
PFO, BATTLO
Leakage Current
BATTLO
Trip Voltage
SHDN
Input Low Voltage
SHDN
Input High Voltage
SHDN
Input Current
V
IL
V
IH
V
OL
K
RATIO
I
QOUT
I
QBATT
I
SHDN,OUT
I
SHDN,BATT
η
V
OUT
= 3.5V (MAX1642)
V
BATT
= 1.0V (MAX1642)
I
LOAD
= 20mA
V
FB
= 1.3V
Falling PFI, hysteresis = 1%
V
PFI
= 650mV
V
PFI
= 0V, V
OUT
= 3.3V, I
SINK
= 1mA
V
PFI
= 650mV, V
PFO
= 6V
V
OUT
= 3.3V, hysteresis = 2% (MAX1643)
% of V
BATT
(MAX1642)
% of V
BATT
(MAX1642)
(MAX1642)
80
10
0.96
1.0
590
614
V
FB
V
OUT
V
FB
< 0.1V
External feedback
External feedback
V
OUT
= 3.3V
V
OUT
= 3.3V
I
DIODE
= 100mA, P-channel switch off
0.9V < V
BATT
< 1.5V (t
ON
= K / V
BATT
)
0.9V < V
BATT
< 1.5V, V
OUT
= 3.3V
V
OUT
= 3.5V
17
1
11
4
0.1
2
80
10
632
10
0.4
1
1.04
20
3.16
2.0
1.18
1.225
1
1.5
0.8
25
35
1.5
18
6.5
1
3.5
µA
µA
µA
µA
%
nA
mV
nA
V
µA
V
%
%
nA
R
L
= 3kΩ, T
A
= +25°C
0.88
-2
3.30
3.44
5.2
1.27
1.5
2.2
SYMBOL
V
BATT(MIN)
CONDITIONS
MIN
TYP
0.7
1.65
MAX
UNITS
V
V
V
mV/°C
V
V
V
Ω
Ω
V
V-µs
2
_______________________________________________________________________________________
High-Efficiency, Step-Up
DC-DC Converters for 1V Inputs
ELECTRICAL CHARACTERISTICS
(V
BATT
= V
SHDN
= 1.3V, I
LOAD
= 0mA, FB = GND,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 4)
PARAMETER
Output Voltage
FB Set Voltage
N-Channel On-Resistance
P-Channel On-Resistance
On-Time Constant
Quiescent Current into OUT
Quiescent Current into BATT
Shutdown Current into OUT
Shutdown Current into BATT
PFI Trip Voltage
BATTLO
Trip Voltage
K
I
QOUT
I
QBATT
I
SHDN,OUT
I
SHDN,BATT
V
OUT
= 3.5V (MAX1642)
V
BATT
= 1.0V (MAX1642)
Falling PFI, hysteresis = 1%
Falling V
BATT
, V
OUT
= 3.3V, hysteresis = 2%
(MAX1643)
550
0.93
SYMBOL
V
OUT
V
FB
V
FB
< 0.1V
External feedback
V
OUT
= 3.3V
V
OUT
= 3.3V
0.9V < V
BATT
< 1.5V (t
ON
= K / V
BATT
)
V
OUT
= 3.5V
12.4
CONDITIONS
MIN
2.99
1.11
MAX
3.56
1.32
1.5
2.2
38.2
18
6.5
1
3.5
662
1.06
UNITS
V
V
Ω
Ω
V-µs
µA
µA
µA
µA
mV
V
MAX1642/MAX1643
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:
t
x V
BATT
t
OFF
=
ON
x RATIO
. This guarantees discontinuous conduction.
V
OUT
- V
BATT
Note 4:
Specifications to -40°C are guaranteed by design, not production tested.
__________________________________________Typical Operating Characteristics
(Circuit of Figure 4, V
BATT
= 1.2V, R1 + R2 = 1MΩ, T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 2.4V)
MAX1642/43 TOC01A
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 2.4V)
MAX1642/43 TOC01B
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 3.3V)
90
80
EFFICIENCY (%)
70
60
50
40
30
20
V
IN
= 1.0V
V
IN
= 0.85V
L1 = 100µH
SUMIDA CD54-101
0.01
0.1
1
10
100
V
IN
= 1.2V
V
IN
= 1.6V
MAX1642/43 TOC02A
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
0.1
1
10
L1 = 100µH
SUMIDA CD54-101
V
IN
= 0.85V
V
IN
= 1.0V
V
IN
= 1.2V
V
IN
= 1.6V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
L1 = 150µH
TDK NLC565050T-151K
0.01
0.1
1
10
V
IN
= 1.0V
V
IN
= 0.85V
V
IN
= 1.2V
V
IN
= 1.6V
100
10
0
100
100
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
_______________________________________________________________________________________
3
High-Efficiency, Step-Up
DC-DC Converters for 1V Inputs
MAX1642/MAX1643
____________________________Typical Operating Characteristics (continued)
(Circuit of Figure 4, V
BATT
= 1.2V, R1 + R2 = 1MΩ, T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 3.3V)
MAX1642/43 TOC02B
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 5.0V)
MAX1642/43 TOC03a
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 5.0V)
90
80
EFFICIENCY (%)
70
60
50
40
30
20
V
IN
= 1.2V
V
IN
= 0.85V
V
IN
= 1.6V
V
IN
= 1.0V
MAX1642/43 TOC03b
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.01
0.1
1
10
L1 = 150µH
TDK NLC565050T-151K
V
IN
= 1.0V
V
IN
= 0.85V
V
IN
= 1.2V
V
IN
= 1.6V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
L1 = 100µH
SUMIDA CD54-101
0.01
0.1
1
10
V
IN
= 1.2V
V
IN
= 0.85V
V
IN
= 1.6V
V
IN
= 1.0V
100
10
0
100
0.01
L1 = 150µH
TDK NLC565050T-151K
0.1
1
10
100
100
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
NO-LOAD BATTERY CURRENT
vs. INPUT VOLTAGE
MAX1642/43 TOC04
NO-LOAD BATTERY CURRENT
vs. TEMPERATURE
MAX1642/43 TOC05
BATT AND OUT PIN QUIESCENT CURRENTS
vs. TEMPERATURE
V
BATT
= 1.2V
V
OUT
= 3.6V
MAX1642/43 TOC06
10,000
140
120
QUIESCENT CURRENT (µA)
100
80
60
40
20
0
V
BATT
= 1.2V
V
OUT
= 3.3V
30
25
QUIESCENT CURRENT (µA)
20
15
I
OUT
10
5
0
QUIESCENT CURRENT (mA)
1000
V
OUT
= 5.0V
100
V
OUT
= 2.5V OR 3.3V
10
0.8
1.0
1.2
1.4
1.6
1.8
INPUT VOLTAGE (V)
I
BATT
-40
-20
0
20
40
60
80
100
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
TEMPERATURE (°C)
MINIMUM START-UP INPUT VOLTAGE
vs. OUTPUT CURRENT
MAX1642/43 TOC07a
MINIMUM START-UP INPUT VOLTAGE
vs. OUTPUT CURRENT
1.5
START-UP INPUT VOLTAGE (V)
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
V
OUT
= 2.4V, 3.3V
V
OUT
= 5V
L1 = 150µH
TDK NLC565050T-151K
MAX1642/43 TOC07b
1.6
1.5
START-UP INPUT VOLTAGE (V)
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0
5
10
15
20
V
OUT
= 2.4V, 3.3V
L1 = 100µH
SUMIDA CD54-101
V
OUT
= 5V
1.6
25
0
2
4
6
8
10
12
14
16
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
4
_______________________________________________________________________________________
High-Efficiency, Step-Up
DC-DC Converters for 1V Inputs
____________________________Typical Operating Characteristics (continued)
(Circuit of Figure 4, V
BATT
= 1.2V, R1 + R2 = 1MΩ, T
A
= +25°C, unless otherwise noted.)
MAX1642/MAX1643
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
MAX1642/43 TOC08b
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
MAX1642/43 TOC08c
SWITCHING WAVEFORMS
MAX1642/43 TOC09
35
MAXIMUM OUTPUT CURRENT (mA)
30
25
20
15
V
OUT
= 3.3V
10
5
0
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
L1 = 100µH
SUMIDA CD54-101
V
OUT
= 5V
V
OUT
= 2.4V
20
18
MAXIMUM OUTPUT CURRENT (mA)
16
14
12
10
8
6
4
2
0
L1 = 150µH
TDK NLC565050T-151K
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
V
OUT
= 5V
V
OUT
= 3.3V
V
OUT
= 2.4V
A
B
C
1.6
1.6
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
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
LOAD-TRANSIENT RESPONSE
MAX1642/43 TOC10
LINE-TRANSIENT RESPONSE
MAX1642/43 TOC11
SHUTDOWN RESPONSE AND
INDUCTOR CURRENT
MAX1642/43 TOC12
A
A
A
B
B
B
C
400µs/div
V
OUT
= 3.3V, V
BATT
= 1.2V
A: OUT, 20mV/div, 3.3V DC OFFSET
B: LOAD, 2mA to 20mA, 10mA/div
400µs/div
V
OUT
= 3.3V, LOAD = 15mA
A: OUT, 50mV/div, 3.3V DC OFFSET
B: V
BATT
, 1V to 1.5V, 500mV/div
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
_______________________________________________________________________________________
5
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