Rainbow Electronics MAX1643 User Manual
_______________General Description
The MAX1642/MAX1643 are high-efficiency, low-voltage,
step-up DC-DC converters intended for devices powered by a single alkaline cell. They feature low quiescent supply currents and are supplied in the ultra-small
µMAX package, which is only 1.1mm high. The guaranteed 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.
________________________Applications
Pagers
Remote Controls
Pointing Devices
Personal Medical Monitors
Single-Cell Battery-Powered Devices
____________________________Features
♦ Built-In Synchronous Rectifier
♦ 0.88V Guaranteed Start-Up
♦ Ultra-Small µMAX Package: 1.1mm High
♦ 83% Efficiency
♦ 4µA Quiescent Supply Current into BATT Pin
♦ 2µA Logic-Controlled Shutdown (MAX1642)
♦ Two Undervoltage Detectors (MAX1643)
♦ 2V to 5.2V Output Range
♦ 20mA Output Current at 1.2V Input
♦ 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
µMAX
TOP VIEW
3
4
6
5
GND
BATTLO
FB
PFO
1
2
8
7
OUT
LX
PFI
BATT
MAX1643
µMAX
3
4
6
5
_________________Pin Configurations
OUT
OUTPUT
3.3V
INPUT
0.88V TO 1.65V
100µH
22µF
22µF
ON
LOW-BATTERY
DETECTOR INPUT
LOW-BATTERY
DETECTOR OUTPUT
OFF
PFO
BATT
LX
MAX1642
SHDN
PFI
GND FB
__________Typical Operating Circuit
______________Ordering Information
PART
MAX1642C/D
MAX1642EUA
MAX1643C/D
0°C to +70°C
-40°C to +85°C
0°C to +70°C
TEMP. RANGE PIN-PACKAGE
Dice*
8 µMAX
Dice*
MAX1643EUA -40°C to +85°C 8 µMAX
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
19-1183; Rev 0; 6/97
*
Dice are tested at TA= +25°C.
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 (TA= +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
RL= 3kΩ, TA= +25°C
VFB= 1.3V
I
LOAD
= 20mA
V
BATT
= 1.0V (MAX1642)
0.9V < V
BATT
< 1.5V (tON= K / V
BATT
)
V
OUT
= 3.5V (MAX1642)
I
DIODE
= 100mA, P-channel switch off
V
OUT
= 3.3V
VFB< 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
nA10FB Input Current
%80
η
Efficiency
µA2 3.5I
SHDN,BATT
Shutdown Current into BATT
µA0.1 1I
SHDN,OUT
Shutdown Current into OUT
µA4 6.5I
QBATT
Quiescent Current into BATT
µA11 18I
QOUT
Quiescent Current into OUT
1 1.5RATIOOff-Time Tracking Ratio (Note 3)
mV/°C-2Start-Up Voltage Tempco
V0.88
V0.7V
BATT(MIN)
Minimum Operating Input Voltage
Start-Up Voltage (Note 2)
V-µs17 25 35KOn-Time Constant
V0.8P-Channel Catch-Diode Voltage
Ω1.5 2.2P-Channel On-Resistance
V3.16 3.30 3.44V
OUT
Output Voltage
V2.0 5.2Output Voltage Range
V1.18 1.225 1.27V
FB
FB Set Voltage
Ω1 1.5N-Channel On-Resistance
UNITSMIN TYP MAXSYMBOLPARAMETER
ELECTRICAL CHARACTERISTICS
(V
BATT
= V
SHDN
= 1.3V, I
LOAD
= 0mA, FB = GND, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
Note 1: The reverse battery current is measured from the
Typical Operating Circuit’s
input terminal to GND when the battery is connected 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.
V1.65Maximum Operating Input Voltage
Falling PFI, hysteresis = 1% mV590 614 632PFI Trip Voltage
V
PFI
= 0V, V
OUT
= 3.3V, I
SINK
= 1mA
V
PFI
= 650mV
V0.4V
OL
PFO, BATTLO Low Output Voltage
nA10PFI Input Current
V
OUT
= 3.3V, hysteresis = 2% (MAX1643)
V
PFI
= 650mV, V
PFO
= 6V
V0.96 1.0 1.04
BATTLO Trip Voltage
µA1
PFO, BATTLO Leakage Current
% of V
BATT
(MAX1642)
% of V
BATT
(MAX1642)
%80V
IH
SHDN Input High Voltage
%20V
IL
SHDN Input Low Voltage
(MAX1642) nA10
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 -40°C 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 (tON= K / V
BATT
)
V
OUT
= 3.5V (MAX1642)
V
OUT
= 3.3V
VFB< 0.1V
External feedback
V
OUT
= 3.5V
V
OUT
= 3.3V
CONDITIONS
mV 550 662PFI Trip Voltage
µA3.5I
SHDN,BATT
Shutdown Current into BATT
µA1I
SHDN,OUT
Shutdown Current into OUT
µA6.5I
QBATT
Quiescent Current into BATT
µA18I
QOUT
Quiescent Current into OUT
V-µs12.4 38.2KOn-Time Constant
Ω2.2P-Channel On-Resistance
V2.99 3.56V
OUT
Output Voltage
V1.11 1.32V
FB
FB Set Voltage
Ω1.5N-Channel On-Resistance
UNITSMIN MAXSYMBOLPARAMETER
ELECTRICAL CHARACTERISTICS
(V
BATT
= V
SHDN
= 1.3V, I
LOAD
= 0mA, FB = GND, TA= -40°C to +85°C, unless otherwise noted.) (Note 4)
Falling V
BATT
, V
OUT
= 3.3V, hysteresis = 2%
(MAX1643)
V0.93 1.06
BATTLO Trip Voltage
__________________________________________Typical Operating Characteristics
(Circuit of Figure 4, V
BATT
= 1.2V, R1 + R2 = 1MΩ, TA = +25°C, unless otherwise noted.)
0
0.01 1 100.1 100
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 2.4V)
10
MAX1642/43 TOC01A
OUTPUT CURRENT (mA)
EFFICIENCY (%)
VIN = 1.6V
L1 = 100µH
SUMIDA CD54-101
VIN = 1.2V
VIN = 0.85V
VIN = 1.0V
20
30
40
50
60
70
80
90
100
0
0.01 1 100.1 100
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 2.4V)
10
MAX1642/43 TOC01B
OUTPUT CURRENT (mA)
EFFICIENCY (%)
VIN = 1.6V
L1 = 150µH
TDK NLC565050T-151K
VIN = 1.2V
VIN = 0.85V
VIN = 1.0V
20
30
40
50
60
70
80
90
100
0
0.01 1 100.1 100
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 3.3V)
10
MAX1642/43 TOC02A
OUTPUT CURRENT (mA)
EFFICIENCY (%)
VIN = 1.6V
L1 = 100µH
SUMIDA CD54-101
VIN = 1.2V
VIN = 0.85V
VIN = 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 = 150µH
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 = 100µH
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 = 1MΩ, TA = +25°C, unless otherwise noted.)
0
0.01 1 100.1 100
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 3.3V)
10
MAX1642/43 TOC02B
OUTPUT CURRENT (mA)
EFFICIENCY (%)
VIN = 1.6V
L1 = 150µH
TDK NLC565050T-151K
VIN = 1.2V
VIN = 0.85V
VIN = 1.0V
20
30
40
50
60
70
80
90
100
100
90
80
0
0.01 1 100.1 100
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 5.0V)
20
10
MAX1642/43 TOC03a
OUTPUT CURRENT (mA)
EFFICIENCY (%)
30
40
50
60
70
VIN = 1.6V
VIN = 0.85V
VIN = 1.0V
L1 = 100µH
SUMIDA CD54-101
VIN = 1.2V
100
90
80
0
0.01 1 100.1 100
EFFICIENCY vs. OUTPUT CURRENT
(V
OUT
= 5.0V)
20
10
MAX1642/43 TOC03b
OUTPUT CURRENT (mA)
EFFICIENCY (%)
30
40
50
60
70
VIN = 1.6V
VIN = 0.85V
VIN = 1.0V
L1 = 150µH
TDK NLC565050T-151K
VIN = 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 (mA)
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 (µA)
60
100
120
80
40
60
-20 4020 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 (µA)
60
20
25
10
15
-20 4020 80 100
30
0
V
BATT
= 1.2V
V
OUT
= 3.6V
I
BATT
I
OUT
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