19-0915; Rev 2; 9/08
CMOS Micropower Step-Up
Switching Regulator
General Description
Maxim’s MAX630 and MAX4193 CMOS DC-DC regula-
tors are designed for simple, efficient, minimum-size
DC-DC converter circuits in the 5mW to 5W range. The
MAX630 and MAX4193 provide all control and power
handling functions in a compact 8-pin package: a
1.31V bandgap reference, an oscillator, a voltage com-
parator, and a 375mA N-channel output MOSFET. A
comparator is also provided for low-battery detection.
Operating current is only 70µA and is nearly indepen-
dent of output switch current or duty cycle. A logic-level
input shuts down the regulator to less than 1µA quies-
cent current. Low-current operation ensures high effi-
ciency even in low-power battery-operated systems.
The MAX630 and MAX4193 are compatible with most
battery voltages, operating from 2.0V to 16.5V.
The devices are pin compatible with the Raytheon bipo-
lar circuits, RC4191/2/3, while providing significantly
improved efficiency and low-voltage operation. Maxim
also manufactures the MAX631, MAX632, and MAX633
DC-DC converters, which reduce the external compo-
nent count in fixed-output 5V, 12V, and 15V circuits.
See Table 2 at the end of this data sheet for a summary
of other Maxim DC-DC converters.
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♦
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Features
High Efficiency—85% (typ)
70µA Typical Operating Current
1µA Maximum Quiescent Current
2.0V to 16.5V Operation
525mA (Peak) Onboard Drive Capability
±1.5% Output Voltage Accuracy (MAX630)
Low-Battery Detector
Compact 8-Pin Mini-DIP and SO Packages
Pin Compatible with RC4191/2/3
MAX630/MAX4193
Ordering Information
PART
MAX630CPA
MAX630CSA
MAX630CJA
MAX630EPA
MAX630ESA
MAX630EJA
MAX630MJA
MAX630MSA/PR
MAX630MSA/PR-T
MAX4193C/D
MAX4193CPA
MAX4193CSA
MAX4193CJA
MAX4193EPA
MAX4193ESA
MAX4193EJA
MAX4193MJA
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
PIN-
PACKAGE
8 PDIP
8 SO
8 CERDIP
8 PDIP
8 SO
8 CERDIP
8 CERDIP**
8 SO†
8 SO†
Dice*
8 PDIP
8 SO
8 CERDIP
8 PDIP
8 SO
8 CERDIP
8 CERDIP**
Applications
+5V to +15V DC-DC Converters
High-Efficiency Battery-Powered DC-DC
Converters
+3V to +5V DC-DC Converters
9V Battery Life Extension
Uninterruptible 5V Power Supplies
5mW to 5W Switch-Mode Power Supplies
Typical Operating Circuit
+5V IN
470μH
6
I
C
8
LBD
5
+V
S
L
X
3
*Dice
are specified at T
A
= +25°C. Contact factory for dice
specifications.
**Contact
factory for availability and processing to MIL-STD-883.
†Contact
factory for availibility.
Pin Configuration
TOP VIEW
LBR 1
V
FB
7
+15V
OUT
MAX630
1
LBR
C
X
2
GND
4
8 LBD
7 V
FB
6
I
C
C
X
L
X
2
3
MAX630
MAX4193
47pF
GND 4
+5 TO +15V CONVERTER
5 +V
S
________________________________________________________________
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.
CMOS Micropower Step-Up
Switching Regulator
MAX630/MAX4193
ABSOLUTE MAXIMUM RATINGS
Supply Voltage .......................................................................18V
Storage Temperature Range ............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C
Operating Temperature Range
MAX630C, MAX4193C........................................0°C to +70°C
MAX630E, MAX4193E .....................................-40°C to +85°C
MAX630M, MAX4193M..................................-55°C to +125°C
Power Dissipation
8-Pin PDIP (derate 6.25mW/°C above +50°C).............468mW
8-Pin SO (derate 5.88mW/°C above +50°C)................441mW
8-Pin CERDIP (derate 8.33mW/°C above +50°C)........833mW
Input Voltage (Pins 1, 2, 6, 7) .....................-0.3V to (+V
S
+ 0.3V)
Output Voltage, L
X
and LBD ..................................................18V
L
X
Output Current ..................................................525mA (Peak)
LBD Output Current ............................................................50mA
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
S
= +6.0V, T
A
= +25°C, I
C
= 5.0µA, unless otherwise noted.)
PARAMETER
Supply Voltage
Internal Reference Voltage
Switch Current
Supply Current (at Pin 5)
Efficiency
Line Regulation
Load Regulation
Operating Frequency Range
Reference Set Internal
Pulldown Resistance
Reference Set Input Voltage
Threshold
Switch Current
Switch Leakage Current
Supply Current (Shutdown)
Low-Battery Bias Current
Capacitor Charging Current
C
X
+ Threshold Voltage
C
X
- Threshold Voltage
V
FB
Input Bias Current
Low-Battery Detector Output
Current
Low-Battery Detector Output
Leakage
I
FB
I
LBD
I
LBDO
V
8
= 0.4V, V
1
= 1.1V
V
8
= 16.5V, V
1
= 1.4V
250
F
O
R
IC
V
IC
I
SW
I
CO
I
SO
I
LBR
I
CX
V
3
= 1.0V
V
3
= 16.5V
I
C
< 0.01µA
0.5V
0
< V
S
< V
0
(Note 1)
V
S
= +5V, P
LOAD
= 0 to
150mW (Note 1)
(Note 2)
V
6
= V
S
0.1
0.5
0.2
100
0.01
0.01
0.01
30
+V
S
- 0.1
0.1
0.01
600
0.01
5.0
10
250
1.0
1.0
10
SYMBOL
+V
S
V
REF
I
SW
I
S
V
3
= 400mV
I
3
= 0mA
CONDITIONS
Operating
Startup
MAX630
MIN
2.0
1.9
1.29
75
1.31
150
70
85
0.08
0.2
40
1.5
0.8
0.2
0.5
75
10
1.3
0.1
0.5
0.2
100
0.01
0.01
0.01
30
+V
S
- 0.1
0.1
0.01
600
0.01
5.0
10
5.0
5.0
10
125
1.33
TYP
MAX
16.5
MIN
2.4
1.24
75
1.31
150
90
85
0.06
0.2
25
1.5
0.8
0.5
0.5
75
10
1.3
MAX4193
TYP
MAX
16.5
1.38
UNITS
V
V
mA
µA
%
% V
OUT
% V
OUT
kHz
MΩ
V
mA
µA
µA
nA
µA
V
V
nA
µA
µA
2
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CMOS Micropower Step-Up
Switching Regulator
ELECTRICAL CHARACTERISTICS
(+V
S
= +6.0V, T
A
= Full Operating Temperature Range, I
C
= 5.0µA, unless otherwise noted.)
PARAMETER
Supply Voltage
Internal Reference Voltage
Supply Current (Pin 5)
Line Regulation
Load Regulation
SYMBOL
+V
S
V
REF
I
S
I
3
= 0mA
0.5V
0UT
< V
S
< V
0UT
(Note 1)
V
S
= 0.5V
0
, P
L
= 0 to
150mW (Note 1)
0°C
≤
T
A
≤
+70°C
Reference Set Internal
Pulldown Resistance
R
IC
V
6
= V
S
-40°C
≤
T
A
≤
+85°C
-55°C
≤
T
A
≤
+125°C
Reference Set Input Voltage
Threshold
Switch Leakage Current
Supply Current (Shutdown)
Low-Battery Detector Output
Current
V
IC
I
CO
I
SO
I
LBD
V
3
= 16.5V
I
C
< 0.01µA
V
8
= 0.4V, V
1
= 1.1V
250
0.45
0.4
0.3
0.2
CONDITIONS
MAX630
MIN
2.2
1.25
1.31
70
0.2
0.5
1.5
1.5
1.5
0.8
0.1
0.01
600
TYP
MAX
16.5
1.37
200
0.5
1.0
10
10
10
1.3
30
10
250
0.45
0.4
0.3
0.2
MIN
3.5
1.20
1.31
90
0.5
0.5
1.5
1.5
1.5
0.8
0.1
0.01
600
MAX4193
TYP
MAX
16.5
1.42
300
1.0
1.0
10
10
10
1.3
30
30
V
µA
µA
µA
MΩ
UNITS
V
V
µA
% V
OUT
% V
OUT
MAX630/MAX4193
Note 1:
Guaranteed by correlation with DC pulse measurements.
Note 2:
The operating frequency range is guaranteed by design and verified with sample testing.
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
L
X
ON-RESISTANCE vs.
TEMPERATURE
MAX630/4193 toc01
SUPPLY CURRENT vs.
TEMPERATURE
MAX630/4193 toc02
SUPPLY CURRENT vs.
SUPPLY VOLTAGE
MAX630/4193 toc03
8
140
120
100
I
S
(μA)
300
250
200
I
S
(μA)
150
100
50
6
+V
S
= 2.5V
L
X
R
ON
(Ω)
4
+V
S
= 6V
2
+V
S
= 16V
0
-50
-25
0
25
50
75
80
60
40
20
0
100 125
-50
-25
0
25
50
75
100 125
2
4
6
8
10
12
14
16
TEMPERATURE (°C)
TEMPERATURE (°C)
+V
S
(V)
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3
CMOS Micropower Step-Up
Switching Regulator
MAX630/MAX4193
Pin Description
PIN
1
2
3
4
5
6
NAME
LBR
C
X
L
X
GND
+V
S
I
C
FUNCTION
Low-Battery Detection Comparator Input. The LBD output, pin 8, sinks current whenever this pin is
below the low-battery detector threshold, typically 1.31V.
An external capacitor connected between this terminal and ground sets the oscillator frequency.
47pF = 40 kHz.
This pin drives the external inductor. The internal N-channel MOSFET that drives L
X
has an output
resistance of 4Ω and a peak current rating of 525mA.
Ground
The positive supply voltage, from 2.0V to 16.5V (MAX630).
The MAX630/MAX4193 shut down when this pin is left floating or is driven below 0.2V. For normal
operation, connect I
C
directly to +V
S
or drive it high with either a CMOS gate or pullup resistor
connected to +V
S
. The supply current is typically 10nA in the shutdown mode
The output voltage is set by an external resistive divider connected from the converter output to V
FB
and ground. The MAX630/MAX4193 pulse the L
X
output whenever the voltage at this terminal is less
than 1.31V.
The Low-Battery Detector output is an open-drain N-channel MOSFET that sinks up to 600μA (typ)
whenever the LBR input, pin 1, is below 1.31V.
7
V
FB
8
LBD
Detailed Description
The operation of the MAX630 can best be understood
by examining the voltage regulating loop of Figure 1.
R1 and R2 divide the output voltage, which is com-
pared with the 1.3V internal reference by comparator
COMP1. When the output voltage is lower than desired,
the comparator output goes high and the oscillator out-
put pulses are passed through the NOR gate latch,
turning on the output N-channel MOSFET at pin 3, L
X
.
As long as the output voltage is less than the desired
voltage, pin 3 drives the inductor with a series of pulses
at the oscillator frequency.
Each time the output N-channel MOSFET is turned on,
the current through the external coil, L1, increases,
storing energy in the coil. Each time the output turns off,
the voltage across the coil reverses sign and the volt-
age at L
X
rises until the catch diode, D1, is forward
biased, delivering power to the output.
When the output voltage reaches the desired level,
1.31V x (1 + R1 / R2), the comparator output goes low
and the inductor is no longer pulsed. Current is then
supplied by the filter capacitor, C1, until the output volt-
age drops below the threshold, and once again L
X
is
switched on, repeating the cycle. The average duty
cycle at L
X
is directly proportional to the output current.
Output Driver (L
X
Pin)
The MAX630/MAX4193 output device is a large
N-channel MOSFET with an on-resistance of 4Ω and a
peak current rating of 525mA. One well-known advan-
tage that MOSFETs have over bipolar transistors in
switching applications is higher speed, which reduces
switching losses and allows the use of smaller, lighter,
less costly magnetic components. Also important is that
MOSFETs, unlike bipolar transistors, do not require
base current that, in low-power DC-DC converters,
often accounts for a major portion of input power.
The operating current of the MAX630 and MAX4193
increases by approximately 1µA/kHz at maximum
power output due to the charging current required by
the gate capacitance of the L
X
output driver (e.g., 40µA
increase at a 40kHz operating frequency). In compari-
son, equivalent bipolar circuits typically drive their NPN
L
X
output device with 2mA of base drive, causing the
bipolar circuit’s operating current to increase by a fac-
tor of 10 between no load and full load.
Oscillator
The oscillator frequency is set by a single external, low-
cost ceramic capacitor connected to pin 2, C
X
. 47pF
sets the oscillator to 40kHz, a reasonable compromise
between lower switching losses at low frequencies and
reduced inductor size at higher frequencies.
4
_______________________________________________________________________________________
CMOS Micropower Step-Up
Switching Regulator
MAX630/MAX4193
LOW BATTERY INPUT
+5V INPUT
R3
169kΩ
1 LBR
R4
100kΩ
COMP 2
1.31V
MAX630
LBD 8
LOW-BATTERY OUTPUT
(LOW IF INPUT < 3V)
L1
470
2 C
X
OSC
40kHz
COMP 1
V
FB
7
R2
47.5kΩ
R1
499kΩ
C
C
SHUTDOWN
3 L
X
R
ON
≅
3Ω
1.31V
BANDGAP
REFERENCE
AND
BIAS GENERATOR
I
C
6
OPERATE
+V
S
5
D1
1N4148
4 GND
C1
470μF
25V
+15V OUTPUT
20mA
Figure 1. +5V to +15V Converter and Block Diagram
Low-Battery Detector
The low-battery detector compares the voltage on LBR
with the internal 1.31V reference. The output, LBD, is an
open-drain N-channel MOSFET. In addition to detecting
and warning of a low battery voltage, the comparator
can also perform other voltage-monitoring operations
such as power-failure detection.
Another use of the low-battery detector is to lower the
oscillator frequency when the input voltage goes below
a specified level. Lowering the oscillator frequency
increases the available output power, compensating for
the decrease in available power caused by reduced
input voltage (see Figure 5).
MAX630’s analog circuitry, oscillator, L
X
, and LBD out-
puts are turned off. The device’s quiescent current dur-
ing shutdown is typically 10nA (1µA max).
Bootstrapped Operation
In most circuits, the preferred source of +V
S
voltage for
the MAX630 and MAX4193 is the boosted output volt-
age. This is often referred to as a “bootstrapped” oper-
ation since the circuit figuratively “lifts” itself up.
The on-resistance of the N-channel L
X
output decreas-
es with an increase in +V
S
; however, the device operat-
ing current goes up with +V
S
(see the
Typical
Operating Characteristics,
I
S
vs. +V
S
graph). In circuits
with very low output current and input voltages greater
than 3V, it may be more efficient to connect +V
S
direct-
ly to the input voltage rather than bootstrap.
Logic-Level Shutdown Input
The shutdown mode is entered whenever I
C
(pin 6) is
driven below 0.2V or left floating. When shut down, the
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