19-1334; Rev 0; 1/98
Regulated, 125mA-Output,
Charge-Pump DC-DC Inverter
________________General Description
The MAX1673 charge-pump inverter provides a low-
cost, compact means of generating a regulated nega-
tive output from a positive input at up to 125mA. It
requires only three small capacitors, and only two resis-
tors to set its output voltage. The input range is 2V to
5.5V. The regulated output can be set from 0V to -V
IN
in
Skip regulation mode or -1.5V to -V
IN
in Linear (LIN)
regulation mode.
In Skip mode, the MAX1673 regulates by varying its
switching frequency as a function of load current. This
On-Demand™ switching gives the MAX1673 two
advantages: very small capacitors and very low quies-
cent supply current. At heavy loads, it transfers energy
from the input to the output by switching at up to
350kHz. It switches more slowly at light loads, using
only 35µA quiescent supply current.
In Linear mode, the MAX1673 switches at a constant
350kHz at all loads and regulates by controlling
the current-path resistance. This provides constant-
frequency ripple, which is easily filtered for low-noise
applications.
This device also features a 1µA logic-controlled shut-
down mode and is available in a standard 8-pin SO
package. For a device that delivers about 10mA and
fits in a smaller package, refer to the MAX868.
____________________________Features
o
Regulated Negative Output Voltage
(up to -1 x V
IN
)
o
125mA Output Current
o
35µA Quiescent Supply Current
(Skip-mode regulation)
o
350kHz Fixed-Frequency, Low-Noise Output
(Linear-mode regulation)
o
2V to 5.5V Input Range
o
1µA Logic-Controlled Shutdown
MAX1673
_______________Ordering Information
PART
MAX1673ESA
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
8 SO
________________________Applications
Hard Disk Drives
Camcorders
Analog Signal-Processing
Applications
Measurement Instruments
Modems
Digital Cameras
Typical Operating Circuit
INPUT 2V TO 5.5V
___________________Pin Configuration
TOP VIEW
LIN/SKIP
CAP+
CAP-
1
2
8
7
IN
CAP+
GND
FB
OUT
CAP-
LIN/SKIP
GND
ON
OFF
SHDN
IN
FB
REGULATED
NEGATIVE
OUTPUT
(UP TO -1 x V
IN
,
UP TO 125mA)
MAX1673
OUT
MAX1673
3
6
5
SHDN
4
SO
On-Demand™ is a trademark of Maxim Integrated Products.
________________________________________________________________
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.
Regulated, 125mA-Output,
Charge-Pump DC-DC Inverter
MAX1673
ABSOLUTE MAXIMUM RATINGS
IN ..............................................................................-0.3V to +6V
CAP+, FB, LIN/SKIP.....................................-0.3V to (V
IN
+ 0.3V)
SHDN........................................................................-0.3V
to +6V
OUT, CAP-................................................................-6V to +0.3V
Continuous Output Current ...............................................135mA
Output Short-Circuit Duration to GND (Note 1) ....................1sec
Continuous Power Dissipation (T
A
= +70°C)
(derate 5.88mW/°C above +70°C) ...............................450mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
Note 1:
Shorting OUT to IN may damage the device and should be avoided.
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
IN
= V
SHDN
= +5V, C
IN
= 10µF, C
OUT
= 22µF, C
FLY
= 2.2µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at
T
A
= +25°C.) (Note 2)
PARAMETER
Input Voltage Range
Minimum Output Voltage
Maximum Output Current
SYMBOL
V
IN
V
OUT
I
OUT(MAX)
LIN/SKIP = IN
R1 =100kΩ, ±1%, (LIN mode)
R2 = 60.4kΩ, ±1%,
I
OUT
= 0mA to
125mA, Figure 1
LIN/SKIP = GND
(Skip mode)
V
FB
= -100mV, V
OUT
= -3V,
LIN/SKIP = IN (LIN mode)
Quiescent Current (I
IN
Current)
I
Q
I
SHDN
V
FB
= -25mV, V
OUT
= -3V,
LIN/SKIP = GND (Skip mode)
SHDN
= GND
V
IN
= 4.5V to 5.5V,
Figure 4,
V
REF
≠
V
IN
LIN/SKIP = IN
(LIN mode)
LIN/SKIP = GND
(Skip mode)
LIN/SKIP = IN
(LIN mode)
LIN/SKIP = GND
(Skip mode)
LIN/SKIP = GND (Skip mode)
SHDN
= GND
CONDITIONS
LIN/SKIP = GND (Skip mode)
LIN/SKIP = IN (LIN mode)
LIN/SKIP = GND
LIN/SKIP = IN
-1.5
125
-2.90
-3.02
-3.15
V
-2.92
-3.02
-3.12
MIN
2.0
2.7
0
TYP
MAX
5.5
5.5
UNITS
V
V
mA
Output Voltage
V
OUT
8
0.035
0.1
0.01
16
mA
0.2
1
µA
Shutdown Current (I
IN
Current)
Line Regulation
∆V
LNR
%/V
1
0.01
%/mA
0.005
3.5
1
10
5
Ω
Ω
Load Regulation
∆V
LDR
I
OUT
= 25mA to
125mA, Figure 1
Open-Loop Output Resistance
(Dropout)
Output Resistance to Ground
in Shutdown Mode
R
O
2
_______________________________________________________________________________________
Regulated, 125mA-Output,
Charge-Pump DC-DC Inverter
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= V
SHDN
= +5V, C
IN
= 10µF, C
OUT
= 22µF, C
FLY
= 2.2µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at
T
A
= +25°C.) (Note 2)
PARAMETER
Switching Frequency
(LIN Mode)
FB Threshold
SYMBOL
ƒ
OSC
V
FBT
T
A
= +25°C
T
A
= -40°C to +85°C
LIN/SKIP = GND (Skip mode)
LIN/SKIP = IN
(LIN mode)
LIN/SKIP = GND
(Skip mode)
CONDITIONS
MIN
250
205
-25
0
150
V
FB
= -25mV
V
FB
= -25mV
1
100
1
V
IH
V
IL
2V
≤
V
IN
≤
5.5V
2V
≤
V
IN
≤
5.5V
0.7 x V
IN
0.3 x V
IN
µA
V
V
TYP
350
MAX
460
515
25
600
nA
UNITS
kHz
mV
MAX1673
FB Input Bias Current
I
FB
Input Bias Current
(SHDN, LIN/SKIP)
Logic High Input
(SHDN, LIN/SKIP)
Logic Low Input
(SHDN, LIN/SKIP)
Note 2:
Specifications to -40°C are guaranteed by design, not production tested.
_______________________________________________________________________________________
3
Regulated, 125mA-Output,
Charge-Pump DC-DC Inverter
MAX1673
Typical Operating Characteristics
(Circuit of Figure 1, V
IN
= +5V, C
FLY
= 2.2µF, C
OUT
= 22µF, T
A
= +25°C, unless otherwise noted.)
OUTPUT RIPPLE
vs. LOAD CURRENT (LIN MODE)
MAX1673 RTOC01
OUTPUT RIPPLE
vs. LOAD CURRENT (SKIP MODE)
MAX1673 TOC02
OUTPUT VOLTAGE
vs. LOAD CURRENT
-3.07
-3.06
-3.05
V
OUT
(V)
SKIP MODE
MAX1673 TOC03
140
120
PEAK-TO-PEAK RIPPLE (mV)
100
C
OUT
= 22µF
80
60
40
20
0
0
25
50
75
100
125
C
OUT
= 47µF
C
C
FLY
=
OUT
10
C
OUT
= 10µF
250
C
OUT
= 10µF
PEAK-TO-PEAK RIPPLE (mV)
200
-3.08
150
C
OUT
= 22µF
100
C
OUT
= 47µF
C
C
FLY
=
OUT
10
0
25
50
75
100
125
150
LOAD CURRENT (mA)
-3.04
-3.03
-3.02
-3.01
50
-3.00
-2.99
-2.98
0
25
50
75
100
LIN MODE
0
150
LOAD CURRENT (mA)
125
150
LOAD CURRENT (mA)
EFFICIENCY vs. LOAD CURRENT
(SKIP MODE)
MAX1673 TOC04
EFFICIENCY vs. LOAD CURRENT
(LIN MODE)
MAX1673 TOC05
EFFICIENCY vs. INPUT VOLTAGE
MAX1673 TOC06
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
V
REF
≠
V
IN
CIRCUIT OF FIGURE 4
20
40
60
80
100
120
V
IN
= 3.5V
V
IN
= 4V
V
IN
= 5V
90
80
70
EFFICIENCY (%)
60
50
40
30
20
10
0
V
REF
≠
V
IN
CIRCUIT OF FIGURE 4
0
20
40
60
80
100
120
V
IN
= 5V
V
IN
= 4V
V
IN
= 4.5V
90
80
EFFICIENCY (%)
70
60
LIN MODE
50
40
30
V
REF
≠
V
IN
100mA LOAD
V
OUT
= -3V
CIRCUIT OF FIGURE 4
3.5
4.0
4.5
V
IN
(V)
5.0
5.5
SKIP MODE
140
140
6.0
LOAD CURRENT (mA)
LOAD CURRENT (mA)
DROPOUT OUTPUT RESISTANCE
vs. INPUT VOLTAGE
MAX1673 TOC07
QUIESCENT CURRENT vs. INPUT VOLTAGE
(LIN MODE)
MAX1673 TOC08
QUIESCENT CURRENT vs. INPUT VOLTAGE
(SKIP MODE)
40
QUIESCENT CURRENT (µA)
35
30
25
20
15
10
DOES NOT INCLUDE BIAS CURRENT
FOR RESISTOR DIVIDER
MAX1673 TOC09
12
10
8
6
4
2
0
2
3
4
V
IN
(V)
5
6
12
10
8
6
4
2
0
2
3
4
V
IN
(V)
DOES NOT INCLUDE BIAS CURRENT
FOR RESISTOR DIVIDER
45
T
A
= +25°C
T
A
= +85°C
T
A
= -40°C
QUIESCENT CURRENT (mA)
R
DROPOUT
(Ω)
V
REF
≠
V
IN
CIRCUIT OF FIGURE 4
5
6
5
0
2
3
4
V
IN
(V)
5
6
4
_______________________________________________________________________________________
Regulated, 125mA-Output,
Charge-Pump DC-DC Inverter
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
IN
= +5V, C
FLY
= 2.2µF, C
OUT
= 22µF, T
A
= +25°C, unless otherwise noted.)
MAX1673
LOAD-TRANSIENT RESPONSE (LIN MODE)
MAX1673 TOC10
LOAD-TRANSIENT RESPONSE (SKIP MODE)
MAX1673 TOC11
I
OUT
100mA/div
125mA
25mA
I
OUT
100mA/div
CIRCUIT OF FIGURE 4
125mA
25mA
V
OUT
50mV/div
CIRCUIT OF FIGURE 4
250µs/div
V
OUT
50mV/div
250µs/div
LINE-TRANSIENT RESPONSE (LIN MODE)
MAX1673 TOC12
LINE-TRANSIENT RESPONSE (SKIP MODE)
MAX1673 TOC13
V
IN
2V/div
5.5V
4.5V
V
IN
2V/div
I
OUT
= 100mA
CIRCUIT OF FIGURE 4
5.5V
4.5V
V
OUT
50mV/div
V
OUT
50mV/div
I
OUT
= 100mA
CIRCUIT OF FIGURE 4
50µs/div
50µs/div
_______________________________________________________________________________________
5
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