General Description
The MAX1852/MAX1853 monolithic, CMOS chargepump voltage inverters in the ultra-small SC70 package
feature a low 15Ω output resistance, permitting loads
up to 30mA with maximum efficiency. The MAX1852/
MAX1853 are available with operating frequencies of
50kHz and 200kHz, respectively, allowing optimization
of supply current or external component size. Small
external components and micropower shutdown mode
make these devices ideal for both battery-powered and
board-level voltage conversion applications.
Oscillator control circuitry and four power-MOSFET
switches are included on-chip. Applications include
generating a negative supply from a +5V or +3.3V logic
supply to power analog circuitry. Both versions come in
a 6-pin SC70 package that is 40% smaller than a
SOT23.
Applications
Negative Supply from +5V or +3.3V Logic Supplies
Small LCD Panels
GaAsFET Bias Supplies
Handy-Terminals, PDAs
Battery-Operated Equipment
Features
♦ 30mA Output Current
♦ Low 15Ω Output Resistance
♦ 68µA Supply Current (MAX1852)
♦ Requires Only Two 0.68µF Capacitors (MAX1853)
♦ +2.5V to +5.5V Input Voltage Range
♦ 0.1µA Logic-Controlled Shutdown
♦ Two Switching Frequencies
50kHz (MAX1852)
200kHz (MAX1853)
♦ Slew-Rate Limited to Reduce EMI
♦ Ultra-Small 6-Pin SC70 Package
MAX1852/MAX1853
SC70 Inverting Charge Pumps
with Shutdown
________________________________________________________________ Maxim Integrated Products 1
Pin Configuration
C1+ C1-
IN
SHDN
OUT
GND
ON
0.68µF
0.68µF
OFF
INPUT
2.5V TO 5.5V
NEGATIVE
OUTPUT
-1
✕
V
IN
30mA
MAX1853
Typical Operating Circuit
19-1792; Rev 0; 9/00
Ordering Information
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
PART
MAX1852EXT - 40°C to + 85°C 6 SC70 AAL
MAX1853EXT - 40°C to + 85°C 6 SC70 AAM
TEMP.
RANGE
PIN PA C K A G E
TOP
MARK
TOP VIEW
OUT
GND
SHDN
1
2
3
MAX1852
MAX1853
SC70-6
C1+
6
C1-
5
IN
4
MAX1852/MAX1853
SC70 Inverting Charge Pumps
with Shutdown
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, capacitors from Table 2, VIN= +5V, SHDN = IN, TA= -40°C to +85°C, unless otherwise noted. Typical values are
at T
A
= +25°C.) (Note 1)
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.
IN to GND .................................................................-0.3V to +6V
C1+, SHDN to GND.....................................-0.3V to (V
IN
+ 0.3V)
C1- to GND...............................................(V
OUT
- 0.3V) to +0.3V
OUT to GND .............................................................+0.3V to -6V
OUT Short-Circuit to GND ..............................................1 minute
Continuous Power Dissipation (T
A
= +70°C)
6-Pin SC70 (derate 3.1mW/°C above +70°C) .............245mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Note 1: All devices are 100% production tested at T
A
= +25°C. All temperature limits are guaranteed by design.
Note 2: Output resistance is guaranteed with capacitor ESR of 0.3Ω or less.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Supply Voltage Range 2.5 5.5 V
Quiescent Supply Current
Shutdown Supply Current SHDN = GND
Oscillator Frequency
Voltage Conversion Efficiency I
Output Resistance (Note 2) I
Output Current Continuous, long-term 30 mA
SHDN Input Logic High +2.5V ≤ VIN ≤ +5.5V 0.7 × V
SHDN Input Logic Low +2.5V ≤ VIN ≤ +5.5V 0.3 × V
SHDN Bias Current SHDN = GND or IN
Wake-Up Time From Shutdown I
MAX1852
MAX1853
MAX1852
MAX1853
= 0 99 99.9 %
OUT
= 10mA
OUT
= 5mA
OUT
TA = +25°C 75 130
T
= -40°C to +85°C 150
A
TA = +25°C 165 320
T
= -40°C to +85°C 350
A
TA = +25°C 0.002 0.5
T
= +85°C 0.01
A
TA = +25°C 325068
T
= -40°C to +85°C2578
A
TA = +25°C 130 200 270
T
= -40°C to +85°C 110 310
A
TA = +25°C1530
T
= -40°C to +85°C40
A
TA = +25°C -100 1 100
T
= +85°C10
A
MAX1852 260
MAX1853 112
IN
IN
µA
µA
kHz
Ω
RMS
V
V
nA
µs
MAX1852/MAX1853
SC70 Inverting Charge Pumps
with Shutdown
_______________________________________________________________________________________ 3
Typical Operating Characteristics
(Circuit of Figure 1, capacitors from Table 2, VIN= +5V, SHDN = IN, TA= +25°C, unless otherwise noted.)
-2.0
-2.5
-3.0
-3.5
-4.0
OUTPUT VOLTAGE (V)
-4.5
-5.0
-5.5
010155 202530
EFFICIENCY vs. LOAD CURRENT
100
90
80
70
60
50
40
EFFICIENCY (%)
30
20
10
0
0105 15202530
MAX1852
OUTPUT VOLTAGE
vs. LOAD CURRENT
VIN = +3.3V
VIN = +5V
LOAD CURRENT (mA)
MAX1853
VIN = +5V
VIN = +3.3V
LOAD CURRENT (mA)
VIN = +2.5V
-2.0
-2.5
MAX1852/3 toc01
-3.0
-3.5
-4.0
OUTPUT VOLTAGE (V)
-4.5
-5.0
-5.5
MAX1852/3 toc04
OUTPUT RESISTANCE (Ω)
MAX1853
OUTPUT VOLTAGE
vs. LOAD CURRENT
VIN = +3.3V
VIN = +5V
010155 202530
LOAD CURRENT (mA)
OUTPUT RESISTANCE vs. INPUT VOLTAGE
23
22
21
20
19
18
17
MAX1852
16
15
14
13
2.5 3.53.0 4.0 4.5 5.0 5.5
MAX1853
INPUT VOLTAGE (V)
MAX1852/3 toc02
MAX1852/3 toc05
SUPPLY CURRENT (µA)
EFFICIENCY vs. LOAD CURRENT
100
90
80
70
60
50
40
EFFICIENCY (%)
30
20
10
VIN = +5V
0
0105 15202530
NO-LOAD SUPPLY CURRENT
200
180
160
140
120
100
80
60
40
20
0
012345
MAX1852
VIN = +3.3V
VIN = +2.5V
LOAD CURRENT (mA)
vs. SUPPLY VOLTAGE
MAX1853
MAX1852
SUPPLY VOLTAGE (V)
MAX1852/3 toc03
MAX1852/3 toc06
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
8
7
6
5
4
3
SUPPLY CURRENT (nA)
2
1
0
-40 -15 10 35 60 85
TEMPERATURE (°C)
MAX1852/3 toc07
OUTPUT RESISTANCE vs. TEMPERATURE
MAX1852
28
26
24
22
20
18
OUTPUT RESISTANCE (Ω)
16
14
12
-40 -15 10 35 60 85
VIN = +2.5V
VIN = +3.3V
VIN = +5V
TEMPERATURE (°C)
MAX1852/3 toc08
OUTPUT RESISTANCE vs. TEMPERATURE
MAX1853
28
26
24
22
20
18
OUTPUT RESISTANCE (Ω)
16
14
12
-40 -15 10 35 60 85
VIN = +2.5V
VIN = +3.3V
VIN = +5V
TEMPERATURE (°C)
MAX1852/3 toc09
MAX1852/MAX1853
4 _______________________________________________________________________________________
SC70 Inverting Charge Pumps
with Shutdown
50
53
52
51
55
54
59
58
57
56
60
-40 -20 0 20 40
60
80
MAX1852
CHARGE-PUMP FREQUENCY
vs. TEMPERATURE
MAX1852/3 toc10
TEMPERATURE (°C)
FREQUENCY (kHz)
200
210
205
215
225
220
230
-40 -20 0 20 40
60
80
MAX1853
CHARGE-PUMP FREQUENCY
vs. TEMPERATURE
MAX1852/3 toc11
TEMPERATURE (°C)
FREQUENCY (kHz)
20
120
70
170
220
270
2.0 3.5 4.02.5 3.0 4.5 5.0 5.5
CHARGE-PUMP FREQUENCY
vs. INPUT VOLTAGE
MAX1852/3 toc12
INPUT VOLTAGE (V)
FREQUENCY (kHz)
MAX1853
MAX1852
-5.5
-4.5
-5.0
-3.5
-4.0
-2.5
-3.0
-2.0
2.0 3.0 3.52.5 4.0 4.5 5.0 5.5
MAX1852 AND MAX1853
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX1852/3 toc13
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
I
LOAD
= 10mA
2µs/div
I
LOAD
= 10mA, AC-COUPLED
MAX1853
OUTPUT NOISE AND RIPPLE
MAX1852/3 toc16
V
OUT
20mV/div
C1 = C2 = 1µF
0
100
50
200
150
300
250
350
0.2 2.21.2 3.2
4.2
0.7 2.71.7 3.7 4.7
OUTPUT VOLTAGE RIPPLE
vs. CAPACITANCE
MAX1852/3 toc14
CAPACITANCE (µF)
OUTPUT VOLTAGE RIPPLE (mV)
MAX1853
C1 = C2
I
LOAD
= 10mA
MAX1852
10µs/div
I
LOAD
= 10mA, AC-COUPLED
MAX1852
OUTPUT NOISE AND RIPPLE
MAX1852/3 toc15
V
OUT
20mV/div
C1 = C2 = 4.7µF
100µs/div
MAX1852
STARTUP FROM SHUTDOWN
MAX1852/3 toc17
SHDN
0
0
V
OUT
2V/div
40µs/div
MAX1853
STARTUP FROM SHUTDOWN
MAX1852/3 toc18
SHDN
0
0
V
OUT
2V/div
Typical Operating Characteristics (continued)
(Circuit of Figure 1, capacitors from Table 2, VIN= +5V, SHDN = IN, TA= +25°C, unless otherwise noted.)
Detailed Description
The MAX1852/MAX1853 charge pumps invert the voltage applied to their input. For highest performance use
low equivalent series resistance (ESR) capacitors (e.g.,
ceramic).
During the first half-cycle, switches S2 and S4 open,
switches S1 and S3 close, and capacitor C1 charges to
the voltage at IN (Figure 2). During the second halfcycle, S1 and S3 open, S2 and S4 close, and C1 is level
shifted downward by VINvolts. This connects C1 in parallel with the reservoir capacitor C2. If the voltage across
C2 is smaller than the voltage across C1, charge flows
from C1 to C2 until the voltage across C2 reaches
-VIN. The actual voltage at the output is more positive
than -VINsince switches S1–S4 have resistance and the
load drains charge from C2.
Efficiency Considerations
The efficiency of the MAX1852/MAX1853 is dominated
by their quiescent supply current (IQ) at low output current and by their output impedance (R
OUT
) at higher
output current; it is given by:
where the output impedance is roughly approximated
by:
The first term is the effective resistance of an ideal
switched-capacitor circuit (Figures 3a and 3b), and
RSWis the sum of the charge pump’s internal switch
resistances (typically 6Ω at V
IN
= +5V). The typical output impedance is more accurately determined from the
Typical Operating Characteristics.
Shutdown
The MAX1852/MAX1853 have a logic-controlled shutdown input. Driving SHDN low places the devices in a
low-power shutdown mode. The charge-pump switching halts, supply current is reduced to 2nA.
Driving SHDN high will restart the charge pump. The
switching frequency and capacitor values determine how
soon the device will reach 90% of the input voltage.
Applications Information
Capacitor Selection
The charge-pump output resistance is a function of the
ESR of C1 and C2. To maintain the lowest output resistance, use capacitors with low ESR. (See Table 1 for a
list of recommended manufacturers.) Tables 2 and 3
suggest capacitor values for minimizing output resistance or capacitor size.
Flying Capacitor (C1)
Increasing the flying capacitor’s value reduces the output resistance. Above a certain point, increasing C1’s
capacitance has negligible effect because the output
resistance is then dominated by internal switch resistance and capacitor ESR.
Output Capacitor (C2)
Increasing the output capacitor’s value reduces the
output ripple voltage. Decreasing its ESR reduces both
output resistance and ripple. Lower capacitance values
can be used with light loads if higher output ripple can
be tolerated. Use the following equation to calculate the
peak-to-peak ripple:
R
1
f x C1
2R 4ESR ESR
OUT
OSC
SW C1 C2
≅
()
++ +
I
II
1
I x R
V
OUT
OUT Q
OUT OUT
IN
η≅
+
−
MAX1852/MAX1853
SC70 Inverting Charge Pumps
with Shutdown
_______________________________________________________________________________________ 5
Pin Description
6
Positive Terminal of the Flying
Capacitor
1
Inverting Charge-Pump Output
2 Ground
3
Shutdown Input. Drive this pin high
for normal operation; drive it low for
shutdown mode.
4
Power-Supply Voltage Input. Input
range is +2.5V to +5.5V.
5
Negative Terminal of the Flying
Capacitor
PIN FUNCTIONNAME
C1+
OUT
GND
SHDN
IN
C1-
Figure 1. Typical Application Circuit
C1
INPUT
2.5V TO 5.5V
C3
ON
OFF
E: (
6
C1+ C1-
41
IN
MAX1852
3
MAX1853
SHDN
GND
5
OUT
R
L
2
NEGATIVE
OUTPUT
-1
C2
✕
V
IN
MAX1852/MAX1853
SC70 Inverting Charge Pumps
with Shutdown
6 _______________________________________________________________________________________
Input Bypass Capacitor (C3)
If necessary, bypass the incoming supply to reduce its
AC impedance and the impact of the MAX1852/
MAX1853s’ switching noise. A bypass capacitor with a
value equal to that of C1 is recommended.
Voltage Inverter
The most common application for these devices is a
charge-pump voltage inverter (Figure 1). This application requires only two external components—capacitors
C1 and C2—plus a bypass capacitor, if necessary.
Refer to the Capacitor Selection section for suggested
capacitor types.
Cascading Devices
Two devices can be cascaded to produce an even
larger negative voltage (Figure 4). The unloaded output
voltage is normally -2 ✕VIN, but this is reduced slightly
by the output resistance of the first device multiplied by
the quiescent current of the second. When cascading
more than two devices, the output resistance rises significantly. For applications requiring larger negative
voltages, see the MAX865 and MAX868 data sheets.
Paralleling Devices
Paralleling multiple MAX1852/MAX1853s reduces the
output resistance. Each device requires its own pump
capacitor (C1), but the reservoir capacitor (C2) serves
all devices (Figure 5). Increase C2’s value by a factor of
n, where n is the number of parallel devices. Figure 5
shows the equation for calculating output resistance.
Combined Doubler/Inverter
In the circuit of Figure 6, capacitors C1 and C2 form the
inverter, while C3 and C4 form the doubler. C1 and C3
are the pump capacitors; C2 and C4 are the reservoir
capacitors. Because both the inverter and doubler use
part of the charge-pump circuit, loading either output
causes both outputs to decline toward GND. Make sure
the sum of the currents drawn from the two outputs
does not exceed 30mA.
Heavy Load Connected to a
Positive Supply
Under heavy loads, where a higher supply is sourcing
current into OUT, the OUT supply must not be pulled
above ground. Applications that sink heavy current into
OUT require a Schottky diode (1N5817) between GND
and OUT, with the anode connected to OUT (Figure 7).
Layout and Grounding
Good layout is important, primarily for good noise performance. To ensure good layout, mount all components as close together as possible, keep traces short
to minimize parasitic inductance and capacitance, and
use a ground plane.
V=
I
2(f )C2
2 I ESR
RIPPLE
OUT
OSC
OUT C2
+× ×
Figure 2. Ideal Voltage Inverter
Figure 3a. Switched-Capacitor Model
R
EQUIV
=
R
EQUIV
V
OUT
R
L
1
V+
f
OSC
✕ C1
C2
Figure 3b. Equivalent Circuit
IN
S1
S3 S4
f
OSC
V+
C1
C1
S2
C2
C2 R
V
= -(VIN)
OUT
V
OUT
L
MAX1852/MAX1853
SC70 Inverting Charge Pumps
with Shutdown
_______________________________________________________________________________________ 7
Table 2. Capacitor Selection to Minimize
Output Resistance
Table 3. Capacitor Selection to Minimize
Capacitor Size
Table 1. Low-ESR Capacitor Manufacturers
PART
FREQUENCY
(kHz)
CAPACITOR
(µF)
TYPICAL
R
OUT
(Ω)
MAX1852 50 4.7 15
MAX1853 200 1 15
PART
FREQUENCY
(kHz)
CAPACITOR
(µF)
TYPICAL
R
OUT
(Ω)
MAX1852 50 3.3 20
MAX1853 200 0.68 20
714-960-6492
803-626-3123
603-224-1430
714-960-6492
803-626-3123
FAXPHONE
803-946-0690
714-969-2491
603-224-1961
803-946-0690
714-969-2491X7R
X7R
593D, 595D series
267 series
TPS series
SERIES
Matsuo
AVX
Sprague
Matsuo
AVX
MANUFACTURER
PRODUCTION
METHOD
Surface-Mount
Tantalum
Surface-Mount
Ceramic
Figure 6. Combined Doubler and Inverter
Figure 7. Heavy Load Connected to a Positive Supply
TRANSISTOR COUNT: 252
Figure 5. Paralleling MAX1852/MAX1853s to Reduce Output
Resistance
Chip Information
Figure 4. Cascading MAX1852/MAX1853s to Increase Output
Voltage
55
MAX1852
C1
22
MAX1853
6
33
SHDN
+V
4
C1
…
IN
61
…
C2
V
OUT
MAX1852
MAX1853
= -nV
IN
4
1
C1
V
C2
OUT
SHDN
5
2
6
3
MAX1852
MAX1853
C3
+V
IN
4
1
D1, D2 = 1N4148
D1
C2
D2
C4
V
OUT
V
OUT
(V
FD1
= -V
IN
= (2VIN) -
) - (V
)
FD2
…
+V
IN
C1
R
=
OUT
R
4
…
5
61
MAX1852
MAX1853
V
OUT
5
MAX1852
MAX1853
22
6
3
SHDN
OF SINGLE DEVICE
OUT
NUMBER OF DEVICES
C1
= -V
4
V
OUT
1
3
IN
C2
MAX1852
MAX1853
GND
OUT
2
1
V+
R
L
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 ___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
© 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
MAX1852/MAX1853
SC70 Inverting Charge Pumps
with Shutdown
________________________________________________________Package Information
SC70, 6L.EPS
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