General Description
The MAX1852/MAX1853 monolithic, CMOS charge-
pump voltage inverters in the ultra-small SC70 package
feature a low 15Ωoutput 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 15ΩOutput 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
5
TOP VIEW
GND C1-
IN
C1+
OUT
SC70-6
16
MAX1852
MAX1853
2
34
SHDN
Pin Configuration
C1+ C1-
IN
SHDN
OUT
GND
ON
0.68µF
0.68µF
OFF
INPUT
2.5V TO 5.5V
NEGATIVE
OUTPUT
-1 ✕ VIN
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 TEMP.
RANGE
PIN -
PA C K A G E
TOP
MARK
MAX1852EXT - 40°C to + 85°C 6 SC70 AAL
MAX1853EXT - 40°C to + 85°C 6 SC70 AAM
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 TA= +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 (VIN + 0.3V)
C1- to GND...............................................(VOUT - 0.3V) to +0.3V
OUT to GND .............................................................+0.3V to -6V
OUT Short-Circuit to GND ..............................................1 minute
Continuous Power Dissipation (TA= +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 TA = +25°C. All temperature limits are guaranteed by design.
Note 2: Output resistance is guaranteed with capacitor ESR of 0.3Ωor less.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Supply Voltage Range 2.5 5.5 V
TA = +25°C 75 130
MAX1852 TA = -40°C to +85°C 150
TA = +25°C 165 320
Quiescent Supply Current
MAX1853 TA = -40°C to +85°C 350
µA
TA = +25°C 0.002 0.5
Shutdown Supply Current SHDN = GND TA = +85°C 0.01 µA
TA = +25°C 325068
MAX1852 TA = -40°C to +85°C2578
TA = +25°C 130 200 270
Oscillator Frequency
MAX1853 TA = -40°C to +85°C 110 310
kHz
Voltage Conversion Efficiency IOUT = 0 99 99.9 %
TA = +25°C1530
Output Resistance (Note 2) IOUT = 10mA TA = -40°C to +85°C40
Ω
Output Current Continuous, long-term 30 mARMS
SHDN Input Logic High +2.5V ≤ VIN ≤ +5.5V 0.7 × VIN V
SHDN Input Logic Low +2.5V ≤ VIN ≤ +5.5V 0.3 × VIN V
TA = +25°C -100 1 100
SHDN Bias Current SHDN = GND or IN TA = +85°C10
nA
MAX1852 260
Wake-Up Time From Shutdown IOUT = 5mA MAX1853 112 µs
MAX1852/MAX1853
SC70 Inverting Charge Pumps
with Shutdown
_______________________________________________________________________________________ 3
12
14
16
18
20
22
24
26
28
-40 -15 10 35 60 85
MAX1853
OUTPUT RESISTANCE vs. TEMPERATURE
MAX1852/3 toc09
TEMPERATURE (°C)
OUTPUT RESISTANCE (Ω)
VIN = +3.3V
VIN = +5V
VIN = +2.5V
12
14
16
18
20
22
24
26
28
-40 -15 10 35 60 85
MAX1852
OUTPUT RESISTANCE vs. TEMPERATURE
MAX1852/3 toc08
TEMPERATURE (°C)
OUTPUT RESISTANCE (Ω)
VIN = +2.5V
VIN = +5V
VIN = +3.3V
0
1
2
3
4
5
6
7
8
-40 -15 10 35 60 85
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX1852/3 toc07
TEMPERATURE (°C)
SUPPLY CURRENT (nA)
-5.5
-4.5
-5.0
-3.5
-4.0
-2.5
-3.0
-2.0
010155 202530
MAX1852
OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX1852/3 toc01
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
VIN = +3.3V
VIN = +5V
0
30
20
10
40
50
60
70
80
90
100
0105 15202530
MAX1853
EFFICIENCY vs. LOAD CURRENT
MAX1852/3 toc04
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN = +3.3V
VIN = +2.5V
VIN = +5V
-5.5
-4.5
-5.0
-3.5
-4.0
-2.5
-3.0
-2.0
010155 202530
MAX1853
OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX1852/3 toc02
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
VIN = +3.3V
VIN = +5V
0
30
20
10
40
50
60
70
80
90
100
0105 15202530
MAX1852
EFFICIENCY vs. LOAD CURRENT
MAX1852/3 toc03
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN = +5V
VIN = +2.5V
VIN = +3.3V
13
16
15
14
17
18
19
20
21
22
23
2.5 3.53.0 4.0 4.5 5.0 5.5
OUTPUT RESISTANCE vs. INPUT VOLTAGE
MAX1852/3 toc05
INPUT VOLTAGE (V)
OUTPUT RESISTANCE (Ω)
MAX1852
MAX1853
0
40
20
100
80
60
120
140
180
160
200
012345
NO-LOAD SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX1852/3 toc06
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
MAX1853
MAX1852
Typical Operating Characteristics
(Circuit of Figure 1, capacitors from Table 2, VIN = +5V, SHDN = IN, TA= +25°C, unless otherwise noted.)
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)
ILOAD = 10mA
2µs/div
ILOAD = 10mA, AC-COUPLED
MAX1853
OUTPUT NOISE AND RIPPLE
MAX1852/3 toc16
VOUT
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
ILOAD = 10mA
MAX1852
10µs/div
ILOAD = 10mA, AC-COUPLED
MAX1852
OUTPUT NOISE AND RIPPLE
MAX1852/3 toc15
VOUT
20mV/div
C1 = C2 = 4.7µF
100µs/div
MAX1852
STARTUP FROM SHUTDOWN
MAX1852/3 toc17
SHDN
0
0
VOUT
2V/div
40µs/div
MAX1853
STARTUP FROM SHUTDOWN
MAX1852/3 toc18
SHDN
0
0
VOUT
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 volt-
age 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 half-
cycle, S1 and S3 open, S2 and S4 close, and C1 is level
shifted downward by VIN volts. This connects C1 in par-
allel 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 -VIN since 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 cur-
rent and by their output impedance (ROUT) 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
RSW is the sum of the charge pump’s internal switch
resistances (typically 6Ωat VIN = +5V). The typical out-
put impedance is more accurately determined from the
Typical Operating Characteristics.
Shutdown
The MAX1852/MAX1853 have a logic-controlled shut-
down input. Driving SHDN low places the devices in a
low-power shutdown mode. The charge-pump switch-
ing 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 resis-
tance, use capacitors with low ESR. (See Table 1 for a
list of recommended manufacturers.) Tables 2 and 3
suggest capacitor values for minimizing output resis-
tance or capacitor size.
Flying Capacitor (C1)
Increasing the flying capacitor’s value reduces the out-
put resistance. Above a certain point, increasing C1’s
capacitance has negligible effect because the output
resistance is then dominated by internal switch resis-
tance 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:
R1
f x C1
2R 4ESR ESR
OUT
OSC
SW C1 C2
≅
()
++ +
I
II
1I x R
V
OUT
OUT Q
OUT OUT
IN
η≅ +−
MAX1852/MAX1853
SC70 Inverting Charge Pumps
with Shutdown
_______________________________________________________________________________________ 5
Pin Description
6Positive Terminal of the Flying
Capacitor
1Inverting Charge-Pump Output
2Ground
3
Shutdown Input. Drive this pin high
for normal operation; drive it low for
shutdown mode.
4Power-Supply Voltage Input. Input
range is +2.5V to +5.5V.
5Negative Terminal of the Flying
Capacitor
PIN FUNCTIONNAME
C1+
OUT
GND
SHDN
IN
C1-
T
E: (
C1
C2
41
3
ON
OFF
5
RL
6
2
C3
C1+ C1-
IN
SHDN
OUT
GND
INPUT
2.5V TO 5.5V NEGATIVE
OUTPUT
-1 ✕ VIN
MAX1852
MAX1853
Figure 1. Typical Application Circuit
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 applica-
tion 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 sig-
nificantly. 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 nis 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 per-
formance. To ensure good layout, mount all compo-
nents 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
+× ×
S1
IN
S2
S3 S4
C1
C2
VOUT = -(VIN)
Figure 2. Ideal Voltage Inverter
V+
C1
fOSC
C2 RL
VOUT
Figure 3a. Switched-Capacitor Model
REQUIV =
REQUIV
VOUT
RL
1
V+
fOSC ✕ C1 C2
Figure 3b. Equivalent Circuit
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
ROUT (Ω)
MAX1852 50 4.7 15
MAX1853 200 115
PART FREQUENCY
(kHz)
CAPACITOR
(µF)
TYPICAL
ROUT (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
MAX1852
MAX1853
4
3
1
VOUT = (2VIN) -
(VFD1) - (VFD2)
C2
+VIN
C1
5
2
6VOUT = -VIN
C4
D1
D1, D2 = 1N4148
C3
D2
SHDN
Figure 6. Combined Doubler and Inverter
MAX1852
MAX1853
2
1
GND
OUT
V+
RL
Figure 7. Heavy Load Connected to a Positive Supply
TRANSISTOR COUNT: 252
MAX1852
MAX1853
MAX1852
MAX1853
4
1VOUT
C2
4
+VIN
C1
C1
55
22
6
33
61
VOUT = -VIN
ROUT = ROUT OF SINGLE DEVICE
NUMBER OF DEVICES
…
…
SHDN
Figure 5. Paralleling MAX1852/MAX1853s to Reduce Output
Resistance
Chip Information
MAX1852
MAX1853
MAX1852
MAX1853
4
1VOUT
C2
4
+VIN
C1
C2
SHDN
C1
55
22
6
33
61
VOUT = -nVIN
…
…
Figure 4. Cascading MAX1852/MAX1853s to Increase Output
Voltage
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
