19-0478; Rev 0; 3/96
Dual-Output Charge Pump with Shutdown
_______________General Description
The MAX864 CMOS, charge-pump, DC-DC voltage
converter produces a positive and a negative output
from a single positive input, and requires only four
capacitors. The charge pump first doubles the input
voltage, then inverts the doubled voltage. The input
voltage ranges from +1.75V to +6.0V.
The internal oscillator can be pin-programmed from
7kHz to 185kHz, allowing the quiescent current, capac-
itor size, and switching frequency to be optimized. The
55Ω output impedance permits useful output currents
up to 20mA. The MAX864 also has a 1µA logic-con-
trolled shutdown.
The MAX864 comes in a 16-pin QSOP package that
uses the same board area as a standard 8-pin SOIC.
For more space-sensitive applications, the MAX865 is
available in an 8-pin µMAX package, which uses half
the board area of the MAX864.
____________________________Features
o
Requires Only Four Capacitors
o
Dual Outputs (Positive and Negative)
o
Low Input Voltages: +1.75V to +6.0V
o
1µA Logic-Controlled Shutdown
o
Selectable Frequencies Allow Optimization
of Capacitor Size and Supply Current
MAX864
______________Ordering Information
PART
MAX864C/D
MAX864EEE
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
Dice*
16 QSOP
________________________Applications
Low-Voltage GaAsFET Bias in Wireless Handsets
VCO and GaAsFET Supply
Split Supply from 2 to 4 Ni Cells or 1 Li+ Cell
Low-Cost Split Supply for Low-Voltage
Data-Acquisition Systems
Split Supply for Analog Circuitry
LCD Panels
*
Contact factory for dice specifications.
__________Typical Operating Circuit
__________________Pin Configuration
TOP VIEW
C1- 1
C2+ 2
GND 3
C2- 4
V- 5
SHDN 6
FC1 7
FC0 8
16 C1+
15 V+
14 N.C.
V
IN
(+1.75V TO +6.0V)
IN
C1+
V+
+2V
IN
C1-
C2+
MAX864
MAX864
13 N.C.
12 IN
11 GND
10 N.C.
9
N.C.
V-
C2-
FC0 FC1 SHDN GND
V
IN
-2V
IN
V
IN
V
IN
QSOP
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
Dual-Output Charge Pump with Shutdown
MAX864
ABSOLUTE MAXIMUM RATINGS
V+ to GND ..............................................................-0.3V to +12V
SHDN,
FC0, FC1 to GND .............................-0.3V to (V+ + 0.3V)
IN to GND ..............................................................-0.3V to +6.2V
V- to GND ...............................................................+0.3V to -12V
V- Output Current .............................................................100mA
V- Short Circuit to GND .................................................Indefinite
Operating Temperature Range
MAX864EEE......................................................-40°C to +85°C
Continuous Power Dissipation (T
A
= +70°C)
QSOP (derate 8.70mW/°C above +70°C) .....................696mW
Storage Temperature Range ............................ -65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
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 (Note 1)
(V
IN
= 5V,
SHDN
= V
IN
, circuit of Figure 1, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SUPPLY
Minimum Start-Up Voltage
Maximum Supply Voltage
R
LOAD
= 10kΩ
R
LOAD
= 10kΩ
FC1 = FC0 = GND, f = 7kHz
Supply Current
FC1 = GND, FC0 = IN, f = 33kHz
FC1 = IN, FC0 = GND, f = 100kHz
FC1 = FC0 = IN, f = 185kHz
Shutdown Current
FC1 = FC0 = IN or GND,
SHDN
= GND
FC1 = FC0 = GND
Oscillator Frequency
FC1 = GND, FC0 = IN
FC1 = IN, FC0 = GND
FC1 = FC0 = IN
INPUTS AND OUTPUTS
Logic Input Low Voltage
Logic Input High Voltage
Logic Input Bias Current
V+ to IN Shutdown Resistance
V- to GND Shutdown Resistance
Output Resistance
(Note 1)
SHDN,
FC0, FC1
SHDN,
FC0, FC1
SHDN,
FC0 = FC1 = GND or IN
I
V+
= 10mA
I
V-
= 10mA
I
V+
= 10mA, I
V-
= 0mA
V+ = 10V, I
V-
= 10mA (forced)
Voltage Conversion Efficiency
V+, R
L
=
∞
V-, R
L
=
∞
T
A
= +25°C
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= T
MIN
to T
MAX
95
95
99
99
34
3.5
-1
22
6
55
2.2
2.8
1
100
50
75
100
50
60
%
Ω
1.0
V
V
µA
Ω
Ω
5
24
70
130
0.6
2.4
7
12
0.1
7
33
100
185
T
A
= +25°C
T
A
= T
MIN
to T
MAX
1.75
2.00
6.0
1.0
3.65
11
18
1
10
48
140
260
kHz
µA
mA
1.25
V
V
SYMBOL
MIN
TYP
MAX
UNITS
Note 1:
Measured using the capacitor values in Table 1. Capacitor ESR contributes approximately 10% of the output impedance
[ESR + 1 / (pump frequency x capacitance)].
2
_______________________________________________________________________________________
Dual-Output Charge Pump with Shutdown
__________________________________________Typical Operating Characteristics
(V
IN
= 5.0V, capacitor values in Table 1, T
A
= +25°C, unless otherwise noted.)
MAX864
EFFICIENCY vs. OUTPUT CURRENT
@ 7kHz PUMP FREQUENCY
MAX864-01
EFFICIENCY vs. OUTPUT CURRENT
@ 33kHz PUMP FREQUENCY
MAX864-02
EFFICIENCY vs. OUTPUT CURRENT
@ 100kHz PUMP FREQUENCY
V
IN
= 3.3V
V+
V
IN
= 5.0V
V-
50
40
30
20
10
0
C1–C4 = 2.2µF
FC1 = 0, FC0 = 0
V-
V+
70
EFFICIENCY V+, V- (%)
60
MAX864-03
100
90
EFFICIENCY V+, V- (%)
80
70
60
50
40
30
20
10
0
0
5
10
15
20
25
30
C1–C4 = 33µF
FC1 = 0, FC0 = 0
V
IN
= 3.3V
V-
V+
V-
V
IN
= 5.0V
V+
90
V
IN
= 3.3V
80
EFFICIENCY V+, V- (%)
70
60
50
40
30
20
10
0
C1–C4 = 6.8µF
FC1 = 0, FC0 = 1
V
IN
= 5.0V
V+
V-
V+
V-
80
35
0
5
10
15
20
25
30
35
0
5
10
15
20
25
30
35
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
EFFICIENCY vs. OUTPUT CURRENT
@ 185kHz PUMP FREQUENCY
MAX864-04
OUTPUT RESISTANCE
vs. SUPPLY VOLTAGE
FC1 = 1, FC0 = 1
(185kHz @ 5V)
MAX864-05
OUTPUT RESISTANCE
vs. TEMPERATURE
V-, V
IN
= 3.0V
V-, V
IN
= 4.5V
V+, V
IN
= 3.0V
MAX864-06
80
70
EFFICIENCY V+, V- (%)
60
V
IN
= 3.3V
160
140
120
R
OUT-
100
80
60
40
R
OUT+
140
125
OUTPUT RESISTANCE (Ω)
110
95
80
65
50
35
V+, V
IN
= 4.5V
V+
V+
V
IN
= 5.0V
50
40
30
20
10
0
0
5
10
15
20
C1–C4 = 1µF
FC1 = 1, FC0 = 1
V-
V-
OUTPUT RESISTANCE (Ω)
25
30
35
1.0
2.0
3.0
4.0
5.0
6.0
-55 -35 -15
5
25
45
65
85 105 125
OUTPUT CURRENT (mA)
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
OUTPUT VOLTAGE
vs. OUTPUT CURRENT
MAX864-07
OUTPUT CURRENT vs. PUMP CAPACITANCE
(V
IN
= 1.9V, V+ +
V-
= 6V)
MAX864-08
OUTPUT CURRENT vs. PUMP CAPACITANCE
(V
IN
= 3.15V, V+ +
V-
= 10V)
OUTPUT CURRENT FROM V+ TO V- (mA)
8
7
6
5
4
3
2
1
0
0
5
C1 = C2 = C3 = C4
10 15 20 25 30 35 40 45 50
PUMP CAPACITANCE (µF)
f = 7kHz
f = 100kHz
f = 33kHz
f = 185kHz
MAX864-09
10
8
6
OUTPUT VOLTAGE (V)
4
2
0
-2
-4
-6
-8
-10
0
5
10
15
20
25
30
35
V- LOADED
V+ LOADED
BOTH V+ AND
V- LOADED EQUALLY
C1–C4 = 1µF
V
IN
= 4.75V
FC1 = 1
FC0 = 1 (185kHz)
V+ LOADED
V- LOADED
OUTPUT CURRENT FROM V+ TO V- (mA)
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
5
f = 33kHz
9
f = 185kHz
f = 7kHz
f = 100kHz
C1 = C2 = C3 = C4
10 15 20 25 30 35 40 45 50
PUMP CAPACITANCE (µF)
40
OUTPUT CURRENT (mA)
_______________________________________________________________________________________
3
Dual-Output Charge Pump with Shutdown
MAX864
____________________________Typical Operating Characteristics (continued)
(V
IN
= 5.0V, capacitor values in Table 1, T
A
= +25°C, unless otherwise noted.)
OUTPUT CURRENT vs. PUMP CAPACITANCE
(V
IN
= 4.75V, V+ +
V-
= 16V)
MAX864-10
OUTPUT VOLTAGE RIPPLE
vs. PUMP CAPACITANCE
(V
IN
= 1.9V, V+ +
V-
= 6V)
MAX864-11
OUTPUT VOLTAGE RIPPLE
vs. PUMP CAPACITANCE
(V
IN
= 3.15V, V+ +
V-
= 10V)
OUTPUT VOLTAGE RIPPLE (mVp-p)
C1 = C2 = C3 = C4
OUTPUT RIPPLE IS
MEASURED FOR THE
LOAD CURRENT INDICATED
IN THE "OUTPUT CURRENT
vs. PUMP CAPACITANCE"
7kHz GRAPH AT V
IN
= 3.15V.
100kHz
33kHz
100
0
185kHz
MAX864-12
MAX864-18
MAX864-15
OUTPUT CURRENT FROM V+ TO V- (mA)
14
33kHz
12
10
100kHz
8
6
4
2
C1 = C2 = C3 = C4
0
0
5
7kHz
185kHz
400
OUTPUT VOLTAGE RIPPLE (mVp-p)
C1 = C2 = C3 = C4
350
300
250
200
150
100
50
0
0
5
OUTPUT RIPPLE IS
MEASURED FOR THE
LOAD CURRENT INDICATED
IN THE "OUTPUT CURRENT
vs. PUMP CAPACITANCE"
GRAPH AT V
IN
= 1.9V.
33kHz
100kHz
185kHz
600
500
400
300
200
7kHz
10 15 20 25 30 35 40 45 50
PUMP CAPACITANCE (µF)
10 15 20 25 30 35 40 45 50
PUMP CAPACITANCE (µF)
0
5
10 15 20 25 30 35 40 45 50
PUMP CAPACITANCE (µF)
OUTPUT VOLTAGE RIPPLE
vs. PUMP CAPACITANCE
(V
IN
= 4.75V, V+ +
V-
= 16V)
MAX864-13
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX864-14
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
3.0
SHUTDOWN SUPPLY CURRENT (µA)
2.5
2.0
1.5
1.0
V
IN
= 5.0V
0.5
V
IN
= 3.3V
0
800
OUTPUT VOLTAGE RIPPLE (mVp-p)
700
600
500
400
300
200
100
0
0
5
33kHz
C1 = C2 = C3 = C4
OUTPUT RIPPLE IS
MEASURED FOR THE
LOAD CURRENT INDICATED
IN THE "OUTPUT CURRENT
vs. PUMP CAPACITANCE"
GRAPH AT V
IN
= 4.75V.
7kHz
100kHz
185kHz
600
SHUTDOWN SUPPLY CURRENT (nA)
500
400
300
200
100
0
10 15 20 25 30 35 40 45 50
PUMP CAPACITANCE (µF)
1.0
2.0
3.0
4.0
5.0
6.0
-55 -35 -15
5
25
45
65
85 105 125
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
SUPPLY CURRENT vs. TEMPERATURE
(V
IN
= 3.3V)
MAX864-16
SUPPLY CURRENT vs. TEMPERATURE
(V
IN
= 5V)
MAX864-17
PUMP FREQUENCY
vs. TEMPERATURE
200
180
PUMP FREQUENCY (kHz)
160
140
120
100
80
60
40
20
0
FC1 = 0, FC0 = 1
FC1 = 0, FC0 = 0
-55 -35 -15
5
25
45
65
85 105 125
FC1 = 1, FC0 = 0
FC1 = 1, FC0 = 1
7
6
SUPPLY CURRENT (mA)
5
4
FC1 = 1, FC0 = 0
3
2
FC1 = 0, FC0 = 1
1
FC1 = 0, FC0 = 0
0
-55 -35 -15
5
25
45
65
FC1 = 1, FC0 = 1
14
12
SUPPLY CURRENT (mA)
10
8
6
4
FC1 = 0, FC0 = 1
2
0
FC1 = 0, FC0 = 0
-55 -35 -15
5
25
45
65
FC1 = 1, FC0 = 0
FC1 = 1, FC0 = 1
85 105 125
85 105 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
4
_______________________________________________________________________________________
Dual-Output Charge Pump with Shutdown
____________________________Typical Operating Characteristics (continued)
(V
IN
= 5.0V, capacitor values in Table 1, T
A
= +25°C, unless otherwise noted.)
MAX864
TIME TO EXIT SHUTDOWN
MAX864-19
+5V
0V
+10V
FC0 = FC1 = GND (7kHz), C1–C4 = 33µF
0V
FC0 = FC1 = IN (185kHz), C1–C4 = 1µF
-10V
1ms/div
_____________________Pin Description
PIN
NAME
C1-
C2+
GND
C2-
V-
FUNCTION
Negative Terminal of the Flying Boost
Capacitor
Positive Terminal of the Flying
Inverting Capacitor
Ground (connect pins 3 and 11 together)
Negative Terminal of the Flying
Inverting Capacitor
Output of the Inverting Charge Pump
Active-Low Shutdown Input. With
SHDN
low, the part is in shutdown
mode and its supply current is less
than 1µA. In shutdown mode, V+
connects to IN through a 22Ω switch,
and V- connects to GND through a
6Ω switch.
Frequency Select, MSB (see Table 1)
Frequency Select, LSB (see Table 1)
No Connect—no internal connection.
Connect these to ground to improve
thermal dissipation.
Positive Power-Supply Input
Output of the Boost Charge Pump
Positive Terminal of the Flying Boost
Capacitor
C2
C1
1 C1-
2
C2+
3
GND
4 C2-
5 V-
6
SHDN
7
FC1
8
FC0
1
2
3, 11
4
5
V
CC
IN
MAX864
C1+
V+
16
15
C3
I
L+
R
L+
V+ OUT
N.C. 14
13
N.C.
IN 12
11
GND
10
N.C.
9
N.C.
6
SHDN
+5V
7
8
9, 10,
13, 14
12
15
16
FC1
FC0
N.C.
IN
V+
C1+
C4
I
L-
R
L-
V- OUT
SEE TABLE 1 FOR CAPACITOR VALUES.
Figure 1. Test Circuit
_______________________________________________________________________________________
5
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