MAX864EEE [MAXIM]
Dual-Output Charge Pump with Shutdown; 双输出电荷泵，带有关断
| 型号： | MAX864EEE |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Dual-Output Charge Pump with Shutdown |
| 文件： | 总12页 (文件大小：124K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-0478; Rev 0; 3/96
Du a l-Ou t p u t Ch a rg e P u m p w it h S h u t d o w n
MAX864
_______________Ge n e ra l De s c rip t io n
____________________________Fe a t u re s
♦ Requires Only Four Capacitors
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.
♦ Dual Outputs (Positive and Negative)
♦ Low Input Voltages: +1.75V to +6.0V
♦ 1µA Logic-Controlled Shutdown
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.
♦ Selectable Frequencies Allow Optimization
of Capacitor Size and Supply Current
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.
______________Ord e rin g In fo rm a t io n
PART
MAX864C/D
MAX864EEE
TEMP. RANGE
0°C to +70°C
PIN-PACKAGE
Dice*
________________________Ap p lic a t io n s
Low-Voltage GaAsFET Bias in Wireless Handsets
VCO and GaAsFET Supply
-40°C to +85°C
16 QSOP
* Contact factory for dice specifications.
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
__________Typ ic a l Op e ra t in g Circ u it
__________________P in Co n fig u ra t io n
V
IN
+2V
IN
IN
V+
TOP VIEW
(+1.75V TO +6.0V)
C1+
C1-
C2+
GND
C2-
1
2
3
4
5
6
7
8
C1+
V+
16
15
14
MAX864
C1-
N.C.
MAX864
13 N.C.
12 IN
C2+
V-
-2V
IN
V-
SHDN
FC1
FC0
11 GND
C2-
10
9
N.C.
N.C.
FC0 FC1 SHDN GND
V
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
Du a l-Ou t p u t Ch a rg e P u m p w it h S h u t d o w n
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 = +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
A
MAX864
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 = 5V, SHDN = V , circuit of Figure 1, T = T
to T
, unless otherwise noted. Typical values are at T = +25°C.)
MAX
A
IN
A
MIN
IN
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
SUPPLY
T
= +25°C
1.75
2.00
1.25
A
Minimum Start-Up Voltage
Maximum Supply Voltage
R
R
= 10kΩ
V
V
LOAD
LOAD
T
A
= T to T
MIN MAX
= 10kΩ
6.0
1.0
3.65
11
FC1 = FC0 = GND, f = 7kHz
0.6
2.4
7
FC1 = GND, FC0 = IN, f = 33kHz
FC1 = IN, FC0 = GND, f = 100kHz
FC1 = FC0 = IN, f = 185kHz
Supply Current
mA
µA
12
18
Shutdown Current
Oscillator Frequency
0.1
7
1
FC1 = FC0 = IN or GND, SHDN = GND
FC1 = FC0 = GND
5
10
FC1 = GND, FC0 = IN
FC1 = IN, FC0 = GND
FC1 = FC0 = IN
24
33
48
kHz
70
100
185
140
260
130
INPUTS AND OUTPUTS
Logic Input Low Voltage
2.2
2.8
1.0
V
V
SHDN, FC0, FC1
Logic Input High Voltage
Logic Input Bias Current
V+ to IN Shutdown Resistance
V- to GND Shutdown Resistance
3.5
-1
SHDN, FC0, FC1
1
µA
Ω
SHDN, FC0 = FC1 = GND or IN
I
= 10mA
= 10mA
22
6
100
50
V+
I
V-
Ω
T
= +25°C
55
75
A
I
= 10mA, I = 0mA
V-
V+
T
A
= T
to T
100
50
MIN
MAX
Output Resistance
(Note 1)
Ω
T
A
= +25°C
34
V+ = 10V, I = 10mA (forced)
V-
T
A
= T
to T
60
MIN
MAX
V+, R = ∞
95
95
99
99
L
Voltage Conversion Efficiency
%
V-, R = ∞
L
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
_______________________________________________________________________________________
Du a l-Ou t p u t Ch a rg e P u m p w it h S h u t d o w n
MAX864
__________________________________________Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s
(V = 5.0V, capacitor values in Table 1, T = +25°C, unless otherwise noted.)
IN
A
EFFICIENCY vs. OUTPUT CURRENT
@ 7kHz PUMP FREQUENCY
EFFICIENCY vs. OUTPUT CURRENT
@ 33kHz PUMP FREQUENCY
EFFICIENCY vs. OUTPUT CURRENT
@ 100kHz PUMP FREQUENCY
90
100
80
70
60
50
40
30
20
10
0
V
= 3.3V
V
= 5.0V
IN
V
IN
= 3.3V
V+
IN
90
80
70
60
50
40
30
20
10
0
80
70
60
50
40
30
20
10
V+
V-
V+
V-
V+
V-
V+
V-
V
IN
= 5.0V
V
= 5.0V
IN
V-
V+
V-
V
= 3.3V
IN
C1–C4 = 2.2µF
FC1 = 0, FC0 = 0
C1–C4 = 6.8µF
FC1 = 0, FC0 = 1
C1–C4 = 33µF
FC1 = 0, FC0 = 0
0
0
5
10 15
20
25
30
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
OUTPUT RESISTANCE
vs. TEMPERATURE
OUTPUT RESISTANCE
vs. SUPPLY VOLTAGE
140
125
80
160
140
120
100
80
V
IN
= 3.3V
V+
FC1 = 1, FC0 = 1
(185kHz @ 5V)
V+
V-, V = 3.0V
IN
70
60
50
40
30
20
10
0
V-, V = 4.5V
IN
110
95
V
= 5.0V
IN
V-
V-
V+, V = 3.0V
R
IN
OUT-
80
R
OUT+
C1–C4 = 1µF
FC1 = 1, FC0 = 1
65
50
35
60
V+, V = 4.5V
IN
40
-35
0
5
10 15
20
25
30
35
-55
-15
5
25 45 65 85 105 125
1.0
2.0
3.0
4.0
5.0
6.0
OUTPUT CURRENT (mA)
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
OUTPUT VOLTAGE
OUTPUT CURRENT vs. PUMP CAPACITANCE
OUTPUT CURRENT vs. PUMP CAPACITANCE
vs. OUTPUT CURRENT
(V = 1.9V, V+ + V- = 6V)
IN
(V = 3.15V, V+ + V- = 10V)
IN
10
8
4.5
4.0
9
8
f = 33kHz
V+ LOADED
V- LOADED
6
f = 100kHz
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
7
6
5
4
3
2
1
0
f = 185kHz
f = 100kHz
f = 33kHz
4
2
f = 185kHz
C1–C4 = 1µF
= 4.75V
f = 7kHz
V
BOTH V+ AND
IN
FC1 = 1
V- LOADED EQUALLY
0
f = 7kHz
FC0 = 1 (185kHz)
-2
-4
-6
-8
V- LOADED
V+ LOADED
C1 = C2 = C3 = C4
C1 = C2 = C3 = C4
-10
10
OUTPUT CURRENT (mA)
0
5
15 20 25 30 35 40
0
5
10 15 20 25 30 35 40 45 50
0
5
10 15 20 25 30 35 40 45 50
PUMP CAPACITANCE (µF)
PUMP CAPACITANCE (µF)
_______________________________________________________________________________________
3
Du a l-Ou t p u t Ch a rg e P u m p w it h S h u t d o w n
____________________________Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s (c o n t in u e d )
(V = 5.0V, capacitor values in Table 1, T = +25°C, unless otherwise noted.)
IN
A
OUTPUT VOLTAGE RIPPLE
vs. PUMP CAPACITANCE
OUTPUT VOLTAGE RIPPLE
vs. PUMP CAPACITANCE
OUTPUT CURRENT vs. PUMP CAPACITANCE
(V = 1.9V, V+ + V- = 6V)
IN
(V = 4.75V, V+ + V- = 16V)
IN
(V = 3.15V, V+ + V- = 10V)
IN
14
400
350
300
600
500
400
33kHz
C1 = C2 = C3 = C4
C1 = C2 = C3 = C4
12
10
8
MAX864
OUTPUT RIPPLE IS
MEASURED FOR THE
LOAD CURRENT INDICATED
IN THE "OUTPUT CURRENT
vs. PUMP CAPACITANCE"
OUTPUT RIPPLE IS
MEASURED FOR THE
LOAD CURRENT INDICATED
IN THE "OUTPUT CURRENT
vs. PUMP CAPACITANCE"
100kHz
185kHz
250
200
150
100
50
GRAPH AT V = 3.15V.
IN
7kHz
GRAPH AT V = 1.9V.
300
200
100
0
IN
7kHz
6
100kHz
33kHz
185kHz
100kHz
4
2
0
33kHz
7kHz
185kHz
C1 = C2 = C3 = C4
0
0
5
10 15 20 25 30 35 40 45 50
0
5
10 15 20 25 30 35 40 45 50
0
5
10 15 20 25 30 35 40 45 50
PUMP CAPACITANCE (µF)
PUMP CAPACITANCE (µF)
PUMP CAPACITANCE (µF)
OUTPUT VOLTAGE RIPPLE
vs. PUMP CAPACITANCE
(V = 4.75V, V+ + V- = 16V)
IN
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
800
700
600
500
400
300
200
100
0
3.0
2.5
2.0
1.5
1.0
0.5
0
600
500
400
300
200
100
0
C1 = C2 = C3 = C4
OUTPUT RIPPLE IS
MEASURED FOR THE
LOAD CURRENT INDICATED
IN THE "OUTPUT CURRENT
vs. PUMP CAPACITANCE"
GRAPH AT V = 4.75V.
IN
7kHz
100kHz
185kHz
33kHz
V
IN
= 5.0V
V
IN
= 3.3V
0
5
10 15 20 25 30 35 40 45 50
-55 -35 -15 5 25 45 65 85 105 125
TEMPERATURE (°C)
1.0
2.0
3.0
4.0
5.0
6.0
PUMP CAPACITANCE (µF)
SUPPLY VOLTAGE (V)
SUPPLY CURRENT vs. TEMPERATURE
SUPPLY CURRENT vs. TEMPERATURE
PUMP FREQUENCY
vs. TEMPERATURE
(V = 3.3V)
IN
(V = 5V)
IN
7
6
14
12
200
180
FC1 = 1, FC0 = 1
FC1 = 1, FC0 = 0
FC1 = 1, FC0 = 1
FC1 = 1, FC0 = 1
FC1 = 1, FC0 = 0
160
140
120
100
80
5
4
3
2
1
0
10
8
FC1 = 1, FC0 = 0
6
60
4
FC1 = 0, FC0 = 1
FC1 = 0, FC0 = 0
FC1 = 0, FC0 = 1
FC1 = 0, FC0 = 0
FC1 = 0, FC0 = 1
FC1 = 0, FC0 = 0
40
20
0
2
0
-55 -35 -15 5 25 45 65 85 105 125
TEMPERATURE (°C)
-55 -35 -15 5 25 45 65 85 105 125
TEMPERATURE (°C)
-55 -35 -15 5 25 45 65 85 105 125
TEMPERATURE (°C)
4
_______________________________________________________________________________________
Du a l-Ou t p u t Ch a rg e P u m p w it h S h u t d o w n
MAX864
____________________________Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s (c o n t in u e d )
(V = 5.0V, capacitor values in Table 1, T = +25°C, unless otherwise noted.)
IN
A
TIME TO EXIT SHUTDOWN
+5V
0V
FC0 = FC1 = IN (185kHz), C1–C4 = 1µF
FC0 = FC1 = GND (7kHz), C1–C4 = 33µF
+10V
0V
-10V
1ms/div
_____________________P in De s c rip t io n
PIN
NAME
FUNCTION
Negative Terminal of the Flying Boost
Capacitor
C1-
1
V
CC
IN
Positive Terminal of the Flying
Inverting Capacitor
2
3, 11
4
C2+
GND
C2-
Ground (connect pins 3 and 11 together)
C1
Negative Terminal of the Flying
Inverting Capacitor
MAX864
16
15
1
2
3
C1-
C1+
V+
5
V-
Output of the Inverting Charge Pump
V+ OUT
C2+
GND
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.
14
13
C2
N.C.
C3
C4
4
C2-
N.C.
R
L+
I
L+
12
11
5
6
6
SHDN
V-
IN
GND
N.C.
SHDN
+5V
10
9
7
8
FC1
FC0
N.C.
7
8
FC1
FC0
Frequency Select, MSB (see Table 1)
Frequency Select, LSB (see Table 1)
R
L-
I
L-
No Connect—no internal connection.
Connect these to ground to improve
thermal dissipation.
9, 10,
13, 14
V- OUT
N.C.
SEE TABLE 1 FOR CAPACITOR VALUES.
12
15
IN
Positive Power-Supply Input
V+
Output of the Boost Charge Pump
Positive Terminal of the Flying Boost
Capacitor
Figure 1. Test Circuit
16
C1+
_______________________________________________________________________________________
5
Du a l-Ou t p u t Ch a rg e P u m p w it h S h u t d o w n
Ch a rg e -P u m p Fre q u e n c y
_______________De t a ile d De s c rip t io n
a n d Ca p a c it o r S e le c t io n
The MAX864 offers four different charge-pump frequen-
cies. To select a desired frequency, define pins FC0 and
FC1 as shown in Table 1. Lower charge-pump frequen-
cies produce lower average supply currents, while high-
er charge-pump frequencies require smaller capacitors.
The MAX864 requires only four external capacitors to
implement a voltage doubler/inverter. These may be
ceramic or polarized capacitors (electrolytic or tanta-
lum) with values ranging from 0.47µF to 100µF.
Figure 2a illustrates the ideal operation of the positive
voltage doubler. The on-chip oscillator generates a
50% duty-cycle clock signal. During the first half cycle,
switches S2 and S4 open, switches S1 and S3 close,
Ta b le 1 a ls o lis ts the re c omme nd e d c ha rg e -p ump
capacitor values for each pump frequency. Using val-
ues larger than those recommended will have little
effect on the output current. Using values smaller than
those recommended will reduce the available output
current and increase the output ripple. To cut the out-
put ripple in half, double the values of C3 and C4.
MAX864
and capacitor C1 charges to the input voltage (V ).
IN
During the s e c ond ha lf c yc le , s witc he s S1 a nd S3
open, switches S2 and S4 close, and capacitor C1 is
le ve l s hifte d up wa rd b y V volts . As s uming id e a l
IN
switches and no load on C3, charge transfers into C3
To maintain the lowest output resistance, use capacitors
with low effective series resistance (ESR). At each switch-
ing frequency, the charge-pump output resistance is a
function of C1, C2, C3, and C4’s ESR. Minimizing the
charge-pump capacitors’ ESR minimizes output resis-
tance. Use ceramic capacitors for best results.
from C1 such that the voltage on C3 will be 2V , gen-
erating the positive supply output (V+).
IN
Figure 2b illustrates the ideal operation of the negative
converter. The switches of the negative converter are
out of phase from the positive converter. During the
s e c ond ha lf c yc le , s witc he s S6 a nd S8 op e n, a nd
s witc he s S5 a nd S7 c los e , c ha rg ing C2 from V+
Table 1. Frequency Selection
(pumped up to 2V by the positive charge pump) to
IN
CAPACITORS
GND. In the first half of the clock cycle, switches S5
a nd S7 op e n, s witc he s S6 a nd S8 c los e , a nd the
charge on capacitor C2 transfers to C4, generating the
negative supply. The eight switches are CMOS power
MOSFETs. Switches S1, S2, S4, and S5 are P-channel
devices, while switches S3, S6, S7, and S8 are N-chan-
nel devices.
FREQUENCY
FC1
FC0
C1–C4
(µF)
(kHz)
0
0
1
1
0
1
0
1
7
33
6.8
2.2
1
33
100
185
a)
b)
V+
V+
S6
S1
S3
C1+ S2
S5
C2+
IN
GND
V-
C2
C3
C1
R +
L
I +
L
R -
L
I -
L
C4
S4
S7
S8
IN
GND
GND
C1-
C2-
Figure 2. Idealized Voltage Quadrupler: a) Positive Charge Pump; b) Negative Charge Pump
_______________________________________________________________________________________
6
Du a l-Ou t p u t Ch a rg e P u m p w it h S h u t d o w n
MAX864
Ch a rg e -P u m p Ou t p u t
The MAX864 is not a voltage regulator: the output
source resistance of either charge pump is approxi-
S h u t d o w n
The MAX864 features a shutdown mode that reduces
the maximum supply current to 1µA over temperature.
The SHDN pin is an active-low TTL logic-level input. If
the shutdown feature is unused, connect SHDN to IN.
In shutdown mode, V+ connects to IN through a 22Ω
switch and V- connects to GND through a 6Ω switch.
mately 55Ω at room temperature (with V = 5V); and V+
IN
and V- approach +10V and -10V, respectively, when
lightly loaded. Both V+ and V- will droop toward GND as
the current draw from either V+ or V- increases, since V-
is derived from V+. Treating each converter separately,
_________Effic ie n c y Co n s id e ra t io n s
the droop of the negative supply (V ) is the prod-
DROOP-
uct of the current draw from V- (I ) and the source
resistance of the negative converter (RS-):
Theoretically, a charge-pump voltage multiplier can
approach 100% efficiency under the following condi-
tions:
V-
V
= I x RS -
V-
DROOP -
• The charge-pump switches have virtually no offset,
The droop of the positive sup ply (V
) is the
and extremely low on-resistance.
DROOP+
product of the current draw from the positive supply
(I ) and the source resistance of the positive con-
• The drive circuitry consumes minimal power.
LOAD+
• The impedances of the reservoir and pump capaci-
verter (RS+), where I
is the combination of I
LOAD+
V-
tors are negligible.
and the external load on V+ (I ):
V+
For the MAX864, the energy loss per clock cycle is the
sum of the energy loss in the positive and negative
converters, as follows:
V
= I
x RS+ = I + I
x RS+
(
)
DROOP+
LOAD+
V+
V-
Determine V+ and V- as follows:
V+ = 2V - V
IN
DROOP+
LOSS
= LOSS
1
+ LOSS
2
CYCLE
POS
NEG
V- = (V+ - V
)
DROOP
= -(2V - V
- V
)
=
C1 V+ − 2 V+
V
IN
IN DROOP+
DROOP -
(
)
(
) (
)
2
The output resistances for the positive and negative
charge pumps are tested and specified separately. The
positive charge pump is tested with V- unloaded. The
negative charge pump is tested with V+ supplied from
an external source, isolating the negative charge pump.
1
2
2
2
+
C2 V+
−
V−
(
)
(
)
where V+ and V- are the actual measured output volt-
ages.
The average power loss is simply:
Resulting in an efficiency of:
Current draw from either V+ or V- is supplied by the
reservoir capacitor alone during one half cycle of the
clock. Calculate the resulting ripple voltage on either
output as follows:
P
= LOSS
x f
CYCLE PUMP
LOSS
1
V
=
I
(1 / f
) (1 / C
)
RESERVOIR
η = Total Output Power / Total Output Power − P
RIPPLE
LOAD
PUMP
(
)
LOSS
2
where I
ple, with an f
is the load on either V+ or V-. For exam-
There will be a substantial voltage difference between
(V+ - V ) and V for the positive pump, and between
LOAD
of 33kHz and 6.8µF reservoir capaci-
PUMP
IN
IN
tors , the rip p le is 26mV whe n I
Remember that, in most applications, the total load on
is 12mA.
V+ and V- if the impedances of the pump capacitors
(C1 and C2) are large with respect to their respective
output loads.
LOAD
V+ is the V+ load current (I ) and the current taken by
V+
the negative charge pump (I ).
V-
La rg e r re s e rvoir c a p a c itor (C3 a nd C4) va lue s will
reduce output ripple. Larger values of both pump and
reservoir capacitors will improve efficiency.
_______________________________________________________________________________________
7
Du a l-Ou t p u t Ch a rg e P u m p w it h S h u t d o w n
P a ra lle lin g De vic e s
__________Ap p lic a t io n s In fo rm a t io n
Paralleling multiple MAX864s reduces the output resis-
tance of both the positive and negative converters
(Figure 4). The effective output resistance is the output
resistance of one device divided by the total number of
devices. Separate C1 and C2 charge-pump capacitors
are required for each MAX864, but the reservoir capac-
itors C3 and C4 can be shared.
P o s it ive a n d Ne g a t ive Co n ve rt e r
The most common application of the MAX864 is as a
dual charge-pump voltage converter that provides pos-
itive and negative outputs of two times a positive input
voltage for biasing analog circuitry (Figure 3). Select a
charge-pump frequency high enough so it does not
interfere with other circuitry, but low enough to maintain
low supply current. See Table 1 for the correct device
configuration.
MAX864
V
IN
(+1.75V TO +6.0V)
C1
MAX864
16
1
2
3
C1-
C1+
15
14
+2 x V
C2+
GND
IN
V+
C2
N.C.
C3
13
4
C2-
N.C.
12
11
5
6
V-
IN
GND
N.C.
SHDN
IN
10
9
7
8
FC1
FC0
SEE TABLE 1
N.C.
C4
-2 x V
IN
Figure 3. Positive and Negative Converter
8
_______________________________________________________________________________________
Du a l-Ou t p u t Ch a rg e P u m p w it h S h u t d o w n
MAX864
V
IN
3.3µF
3.3µF
3.3µF
1
2
8
7
1
2
8
7
C1-
C1-
V+
V+ OUT
V+
MAX864
MAX864
C2+
C2+
C1+
3.3µF
C1+
3.3µF
3
4
3
4
6
5
6
5
V
IN
IN
C2-
V-
IN
C2-
V-
GND
GND
GND
3.3µF
V- OUT
Figure 4. Paralleling Two MAX864s
He a vy Ou t p u t Cu rre n t Lo a d s
When under heavy loads, where V+ is sourcing current
into V- (i.e., load current flows from V+ to V-, rather than
from supply to ground), do not allow the V- supply to
pull above ground. In applications where large currents
flow from V+ to V-, use a Schottky diode (1N5817)
between GND and V-, with the anode connected to
GND (Figure 5).
11
5
GND
V-
La yo u t a n d Gro u n d in g
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
us e a g round p la ne . Conne c ting a ll N.C. p ins to a
ground plane improves thermal dissipation.
MAX864
Figure 5. High V- Load Circuit
_______________________________________________________________________________________
9
Du a l-Ou t p u t Ch a rg e P u m p w it h S h u t d o w n
___________________Ch ip To p o g ra p h y
C1-
C1+
V+
C2+
MAX864
GND
0. 120"
(3. 05mm)
C2-
V-
IN
GND
SHDN
FC1 FC0
0. 080"
(2. 03mm)
TRANSISTOR COUNT: 143
SUBSTRATE CONNECTED TO V+
10 ______________________________________________________________________________________
Du a l-Ou t p u t Ch a rg e P u m p w it h S h u t d o w n
MAX864
________________________________________________________P a c k a g e In fo rm a t io n
INCHES
MILLIMETERS
INCHES
MILLIMETERS
DIM
DIM PINS
MIN
0.061
MAX
MIN
MAX
1.73
0.25
1.55
0.31
0.25
MIN MAX MIN
MAX
4.98
0.18
8.74
1.40
8.74
0.76
9.98
A
0.068
1.55
16 0.189 0.196 4.80
16 0.0020 0.0070 0.05
20 0.337 0.344 8.56
20 0.0500 0.0550 1.27
24 0.337 0.344 8.56
24 0.0250 0.0300 0.64
28 0.386 0.393 9.80
28 0.0250 0.0300 0.64
D
S
D
S
D
S
D
S
D
A1 0.004 0.0098 0.127
A2 0.055
0.061
0.012
1.40
0.20
0.19
B
C
D
E
e
0.008
A
0.0075 0.0098
SEE VARIATIONS
e
0.150
0.157
3.81
3.99
A1
B
0.25 BSC
0.635 BSC
0.76
21-0055A
H
h
0.230
0.010
0.016
0.244
0.016
0.035
5.84
0.25
0.41
6.20
0.41
0.89
S
L
N
S
α
SEE VARIATIONS
SEE VARIATIONS
0°
8°
0°
8°
E
H
QSOP
QUARTER
SMALL-OUTLINE
PACKAGE
h x 45°
α
A2
N
E
L
C
______________________________________________________________________________________ 11
Du a l-Ou t p u t Ch a rg e P u m p w it h S h u t d o w n
MAX864
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.
12 __________________Ma x im In t e g ra t e d P ro d u c t s , 1 2 0 S a n Ga b rie l Drive , S u n n yva le , CA 9 4 0 8 6 (4 0 8 ) 7 3 7 -7 6 0 0
© 1996 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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