MAX682 [MAXIM]
3.3V-Input to Regulated 5V-Output Charge Pumps; 3.3V ，输入为5V稳压输出电荷泵
| 型号： | MAX682 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 3.3V-Input to Regulated 5V-Output Charge Pumps |
| 文件： | 总12页 (文件大小：155K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-0177; Rev 1; 8/98
3 .3 V-In p u t t o Re g u la t e d 5 V-Ou t p u t
Ch a rg e P u m p s
23/MAX684
Ge n e ra l De s c rip t io n
Fe a t u re s
The MAX682/MAX683/MAX684 charge-pump regula-
tors generate 5V from a 2.7V to 5.5V input. They are
specifically designed to serve as high-efficiency auxil-
iary supplies in applications that demand a compact
design. The MAX682, MAX683, and MAX684 deliver
250mA, 100mA, and 50mA output current, respectively.
♦ Ultra-Small: 1µF Capacitors per 100mA of Output
Current
♦ No Inductors Required
♦ 1.1mm Height in µMAX Package (MAX683/MAX684)
♦ Up to 250mA Output Current (MAX682)
♦ Regulated ±4% Output Voltage
These complete 5V regulators require only one resistor
and three external capacitors—no inductors are need-
ed. High switching frequencies (externally adjustable
up to 2MHz) and a unique regulation scheme allow the
use of capacitors as small as 1µF per 100mA of output
current. The MAX683/MAX684 are offered in a space-
saving 8-pin µMAX package that is only 1.1mm high,
while the MAX682 is available in an 8-pin SO.
♦ 50kHz to 2MHz Adjustable Switching Frequency
♦ 2.7V to 5.5V Input Voltage
♦ 100µA Quiescent Current in Pulse-Skipping Mode
♦ 0.1µA Shutdown Current
Ap p lic a t io n s
Flash Memory Supplies
Ord e rin g In fo rm a t io n
Battery-Powered Applications
Miniature Equipment
PART
MAX682ESA
MAX683EUA
MAX684EUA
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 SO
PCMCIA Cards
8 µMAX
3.3V to 5V Local Conversion Applications
Backup-Battery Boost Converters
3V to 5V GSM SIMM Cards
8 µMAX
Typ ic a l Op e ra t in g Circ u it
P in Co n fig u ra t io n s
TOP VIEW
CXN
CXP
SKIP
SHDN
IN
1
2
3
4
8
7
6
5
OUT
CXP SHDN
CXN IN
PGND GND
SKIP
1
2
3
4
8
7
6
5
OUT
CXP
MAX682
INPUT
2.7V TO 5.5V
OUTPUT
5V/250mA
IN
SKIP
OUT
MAX682
MAX683
MAX684
CXN
PGND
R
EXT
GND
SHDN
GND
PGND
SO
µMAX
________________________________________________________________ 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.
3 .3 V-In p u t t o Re g u la t e d 5 V-Ou t p u t
Ch a rg e P u m p s
ABSOLUTE MAXIMUM RATINGS
Continuous Power Dissipation (T = +70°C)
IN, OUT, SHDN, SKIP to GND.................................-0.3V to +6V
PGND to GND.....................................................................±0.3V
A
8-Pin SO (derate 5.9mW/°C above +70°C).................471mW
8-Pin µMAX (derate 4.1mW/°C above +70°C) ............330mW
Operating Temperature Range
CXN to GND ................................................-0.3V to (V + 0.3V)
IN
CXP to GND..............................................-0.3V to (V
+ 0.3V)
OUT
MAX68_E_A ....................................................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
Continuous Output Current
MAX682........................................................................300mA
MAX683........................................................................150mA
MAX684..........................................................................75mA
Output Short-Circuit Duration ...............................................5sec
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 = 3V, V
= 0V, C = 1µF, C = 0.47µF, C
= 2µF, I
= 22µA; I
= 250mA for MAX682, I
= 100mA for MAX683,
IN
SKIP
IN
X
OUT
SHDN
MAX
MAX
I
= 50mA for MAX684; T = T
to T , unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
MAX A
MAX
A
MIN
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Regulation with V > 3.6V requires
IN
SKIP = high
Input Voltage Range
V
IN
2.7
5.5
V
Input Undervoltage Lockout
Threshold
2.0
2.35
100
2.6
V
Input Undervoltage Lockout
Hysteresis
mV
23/MAX684
0 < I
≤ I
;
LOAD
MAX
Output Voltage
V
OUT
3.0V ≤ IN ≤ 3.6V for SKIP = 0,
4.80
5.05
5.20
V
3.0V ≤ IN ≤ 5.5V for SKIP = IN
MAX682
MAX683
MAX684
250
100
50
Maximum Output Current
I
mA
MAX
0.1
7.5
2.5
1.7
-3
0.18
SKIP = 0, V = 3.6V
IN
MAX682
MAX683
MAX684
No-Load Input Current
I
mA
Q
SKIP = V = 3.6V
IN
Load Regulation
∆V
%
V
SKIP = high, 0 ≤ I
≤ I
MAX
LDR
LOAD
V
0.35
750
50
SHDN Logic Low Input
SHDN On Bias Voltage
SHDN Input Current Range
INL, SHDN
V
T
A
= +25°C
630
1
690
mV
µA
ON, SHDN
I
(Note 2)
SHDN
0°C < T < +85°C
850
750
160
150
1000
1000
200
200
0.1
1200
1300
250
270
5
A
I
= 22µA
=4.4µA
SHDN
-40°C < T < +85°C
A
Switching Frequency (Note 2)
kHz
0°C < T < +85°C
A
I
SHDN
-40°C < T < +85°C
A
Shutdown Supply Current
Shutdown Exit Time
I
µA
µs
Q, SHDN
SHDN = 0, V = 5.5V, V
= 0
IN
OUT
t
R
= 5V/I
L
50
START
MAX
2
_______________________________________________________________________________________
3 .3 V-In p u t t o Re g u la t e d 5 V-Ou t p u t
Ch a rg e P u m p s
23/MAX684
ELECTRICAL CHARACTERISTICS (continued)
(V = 3V, V
= 0V, C = 1µF, C = 0.47µF, C
= 2µF, I
= 22µA; I
= 250mA for MAX682, I
= 100mA for MAX683,
IN
SKIP
IN
X
OUT
SHDN
MAX
MAX
I
= 50mA for MAX684; T = T
to T , unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
MAX A
MAX
A
MIN
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
V
0.8
SKIP Input Voltage Low
SKIP Input Voltage High
SKIP Input Leakage Current
INL, SKIP
V
V
= 5.5V
2.4
-1
INH, SKIP
IN
I
V
IN
= 5.5V, V = 0V or 5.5V
SKIP
1
µA
SKIP
Note 1: Specifications to -40°C are guaranteed by design and not production tested.
Note 2: Current into SHDN determines oscillator frequency: R (kΩ) = 45000 (V - 0.69V) / f (kHz)
OSC
EXT
IN
__________________________________________Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s
(Circuit of Figure 5, V = 3.3V, component values from Tables 2 and 3, T = +25°C, unless otherwise noted.)
IN
A
NO-LOAD SUPPLY CURRENT
vs. SUPPLY VOLTAGE
OUTPUT VOLTAGE vs. LOAD CURRENT
(SKIP = LOW)
OUTPUT VOLTAGE vs. LOAD CURRENT
(SKIP = HIGH)
5.50
5.25
5.00
5.50
5.25
5.00
10
8
SKIP = HIGH
SKIP = HIGH
I
= 22µA
SHDN
I
= 22µA
SHDN
MAX682
MAX684
6
MAX684
MAX683
MAX682
MAX683
4.75
4.50
4.75
4.50
4
MAX682
MAX683
MAX684
2
4.25
4.00
4.25
4.00
0
2
3
4
5
6
1
10
100
1000
1
10
100
1000
SUPPLY VOLTAGE (V)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
NO-LOAD SUPPLY CURRENT vs.
SHUTDOWN PIN INPUT CURRENT
OSCILLATOR FREQUENCY vs.
SHUTDOWN PIN INPUT CURRENT
OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
100
10
1
10M
1M
5.50
SKIP = HIGH
MAX682
SKIP = LOW
5.25
5.00
4.75
4.50
4.25
4.00
3.75
3.50
MAX683
SKIP = HIGH
100k
10k
MAX684
0.1
0.1
1
10
100
2
3
4
5
6
0.1
1
10
100
SHDN INPUT CURRENT (µA)
SUPPLY VOLTAGE (V)
SHDN INPUT CURRENT (µA)
_______________________________________________________________________________________
3
3 .3 V-In p u t t o Re g u la t e d 5 V-Ou t p u t
Ch a rg e P u m p s
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 )
(Circuit of Figure 5, V = 3.3V, component values from Tables 2 and 3, T = +25°C, unless otherwise noted.)
IN
A
MAX682 EFFICIENCY
MAX684 EFFICIENCY
MAX683 EFFICIENCY
vs. LOAD CURRENT (SKIP = LOW)
vs. LOAD CURRENT (SKIP = LOW)
vs. LOAD CURRENT (SKIP = LOW)
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
V
IN
= 3.0V
V
= 3.0V
V = 3.0V
IN
IN
V
IN
= 3.3V
V = 3.3V
IN
V
IN
= 3.3V
V
IN
= 3.6V
V
IN
= 3.6V
V = 3.6V
IN
0.1
1
10
100
1000
0.1
1
10
100
0.1
1
10
100
1000
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
MAX682 EFFICIENCY
vs. LOAD CURRENT (SKIP = HIGH)
MAX683 EFFICIENCY
vs. LOAD CURRENT (SKIP = HIGH)
MAX684 EFFICIENCY
vs. LOAD CURRENT (SKIP = HIGH)
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
90
80
70
60
50
40
30
20
10
0
V
= 3.0V
IN
V
IN
= 3.0V
23/MAX684
V
IN
= 3.0V
V
= 3.3V
IN
V
= 3.3V
IN
V
= 3.3V
IN
V
= 5.0V
IN
V
IN
= 5.0V
V
= 5.0V
IN
I
= 22µA
I
= 22µA
I
= 22µA
SHDN
SHDN
SHDN
1
10
100
1000
1
10
100
1000
1
10
LOAD CURRENT (mA)
100
LOAD CURRENT (mA)
LOAD CURRENT (mA)
OUTPUT WAVEFORM
(SKIP = HIGH)
OUTPUT WAVEFORM
(SKIP = LOW)
MAX682 TOC16
MAX682 TOC17
50mV/div
50mV/div
200ns/div
200ns/div
SKIP = HIGH, I
= 22µA, I
= 250mA, MAX682
SHDN
LOAD
SKIP = LOW, I
= 250mA, MAX682
LOAD
4
_______________________________________________________________________________________
3 .3 V-In p u t t o Re g u la t e d 5 V-Ou t p u t
Ch a rg e P u m p s
23/MAX684
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 )
(Circuit of Figure 5, V = 3.3V, component values from Tables 2 and 3, T = +25°C, unless otherwise noted.)
IN
A
SHUTDOWN TIMING
LINE-TRANSIENT RESPONSE
LOAD-TRANSIENT RESPONSE
MAX682 TOC18
MAX682 TOC20
MAX682 TOC19
A
A
B
A
B
B
100µs/div
2ms/div
A: INPUT VOLTAGE: V = 3.1V TO 3.6V, 500mV/div
2ms/div
A: LOAD CURRENT: I = 5mA TO 250mA, 500mA/div
LOAD
A: OUTPUT VOLTAGE: SKIP = HIGH, R = 5V / I , 2V/div
L
MAX
IN
B: SHDN VOLTAGE: 1V/div
B: OUTPUT VOLTAGE: SKIP = HIGH, I
= 22µA,
SHDN
B: OUTPUT VOLTAGE: SKIP = HIGH, I
= 22µA,
SHDN
I
= 250mA, 50mV/div, MAX682
LOAD
100mV/div, MAX682
P in De s c rip t io n
PIN
NAME
FUNCTION
When SKIP = low, the regulator operates in low-quiescent-current skip mode. When SKIP = high, the
regulator operates in constant-frequency mode, minimizing output ripple and noise. SKIP must be tied
high for input voltages above 3.6V.
1
SKIP
Shutdown Input. Drive SHDN through an external resistor. When SHDN = low, the device turns off. When
2
3
SHDN
current is sourced into SHDN through R
, the device activates, and the SHDN pin input current sets the
EXT
oscillator’s switching frequency. R
(kΩ) = 45000 (V - 0.69V) / f
(kHz).
EXT
IN
OSC
Input Supply Pin. Can range from 2.7V to 5.5V for SKIP = high, and 2.7V to 3.6V for SKIP = low. Bypass to
PGND with a suitable value capacitor (see Capacitor Selection section).
IN
4
5
6
7
8
GND
PGND
CXN
Ground Pin. Connect to PGND through a short trace.
Power Ground Pin
Negative Terminal of the Charge-Pump Transfer Capacitor
Positive Terminal of the Charge-Pump Transfer Capacitor
Fixed 5V Power Output. Bypass to PGND with output filter capacitor.
CXP
OUT
_______________________________________________________________________________________
5
3 .3 V-In p u t t o Re g u la t e d 5 V-Ou t p u t
Ch a rg e P u m p s
De t a ile d De s c rip t io n
The MAX682/MAX683/MAX684 charge pumps provide
S2
IN
OUT
a regulated 5V output from a 2.7V to 5.5V input. They
deliver a maximum of 250mA, 100mA, or 50mA load
current, respectively. Designed specifically for com-
C
X
S1
pact applications, a complete regulator circuit requires
only three small external capacitors and one resistor.
C
IN
C
OUT
An externally adjustable switching frequency and inno-
vative control scheme allow the circuit to be optimized
for efficiency, size, or output noise. The devices also
contain a shutdown feature.
OSC
The MAX682/MAX683/MAX684 c ons is t of a n e rror
amplifier, a 1.23V bandgap reference, an internal resis-
tive feedback network, an oscillator, high-current MOS-
FET switches, and shutdown and control logic (Figure
1). Figure 2 shows an idealized unregulated charge-
pump voltage doubler. The oscillator runs at a 50%
duty cycle. During one half of the period, the transfer
Figure 2. Unregulated Voltage Doubler
S2
capacitor (C ) charges to the input voltage. During the
X
IN
OUT
other half, the doubler stacks the voltage across C
X
and the input voltage, and transfers the sum of the two
voltages to the output filter capacitor (C ). Rather
C
X
S1
OUT
tha n s imp ly d oub ling the inp ut volta g e , the
MAX682/MAX683/MAX684 provide a regulated fixed
output voltage (5V) using either skip mode or constant-
frequency mode. Skip mode and constant-frequency
mode are externally selected via the SKIP input pin.
23/MAX684
C
IN
EN
OSCILLATOR
OUT
IN
Figure 3. Skip-Mode Regulation
S k ip Mo d e
In skip mode (SKIP = low), the error amplifier disables
switching when it detects an output higher than 5V. The
device then skips switching cycles until the output volt-
age drops. Then the error amplifier reactivates the
oscillator. Figure 3 illustrates the regulation scheme.
This regulation method minimizes operating current
because the device does not switch continuously. SKIP
is a logic input and should not remain floating.
1.23V
SKIP
CONTROL
LOGIC
CXP
SHDN
SWITCHES
SHDN
CXN
OSC
Co n s t a n t -Fre q u e n c y Mo d e
When SKIP is high, the charge pump runs continuously
at the selected frequency. Figure 4 shows a block dia-
gram of the device in constant-frequency mode. The
PGND
error amplifier controls the charge on C by driving the
X
gate of the N-channel FET. When the output voltage
falls, the gate drive increases, resulting in a larger volt-
age across C . This regulation scheme minimizes out-
X
put ripple. Since the device switches continuously, the
Figure 1. Functional Block Diagram
6
_______________________________________________________________________________________
3 .3 V-In p u t t o Re g u la t e d 5 V-Ou t p u t
Ch a rg e P u m p s
23/MAX684
max) of supply current in this mode and the output pre-
sents a 50kΩ impedance to ground. The device exits
shutdown once SHDN is forward biased (minimum of
1µA of current). The typical no-load shutdown exit time
is 50µs.
IN
OUT
S2
C
X
S1
When SHDN is pulled high through an external resistor
C
IN
OSC
to V , the b ia s c urre nt into SHDN d e te rmine s the
IN
C
OUT
charge-pump frequency. To select the frequency, cal-
culate the external resistor value, R , using the fol-
EXT
lowing formula:
N-CHANNEL
R
= 45000 (V - 0.69V) / f
IN OSC
EXT
where R
is in kΩ and f
is in kHz. Program the
EXT
OSC
frequency in the 50kHz to 2MHz range. This frequency
range corresponds to SHDN input currents between
1µA and 50µA. Proper operation of the oscillator is not
guaranteed beyond these limits. Currents lower than
1µA may shut down the device. The forward-biased
diode voltage from the SHDN input to GND has a tem-
perature coefficient of -2mV/°C.
Figure 4. Constant-Frequency-Mode Regulation
Table 1. Tradeoffs Between Operating
Modes
Un d e rvo lt a g e Lo c k o u t
The MAX682/MAX683/MAX684 have an undervoltage-
lockout feature that deactivates the devices when the
input voltage falls below 2.25V. Regulation at low input
voltages cannot be maintained. This safety feature
ensures that the device shuts down before the output
voltage falls out of regulation by a considerable amount
(typically 10% with no load). Once deactivated, hys-
teresis holds the device in shutdown until the input volt-
age rises 100mV above the lockout threshold.
CONSTANT-
FREQUENCY MODE
SKIP MODE
(SKIP = LOW)
FEATURE
(SKIP = HIGH)
Best Light-Load
Efficiency
✔
Smallest External
Component Size
✔
Output Ripple
Amplitude and
Frequency
Relatively large
Relatively small
amplitude, variable amplitude, constant
frequency
frequency
Ap p lic a t io n s In fo rm a t io n
Load Regulation
Very Good
Good
Ca p a c it o r S e le c t io n
The MAX682/MAX683/MAX684 require only three exter-
nal capacitors (Figure 5). Their values are closely linked
to the output current capacity, oscillator frequency, out-
put noise content, and mode of operation.
output noise contains well-defined frequency compo-
nents, and the circuit requires much smaller external
capacitors for a given output ripple. However, constant-
frequency mode, due to higher operating current, is
less efficient at light loads than skip mode. Note: For
input voltages above 3.6V, the devices must operate in
constant-frequency mode. Table 1 summarizes the
tradeoffs between the two operating modes.
Generally, the transfer capacitor (C ) will be the small-
X
est, and the input capacitor (C ) is twice as large as
IN
C . Hig he r s witc hing fre q ue nc ie s a llow the us e of
X
smaller C and C . The output capacitor (C ) can
X
IN
OUT
be anywhere from 5-times to 50-times larger than C ,
depending on the mode of operation and ripple toler-
ance. In continuous switching mode, smaller output rip-
Fre q u e n c y S e le c t io n a n d S h u t d o w n
The SHDN pin on the MAX682/MAX683/MAX684 per-
forms a dual function: it shuts down the device and
determines the oscillator frequency. The SHDN input
looks like a d iode to ground a nd should be d rive n
through a resistor.
X
ple allows smaller C
. In skip mode, a larger C
OUT
is
OUT
required to maintain low output ripple. Tables 2 and 3
show capacitor values recommended for lowest sup-
ply-current operation (skip mode) and smallest size oper-
ation (constant-frequency mode), respectively.
Driving SHDN low p la c e s the d e vic e in s hutd own
mode. This disables all switches, the oscillator, and
control logic. The device typically draws 0.1µA (5µA
_______________________________________________________________________________________
7
3 .3 V-In p u t t o Re g u la t e d 5 V-Ou t p u t
Ch a rg e P u m p s
Table 2. Recommended Capacitor Values
for Quiescent Current (Skip Mode)
7
CXP
R
EXT
ON
V
ON
2
C
X
OFF
SHDN
MAX682
MAX683
MAX684
V
OUT
RIPPLE
(mV)
C
(µF)
6
8
OUT
OUTPUT C
C
X
CXN
OUT
IN
PART
3
1
(mA)
(µF) (µF)
IN
IN
TANTALUM CERAMIC
OUT
SKIP
GND
PGND
5
MAX682
MAX683
250
2.2
1
1
47
22
10
100
100
C
IN
C
OUT
4
100
0.47
4.7
MAX684
50
0.47 0.22
10
2.2
100
Figure 5. Standard Operating Circuit
5V/500mA
3.3V
IN
Table 3. Recommended Capacitor Values
for Smallest Size (Constant-Frequency
IN
SKIP
OUT
IN
SKIP
OUT
Mode, I
= 22µA, 1MHz)
SHDN
CERAMIC
V
OUT
RIPPLE
(mV)
OUTPUT
(mA)
C
(µF)
C
X
IN
PART
C
(µF)
OUT
100k
100k
(µF)
0.47
0.22
MAX682
MAX682
1µF
4.7µF
SHDN
SHDN
CXP
1µF
MAX682
MAX683
250
100
1
2.2
80
80
CXP
23/MAX684
0.47µF
0.47µF
0.47
1
CXN
CXN
GND PGND
GND PGND
MAX684
50
0.22
0.1
0.47
80
Figure 6. Paralleling Two MAX682s
Table 4. Recommended Capacitor
Manufacturers
where ESR
is the ESR of the output filter capaci-
COUT
TX
tance, and R is the open-loop output transfer resist-
ance of the IC. R is typically 0.8Ω for the MAX682,
1.6Ω for the MAX683, and 3Ω for the MAX684. In con-
PHONE
NUMBER
TX
VALUE
DESCRIPTION MANUFACTURER
stant-frequency mode, output ripple is dominated by
595D-series
tantalum
surface mount
C
and is approximately:
OUT
47µF to
10µF
Sprague
(603) 224-1961
V
I
/ (2 x f
x C
)
OUT
RIPPLE(const-freq)
OUT
OSC
All capacitors must maintain a low (<100mΩ) equiva-
lent series resistance (ESR). Table 4 lists the manufac-
ture rs of re c omme nd e d c a p a c itors . Surfa c e -mount
tantalum capacitors will work well for most applications.
Ceramic capacitors will provide the lowest ripple due to
their typically lower ESR.
47µF to TPS-series
AVX
TDK
(803) 946-0690
(847) 390-4373
10µF
surface mount
0.1µF to Ceramic
2.2µF
surface mount
In addition, the following two equations approximate
output ripple for each mode. In skip mode, output rip-
ple is dominated by ESR, and is approximately:
If the source impedance or inductance of the input sup-
ply is large, additional input bypassing (2.2µF to 22µF)
may be needed. This additional capacitance need not
be a low-ESR type.
V
(2V - V
)ESR
/ R
RIPPLE(SKIP)
IN
OUT
COUT TX
8
_______________________________________________________________________________________
3 .3 V-In p u t t o Re g u la t e d 5 V-Ou t p u t
Ch a rg e P u m p s
23/MAX684
P o w e r Dis s ip a t io n
The power dissipated in the MAX682/MAX683/MAX684
depends on output current and is accurately described
by:
P a ra lle lin g De vic e s
The MAX682/MAX683/MAX684 can be paralleled to
yield higher load currents. The circuit of Figure 6 can
deliver 500mA at 5V. It uses two MAX682s in parallel.
The devices can share the output capacitors, but each
P
= I
(2V - V
)
DISS
OUT
IN
OUT
one requires its own transfer capacitor (C ) and input
X
P
must be less than that allowed by the package
DISS
capacitor. For best performance, the paralleled devices
should operate in the same mode (skip or constant fre-
quency).
rating. See the Absolute Maximum Ratings for 8-pin
µMAX (MAX683/MAX684) and SO (MAX682) power-
dissipation limits and deratings.
Ch ip In fo rm a t io n
La yo u t Co n s id e ra t io n s
All capacitors should be soldered in close proximity to
the IC. Connect ground and power ground through a
short, low-impedance trace. If a high-value resistor is
driving the shutdown input and is picking up noise (i.e.,
frequency jitter at CXP and CXN), bypass SHDN to
GND with a small capacitor (0.01µF).
TRANSISTOR COUNT: 659
SUBSTRATE CONNECTED TO GND
P a c k a g e In fo rm a t io n
_______________________________________________________________________________________
9
3 .3 V-In p u t t o Re g u la t e d 5 V-Ou t p u t
Ch a rg e P u m p s
P a c k a g e In fo rm a t io n
23/MAX684
10 ______________________________________________________________________________________
3 .3 V-In p u t t o Re g u la t e d 5 V-Ou t p u t
Ch a rg e P u m p s
23/MAX684
NOTES
______________________________________________________________________________________ 11
3 .3 V-In p u t t o Re g u la t e d 5 V-Ou t p u t
Ch a rg e P u m p s
NOTES
23/MAX684
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
© 1998 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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