MAX1697SEUT+T [MAXIM]
Switched Capacitor Converter, 0.06A, 60kHz Switching Freq-Max, CMOS, PDSO6, ROHS COMPLIANT, SOT-23, 6 PIN;
| 型号： | MAX1697SEUT+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Switched Capacitor Converter, 0.06A, 60kHz Switching Freq-Max, CMOS, PDSO6, ROHS COMPLIANT, SOT-23, 6 PIN 光电二极管 |
| 文件： | 总13页 (文件大小：374K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1499; Rev 3; 12/08
60mA, SOT23 Inverting Charge Pump
with Shutdown
General Description
Features
The MAX1697 ultra-small, monolithic, CMOS charge-
pump voltage inverter accepts an input voltage ranging
from +1.25V to +5.5V. This device features an ultra-low
12Ω output resistance, permitting loads of up to 60mA
with maximum efficiency. The MAX1697 is available
with operating frequencies of 12kHz, 35kHz, 125kHz, or
250kHz, allowing optimization of supply current or
external component size. Its small external components
and micropower shutdown mode make this device
ideal for both battery-powered and board-level voltage
conversion applications.
♦ 60mA Output Current
♦ Low 12Ω Output Resistance
♦ 150µA Supply Current (MAX1697R)
♦ Requires Only Two 1µF Capacitors (MAX1697U)
♦ Start-Up Current Limited
♦ +1.25V to +5.5V Input Voltage Range
♦ Slew-Rate Limited to Reduce EMI
Ordering Information
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. All versions come in a
6-pin SOT23 package and deliver 60mA.
PART
TEMP RANGE
PIN-PACKAGE
MAX1697_EUT-T
6 SOT23
-40°C to +85°C
Note 1: The MAX1697 requires special solder temperature pro-
file described in the Absolute Maximum Ratings section.
For applications with lower current requirements, the
MAX1719/MAX1720/MAX1721 are pin-compatible
SOT23 charge pumps that supply up to 25mA.
Note 2: The MAX1697 is available with four different operating
frequencies. Choose the desired frequency from the table
below and insert the suffix in the blank above to complete the
part number.
Applications
Negative Supply from +5V or +3.3V Logic Supplies
TOP MARK
+T
PART NO.
SUFFIX
FREQUENCY
(kHz)
-T
#T
R
S
T
12
35
AABV
AABW
AABX
AABY
AABV
ACBT
ACCK
ACCL
ACCM
Small LCD Panels
AABW
AABX
GaAsFET Bias Supplies
125
250
Handy-Terminals, PDAs
U
AABY
Battery-Operated Equipment
Note 3: MAX1697 is available in different package material.
Add the following suffix to the part number when ordering:
-T = Denotes a package containing lead(Pb).
+T = Denotes a lead(Pb)-free/RoHS-compliant package.
#T = Denotes an RoHS-compliant device that may include
lead(Pb) that is exempt under the RoHS requirements.
Pin Configuration
Typical Operating Circuit
TOP VIEW
+
1μF
OUT
1
2
3
C1+
6
5
4
C1+
C1-
OUT
NEGATIVE
OUTPUT
✕
INPUT
1.5V to 5.5V
MAX1697
SHDN
GND
IN
IN
-1
V
IN
60mA
MAX1697U
C1-
1μF
SHDN
ON
SOT23
OFF
GND
Note 4: Leaded and lead-free top marks are identical. Per
Maxim guideline, the pin 1 indicator for leaded package is
a ‘•’ and the lead-free package is a ‘+’.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim's website at www.maxim-ic.com.
60mA, SOT23 Inverting Charge Pump
with Shutdown
ABSOLUTE MAXIMUM RATINGS
IN to GND.................................................................-0.3V to +6V
Continuous Power Dissipation (T = +70°C)
A
6-Pin SOT23 (derate 14mW/°C above +70°C) (Note 5)...1.1W
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature ..........................................................(Note 6)
C1+, SHDN to GND.....................................-0.3V to (V + 0.3V)
IN
C1- to GND..............................................(V
- 0.3V) to + 0.3V
OUT
OUT to GND .............................................................+0.3V to -6V
OUT Output Current............................................................90mA
OUT Short-Circuit to GND .............................................Indefinite
Note 5: Thermal properties are specified with product mounted on the PC board with one square-inch of copper area and still air.
Note 6: This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the
device can be exposed to during board level solder attach and rework. Maxim recommends the use of the solder profiles
recommended in the industry standard specification, JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and Convection
reflow processes. Preheating, per this standard, is required. Hand or wave soldering is not recommended.
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
(Circuit of Figure 1, capacitors from Table 2, V = +5V, SHDN = IN, T = 0°C to +85°C, unless otherwise noted. Typical values are at
IN
A
T
= +25°C.)
A
PARAMETER
CONDITIONS
MIN
1.25
1.5
TYP
MAX
5.5
UNITS
T
A
T
A
T
A
T
A
= +25°C
MAX1697R/S, R = 5kΩ
L
= 0°C to +85°C
= +25°C
5.5
Supply Voltage Range
V
1.4
5.5
MAX1697T/U, R = 5kΩ
L
= 0°C to +85°C
1.5
5.5
MAX1697R
MAX1697S
MAX1697T
MAX1697U
150
350
950
1800
0.002
0.03
170
12
300
650
1700
3400
1
Quiescent Supply Current
(Note 9)
T
= +25°C
µA
A
T
A
T
A
= +25°C
= +85°C
Shutdown Supply Current
Short-Circuit Current
µA
SHDN = GND
Output shorted to ground, T = +25°C
mA
A
MAX1697R
7
20
17
50
MAX1697S
MAX1697T
MAX1697U
35
Oscillator Frequency
T
A
= +25°C
kHz
70
125
250
99.9
12
180
360
140
99
Voltage Conversion Efficiency
Output Resistance (Note 7)
I
I
= 0, T = +25°C
A
%
OUT
T
T
= +25°C
25
33
A
= 60mA
Ω
OUT
= 0°C to +85°C
A
OUT to GND Shutdown
Resistance
SHDN = GND, OUT is internally pulled to GND
in shutdown
3
8
Ω
V
2.5V ≤ V ≤ 5.5V
2.0
IN
SHDN Input Logic High
SHDN Input Logic Low
SHDN Bias Current
V
≤ V ≤ 2.5V
V
- 0.2
IN
IN(MIN)
IN
2.5V ≤ V ≤ 5.5V
0.6
0.2
IN
V
V
≤ V ≤ 2.5V
IN
IN(MIN)
T
T
= +25°C
= +85°C
-100
0.05
10
+100
A
nA
SHDN = GND or IN
A
2
_______________________________________________________________________________________
60mA, SOT23 Inverting Charge Pump
with Shutdown
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, capacitors from Table 2, V = +5V, SHDN = IN, T = 0°C to +85°C, unless otherwise noted. Typical values are at
IN
A
T
A
= +25°C.)
PARAMETER
CONDITIONS
MIN
TYP
1200
600
100
70
MAX
UNITS
MAX1697R
MAX1697S
MAX1697T
MAX1697U
Wake-Up Time from Shutdown
I
= 15mA
µs
OUT
THERMAL SHUTDOWN
Trip Temperature
Hysteresis
Temperature increasing
150
15
°C
°C
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, capacitors from Table 2, V = +5V, SHDN = IN, T = -40°C to +85°C, unless otherwise noted.) (Note 8)
IN
A
PARAMETER
Supply Voltage Range
Output Current
CONDITIONS
MIN
1.5
MAX
5.5
UNITS
MAX1697R/S
MAX1697T/U
R = 5kΩ
V
L
1.6
5.5
Continuous, long-term
MAX1697R
60
mA
RMS
350
750
1800
3600
21
MAX1697S
Quiescent Current
(Note 9)
µA
MAX1697T
MAX1697U
MAX1697R
6
MAX1697S
16
60
Oscillator Frequency
kHz
MAX1697T
60
200
400
33
MAX1697U
120
Output Resistance (Note 7)
I
= 60mA
Ω
Ω
OUT
OUT to GND Shutdown
Resistance
SHDN = GND, OUT is internally pulled to GND in
shutdown
8
2.5V ≤ V ≤ 5.5V
2.1
IN
V
V
SHDN Input Logic High
SHDN Input Logic Low
V
≤ V ≤ 2.5V
V
- 0.2
IN(MIN)
IN
IN
2.5V ≤ V ≤ 5.5V
0.6
0.2
IN
V
≤ V ≤ 2.5V
IN
IN(MIN)
Note 7: Output resistance is guaranteed with capacitor ESR of 0.3Ω or less.
Note 8: All specifications from -40°C to +85°C are guaranteed by design, not production tested.
Note 9: The MAX1697 may draw high supply current during startup, up to the minimum operating supply voltage. To guarantee
proper startup, the input supply must be capable of delivering 90mA more than the maximum load current.
_______________________________________________________________________________________
3
60mA, SOT23 Inverting Charge Pump
with Shutdown
Typical Operating Characteristics
(Circuit of Figure 1, capacitors from Table 2, V = +5V, SHDN = IN, T = +25°C, unless otherwise noted.)
IN
A
MAX1697T
MAX1697R
MAX1697S
OUTPUT VOLTAGE
vs. OUTPUT CURRENT
OUTPUT VOLTAGE
vs. OUTPUT CURRENT
OUTPUT VOLTAGE
vs. OUTPUT CURRENT
0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
-4.0
-4.5
-5.0
0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
-4.0
-4.5
-5.0
0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
-4.0
-4.5
-5.0
V
= +2V
IN
IN
V
= +2V
IN
V
= +2V
IN
V
V
= +3.3V
V
= +3.3V
IN
= +3.3V
IN
V
= +5V
V
= +5V
IN
V = +5V
IN
IN
0
10 20 30 40 50 60 70 80
OUTPUT CURRENT (mA)
0
10 20 30 40 50 60 70 80
OUTPUT CURRENT (mA)
0
10 20 30 40 50 60 70 80
OUTPUT CURRENT (mA)
MAX1697U
OUTPUT VOLTAGE
vs. OUTPUT CURRENT
MAX1697S
EFFICIENCY vs. OUTPUT CURRENT
MAX1697R
EFFICIENCY vs. OUTPUT CURRENT
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
-4.0
-4.5
-5.0
V
= +5V
V
= +5V
IN
IN
V
= +2V
IN
V
= +3.3V
V
= +3.3V
IN
IN
V
= +3.3V
IN
V
= +2V
IN
V
= +2V
IN
V
= +5V
IN
0
10 20 30 40 50 60 70 80
OUTPUT CURRENT (mA)
0
10 20 30 40 50 60 70 80
OUTPUT CURRENT (mA)
0
10 20 30 40 50 60 70 80
OUTPUT CURRENT (mA)
MAX1697R/S/T/U
OUTPUT IMPEDANCE vs. INPUT VOLTAGE
MAX1697T
EFFICIENCY vs. OUTPUT CURRENT
MAX1697U
EFFICIENCY vs. OUTPUT CURRENT
30
25
20
15
10
5
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
V
= +5V
IN
V
= +5V
IN
V
= +3.3V
IN
V
= +3.3V
IN
V = +2V
IN
V
= +2V
IN
0
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
0
10 20 30 40 50 60 70 80
OUTPUT CURRENT (mA)
0
10 20 30 40 50 60 70 80
OUTPUT CURRENT (mA)
4
_______________________________________________________________________________________
60mA, SOT23 Inverting Charge Pump
with Shutdown
Typical Operating Characteristics (continued)
(Circuit of Figure 1, capacitors from Table 2, V = +5V, SHDN = IN, T = +25°C, unless otherwise noted.)
IN
A
MAX1697R/S/T/U
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX1697R
OUTPUT RESISTANCE
vs. TEMPERATURE
SUPPLY CURRENT
vs. INPUT VOLTAGE
35
30
25
20
15
10
5
2.5
2.0
1.5
1.0
0.5
0
35
30
25
20
15
10
5
V
= +1.5V
IN
MAX1697U
V
= +5V
IN
V
= +2V
IN
MAX1697T
MAX1697S
V
V
= +3.3V
= +2V
IN
V
= +3.3V
= +5V
IN
V
IN
IN
MAX1697R
0
0
-40
-20
0
20
40
60
80
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
-40
-40
V
-20
0
20
40
60
80
TEMPERATURE (°C)
TEMPERATURE (°C)
MAX1697U
OUTPUT RESISTANCE
vs. TEMPERATURE
MAX1697S
OUTPUT RESISTANCE
vs. TEMPERATURE
MAX1697T
OUTPUT RESISTANCE
vs. TEMPERATURE
45
40
35
30
25
20
15
10
5
30
25
20
15
10
5
35
30
25
20
15
10
5
V
= +1.5V
IN
V
= +1.5V
IN
V
= +1.5V
IN
V
= +2V
IN
V
= +2V
IN
V
= +2V
IN
V
= +3.3V
IN
V
= +3.3V
= +5V
IN
V
V
= +3.3V
= +5V
IN
V
V
= +5V
IN
IN
IN
0
0
0
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
MAX1697T/U
OUTPUT NOISE AND RIPPLE
PUMP FREQUENCY
vs. TEMPERATURE
MAX1697R/S
OUTPUT NOISE AND RIPPLE
MAX1697 TOC17
MAX1697 TOC18
1000
100
10
V
MAX1697U
OUT
MAX1697R
(12kHz)
V
OUT
MAX1697T
(125kHz)
MAX1697T
MAX1697S
MAX1697R
V
OUT
V
MAX1697S
(35kHz)
OUT
MAX1697U
(250kHz)
V
= +1.5V TO +5V
IN
1
2μs/div
= 5mA,
OUT
-40
-20
0
20
40
60
80
20μs/div
= 5mA,
10mV/div, AC-COUPLED
= +3.3V, I
V
= +3.3V, I
OUT
TEMPERATURE (°C)
IN
IN
10mV/div, AC-COUPLED
_______________________________________________________________________________________
5
60mA, SOT23 Inverting Charge Pump
with Shutdown
Typical Operating Characteristics (continued)
(Circuit of Figure 1, capacitors from Table 2, V = +5V, SHDN = IN, T = +25°C, unless otherwise noted.)
IN
A
MAX1697R
OUTPUT CURRENT
vs. CAPACITANCE
START-UP FROM SHUTDOWN
START-UP FROM SHUTDOWN
MAX1697 TOC20
MAX1697 TOC19
70
60
50
40
30
20
10
0
0V
0V
V
= +4.75V, V
= -4.0V
IN
OUT
MAX1697U
(250kHz)
MAX1697S
(35kHz)
V
, 2V/div
V
, 2V/div
OUT
V
= +3.15V, V
= -2.5V
= -1.5V
OUT
IN
OUT
0V
0V
MAX1697T
(125kHz)
MAX1697R
(12kHz)
V
, 2V/div
V
, 2V/div
V = +1.9V, V
IN
OUT
OUT
OUT
SHDN
SHDN
50μs/div
0
5
10 15 20 25 30 35 40 45 50
400μs/div
CAPACITANCE (μF)
MAX1697T
MAX1697S
MAX1697U
OUTPUT CURRENT
vs. CAPACITANCE
OUTPUT CURRENT
vs. CAPACITANCE
OUTPUT CURRENT
vs. CAPACITANCE
70
60
50
40
30
20
10
0
80
70
60
50
40
30
20
10
0
80
70
60
50
40
30
20
10
0
V
= +4.75V, V
= -4.0V
= -2.5V
V
= +4.75V, V
= -4.0V
IN
OUT
IN
OUT
V
= +4.75V, V
= -4.0V
IN
OUT
V
= +3.15V, V
OUT
IN
V
= +3.15V, V
= -2.5V
IN
OUT
V
= +3.15V, V
= -2.5V
IN
OUT
V
= +1.9V, V
= -1.5V
IN
OUT
V
= +1.9V, V
= -1.5V
OUT
IN
V
= +1.9V, V
= -1.5V
IN
OUT
0
1
2
3
4
5
6
7
8
9
10
0
5
10 15 20 25 30 35 40 45
0
1
2
3
4
5
6
7
8
9
10
CAPACITANCE (μF)
CAPACITANCE (μF)
CAPACITANCE (μF)
MAX1697R
OUTPUT RIPPLE vs. CAPACITANCE
MAX1697S
OUTPUT RIPPLE vs. CAPACITANCE
500
450
400
350
300
250
200
150
100
50
500
450
400
350
300
250
200
150
100
50
V
= +4.75V, V
= +3.15V, V
= -4.0V
= -2.5V
IN
OUT
V
= +4.75V, V
= -4.0V
= -2.5V
IN
OUT
V
IN
OUT
V
= +1.9V, V
= -1.5V
IN
OUT
V
= +3.15V, V
OUT
IN
V
= +1.9V, V
= -1.5V
IN
OUT
0
0
0
5
10 15 20 25 30 35 40 45 50
0
5
10 15 20 25 30 35 40 45 50
CAPACITANCE (μF)
CAPACITANCE (μF)
6
_______________________________________________________________________________________
60mA, SOT23 Inverting Charge Pump
with Shutdown
Typical Operating Characteristics (continued)
(Circuit of Figure 1, capacitors from Table 2, V = +5V, SHDN = IN, T = +25°C, unless otherwise noted.)
IN
A
MAX1697T
OUTPUT RIPPLE vs. CAPACITANCE
MAX1697U
OUTPUT RIPPLE vs. CAPACITANCE
500
450
400
350
300
250
200
150
100
50
500
450
400
350
300
250
200
150
100
50
V
= +4.75V, V
= -4.0V
IN
V
OUT
V
= +4.75V, V
= -4.0V
IN
V
OUT
= +3.15V, V
= -2.5V
IN
OUT
= +3.15V, V
= -2.5V
OUT
IN
V
= +1.9V, V
= -1.5V
IN
OUT
V
= +1.9V, V
= -1.5V
OUT
IN
0
0
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
CAPACITANCE (μF)
CAPACITANCE (μF)
Pin Description
C1
PIN
NAME
FUNCTION
6
C1+
3
C1-
INPUT
1.5V to 5.5V
OUT
Inverting Charge-Pump Output
1
NEGATIVE
OUTPUT
✕
2
1
IN
OUT
Power-Supply Voltage Input. Input
range is 1.5V to 5.5V.
2
IN
-1
V
IN
C3
R
L
MAX1697
C2
Negative Terminal of the Flying
Capacitor
3
4
C1-
5
ON
OFF
SHDN
GND
4
GND
Ground
Shutdown Input. Drive this pin high
for normal operation; drive it low for
shutdown mode. OUT is actively
pulled to ground during shutdown.
TE: (
5
6
SHDN
Figure 1. Typical Application Circuit
C2 is smaller than the voltage across C1, charge flows
from C1 to C2 until the voltage across C2 reaches
Positive Terminal of the Flying
Capacitor
C1+
-V . The actual voltage at the output is more positive
IN
than -V , since switches S1–S4 have resistance and the
IN
Detailed Description
load drains charge from C2.
The MAX1697 capacitive charge pumps invert the volt-
age applied to their input. For highest performance, use
low equivalent series resistance (ESR) capacitors (e.g.,
ceramic).
Efficiency Considerations
The efficiency of the MAX1697 is dominated by its qui-
escent supply current (I ) at low output current and by
Q
its output impedance (R
is given by:
) at higher output current; it
OUT
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 V volts. This connects C1 in par-
IN
allel with the reservoir capacitor C2. If the voltage across
⎛
⎞
I
I
x R
OUT
OUT OUT
η ≅
1−
⎜
⎟
I
+I
V
IN
⎝
⎠
OUT
Q
_______________________________________________________________________________________
7
60mA, SOT23 Inverting Charge Pump
with Shutdown
R
EQUIV
S1
S2
V+
IN
V
OUT
1
R
EQUIV
=
C1
✕
f
C1
C2
OSC
R
L
C2
S3
S4
V
= -(V )
IN
OUT
Figure 3b. Equivalent Circuit
Thermal Shutdown
The MAX1697 has a thermal shutdown mode for addi-
tional protection against fault conditions. When the tem-
perature of the die exceeds +150°C, the internal clock
stops, suspending the device’s operation. The
MAX1697 resumes operation when the die temperature
falls 15°C. This prevents the device from rapidly oscil-
lating around the temperature trip point.
Figure 2. Ideal Voltage Inverter
f
OSC
V+
V
OUT
C2
R
L
C1
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.
Figure 3a. Switched-Capacitor Model
where the output impedance is roughly approximated
by:
1
R
≅
+ 2R
+ 4ESR + ESR
SW C1 C2
OUT
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.
f
x C1
OSC
The first term is the effective resistance of an ideal
switched-capacitor circuit (Figures 3a and 3b), and
R
is the sum of the charge pump’s internal switch
SW
resistances (typically 4Ω to 5Ω at V = +5V). The typi-
IN
cal output impedance is more accurately determined
from the Typical Operating Characteristics.
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:
Current Limit
The MAX1697 limits its input current upon start-up to
170mA (typ). This prevents low-current or higher output
impedance input supplies (such as alkaline cells) from
being overloaded when power is applied or when the
device awakes from shutdown.
I
OUT
V
=
+2×I
×ESR
RIPPLE
OUT C2
Shutdown
The MAX1697 has a logic-controlled shutdown input.
Driving SHDN low places the device in a low-power
shutdown mode. The charge-pump switching halts,
supply current is reduced to 2nA, and OUT is actively
pulled to ground through a 3Ω resistance.
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.
2(f
)C2
OSC
Input Bypass Capacitor (C3)
If necessary, bypass the incoming supply to reduce its
AC impedance and the impact of the MAX1697’s switch-
ing noise. A bypass capacitor with a value equal to that
of C1 is recommended.
8
_______________________________________________________________________________________
60mA, SOT23 Inverting Charge Pump
with Shutdown
is the number of parallel devices. Figure 5 shows the
equation for calculating output resistance.
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.
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 60mA.
Cascading Devices
Two devices can be cascaded to produce an even
larger negative voltage (Figure 4). The unloaded output
✕
voltage is normally -2 V , but this is reduced slightly
IN
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 dra-
matically. For applications requiring larger negative
voltages, see the MAX865 and MAX868 data sheets.
The maximum load current and startup current of the
nth cascaded circuit must not exceed the maximum
output current capability of the (n-1)th circuit to ensure
proper startup.
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.
Paralleling Devices
Paralleling multiple MAX1697s reduces the output resis-
tance. 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
Table 1. Low-ESR Capacitor Manufacturers
PRODUCTION
MANUFACTURER
SERIES
PHONE
FAX
METHOD
AVX
Matsuo
Sprague
AVX
TPS series
267 series
593D, 595D series
X7R
803-946-0690
714-969-2491
603-224-1961
803-946-0690
714-969-2491
803-626-3123
714-960-6492
603-224-1430
803-626-3123
714-960-6492
Surface-Mount
Tantalum
Surface-Mount
Ceramic
Matsuo
X7R
Table 2. Capacitor Selection to Minimize
Output Resistance
Table 3. Capacitor Selection to Minimize
Capacitor Size
FREQUENCY
(kHz)
CAPACITOR TYPICAL
FREQUENCY
(kHz)
CAPACITOR TYPICAL
PART
PART
(µF)
R
(Ω)
(µF)
R
OUT
(Ω)
OUT
MAX1697R
MAX1697S
MAX1697T
MAX1697U
12
35
22
12
MAX1697R
MAX1697S
MAX1697T
MAX1697U
12
35
10
17
6.8
2.2
1
12
12
12
3.3
1
17
17
17
125
250
125
250
0.47
_______________________________________________________________________________________
9
60mA, SOT23 Inverting Charge Pump
with Shutdown
SHDN
…
+V
IN
+V
IN
5
2
1
2
1
3
4
2
1
D1, D2 = 1N4148
3
4
3
4
C1
MAX1697
MAX1697
MAX1697
C1
C1
D1
D2
V
OUT
6
6
6
V
OUT
= -V
IN
…
C2
C4
C2
5
5
C2
V
= (2V ) -
IN
OUT
(V ) - (V
)
FD1
FD2
SHDN
C3
V
= -nV
IN
OUT
Figure 4. Cascading MAX1697s to Increase Output Voltage
Figure 6. Combined Doubler and Inverter
…
+V
IN
4
V+
GND
2
1
2
1
3
4
6
3
4
6
MAX1697
R
L
MAX1697
MAX1697
C1
1
C1
OUT
V
OUT
5
5
…
Figure 7. Heavy Load Connected to a Positive Supply
SHDN
C2
V
OUT
= -V
IN
R
OF SINGLE DEVICE
NUMBER OF DEVICES
OUT
R
OUT
=
Figure 5. Paralleling MAX1697s to Reduce Output Resistance
Chip Information
TRANSISTOR COUNT: 275
10 ______________________________________________________________________________________
60mA, SOT23 Inverting Charge Pump
with Shutdown
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
21-0058
6 SOT23
U6F-6
PACKAGE OUTLINE, SOT 6L BODY
1
21-0058
I
2
______________________________________________________________________________________ 11
60mA, SOT23 Inverting Charge Pump
with Shutdown
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PACKAGE OUTLINE, SOT 6L BODY
2
21-0058
I
2
12 ______________________________________________________________________________________
60mA, SOT23 Inverting Charge Pump
with Shutdown
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
DESCRIPTION
CHANGED
3
12/08
Added additional available top mark for RoHS compliance
1
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600___________________ 13
© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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