19-4241; Rev 1; 6/09
30mA Inverting Charge Pump in SOT23
for EMI-Sensitive Automotive Applications
General Description
The MAX16945 ultra-small, monolithic, CMOS charge-
pump voltage inverter accepts an input voltage ranging
from +1.4V to +5.5V. This device features an ultra-low
12Ω output resistance, permitting loads of up to 30mA
at +105°C with maximum efficiency. The MAX16945
operates at a frequency of 125kHz, allowing use of
small external components. Its small external compo-
nents, micropower shutdown mode, and wide tempera-
ture range make this device ideal for both automotive
and industrial applications.
Oscillator control circuitry and four power MOSFET
switches are included on-chip. The MAX16945 comes
in a 6-pin SOT23 package and operates over -40°C
to +105°C.
o
+1.4V to +5.5V Input Voltage Range
o
30mA Guaranteed Output Current at +105°C
o
Slew-Rate Limited to Reduce EMI
o
0.1µA Logic-Controlled Shutdown
o
Low 12Ω Output Resistance
o
Startup Current Limited
o
6-Pin SOT23 Package
o
AEC-Q100 Qualified
Features
MAX16945
Applications
Automotive and Industrial Equipment
Small LCD Panels
Negative Supply from +5V or +3.3V Logic
Supplies
GaAsFET Bias Supplies
Handy-Terminals, PDAs
PART
MAX16945TGUT#
MAX16945TGUT/V+
Ordering Information
TEMP RANGE
-40°C to +105°C
-40°C to +105°C
PIN-PACKAGE
6 SOT23
6 SOT23
#Denotes
a RoHS-compliant device that may include lead that
is exempt under RoHS requirements.
/V denotes an automotive qualified part.
+Denotes
a lead(Pb)-free/RoHS-compliant package.
Note:
The MAX16945 requires a special solder temperature
profile described in the Absolute Maximum Ratings section.
Typical Operating Circuit
Pin Configuration
1µF
TOP VIEW
INPUT
1.5V TO 5.5V
C1+
IN
C1-
OUT
NEGATIVE
OUTPUT
-1
✕
V
IN
60mA
1µF
C1-
GND
3
4
GND
OUT
1
6
C1+
MAX16945
ON
OFF
SHDN
IN
2
MAX16945
5
SHDN
SOT23
________________________________________________________________
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.
30mA Inverting Charge Pump in SOT23
for EMI-Sensitive Automotive Applications
MAX16945
ABSOLUTE MAXIMUM RATINGS
IN to GND .................................................................-0.3V to +6V
C1+,
SHDN
to GND .......................................0.3V to (V
IN
+0.3V)
C1- to GND...............................................(V
OUT
- 0.3V) to +0.3V
OUT to GND .............................................................+0.3V to -6V
OUT Output Current............................................................90mA
OUT Short Circuit to GND..............................................Indefinite
Continuous Power Dissipation (T
A
= +70°C)
6-Pin SOT23 (derate 7.4mW/°C above +70°C) (Note 1) .....595mW
Junction-to-Case Thermal Resistance (θ
JC
) (Note 1)
6-Pin SOT23 ................................................................39°C/W
Junction-to-Ambient Thermal Resistance (θ
JA
) (Note 1)
6-Pin SOT23 ..............................................................134°C/W
Operating Temperature Range .........................-40°C to +105°C
Junction Temperature. .....................................................+150°C
Storage Temperature Range ............................-65°C to +150°C
Lead Temperature.......................................................... (Note 2)
Note 1:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to
www.maxim-ic.com/thermal-tutorial.
Note 2:
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 recom-
mended 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, C1 = C2 =2.2µF, V
IN
= V
SHDN
= +5V, V
GND
= 0,
T
A
= 0°C to +105°C,
unless otherwise noted. Typical values are
at T
A
= +25°C.)
PARAMETER
Supply Voltage Range
Quiescent Supply Current
Shutdown Supply Current
Short-Circuit Current
Oscillator Frequency
Voltage Conversion Efficiency
Output Resistance
R
L
= 5kΩ
T
A
= +25°C (Note 3)
V
SHDN
= 0
T
A
= +25°C
T
A
= 0°C to +105°C
70
99
T
A
= +25°C
T
A
= 0°C to +105°C
3
2.0
V
IN
- 0.2
0.6
0.2
T
A
= +25°C
T
A
= 0°C to +105°C
-100
+0.05
10
100
+100
CONDITIONS
T
A
= +25°C
T
A
= 0°C to +105°C
MIN
1.4
1.5
950
0.002
0.03
170
125
99.9
12
25
36
8.5
180
TYP
MAX
5.5
5.5
1700
1
UNITS
V
µA
µA
mA
kHz
%
Ω
Ω
Output shorted to ground, T
A
= +25°C
T
A
= +25°C
I
OUT
= 0, T
A
= +25°C
I
OUT
= 30mA (Note 4)
OUT-to-GND Shutdown Resistance
V
SHDN
= 0, OUT is internally pulled to GND
in shutdown
2.5V
≤
V
IN
≤
5.5V
V
IN(MIN)
≤
V
IN
≤
2.5V
2.5V
≤
V
IN
≤
5.5V
V
IN(MIN)
≤
V
IN
≤
2.5V
SHDN
= GND or IN
I
OUT
= 15mA
SHDN
Input Logic-High
SHDN
Input Logic-Low
SHDN
Bias Current
Wake-Up Time from Shutdown
V
V
nA
µs
2
_______________________________________________________________________________________
30mA Inverting Charge Pump in SOT23
for EMI-Sensitive Automotive Applications
MAX16945
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, C1 = C2 =2.2µF, V
IN
= V
SHDN
= +5V, V
GND
= 0,
T
A
= 0°C to +105°C,
unless otherwise noted. Typical values are
at T
A
= +25°C.)
PARAMETER
Supply Voltage Range
Output Current
Quiescent Supply Current
Oscillator Frequency
Output Resistance
OUT-to-GND Shutdown Resistance
SHDN
Input Logic-High
SHDN
Input Logic-Low
I
OUT
= 30mA (Note 5)
V
SHDN
= 0, OUT is internally pulled to GND
in shutdown
2.5V
≤
V
IN
≤
5.5V
V
IN(MIN)
≤
V
IN
≤
2.5V
2.5V
≤
V
IN
≤
5.5V
V
IN(MIN)
≤
V
IN
≤
2.5V
2.1
V
IN
- 0.2
0.6
0.2
R
L
= 5kΩ
Continuous, long-term
(Note 3)
60
125
CONDITIONS
MIN
1.6
TYP
MAX
5.5
60
1800
200
36
8.5
UNITS
V
mA
RMS
µA
kHz
Ω
Ω
V
V
Note 3:
The MAX16945 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.
Note 4:
Output resistance is guaranteed with capacitor ESR of 0.3Ω or less.
Note 5:
All specifications from -40°C to +105°C are guaranteed by design, not production tested.
Typical Operating Characteristics
(Circuit of Figure 1, C1 = C2 = 2.2µF, V
IN
= V
SHDN
= +5V, V
GND
= 0, T
A
= +25°C, unless otherwise noted.)
OUTPUT VOLTAGE
vs. OUTPUT CURRENT
MAX16945 toc01
EFFICIENCY vs. OUTPUT CURRENT
90
80
EFFICIENCY (%)
70
60
50
40
30
V
IN
= +3.3V
V
IN
= +2V
V
IN
= +5V
MAX16945 toc02
OUTPUT IMPEDANCE
vs. INPUT VOLTAGE
35
OUTPUT IMPEDANCE (Ω)
30
25
20
15
10
5
0
MAX16945 toc03
0
-0.5
-1.0
OUTPUT VOLTAGE (V)
-1.5
-2.0
-2.5
-3.0
-3.5
-4.0
-4.5
-5.0
0
10
20
30
40
V
IN
= +5V
V
IN
= +3.3V
V
IN
= +2V
100
40
20
10
0
50
0
10
20
30
40
50
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
INPUT VOLTAGE (V)
_______________________________________________________________________________________
3
30mA Inverting Charge Pump in SOT23
for EMI-Sensitive Automotive Applications
MAX16945
Typical Operating Characteristics (continued)
(Circuit of Figure 1, C1 = C2 = 2.2µF, V
IN
= V
SHDN
= +5V, V
GND
= 0, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX16945 toc04
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX16945 toc05
OUTPUT IMPEDANCE
vs. TEMPERATURE
35
OUTPUT IMPEDANCE (Ω)
30
25
20
15
V
IN
= +5V
10
5
0
V
IN
= +2V
V
IN
= +3.3V
MAX16945 toc06
2.5
700
600
SUPPLY CURRENT (nA)
500
400
V
IN
= +3.3V
300
200
100
V
IN
= +2V
40
2.0
SUPPLY CURRENT (mA)
V
IN
= +5V
1.5
1.0
0.5
0
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY VOLTAGE (V)
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
PUMP FREQUENCY
vs. TEMPERATURE
119
PUMP FREQUENCY (kHz)
118
117
116
115
114
113
112
111
110
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
MAX16945 toc07
OUTPUT NOISE AND RIPPLE
MAX16945 toc08
120
10mV/div
2µs/div
STARTUP FROM SHUTDOWN
MAX16945 toc09
SHDN
5V/div
V
OUT
2V/div
40µs/div
4
_______________________________________________________________________________________
30mA Inverting Charge Pump in SOT23
for EMI-Sensitive Automotive Applications
MAX16945
Typical Operating Characteristics (continued)
(Circuit of Figure 1, C1 = C2 = 2.2µF, V
IN
= V
SHDN
= +5V, V
GND
= 0, T
A
= +25°C, unless otherwise noted.)
OUTPUT CURRENT
vs. CAPACITANCE
MAX16945 toc10
OUTPUT RIPPLE
vs. CAPACITANCE
MAX16945 toc11
60
50
OUTPUT CURRENT (mA)
40
30
20
V
IN
= +1.7V, V
OUT
= -1.5V
10
0
0
1
2
3
4
5
6
7
8
9
V
IN
= +4.375V, V
OUT
= -4V
V
IN
= +2.825V, V
OUT
= -2.5V
250
200
OUTPUT RIPPLE (mV)
V
IN
= +4.375V, V
OUT
= -4V
150
V
IN
= +2.825V, V
OUT
= -2.5V
100
V
IN
= +1.7V, V
OUT
= -1.5V
50
0
10
0
1
2
3
4
5
6
7
8
9
10
CAPACITANCE (µF)
CAPACITANCE (µF)
Pin Description
PIN
1
2
3
4
NAME
OUT
IN
C1-
GND
FUNCTION
Inverting Charge-Pump Output
Power-Supply Voltage Input. Input range
is 1.4V to 5.5V.
Negative Terminal of the Flying Capacitor
Ground
Shutdown Input. Drive
SHDN
high for
normal operation; drive
SHDN
low for
shutdown mode. OUT is actively pulled to
ground during shutdown.
Positive Terminal of the Flying Capacitor
INPUT
1.5V TO 5.5V
C3
6
C1+
IN
C1
3
C1-
OUT
2
1
R
L
NEGATIVE
OUTPUT
-1
✕
V
IN
C2
MAX16945
ON
OFF
5
SHDN
GND
4
5
SHDN
Figure 1. Typical Application Circuit
S1
IN
C1
S2
6
C1+
Detailed Description
The MAX16945 capacitive charge pump inverts the
voltage applied to its input. For highest performance,
use low-ESR capacitors.
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
IN
volts. This connects C1
in parallel 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 -V
IN
. The absolute value of the inverting output
S3
S4
C2
V
OUT
= -(V
IN
)
Figure 2. Ideal Voltage Inverter
voltage is always smaller than the value of the input
voltage due to the losses of the flying capacitor C1 and
the resistance of the switches S1–S4.
_______________________________________________________________________________________
5
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