_______________General Description
The MAX1822 high-side supply, using a regulated
charge pump, generates a regulated output voltage
11V greater than the input supply voltage to power
high-side switching and control circuits. The MAX1822
allows low-resistance N-channel MOSFETs (FETs) to be
used in circuits that normally require costly, less effi-
cient P-channel FETs and PNP transistors. The high-
side output also eliminates the need for logic FETs in
+5V and other low-voltage switching circuits.
A +3.5V to +16.5V input supply range and a typical qui-
escent current of only 150µA make the MAX1822 ideal
for a wide range of line- and battery-powered switching
and control applications where efficiency is crucial.
Also provided is a logic-level power-ready output (PR)
to indicate when the high-side voltage reaches the
proper level.
The MAX1822 comes in an 8-pin SO package and
requires three inexpensive external capacitors. The
MAX1822 is a pin-for-pin replacement to the MAX622.
________________________Applications
High-Side Power Control with N-Channel FETs
Low-Dropout Voltage Regulators
Power Switching from Low Supply Voltages
H-Switches
Stepper Motor Drivers
Battery-Load Management
Portable Computers
____________________________Features
♦+3.5V to +16.5V Operating Supply Voltage Range
♦Output Voltage Regulated to VCC + 11V (typ)
♦150µA (typ) Quiescent Current
♦Power-Ready Output
MAX1822
High-Side Power Supply
________________________________________________________________ Maxim Integrated Products 1
C2+
VOUT
GND
1
2
8
7
VCC
C1-C2-
PR
C1+
SO
TOP VIEW
3
4
6
5
MAX1822
Pin Configuration
MAX1822
+3.5V TO +16.5V
0.1µF
CERAMIC
GND
+12.5V TO +27.5V
1
8
5
3
PR
VOUT
VCC
7
C1
C3
4
C1+
C1-
C2+
C2-
6
2
C2
Typical Operating Circuit
19-1892; Rev 0; 1/01
PART
MAX1822ESA -40°C to +85°C
TEMP. RANGE PIN-PACKAGE
8 SO
Ordering Information
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX1822
High-Side Power Supply
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = +5V, TA= TMIN to TMAX, unless otherwise noted.)
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.
Note 1: High-side voltage measured with respect to ground.
Note 2: For VCC > +13V on the MAX1822, use C1 = C2 = 0.01µF.
Note 3: Power-Ready Threshold is the voltage with respect to ground at VOUT when PR switches high (PR = VCC).
VCC ......................................................................................+17V
VOUT ....................................................................................+30V
IOUT ...................……………………………………………….25mA
Continuous Total Power Dissipation (TA= +70°C)
8-pin SO (derate 5.88mW/°C above +70°C)...............471mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Supply Voltage VCC 3.5 16.5 V
IOUT = 0, VCC = 3.5V,
C1 = C2 = 0.047µF, C3 = 1µF 11.5 12.5 16.5
IOUT = 0, VCC = 4.5V, C1 = C2 = 0.047µF,
C3 = 1µF 14.5 15.5 17.5
IOUT = 0, VCC = 16.5V, C1 = C2 = 0.01µF,
C3 = 1µF (Note 2) 26.5 27.5 29.5
IOUT = 50µA, VCC = 3.5V,
C1 = C2 = 0.047µF, C3 = 1µF 8.5 10.5 16.5
IOUT = 250µA, VCC = 5V,
C1 = C2 = 0.047µF, C3 = 1µF 15 18
High-Side Voltage (Note 1) VOUT
IOUT = 500µA, VCC = 16.5V,
C1 = C2 = 0.01µF, C3 = 1µF (Note 2) 26.5 29.5
V
Power-Ready Threshold PRT IOUT = 0 (Note 3) 12 13.5 14.5 V
Power-Ready Output High PROH ISOURCE = 100µA 3.8 4.3 5 V
Power-Ready Output Low PROL ISINK = 1mA 0.4 V
Output Voltage Ripple VR C1 = C2 = 0.01µF, C3 = 10µF,
IOUT = 1mA, VCC = 16.5V 50 mV
Switching Frequency FO 90 kHz
IOUT = 0, VCC = 5V, C1 = C2 = 0.047µF,
C3 = 1µF, TA = +25°C 150 500
Quiescent Supply Current IQ IOUT = 0, VCC = 16.5V, C1 = C2 = 0.047µF,
C3 = 1µF, TA = +25°C 150 350
µA
MAX1822
High-Side Power Supply
_______________________________________________________________________________________ 3
50
150
100
250
200
350
300
400
1342 5678910
MAX1822
SUPPLY CURRENT
vs. C3 CAPACITOR VALUE
MAX1822 toc01
C3 CAPACITOR VALUE (µF)
SUPPLY CURRENT (µA)
VCC = +5V, IOUT = 0
TA = +25°C
C1 = C2 = C*
C* = 0.01µF
C* = 0.1µF
C* = 0.033µF
C* = 0.047µF
C* =
0.022µF
50
150
100
200
250
350
300
400
14523 678910
MAX1822 toc02
C3 CAPACITOR VALUE (µF)
SUPPLY CURRENT (µA)
MAX1822
SUPPLY CURRENT
vs. C3 CAPACITOR VALUE
VCC = +16.5V
IOUT = 0
TA = +25°C
C1 = C2 = 0.01µF
0
0.2
0.6
0.4
1.0
1.2
0.8
1.4
2684 1012141618
MAX1822 toc03
VCC (V)
SUPPLY CURRENT (mA)
MAX1822
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
C1 = C2 = 0.01µF
IOUT = 0
C3 = 1µF
TA = +25°C
C1 = C2 = 0.47µF
12
13
14
15
16
17
0 0.8 1.00.4 0.60.2 1.2 1.4 1.6 1.8 2.0
MAX1822 toc05
IOUT (mA)
VOUT (V)
MAX1822
OUTPUT VOLTAGE
vs. OUTPUT CURRENT
C1 = C2 = 0.01µF
VCC = +5V
C3 = 10µF
TA = +25°C
C1 = C2 = 0.22µF
C1 = C2 = 0.47µF
0
200
100
400
300
600
500
700
900
800
1000
0.01 0.1
MAX1822 toc04
C1 = C2 CAPACITANCE VALUE (µF)
MAXIMUM IOUT (µA)
MAX1822
MAXIMUM OUTPUT CURRENT
vs. C1 = C2 CAPACITOR VALUE
VCC = +5V
C3 = 10µF
TA = +25°C
NOTE: MAXIMUM IOUT IS THE LOAD
CURRENT AT THE POINT
WHERE VOUT BEGINS TO
LOSE REGULATION.
18
21
20
19
22
23
24
04312 5678910
MAX1822 toc05
IOUT (mA)
VOUT (V)
MAX1822
OUTPUT VOLTAGE
vs. OUTPUT CURRENT
C1 = C2
0.047µF
C1 = C2
0.022µF
C1 = C2
0.01µF
VCC = +12V
C3 = 10µF
TA = +25°C
__________________________________________Typical Operating Characteristics
MAX1822
High-Side Power Supply
4 _______________________________________________________________________________________
Pin Description
0
40
20
80
60
120
100
140
180
160
200
1 3452 678910
MAX1822 toc07
RESERVOIR CAPACITOR (µF)
VOUT RIPPLE (mV)
MAX1822
OUTPUT VOLTAGE RIPPLE
vs. RESERVOIR CAPACITOR C3
TA = +25°C
VCC = +5V
IOUT = 500µA
C1 = C2 = 0.047µF
VCC = +16.5V
IOUT = 1mA
C1 = C2 = 0.01µF
0 5 10 15 20
MAX1822 toc08
VCC (V)
0.1
1
10
TURN-ON TIME (ms)
MAX1822
TURN-ON TIME
vs. SUPPLY VOLTAGE
IOUT = 0
TA = +25°C
Typical Operating Characteristics (continued)
PIN NAME FUNCTION
1 C1+ Positive terminal to primary charge-pump capacitor
2 C2- Negative terminal to secondary charge-pump capacitor
3 PR Power-Ready Output. High when VOUT is ≥ VCC + 8.5V with respect to GND.
4 GND Ground
5V
OUT High-Side Voltage Out
6 C2+ Positive terminal to secondary charge-pump capacitor
7 C1- Negative terminal to primary charge-pump capacitor
8V
CC Input Supply
MAX1822
High-Side Power Supply
_______________________________________________________________________________________ 5
Detailed Description
Charge-Pump Operation
The MAX1822 is a multistage charge-pump power sup-
ply. Although the charge pump is capable of multiply-
ing VCC up to four times, the output is regulated to VCC
+ 11V by an internal feedback circuit for inputs above
4V. The charge pump typically operates at 90kHz, but
regulates by pulse skipping. When VOUT exceeds VCC
+ 11V, the oscillator shuts off. As VOUT dips below VCC
+ 11V, the oscillator turns on.
Power-Ready Output
The Power-Ready Output (PR) signals control circuitry
when the high-side voltage reaches a preset level. This
feature can be used to protect external FET switches
from excess dissipation and damage by preventing them
from turning on, except when adequate gate drive levels
are present. When power is applied, PR remains low until
VOUT reaches approximately VCC + 8.5V. PR also goes
low if VOUT falls below this level during operation, i.e., if
the output is overloaded. The PR high level is VCC.
Applications Information
Quiescent Supply Current
MAX1822 quiescent supply current varies with VCC and
with the values of C1, C2, and C3 (Typical Operating
Characteristics). Even with no external load, the device
must still pump to overcome internal losses. Large ratios
between C3 and C1 or C2 require more charge-pump
cycles to restore VOUT. As VCC falls below 5V, quiescent
current rises fairly rapidly to about 1mA at 4V (Typical
Operating Characteristics). This rise occurs because
VOUT no longer pulse skips to regulate at low input volt-
ages; the oscillator runs continuously, so supply current
is higher. Figure 2 shows the test circuit for the
MAX1822 quiescent supply current.
Figure 1. MAX1822 Block Diagram
C3
C1 S2
S1
TWO-STAGE CHARGE PUMP
(SWITCHES SHOWN IN REFRESH MODE)
S5
RC OSCILLATOR
+
CONTROL LOGIC
OVERVOLTAGE
COMPARATOR
POWER-READY
COMPARATOR
PR DRIVER
GND
PR
VCC
11V 8.5V
VOUT
C2
S6
S7
VINT
S8
S3
S4
MAX1822
Output Ripple
VOUT ripple is typically 50mVp-p with VCC = +5V, C1
and C2 = 0.047µF, and C3 = 1µF (Typical Operating
Characteristics). Ripple can be reduced by increasing
the ratio between the output storage capacitors C3 and
C1 and C2. This is usually accomplished by increasing
C3 and keeping C1 and C2 in the 0.01µF to 0.047µF
range. For example, if C1 and C2 are 0.047µF (VCC
must not exceed 13V) and C3 is 10µF, output ripple
typically falls to 15mV (Typical Operating Character-
istics).
Capacitor Selection
Capacitor type is unimportant when selecting capaci-
tors for the MAX1822. However, when VCC exceeds
13V, C1 and C2 must be no greater than 0.01µF. Using
larger value capacitors with input voltages above 13V
causes excessive amounts of energy to pass through
High-Side Power Supply
6 _______________________________________________________________________________________
Figure 2. MAX1822 Quiescent Supply-Current Test Circuit
MAX1822
C4
1000µF
LOW ESR
GND
C3
1.0µF
1
8
5
VOUT
VCC
7
C2
0.047µF
4
C1+
VSUPPLY
C1-
C2+
C2-
6
2
C2
0.047µF
V
A
Figure 3. Single MAX1822 Driving Six High-Side Switches
MAX1822
SW1
SW2
SW3
SW4
SW5
SW6
GND
ALL PULLUP RESISTORS = 1M
74C906
14
1
3
5
9
11
13
2
4
6
8
10
12
7
ALL TRANSISTORS = 1RF541 (NOTE 2)
C4
1µF
C3
10µF
1
8
5
VOUT
VCC
7
C2
0.047µF
4
C1+
+5V
C1-
C2+
C2-
6
2
C2
0.047µF
ALL CAPACITORS = 1µF
(NOTE 1)
NOTE 1: 1µF CAPACITORS SUPPRESS SWITCHING TRANSIENTS, SIZE DEPENDS ON LOAD CURRENTS.
NOTE 2: POWER TRANSISTOR TYPE DEPENDS ON LOAD-CURRENT REQUIREMENTS.
TO 1A LOAD
TO 1A LOAD
TO 1A LOAD
TO 1A LOAD
TO 1A LOAD
TO 1A LOAD
6-CHANNEL LOAD SWITCH
internal switches during charge-pump cycles. This may
damage the device.
Output Protection
The MAX1822 is not internally short-circuit protected. In
applications where the output is susceptible to short
circuit, external output short-circuit protection must be
provided. Accomplish this by connecting a resistor
between VOUT and the load to limit output current to
less than 25mA. The resistor value is determined by the
following formula:
Typical Applications
One MAX1822 Drives
Six High-Side Switches
Multiple subsystems or modules can be turned on and
off using a single MAX1822 and an open-drain hex
buffer such as the 74C906 (Figure 3). The drains of all
buffer outputs are pulled through resistors to the
MAX1822’s VOUT. The pullup resistance depends on
the number of channels being used with the MAX1822
and power-dissipation limitations. The minimum pullup
resistor value is determined by the number of channels
paralleled on each high-side power supply and the
high-side output current from the MAX1822 at a given
supply voltage, calculated as follows:
where VOUT is the high-side output voltage and IOUT is
the output current of the MAX1822.
For example, assuming an output current of 1mA and
six channels, as in Figure 3, the minimum pullup resis-
tor value that will not excessively load the MAX1822 is
about 100kΩ, assuming all six channels are pulled low
at the same time. The value of the pullup resistor also
affects the turn-on time of each FET, and hence the
amount of energy dissipated in the FET during turn-on.
The rate of rise of VGS is limited by the RC time con-
stant of the pullup resistor and FET gate capacitance;
waste power will be dissipated in the FET equal to
(ILOAD)2x rDS during the RC time period.
H-Bridge Motor Driver
An H-bridge motor driver is shown in Figure 4. The
motor direction can be controlled by toggling between
IN1 and IN2 of the DG303 analog switch. Each switch
section turns on the appropriate FET pair, which pass-
es current through the motor in the desired direction.
RV x number of channels
I
MIN OUT
OUT
= ()
RV
mA
CL CC
≥ 25
MAX1822
High-Side Power Supply
_______________________________________________________________________________________ 7
Figure 4. H-Bridge Motor Controller
MAX1822 DG303
C1
1
+5V
7
C1
0.047µF
C3
10µF
H-BRIDGE MOTOR CONTROL
C2
0.047µF
6
2
4
REVERSE
FORWARD
5
V+
6
9
73 12
11
10 IRF541
IRF541
IRF541
IRF541
13
+–
5
4D1
D2
IN1
IN2 S1
S4
DC MOTOR
+5V
S2
S3
GND D3 D4
8
C1-
C2+
C2- GND
VCC
VOUT
14
MAX1822
4-Channel Load Switch with
No Pullup Resistors
Multiple high-side switches can be driven from a single
MAX1822 high-side power supply with no pullup resis-
tors on the FET gates. In Figure 5, a MAX1822 supplies
high-side voltage to a MAX333 quad analog switch to
control any one of four high-side switches. The FET
gates are normally connected to ground when the
MAX333 logic inputs are low.
Low-Dropout Regulator
In Figure 6, a MAX1822 high-side power supply powers
an LM10 reference and op-amp combination, providing
sufficient gate drive to turn on the FET. This allows the
regulator to achieve less than 70mV dropout at 1A load
using an IRF541, and just under 20mV for a
SMP60N06.
The 200mV reference section is configured for a gain of
25 (e.g., 200mV x 25 = 5V) and connects to the nonin-
verting input of the op amp; the regulator’s output con-
nects directly to the inverting input. The op amp
amplifies the error between its inputs and varies the
gate drive to the FET, regulating the output. Capacitor
C6 reduces transients due to load changes; its size
depends on the magnitude of the load change in the
application and can be reduced or eliminated if the
load remains relatively constant. With C6 = 1000µF, the
output transient to a 1A load pulsed at 20Hz is typically
less than 150mV. The regulator is turned on by apply-
ing VBATT to the Enable/Shutdown input and turned off
by pulling this input to ground.
The regulator output voltage, VOUT, is set by the ratio of
R1 to R2, calculated as follows:
If the application does not require logic shutdown, con-
nect the MAX1822 VCC pin directly to the battery and
eliminate D2.
RR
VOUT
21
02 1 .
=−
High-Side Power Supply
8 _______________________________________________________________________________________
Figure 5. MAX1822 Powering a MAX333 Quad Analog Switch, Realizing a 4-Channel Load Switch with No Pullup Resistors
MAX1822 MAX333
C1+
1
7
C1
0.01µF
C4
1µF
C3 10µF
+3.5V TO +16.5V
C2
0.01µF
6
2
4
5
8
C1-
C2+
4-CHANNEL LOAD SWITCH—NO PULLUP RESISTORS
C2- GND TO LOAD
ALL CAPACITORS = 1µF (NOTE 2)
ALL TRANSISTORS = IRF541 (NOTE 1)
VCC VOUT
TO LOAD
TO LOAD
TO LOAD
3
16
2
9
12
19
4
7
14
17
5
8
13
18
V-
IN1
SW1
SW2
SW3
SW4
1101120
IN2 IN3 IN4
NC4
NC3
NC1
N04
N03
N02
N01
V+
NC2
COM4
COM3
COM2
COM1
NOTE 1: TRANSISTOR TYPE DEPENDS
ON LOAD-CURRENT REQUIREMENTS.
NOTE 2: 1µF CAPACITORS SUPRESS SWITCHING
TRANSIENTS—VALUE DEPENDS
ON LOAD CURRENT.
MAX1822
High-Side Power Supply
_______________________________________________________________________________________ 9
Chip Information
TRANSISTOR COUNT: 158
Figure 6. Ultra-Low Dropout Positive Voltage Regulator with Logic-Controlled Enable/
Shutdown
.
0
50
25
125
100
75
200
175
150
225
0.1 1 10
DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX1822 Fig 06
LOAD CURRENT (A)
DROPOUT VOLTAGE (mV)
MAX1822
VOUT
VBATT
PR
GND
D2
1N914
C1-
C1+
R2
24k
R3
1k
D1
1N914 R1
1k
C1
0.01µF
C5
0.1µF C3 10µF
C4
0.1µF
C6
1000µF
1
8
4
5
6
4
2
Q1
IRF541
3718
3
C2
0.01µF
6
2+5V
C2-
C2+
VCC
7
ENABLE/SHUTDOWN
LM10
TA = +25°C
IRF541 IRFZ40
SMP60N06
MAX1822
High-Side Power Supply
________________________________________________________Package Information
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.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
SOICN.EPS
