MAX1822ESA+ Maxim Integrated Products, MAX1822ESA+ Datasheet - Page 8

• Manufacturer Part Number: MAX1822ESA+
• Description: IC POWER SUPPLY HI SIDE 8-SOIC
• Manufacturer: Maxim Integrated Products
• Type: Switched Capacitor (Charge Pump)r

Specifications of MAX1822ESA+

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 14.5 ~ 27.5 V
• Current - Output: 25mA
• Frequency - Switching: 90kHz
• Voltage - Input: 3.5 ~ 16.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Power - Output: 471mW
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Maximum Power Dissipation: 471 mW
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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
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.
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
High-Side Power Supply
Figure 5. MAX1822 Powering a MAX333 Quad Analog Switch, Realizing a 4-Channel Load Switch with No Pullup Resistors
8
_______________________________________________________________________________________
NOTE 2:
NOTE 1:
+3.5V TO +16.5V
1µF CAPACITORS SUPRESS SWITCHING
TRANSISTOR TYPE DEPENDS
TRANSIENTS—VALUE DEPENDS
ON LOAD CURRENT.
ON LOAD-CURRENT REQUIREMENTS.
0.01µF
0.01µF
C1
C2
C4
1µF
4-Channel Load Switch with
1
7
6
2
Figure 5, a MAX1822 supplies
Low-Dropout Regulator
C1+
C1-
C2+
C2-
No Pullup Resistors
MAX1822
GND
V
CC
4-CHANNEL LOAD SWITCH—NO PULLUP RESISTORS
8
4
V
OUT
5
SW1
SW2
SW3
SW4
C3 10µF
16
12
19
14
17
2
9
4
7
5
V+
N01
N02
N03
N04
NC1
NC2
NC3
NC4
V-
IN1
1
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 V
by pulling this input to ground.
The regulator output voltage, V
R1 to R2, calculated as follows:
If the application does not require logic shutdown, con-
nect the MAX1822 V
eliminate D2.
IN2
MAX333
10
BATT
IN3
11
COM1
COM2
COM3
COM4
to the Enable/Shutdown input and turned off
IN4
20
3
8
13
18
R
2
=
CC
R
1
pin directly to the battery and



V
ALL CAPACITORS = 1µF (NOTE 2)
OUT
0 2
ALL TRANSISTORS = IRF541 (NOTE 1)
.
OUT
−
, is set by the ratio of
1



TO LOAD
TO LOAD
TO LOAD
TO LOAD