ADP222ACPZ-1218-R7 AD [Analog Devices], ADP222ACPZ-1218-R7 Datasheet - Page 17

• Manufacturer Part Number: ADP222ACPZ-1218-R7
• Description: Dual, 300 mA Output, Low Noise
• Manufacturer: AD [Analog Devices]

Data Sheet
GND
THEORY OF OPERATION
The
current, fixed and adjustable dual output, low dropout linear
regulators that operate from 2.5 V to 5.5 V and provide up to
300 mA of current from each output. Drawing a low 300 μA
quiescent current (typical) at full load make the ADP222/
ADP223/ADP224/ADP225
equipment. Shutdown current consumption is typically 200 nA.
Optimized for use with small 1 μF ceramic capacitors, the
ADP222/ADP223/ADP224/ADP225
transient performance.
Internally, the
reference, two error amplifiers, and two PMOS pass transistors.
Output current is delivered via the PMOS pass device, which is
EN1
EN2
GND
VIN
EN1
EN2
VIN
ADP222/ADP223/ADP224/ADP225
ADP223/ADP225
ADP222/ADP224
SHUTDOWN
SHUTDOWN
CONTROL
THERMAL
CONTROL
THERMAL
Figure 62. Internal Block Diagram,
Figure 63. Internal Block Diagram,
ENABLE
ENABLE
LOGIC
LOGIC
AND
AND
ADP222/ADP223/ADP224/ADP225
CURRENT
CURRENT
REFERENCE
CURRENT
CURRENT
LIMIT
LIMIT
LIMIT
REFERENCE
LIMIT
ideal for battery-operated portable
ADP224
ONLY
ADJ2
ADJ1
provide excellent
ADP223/ADP225
ADP222/ADP224
ADP225 ONLY
SENSE2
SENSE1
are low quiescent
140Ω
140Ω
140Ω
140Ω
consist of a
VOUT1
VOUT2
VOUT1
VOUT2
Rev. B | Page 17 of 24
controlled by the error amplifier. The error amplifier compares
the reference voltage with the feedback voltage from the output
and amplifies the difference. If the feedback voltage is lower
than the reference voltage, the gate of the PMOS device is
pulled lower, allowing more current to flow and increasing the
output voltage. If the feedback voltage is higher than the
reference voltage, the gate of the PMOS device is pulled higher,
allowing less current to flow and decreasing the output voltage.
The
ADP224
disconnected and the feedback input of the error amplifiers is
brought out for each output. The output voltages can be set
according to the following equations:
The value of R1 and R3 should be less than 200 kΩ to minimize
errors in the output voltage caused by the ADJx pin input current.
For example, when R1 and R2 each equal 200 kΩ, the output
voltage is 1.0 V. The output voltage error introduced by the ADJx
pin input current is 2 mV or 0.20%, assuming a typical ADJx pin
input current of 10 nA at 25°C.
The output voltage of the
0.5 V to 5.0 V.
The
options ranging from 0.8 V to 3.3 V.
The
with the addition of a quick output discharge (QOD) feature.
This allows the output voltage to start up from a known state.
The
to enable and disable the VOUT1/VOUT2 pins under normal
operating conditions. When EN1/EN2 are high, VOUT1/VOUT2
turn on; when EN1/EN2 are low, VOUT1/VOUT2 turn off. For
automatic startup, EN1/EN2 can be tied to VIN.
ADP223/ADP225
ADP222/ADP224
ADP224/ADP225
ADP222/ADP223/ADP224/ADP225
V
V
Figure 64. Typical Application Circuit for Setting Output Voltages,
V
IN
OUT1
OUT2
OFF
OFF
= 4.2V
except that the output voltage dividers are internally
ADP222/ADP223/ADP224/ADP225
= 0.50 V(1 + R1/R2)
= 0.50 V(1 + R3/R4)
+ C1
ON
ON
1µF
1
2
3
4
EN1
EN2
GND
ADJ2
are available in multiple output voltage
are exactly the same as the ADP222/
are identical to the
ADP223/
ADP225
ADP223/ADP225
ADP223/ADP225
VOUT1
VOUT2
ADJ1
VIN
8
7
6
5
R3
R4
use the EN1/EN2 pins
R2
R1
ADP222/ADP223
VOUT1 = 2.8V
may be set from
+ C2
VOUT2 = 2.0V
1µF
+ C3
1µF