MAX8863 ON Semiconductor, MAX8863 Datasheet - Page 4

• Manufacturer Part Number: MAX8863
• Description: 120 mA Linear Regulator
• Manufacturer: ON Semiconductor

DETAILED DESCRIPTION
low–quiescent current linear regulator designed specifically
for portable, battery–operated equipment such as cellular
phones, cordless phones, and modems. A 1.20 V reference,
error amplifier, MOSFET driver, P–channel pass transistor,
comparator, and internal feedback voltage divider comprise
the MAX8863 (see Figure 3).
amplifier’s inverting input. The error amplifier then
compares the reference with the selected feedback voltage
and amplifies the difference. The MOSFET driver, reading
the error signal, applies the correct drive to the P–channel
pass transistor. If the feedback voltage is lower than the
reference, the pass–transistor is pulled lower to allow more
current through, and to increase the output voltage.
Conversely, if the feedback voltage is higher than the
reference, the pass–transistor is pulled up, which allows less
current through to the output.
Turn On Response
categories, Wake Up Time (t
when released from shutdown. See Figure 2 for the Wake
Up Time designated as t
as the time it takes for the output to rise to 2.0% of the V
value after being released from shutdown.
The MAX8863 is a fixed output, low–dropout,
The bandgap reference is connected to the error
The turn on response is defined as two separate response
The MAX8863 has a fast Wake Up Time (10 sec typical)
SHDN
GND
GND
IN
WK
. The Wake Up Time is defined
SHUTDOWN
THERMAL
SENSOR
WK
LOGIC
) and Settling Time (t
Figure 3. Functional Block Diagram
1.2 V
REF
http://onsemi.com
OUT
S
MAX8863
).
4
(t
defined as the condition when the output is within 2.0% of
its fully enabled value (140 sec typical) when released
from shutdown. The settling time of the output voltage is
dependent on load conditions and output capacitance on
V
Internal P–Channel Pass Transistor
MAX8863 offers longer battery life than similar designs
using PNP pass transistors, which waste current in dropout
when the pass transistor saturates. PNP–based regulators
also use high base–drive currents under large loads. The
P–channel MOSFET, however, does not require a base drive
current, which reduces quiescent current. The MAX8863
uses only 50 A of quiescent current.
SHDN
V
–
+
S
OUT
The total turn on response is defined as the Settling Time
Featuring a 1.1
OUT
), see Figure 2. Settling Time (inclusive with t
(RC response).
MOS DRIVER
Figure 2. Wake Up Response Time
WITH I
LIMIT
P–channel MOSFET pass transistor, the
(MAX8863 Only)
V
IL
N
2%
V
P
IH
t
WK
98%
t
S
OUT
WK
) is