ILC7280CS-2530 Impala Linear Corporation, ILC7280CS-2530 Datasheet - Page 7

• Manufacturer Part Number: ILC7280CS-2530
• Description: MICROPOWER DUAL 150MA CMOS RF LDO REGULATORS WITH 75DB RIPPLE REJECTION
• Manufacturer: Impala Linear Corporation

These pins are connected internally through a galvanic
connection for maximum power from each regulator, both
V
Enable/Shutdown
Forcing EN
enables the regulator(s). These inputs are CMOS logic
compatible gates. If this feature is not required, connect
EN
nected internally. To minimize the effect of imbalanced
current sharing and possible noise, both V
should also be connected externally.
Input Capacitor
A 1µF capacitor should be placed from V
there is more than 10 inches of wire between the input and
the ac filter capacitor or if a battery is used as the input.
Reference Bypass Capacitor
C
nected to the internal V
A and B. A 22pF capacitor connected between C
GND decouples the reference output voltage and provides
a significant reduction in regulator output noise. An effect
of C
using C
required to maintain stability.
Also affected by C
The speed is inversely proportional to the value of C
a slow or delayed start up time is desired, a larger value of
C
applications will require smaller values of C
sion with the pin left open. The trade-off of noise to response
should be considered.
ILC7280 1.8
+V
APPLICATIONS INFORMATION
INA
NOISE
NOISE
Micropower Dual 150mA CMOS RF LDO™ Regulators with 75dB Ripple Rejection
A
IN
NOISE
and V
and/or EN
Impala Linear Corporation
A and B
is used. Conversely, faster start up times or instant-on
(the reference voltage bypass capacitor) is con-
NOISE
also reduces the regulator phase margin. When
INB
A
, output capacitors of 2.2µF or greater are
and/or EN
must be connected externally to V
B
to V
NOISE
IN
. Note that V
is the start up speed of the ICL7280.
ref
B
which is common to regulator's
to a voltage greater than 2V,
INA
+V
EN
-V
and V
IN
IN
A
NOISE
/EN
External Diode, Dext inhibits significant voltage excursions
INA/B
[phone]
B
INA
below ground in a split power supply load return.
INB
or its omis-
to GND if
NOISE
and V
DD
are con-
Dual Regulator
NOISE
ILC7280
.
and
INB
. If
V
Dext
OUTA
Output Capacitor
An output capacitor is required from V
GND to prevent oscillation and minimize the effect of load
transient currents. The minimum size of the output capac-
itor(s) is dependent on the usage of C
Without C
C
(See figure 1). Larger values of output capacitance will
slow the regulator's response during power up. The upper
limit of capacitance is indefinite, however, it should have
an equivalent series resistance (ESR) of approximately
5
is assured with the use of a capacitor having ultra-low
ESR and as such will not produce low amplitude oscilla-
tions nor an underdamped transient response. This
allows the use of modern ceramic capacitors in prefer-
ence to their more costly Tantalum counterparts.
If the system design calls for smaller load currents, lower
capacitance may be used. Below 10mA the capacitance
may be reduced to 0.47µF and below 1mA to 0.33µF.
No-Load Stability
The ILC7280 will remain stable and in regulation with no
load current. These are desirable performance features
for applications such as keep-alive modes in CMOS sys-
tems.
Split-Supply Operation
When using the ILC7280 in a system requiring that the
load be returned to the negative voltage source, the out-
put(s) must be diode clamped to inhibit significant volt-
age excursions below ground. A simple external diode
clamp to ground will afford protection from damage to
the device. (See figure below).
www.impalalinear.com
NOISE
or V
or less and a series resonance above 1MHz. Stability
OUTB
= 22pF, a minimum of 2.2µF is recommended
NOISE
Rload
, a minimum of 1µF is recommended. For
NOISE
OUTA
May 2000
and V
and its value.
Advance
OUTB
7
to