The ILC7281 provides two independant 150mA low dropout
(LDO) voltage regulators and power supply reset monitor in
an 8-pin MSOP package. Each regulator output is inde-
pendantly short circuit protected and has independant shut-
down. The device offers a unique combination of low
dropout voltage and low quiescent current of CMOS and
low noise and high ripple rejection characteristics of bipolar
LDO regulators. Moreover, only one input capacitor is
required. The power supply reset monitor is available in a
1% accurate trip voltage to fit most microprocessor appli-
cations. Even though its output can sink 2mA, the monitor
draws only 1A in normal operation. Additionally, a built-in
hysteresis of 5% of detect voltage simplifies system design.
Dropout Voltage: Typically 150mV at 150mA load, and
1mV at 1mA load.
Ground pin current: Typically 20A at 1mA load, and
30A at 150mA load.
Ripple rejection: 75dB at 1kHz and 60dB at 100kHz.
Shutdown mode: Less than 0.5A quiescent current in
shutdown mode.
Small package: 8-pin MSOP.
Small capacitor: Requires only a 0.47F external cpacitor
on the regulator output.
Precision output: Output voltage trimmed to 1% accuracy.
ILC7281
Micropower Dual 150mA CMOS RF LDOTM Regulators
with Power Supply Reset Monitor
Impala Linear Corporation
Impala Linear Corporation
1
(408) 574-3939
www.impalalinear.com
Nov 2000
ILC7281 1.0
Advance
Guaranteed 150mA output per regulator
Ultra low 150mV dropout at 150mA
1% output voltage accuracy
Built-in hysteresis of 5% of detection voltage
Requires only 0.47F output capacitor
Only 30A ground current at 150mA load
75dB ripple rejection at 1kHz (C
OUT
= 0.47F)
80V
RMS
noise at BW = 300Hz to 50kHz
Excellent line and load transient rsponse
Over current / over temperature protection
8-pin MSOP package
-80dB cross talk
Cellular Phones, pagers and wireless headsets
Microprocessor reset circuits
Palmtops, oragnizers, PDA's and portable electronics
Microprocessor reset circuits
Battery powered portable appliances
Memory battery back-up circuitry
V
IN
1F
ceramic
0.47-2.2F
ceramic
+
+
V
OUTB
C
NOISE
470pF
+
+
10K
V
OUT
RESET
GND
V
OUTA
EN
A
0.47-2.2F
ceramic
EN
B
Ordering Information* (T
A
= -40C to +85C)
ILC7281CS-2530
150mA 2.5V and 3.0V LDO regulators with
2.7V detect fail voltage (V
DF
) Monitor
Note: Enable may be connected to V
IN
, C
NOISE
connects to both LDO's
General Description
Features
Applications
Figure 1
Micropower Dual 150mA CMOS RF-LDOTM Regulators with Power Supply Reset Monitor
Impala Linear Corporation
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ILC7281 1.0
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Pin Number
1
2
3
4
5
6
7
8
Pin Name
V
IN
V
OUTB
C
NOISE(optional)
EN
B
EN
A
V
OUTA
GND
V
OUT RESET
C
NOISE(optional)
1
2
3
4
5
6
7
8
V
OUTA
EN
A
GND
EN
B
V
OUT RESET
V
OUTB
V
IN
MSOP
(TOP VIEW)
ILC7281CS-XXXX
Pin Description
Supply Input
Regulator Output B
Voltage Reference Bypass: Connect external 470pF capacitor to GND to
reduce output noise in regulator "A" or "B." May be left open.
Enable/Shutdown B (Input): CMOS compatible input. Logic high = enable,
logic low or open = shutdown. Do not leave floating.
Enable/Shutdown A (Input): CMOS compatible input. Logic high = enable,
logic low or open = shutdown. Do not leave floating.
Regulator Output A
Ground
Power supply reset monitor output. N-CH open drain output, must connect
through a resistor to supply voltage.
Pin-Package Configurations
Pin Functions ILC7281
Figure 2
Micropower Dual 150mA CMOS RF-LDOTM Regulators with Power Supply Reset Monitor
Impala Linear Corporation
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ILC7281 1.0
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Parameter
Input Voltage
S/D Input Voltage
Output Current
Output Voltage
Power Dissipation
Maximum Junction Temp Range
Storage Temperature
ESD Rating
Operating Input Voltage
Operating Ambient Temperature
Package Thermal Resistance
Symbol
V
IN
V
S/D
I
OUT
V
OUT
P
d
T
J(max)
T
stg
V
IN
T
A
JA
Ratings
-0.3 to +12
-0.3 to V
IN
Short circuit protected
-0.3 to 10
Internally Limited
-40~+125
-40~+125
2
2.1 to 10
-40 to +85
200
Units
V
mA
V
mW
C
C
kV
V
C
C/W
Parameter
Output Voltage
Output Voltage
Output Voltage
Line Regulation
Dropout Voltage (Note 3)
Dropout Voltage (Note 3)
Dropout Voltage (Note 3)
Ground Pin Current
Ground Pin Current
Ground Pin Current
Shutdown Current
Symbol
V
OUT
V
OUT
V
OUT
V
O
/
V
IN
V
IN
- V
OUT
V
IN
- V
OUT
V
IN
- V
OUT
I
GND
I
GND
I
GND
I
S/D
Conditions
I
OUT
= 1mA
1mA < I
OUT
< 100mA
1mA < I
OUT
< 100mA
1mA < I
OUT
< 150mA
1mA < I
OUT
< 150mA
V
O(NOM)
+ 1V < V
IN
< 10V
I
OUT
= 0mA
I
OUT
= 10mA
I
OUT
=150mA
I
OUT
= 0mA
I
OUT
= 10mA
I
OUT
= 150mA
Units
%V
(Nom.)
%V
(Nom.)
%V
(Nom.)
%/V
mV
mV
mV
A
A
A
A
Max
+1
+1.5
+2.5
2.5
+3.5
0.014
0.032
1
2
15
20
175
200
60
80
70
90
80
120
1
Typ
V
OUT
(Nom.)
V
OUT
(Nom.)
V
OUT
(Nom.)
0.007
0.1
10
150
20
25
30
0.1
Min
-1
-1.5
-2.5
-2.5
-3.5
Absolute Maximum Ratings for Regulators (Note 1)
Electrical Characteristics ILC7281CS
Unless otherwise specified, all limits are at T
A
= 25C; V
IN
= V
O(NOM)
+ 1V, I
OUT
= 1mA, C
OUT
= 0.47F, V
S/D
= 2V.
Boldface limits apply over the operating temperature range. (Note 2)
Micropower Dual 150mA CMOS RF-LDOTM Regulators with Power Supply Reset Monitor
Impala Linear Corporation
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ILC7281 1.0
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Parameter
Shutdown Input Voltage
Peak Output Current (Note 4)
Output Noise Voltage (RMS)
Ripple Rejection
Dynamic Line Regulation
Dynamic Load Regulation
Short Circuit Current
Cross Talk
Conditions
High = Regulator On
Low = Regulator Off
V
OUT
> 0.95V
O(NOM)
BW = 300Hz to 50kHz, C
NOISE
= 0pF
freq = 1kHz
freq = 10kHz
freq = 100kHz
V
IN
: V
O(NOM)
+ 1V to V
O(NOM)
+ 2V; dV
IN/dt
= 1V/
S;lo
= 150mA
I
OUT
: 0 to 150mA; d(l
OUT
)/dt = 50A/s, with
C
OUT
= 2.2F
V
OUT
= 0V
Symbol
V
S/D
I
O(peak)
e
N
V
O
/
V
IN
V
O(line)
V
O(load)
I
SC
Units
V
mA
V
RMS
dB
mV
mV
mA
dB
Max
10
0.6
Typ
500
80
75
70
60
10
40
20
300
-60
Min
2.0
300
Note1: Absolute maximum ratings indicate limits which when exceeded may result in damage to the component. Electrical specifications do not apply
when operating the device outside of its rated operating conditions.
Note 2: Specified Min/Max limits are production tested or guaranteed through correlation based on statistical control methods. Measurements are
taken at constant junction temperature as close to ambient as possible using low duty pulse testing.
Note 3: Dropout voltage is defined as the input to output differential voltage at which the output voltage drops 2% below the nominal value measured with a 1V differential.
Note 4: Guaranteed by design
Electrical Characteristics ILC7281CS
Unless otherwise specified, all limits are at T
A
= 25C; V
IN
= V
O(NOM)
+ 1V, I
OUT
= 1mA, C
OUT
= 0.47F, V
S/D
= 2V.
Boldface limits apply over the operating temperature range. (Note 2)
Micropower Dual 150mA CMOS RF-LDOTM Regulators with Power Supply Reset Monitor
Impala Linear Corporation
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Nov 2000
ILC7281 1.0
Advance
Symbol
V
DF
V
HYS
I
SS
V
IN
I
OUT
V
DF
/(
T
opr
V
DF
)
t
DLY
(V
DR
V
OUT
Inversion)
Typ
V
DF
V
DF
X 0.05
0.9
1.0
1.3
1.6
2.0
2.2
7.7
10.1
11.5
13.0
100
Paramter
Detect Fail Voltage
Hysteresis Range
Supply Current
Operating Voltage
Output Current
Temperature Characteristics
Delay Time (Release Voltage
Output Inversion)
Conditions
A grade
V
IN
= 1.5V
V
IN
= 2.0V
V
IN
= 3.0V
V
IN
= 4.0V
V
IN
= 5.0V
V
DF
= 2.1~6.0V
N-ch V
DS
= 0.5V
V
IN
= 1.0V
V
IN
= 2.0V
V
IN
= 3.0V
V
IN
= 4.0V
V
IN
= 5.0V
-30C < T
opr
< 80C
Parameter
Input Voltage
Output Current
Output Voltage
Continuous Total
Power Dissipation (SOT-23)
Operating Ambient Temperature
Storage Temperature
Symbol
V
IN
I
OUT
V
OUT
P
d
T
opr
T
stg
Units
V
mA
V
mW
C
C
Ratings
12
50
V
SS
-0.3~V
IN
+0.3
150
-30~+80
-40~+125
Min
V
DF
X 0.99
V
DF
X 0.02
1.5
Max
V
DF
X 1.01
V
DF
X 0.08
2.6
3.0
3.4
3.8
4.2
10.0
0.2
Units
V
V
A
V
mA
ppm/C
ms
Note:
1. An additional resistor between the V
IN
pin and supply voltage may cause deterioration of the characteristics due to increasing of V
DR
.
Absolute Maximum Ratings Supply Reset Monitor (T
A
= 25C)
Electrical Characteristics
Power Supply Reset Monitor (T
A
= 25C)
Micropower Dual 150mA CMOS RF-LDOTM Regulators with Power Supply Reset Monitor
Impala Linear Corporation
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ILC7281 1.0
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N - Channel Open Drain Output
V
REF
V
IN
GND
V
OUT
CURRENT LIMIT
THERMAL SHUTDOWN
BANDGAP
REF.
-
+
CURRENT LIMIT
THERMAL SHUTDOWN
BANDGAP
REF.
-
+
V
OUTA
V
OUTB
C
NOISE
GND
EN
B
V
INB
EN
A
V
INA
Micropower Dual 150mA CMOS RF-LDOTM Regulators with Power Supply Reset Monitor
Impala Linear Corporation
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ILC7281 1.0
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Dual-Supply Operation
When used in dual supply systems where the regulator load is
returned to a negative supply, the output voltage must be
diode clamped to ground.
Thermal Considerations
Multilayer boards having a ground plane, wide traces near the
pads, and large supply bus lines provide better thermal con-
ductivity. The 8-lead MSOP has a thermal resistance of
200C/W when mounted on an FR4 board with minimum trace
widths and no ground plane.
Thermal Evaluation Examples
For example, at 50C ambient temperature, the maximum
package power dissipation is:
P D(max) = (125C - 50C)/200C/W
P D(max) = 375mW
If the intent is to operate the part from a 4V supply at the full
150mA load for both outputs in a 50C maximum ambient
temperature, make the following calculations:
P D(each regulator) = (V
IN
- V
OUT
)
I
OUT
+ (V
IN
I
GND
)
P D(each regulator) = (4V - 3V)
150mA + (4V
0.12mA)
P D(each regulator) = 150mW
P D(both regulators) = 2 regulators
150mW
P D(both regulators) = 300mW
The actual total power dissipation of 300mW is below the
375mW package maximum; therefore the regulator can be
used. Note that both regulators cannot always be used at their
maximum current rating. For example, in a 5V input to 3.0V
output application at 50C, if one regulator supplies 150mA,
the other regulator is limited to a much lower current. The first
regulator dissipates:
P D = (5V - 3.0V) 150 + 0.12mA (5V)
P D = 267.5mW
Then, the load that the remaining regulator can dissipate must
not exceed: 375mW - 267.5mW = 107.5mW. This means,
using the same 5V input and 3.3V output voltage, the second
regulator is limited to about 60mA
Taking advantage of the extremely low dropout voltage char-
acteristics of the ILC7281, power dissipation can be reduced
by using the lowest possible input voltage to minimize the
input to output voltage drop.
APPLICATIONS INFORMATION - Regulators
Enable/Shutdown
Forcing EN
A/B
(enable/shutdown) high (>2V) enables the reg-
ulator. EN
A/B
is compatible with CMOS logic gates. If the
enable/shutdown feature is not required, connect EN
A/B
to
V
INA/B
(supply input).
Input Capacitor
A 1F capacitor should be placed from V
INA/B
to GND if 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
NOISE
(reference bypass) is connected to the internal volt-
age reference of regulator A and B. A 470pF capacitor
connected from C
NOISE
to GND decouples the reference,
providing a significant reduction in output noise. C
NOISE
reduces the regulator phase margin; when using C
NOISE
,
output capacitors of 2.2F or greater are generally
required to maintain stability. The start-up speed of the
ILC7281 is inversely proportional to the size of the refer-
ence bypass capacitor. Applications requiring a slow
ramp-up of output voltage should consider larger values of
C
NOISE
. Likewise, if rapid turn-on is necessary, consider
omitting C
NOISE
. If output noise is not a major concern,
omit C
NOISE
and leave the pin open.
Output Capacitor
An output capacitor is required between V
OUTA/B
and GND to
prevent oscillation. The minimum size of the output capacitor
is dependent upon whether a reference bypass capacitor is
used. 1.0F minimum is recommended when C
NOISE
is not
used (see figure 2). 2.2F minimum is recommended when
C
NOISE
is 470pF (see figure 1). Larger values slow the regu-
lator's transient response. The output capacitor value may be
increased without limit. The output capacitor should have an
ESR (effective series resistance) of about 5 or less and a res-
onant frequency above 1MHz. Ultra low ESR capacitors may
be used and will not cause a low-amplitude oscillation and/or
underdamped transient response which shows up in some
LDO regulators. Most ceramic capacitors are adequate so
there is no need for more expensive tantalum capacitors.
At lower values of output current, less output capacitance is
required for output stability. The capacitor can be reduced to
0.47F for current below 10mA or 0.33F for currents below
1mA
No-Load Stability
The ILC7281 will remain stable and in regulation with no load
unlike many other voltage regulators. This is expecially impor-
tant in CMOS RAM KeepAlive applications.
Micropower Dual 150mA CMOS RF-LDOTM Regulators with Power Supply Reset Monitor
Impala Linear Corporation
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ILC7281 1.0
Advance
6
5
4
3
1
2
INPUT VOLTAGE (V
IN
)
DETECT RELEASE VOLTAGE (V
DR
)
DETECT FAIL VOLTAGE (V
DF
)
MINIMUM OPERATING VOLTAGE (V
MIN
)
GROUND VOLTAGE (V
SS
)
OUTPUT VOLTAGE (V
OUT
)
GROUND VOLTAGE (V
SS
)
The following designators 1~6 refer to the timing diagram below.
1. While the input voltage (V
IN
) is higher than the detect fail
voltage (V
DF
); the V
OUT
output pin is at high impedence state.
2. When the input V
IN
voltage falls lower than V
DF
, V
OUT
drops near to ground voltage.
3. If the input voltage decreases below the minimum oper-
ating voltage (V
MIN
), the V
OUT
output becomes unstable. In
this condition, if the V
OUT
pin is pulled up, V
OUT
indicates the
V
IN
voltage.
4. During an increase of the input voltage from V
SS
voltage,
V
OUT
is not stable in the voltage below the V
MIN
. Exceeding
that level, the output stays at the ground level (V
SS
)
between the minimum operating voltage (V
MIN
) and detect
release voltage (V
DR
).
5. If the input voltage increases more than V
DR
, the V
OUT
output pin is at high impedence state.
6. The difference between V
DR
and V
DF
is the hysteresis in
the system.
Functional Descriptin - Power Supply Reset Monitor
Timing Diagram
Micropower Dual 150mA CMOS RF-LDOTM Regulators with Power Supply Reset Monitor
Impala Linear Corporation
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Nov 2000
ILC7281 1.0
Advance
0.0215
0.037
3 TYP
0.006 RAD. TYP
0.116
12 TYP
12 TYP
0.118
0.000-0.005 RAD. TYP
0.040
0.004
SEATING PLANE
0.118 0.004
0.020 TYP
0.013 TYP
0.0256 BSC
0.118 0.004
Devices sold by Impala Linear Corporation are covered by the warranty and patent indemnification provisions appearing
in its Terms of Sale only. Impala Linear Corporation makes no warranty, express, statutory, implied, or by description
regarding the information set forth herein or regarding the freedom of the described devices from patent infringement.
Impala Linear Corporation makes no warranty of merchantability or fitness for any purpose. Impala Linear Corporation
reserves the right to discontinue production and change specifications and prices at any time and without notice.
This product is intended for use in normal commercial applications. Applications requiring an extended temperature
range, unusual environmental requirements, or high reliability applications, such as military and aerospace, are specif-
ically not recommended without additional processing by Impala Linear Corporation.
Impala Linear Corporation assumes no responsibility for the use of any circuitry other than circuitry embodied in an
Impala Linear Corporation product. No other circuits, patents, licenses are implied.
Life Support Policy
Impala Linear Corporation's products are not authorized for use as critical components in life support devices or systems.
1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or
(b) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use pro-
vided in the labelling, can be reasonably expected to result in a significant injury to the user.
2. A critical component is any component of a life support device or system whose failure to perform can be reason-
bly expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.
Package Dimensions
MSOP-8
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