LP2950/LP2951
ADJUSTABLE MICROPOWER VOLTAGE REGULATORS
WITH SHUTDOWN
FEATURES
•
•
•
•
•
•
•
Wide Input Range…up to 30 V
Rated Output Current of 100 mA
Low Dropout…380 mV (Typ) at 100 mA
Low Quiescent Current…75
µA
(Typ)
Tight Line Regulation…0.03% (Typ)
Tight Load Regulation…0.04% (Typ)
High V
O
Accuracy
– 1.4% at 25°C
– 2% Over Temperature
Can Be Used as a Regulator or Reference
•
•
•
Stable With Low ESR (>12 mΩ) Capacitors
Current- and Thermal-Limiting Features
LP2950 Only (3-Pin Package)
– Fixed-Output Voltages of 5 V, 3.3 V,
and 3 V
LP2951 Only (8-Pin Package)
– Fixed- or Adjustable-Output Voltages:
5 V/ADJ, 3.3 V/ADJ, and 3 V/ADJ
– Low-Voltage Error Signal on Falling Output
– Shutdown Capability
– Remote Sense Capability for Optimal
Output Regulation and Accuracy
•
•
LP2950...LP (TO-226/TO-92 PACKAGE
(BOTTOM VIEW)
LP2951...D (SOIC) PACKAGE
(TOP VIEW)
OUTPUT
GND
INPUT
OUTPUT
SENSE
SHUTDOWN
GND
1
2
3
4
8
7
6
5
INPUT
FEEDBACK
V
TAP
ERROR
DESCRIPTION
The LP2950 and LP2951 devices are bipolar, low-dropout voltage regulators that can accommodate a wide input
supply-voltage range of up to 30 V. The easy-to-use, 3-pin LP2950 is available in fixed-output voltages of 5 V,
3.3 V, and 3 V. However, the 8-pin LP2951 is able to output either a fixed or adjustable output from the same
device. By tying the OUTPUT and SENSE pins together, and the FEEDBACK and V
TAP
pins together, the
LP2951 outputs a fixed 5 V, 3.3 V, or 3 V (depending on the version). Alternatively, by leaving the SENSE and
V
TAP
pins open and connecting FEEDBACK to an external resistor divider, the output can be set to any value
between 1.235 V to 30 V.
The 8-pin LP2951 also offers additional functionality that makes it particularly suitable for battery-powered
applications. For example, a logic-compatible shutdown feature allows the regulator to be put in standby mode
for power savings. In addition, there is a built-in supervisor reset function in which the ERROR output goes low
when V
OUT
drops by 6% of its nominal value for whatever reasons – due to a drop in V
IN
, current limiting, or
thermal shutdown.
The LP2950 and LP2951 are designed to minimize all error contributions to the output voltage. With a tight
output tolerance (0.5% at 25°C), a very low output voltage temperature coefficient (20 ppm typical), extremely
good line and load regulation (0.3% and 0.4% typical), and remote sensing capability, the parts can be used as
either low-power voltage references or 100-mA regulators.
http://www.hgsemi.com.cn
1
2014 OCT
LP2950/LP2951
LP2950 FUNCTIONAL BLOCK DIAGRAM
Unregulated DC
+
INPUT
OUTPUT
+
−
V
OUT
I
L
3
100 mA
+
ERROR
Amplifier
See Application
Information
+
1.23-V
Reference
GND
LP2951 FUNCTIONAL BLOCK DIAGRAM
Unregulated DC
+
V
OUT
I
L
3
100 mA
8
INPUT
1
OUTPUT
7
FEEDBACK
2
SENSE
+
−
3
From
CMOS
or TTL
SHUTDOWN
ERROR
Amplifier
6
V
TAP
+
See Application
Information
+
+
330 kW
5
ERROR
−
See Application Information
To CMOS
or TTL
60 mV
+
1.235-V
Reference
GND
4
ERROR Detection Comparator
http://www.hgsemi.com.cn
2
2014 OCT
LP2950/LP2951
Absolute Maximum Ratings
(1)
over operating free-air temperature range (unless otherwise noted)
MIN
V
IN
V
SHDN
V
FDBK
θ
JA
T
J
T
stg
(1)
(2)
(3)
(4)
(5)
Continuous input voltage range
SHUTDOWN input voltage range
ERROR comparator output voltage range
(2)
FEEDBACK input voltage
range
(2) (3)
D package
LP package
–65
–0.3
–1.5
–1.5
–1.5
MAX
30
30
30
30
97
140
150
150
UNIT
V
V
V
V
°C/W
°C
°C
Package thermal impedance
(4) (5)
Operating virtual junction temperature
Storage temperature range
Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating
conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
May exceed input supply voltage
If load is returned to a negative power supply, the output must be diode clamped to GND.
Maximum power dissipation is a function of T
J
(max),
θ
JA
, and T
A
. The maximum allowable power dissipation at any allowable ambient
temperature is P
D
= (T
J
(max) – T
A
)/θ
JA
. Operating at the absolute maximum T
J
of 150°C can affect reliability.
The package thermal impedance is calculated in accordance with JESD 51-7.
Recommended Operating Conditions
MIN
V
IN
T
J
(1)
Supply input voltage
Operating virtual junction temperature
Minimum V
IN
is the greater of:
a. 2 V (25°C), 2.3 V (over temperature), or
b.
V
OUT(MAX)
+ Dropout (Max) at rated I
L
(1)
MAX
30
125
UNIT
V
°C
–40
http://www.hgsemi.com.cn
3
2014 OCT
LP2950/LP2951
Electrical Characteristics
V
IN
= V
OUT
(nominal) + 1 V, I
L
= 100
µA,
C
L
= 1
µF
(5-V versions) or C
L
= 2.2
µF
(3-V and 3.3-V versions),
8-pin version: FEEDBACK tied to V
TAP
, OUTPUT tied to SENSE, V
SHUTDOWN
≤
0.7 V
PARAMETER
3-V VERSION (LP295x-30)
V
OUT
Output voltage
I
L
= 100µA
25°C
–40°C to 125°C
25°C
–40°C to 125°C
25°C
–40°C to 125°C
2.970
2.940
3.267
3.234
4.950
4.900
3
3
3.3
3.3
5
5
3.030
3.060
3.333
3.366
5.050
5.100
V
TEST CONDITIONS
T
J
MIN
TYP
MAX
UNIT
3.3-V VERSION (LP295x-33)
V
OUT
Output voltage
I
L
= 100µA
V
5-V VERSION (LP295x-50)
V
OUT
Output voltage
I
L
= 100µA
V
ALL VOLTAGE OPTIONS
Output voltage temperature
coefficient
(1)
Line regulation
(2)
Load regulation
(2)
I
L
= 100
µA
V
IN
= [V
OUT(NOM)
+ 1 V] to 30 V
I
L
= 100
µA
to 100 mA
I
L
= 100
µA
V
IN
– V
OUT
Dropout voltage
(3)
I
L
= 100 mA
I
L
= 100
µA
I
GND
GND current
I
L
= 100 mA
Dropout ground current
Current limit
Thermal regulation
(4)
V
IN
= V
OUT(NOM)
– 0.5 V,
I
L
= 100
µA
V
OUT
= 0 V
I
L
= 100
µA
C
L
= 1
µF
(5 V only)
Output noise (RMS),
10 Hz to 100 kHz
C
L
= 200
µF
LP2951-50: C
L
= 3.3
µF,
C
Bypass
= 0.01
µF
between pins 1
and 7
25°C
100
–40°C to 125°C
25°C
–40°C to 125°C
25°C
–40°C to 125°C
25°C
–40°C to 125°C
25°C
–40°C to 125°C
25°C
–40°C to 125°C
25°C
–40°C to 125°C
25°C
–40°C to 125°C
25°C
–40°C to 125°C
25°C
0.05
430
160
µV
160
110
8
75
380
50
0.04
20
0.03
100 ppm/°C
0.2
0.4
0.2
0.3
80
150
450
600
120
140
12
14
170
200
200
220
0.2
µA
mA
µA
mA
%/W
mV
%/V
%
(LP2951-xx) 8-PIN VERSION ONLY ADJ
25°C
–40°C to 125°C
Reference voltage
V
OUT
= V
REF
to (V
IN
– 1 V),
V
IN
= 2.3 V to 30 V,
I
L
= 100
µA
to 100 mA
–40°C to 125°C
25°C
1.218
1.212
1.200
20
1.235
1.252
1.257
V
1.272
ppm/°C
Reference voltage
temperature coefficient
(1)
(1)
(2)
(3)
(4)
Output or reference voltage temperature coefficient is defined as the worst-case voltage change divided by the total temperature range.
Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to
heating effects are covered under the specification for thermal regulation.
Dropout voltage is defined as the input-to-output differential at which the output voltage drops 100 mV, below the value measured at 1-V
differential. The minimum input supply voltage of 2 V (2.3 V over temperature) must be observed.
Thermal regulation is defined as the change in output voltage at a time (T) after a change in power dissipation is applied, excluding load
or line regulation effects. Specifications are for a 50-mA load pulse at V
IN
= 30 V, V
OUT
= 5 V (1.25-W pulse) for t = 10 ms.
4
http://www.hgsemi.com.cn
2014 OCT
LP2950/LP2951
Electrical Characteristics (continued)
V
IN
= V
OUT
(nominal) + 1 V, I
L
= 100
µA,
C
L
= 1
µF
(5-V versions) or C
L
= 2.2
µF
(3-V and 3.3-V versions),
8-pin version: FEEDBACK tied to V
TAP
, OUTPUT tied to SENSE, V
SHUTDOWN
≤
0.7 V
PARAMETER
FEEDBACK bias current
FEEDBACK bias current
temperature coefficient
ERROR COMPARATOR
Output leakage current
Output low voltage
Upper threshold voltage
(ERROR output high)
(5)
Lower threshold voltage
(ERROR output low)
(5)
Hysteresis
(6)
SHUTDOWN INPUT
Input logic voltage
Low (regulator ON)
High (regulator OFF)
V
TAP
= 2.4 V
SHUTDOWN input current
V
TAP
= 30 V
Regulator output current
in shutdown
(5)
V
SHUTDOWN
≥
2 V,
V
IN
≤
30 V, V
OUT
= 0,
FEEDBACK tied to V
TAP
–40°C to 125°C
25°C
–40°C to 125°C
25°C
–40°C to 125°C
25°C
–40°C to 125°C
3
450
0.7
2
30
50
100
600
750
10
20
µA
µA
V
V
OUT
= 30 V
V
IN
= V
OUT(NOM)
– 0.5 V,
I
OL
= 400
µA
25°C
–40°C to 125°C
25°C
–40°C to 125°C
25°C
–40°C to 125°C
25°C
–40°C to 125°C
25°C
15
40
25
75
95
140
60
150
0.01
1
2
250
400
µA
mV
mV
mV
mV
TEST CONDITIONS
T
J
25°C
–40°C to 125°C
25°C
0.1
MIN
TYP
20
MAX
40
60
UNIT
nA
nA/°C
(6)
Comparator thresholds are expressed in terms of a voltage differential equal to the nominal reference voltage (measured at
V
IN
– V
OUT
= 1 V) minus FEEDBACK terminal voltage. To express these thresholds in terms of output voltage change, multiply by the
error amplifier gain = V
OUT
/V
REF
= (R1 + R2)/R2. For example, at a programmed output voltage of 5 V, the ERROR output is specified to
go low when the output drops by 95 mV
×
5 V/1.235 V = 384 mV. Thresholds remain constant as a percentage of V
OUT
(as V
OUT
is
varied), with the low-output warning occurring at 6% below nominal (typ) and 7.7% (max).
Comparator thresholds are expressed in terms of a voltage differential equal to the nominal reference voltage (measured at
V
IN
– V
OUT
= 1 V) minus FEEDBACK terminal voltage. To express these thresholds in terms of output voltage change, multiply by the
error amplifier gain = V
OUT
/V
REF
= (R1 + R2)/R2. For example, at a programmed output voltage of 5 V, the ERROR output is specified to
go low when the output drops by 95 mV
×
5 V/1.235 V = 384 mV. Thresholds remain constant as a percentage of V
OUT
(as V
OUT
is
varied), with the low-output warning occurring at 6% below nominal (typ) and 7.7% (max).
http://www.hgsemi.com.cn
5
2014 OCT
电子工程世界
