INTEGRATED CIRCUITS
LP2985-XX
Micropower 150 mA low noise,
low dropout linear regulator
Product data
File under Integrated Circuits, Standard Analog
2001 Oct 03
Philips
Semiconductors
Philips Semiconductors
Product data
Micropower 150 mA low noise,
low dropout linear regulator
LP2985-XX
GENERAL DESCRIPTION
The LP2985-XX is a 150 mA, fixed output voltage regulator designed
to provide very low dropout and low noise in battery powered and
portable applications. The output voltage is preset to 1.8, 2.8, 3.0,
3.3, 3.6, or 5.0 V.
Designed with an optimized PNP process, the LP2985-XX achieves
unequalled performance in all specifications critical to
battery-powered designs such as low supply-current, low dropout
voltage, low power consumption, small size, fast dynamic response
to line and load, precision output, etc. This regulator consists of an
internal voltage reference, an error amplifier, a driver with current
limiter and a thermal shut-down mechanism.
The LP2985-XX is housed in a SOT23-5 5-lead package.
FEATURES
•
Very low consumption current: 85 mA typ. (when not loaded),
0.1 mA max. (when off)
APPLICATIONS
•
Very low dropout voltage: 100 mV typ. (I
OUT
= 50 mA)
•
High precision output voltage:
±2%
•
Output current capacity: 150 mA
•
Low noise: 30 mV
RMS
@ 20 Hz to 80 kHz (C
n
= 10 nF)
•
Good line regulation: 0.01%/V typ.
•
Good load regulation: 30 mV typ. (I
OUT
= 1 to 150 mA)
•
Low temperature drift co-efficient to V
OUT
:
±100
ppm/°C
•
Built-in current limit and thermal shut-down
•
Wide operating temperature range: –30 to +85
°C
•
Preset output voltages: 1.8, 2.8, 3.0, 3.3, 3.6, or 5.0 V
SIMPLIFIED DEVICE DIAGRAM
LP2985-XX
V
IN
1
•
Cellular phones, cordless phones, and 2-way radios
•
Electronic notebooks, PDAs and palmtop computers
•
Cameras, VCRs and camcorders
•
PCMCIA cards
•
Modems
•
Battery-powered or hand-held instruments
5
V
OUT
3
ON/OFF
BIAS
CURRENT
LIMIT
DRIVER
REFERENCE
NOISE
4
THERMAL
SHUTDOWN
GND
2
SL01545
Figure 1. Simplified device diagram.
2001 Oct 03
2
853–2291 27197
Philips Semiconductors
Product data
Micropower 150 mA low noise,
low dropout linear regulator
LP2985-XX
ORDERING INFORMATION
PACKAGE
TYPE NUMBER
LP2985-XXD
NAME
SOT23-5,
SOT25, SO5
DESCRIPTION
plastic small outline package; 5 leads (see dimensional drawing)
TEMPERATURE
RANGE
–30 to +85
°C
NOTE:
The device has five voltage output options, indicated by the
XX
on
the Type Number.
XX
18
28
30
33
36
50
VOLTAGE (Typical)
1.8 V
2.8 V
3.0 V
3.3 V
3.6 V
5.0 V
Part number marking
Each device is marked with a four letter code. The first three letters
designate the product. The fourth letter, represented by ‘x’, is a date
tracking code.
Part number
LP2985-18D
LP2985-28D
LP2985-30D
LP2985-33D
LP2985-36D
LP2985-50D
Marking
AABx
AACx
ABGx
ABHx
ANBx
ABJx
PIN CONFIGURATION
PIN DESCRIPTION
PIN
SYMBOL
V
IN
GND
ON/OFF
NOISE
V
OUT
Voltage input.
Device ground.
ON/OFF control pin. Connect to V
IN
if not used.
Noise decrease pin, for connecting external
capacitor.
Voltage output.
DESCRIPTION
1
2
3
4
4
NOISE
GND
2
ON/OFF
3
LP2985-XX
V
IN
1
5
V
OUT
5
SL01544
Figure 2. Pin configuration.
MAXIMUM RATINGS
SYMBOL
V
IN
T
oper
T
stg
P
D
Supply voltage
Operating temperature
Storage temperature
Power dissipation
PARAMETER
MIN.
–0.3
–30
–40
–
MAX.
+12.0
+85
+150
150
UNIT
V
°C
°C
mW
2001 Oct 03
3
Philips Semiconductors
Product data
Micropower 150 mA low noise,
low dropout linear regulator
LP2985-XX
ELECTRICAL CHARACTERISTICS
T
amb
= 25
°C,
V
IN
= V
OUT(nom)
+ 1 V, V
ON/OFF
= 2.0 V, unless otherwise specified.
SYMBOL
I
CC
I
CC(OFF)
V
OUT
PARAMETER
No-load input current
Standby input current
Output voltage
LP2885-18
LP2885-28
LP2885-30
LP2885-33
LP2885-36
LP2885-50
V
IN
–V
OUT
∆V
LNR
∆V
LDR
∆V
OUT
/∆T
RR1
RR2
V
n
I
ON/OFF
V
OFF
V
ON
Dropout voltage
Line regulation
Load regulation
V
OUT
temperature coefficient
Ripple rejection 1
Ripple rejection 2
Output noise voltage
ON/OFF pin input current
ON/OFF low threshold voltage
ON/OFF high threshold voltage
V
IN
= V
OUT(typ)
+ 1 to 10 V
V
IN
= V
OUT(typ)
+ 1 to 10 V
I
OUT
= 1 to 150 mA
–30
°C ≤
T
j
≤
+85
°C
f = 120 Hz; V
ripple
= 1 V
f = 1 kHz; C
n
= 0.01
µF;
V
ripple
= 1 V
f
BW
= 20 Hz to 80 kHz; C
n
= 0.01
µF
V
ON/OFF
= 5.0 V
I
OUT
= 0 mA
V
ON/OFF
CONDITIONS
MIN.
–
–
98
1.764
2.744
2.940
3.234
3.528
4.900
–
–
–
–
50
–
–
–
–0.3
1.6
TYP.
85
0
–
1.8
2.8
3.0
3.3
3.6
5.0
0.1
10
30
100
70
60
30
5
–
–
MAX.
130
0.1
102
1.836
2.856
3.060
3.366
3.672
5.100
0.2
20
90
–
–
–
–
15
0.4
V
IN
+ 0.3
UNIT
µA
µA
% V
nom
V
V
V
V
V
V
V
mV
mV
ppm/°C
dB
dB
µV
RMS
µA
V
V
2001 Oct 03
4
Philips Semiconductors
Product data
Micropower 150 mA low noise,
low dropout linear regulator
LP2985-XX
TECHNICAL DISCUSSION
As illustrated in Figure 3, the LP2985-XX consists of a band-gap
voltage reference, an error amplifier, P-channel pass transistor,
current limit circuit and an internal feedback voltage divider. The
output voltage is fed back through an internal resistor voltage divider
connected to the V
OUT
pin.
The reference is connected to the error amplifier’s inverting input.
The error amplifier compares the reference with the feedback
voltage and amplifies the difference. If the feedback voltage is lower
than the reference voltage, the pass transistor’s gate is pulled lower,
which allows more current to pass to the output and increase the
output voltage. If the feedback voltage is too high, the pass
transistor gate is pulled up, allowing less current to pass to the
output, resulting in a decrease in output voltage.
An external bypass capacitor connected to the NOISE pin reduces
noise at the output.
Additional functional blocks include a current-limiter, thermal sensor
and shut-down logic. The current-limiter monitors and controls the
pass-transistor’s gate voltage, limiting the output current to its
specified maximum value. Thus it can withstand a short-circuited
output for an indefinite amount of time without damaging the part.
LP2985-XX
V
IN
1
5
V
OUT
3
ON/OFF
BIAS
CURRENT
LIMIT
DRIVER
REFERENCE
NOISE
4
THERMAL
SHUTDOWN
GND
2
SL01545
Figure 3. Block diagram.
2001 Oct 03
5