1/13July 2003
■VERY LOW DROPOUT VOLTAGE (280mV
AT 150mA AND 7mV AT 1mA LOAD)
■VERY LOW QUIESCENT CURRENT (2mA
TYP. AT 150mA LOAD AND 80µAATNO
LOAD)
■OUTPUT CURRENT UP TO 150mA
■LOGIC CONTROLLED ELECTRONIC
SHUTDOWN
■OUTPUT VOLTAGE OF 1.5, 1.8, 2.5, 2.8,
2.85,3,3.1,3.2,3.3,3.5,3.6,3.8,4,4.7,5V
■INTERNAL CURRENT AND THERMAL LIMIT
■AVAILABLE IN ± 1% TOLLERANCE (AT 25°C,
AVERSION)
■LOW OUTPUT NOISE VOLTAGE 30µVrms
■SMALLEST PACKAGE SOT23-5L
■TEMPERATURE RANGE: -40°C TO 125°C
DESCRIPTION
The LD2985 is a 150mA fixed output voltage
regulator. The ultra low drop voltage and the low
quiescent current make them particularly suitable
for low noise, low power applications, and in
battery powered systems. In sleep mode
quiescent current is less than 1µA when INHIBIT
pin is pulled low. Shutdown Logic Control Function
is available on pin3 (TTL compatible). This means
that when the device is used as local regulator, it
is possible to put a part of the board in standby,
decreasing the total power consumption.
An external capacitor, CBYP=10nF, connected
between bypass pin and GND reduce the noise
to 30µVrms.
Typical application are in cellular phone, palmtop
laptop computer, personal digital assistant (PDA),
personal stereo, camcorder and camera.
LD2985
SERIES
VERY LOW DROP AND LOW NOISE VOLTAGE REGULATOR
LOW ESR CAP. COMPATIBLE, WITH INHIBIT FUNCTION
SCHEMATIC DIAGRAM
SOT23-5L
LD2985 SERIES
2/13
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is
not implied.
THERMAL DATA
CONNECTION DIAGRAM (top view) PIN DESCRIPTION
ORDERING CODES
Symbol Parameter Value Unit
VIDC Input Voltage 16 V
VINH INHIBIT Input Voltage 16 V
IOOutput Current Internally limited
Ptot Power Dissipation Internally limited
Tstg Storage Temperature Range -65 to +150 °C
Top Operating Junction Temperature Range -40 to +125 °C
Symbol Parameter SOT23-5L Unit
Rthj-case Thermal Resistance Junction-case 81 °C/W
SOT23-5L
Pin N° Symbol Name and Function
1 IN Input Port
2 GND Ground Pin
3 INHIBIT Control switch ON/OFF. Inhibit is not
internally pulled-up; it cannot be left
floating. Disable the device when
connected to GND or to a positive
voltage less than 0.18V
4 Bypass Bypass Pin: Capacitor to be
connected to GND in order to
improve the thermal noise
performances.
5 OUT Output Port
A VERSION B VERSION OUTPUT VOLTAGES
LD2985AM15R LD2985BM15R 1.5V
LD2985AM18R LD2985BM18R 1.8V
LD2985AM25R LD2985BM25R 2.5V
LD2985AM28R LD2985BM28R 2.8V
LD2985AM285R LD2985BM285R 2.85V
LD2985AM30R LD2985BM30R 3.0V
LD2985AM31R LD2985BM31R 3.1V
LD2985AM32R LD2985BM32R 3.2V
LD2985AM33R LD2985BM33R 3.3V
LD2985AM35R LD2985BM35R 3.5V
LD2985AM36R LD2985BM36R 3.6V
LD2985AM38R LD2985BM38R 3.8V
LD2985AM40R LD2985BM40R 4.0V
LD2985AM47R LD2985BM47R 4.7V
LD2985AM50R LD2985BM50R 5.0V
LD2985 SERIES
3/13
ELECTRICAL CHARACTERISTICS FOR LD2985A (TJ= 25°C, VI=VO+1V, IO=1mA, VSHDN=2V,
CI=1µF, CO=1µF, unless otherwise specified)
Symbol Parameter Test Conditions Min. Typ. Max. Unit
VOp Operating Input Voltage 2.5 16 V
VOOutput Voltage VI= 2.5V 1.485 1.5 1.515 V
IO= 1 to 50mA 1.462 1.538 V
IO=1to50mA T
J
= -40 to 125°C 1.447 1.553 V
VOOutput Voltage VI= 2.8V 1.782 1.8 1.818 V
IO= 1 to 150mA 1.755 1.845 V
IO= 1 to 150mA TJ= -40 to 125°C 1.737 1.863 V
VOOutput Voltage VI= 3.5V 2.475 2.5 2.525 V
IO= 1 to 150mA 2.4375 2.5625 V
IO= 1 to 150mA TJ= -40 to 125°C 2.4125 2.5875 V
VOOutput Voltage VI= 3.8V 2.772 2.8 2.828 V
IO= 1 to 150mA 2.730 2.870 V
IO= 1 to 150mA TJ= -40 to 125°C 2.702 2.898 V
VOOutput Voltage VI= 3.85V 2.821 2.85 2.879 V
IO= 1 to 50mA 2.778 2.921 V
IO=1to50mA T
J
= -40 to 125°C 2.750 2.950 V
VOOutput Voltage VI= 4.0V 2.970 3.0 3.030 V
IO= 1 to 150mA 2.925 3.075 V
IO= 1 to 150mA TJ= -40 to 125°C 2.895 3.105 V
VOOutput Voltage VI= 4.1V 3.069 3.1 3.131 V
IO= 1 to 150mA 3.022 3.1775 V
IO= 1 to 150mA TJ= -40 to 125°C 2.9915 3.2085 V
VOOutput Voltage VI= 4.2V 3.168 3.2 3.232 V
IO= 1 to 150mA 3.120 3.280 V
IO= 1 to 150mA TJ= -40 to 125°C 3.088 3.312 V
VOOutput Voltage VI= 4.3V 3.267 3.3 3.333 V
IO= 1 to 150mA 3.2175 3.3825 V
IO= 1 to 150mA TJ= -40 to 125°C 3.1845 3.4155 V
VOOutput Voltage VI= 4.5V 3.465 3.5 3.535 V
IO= 1 to 150mA 3.412 3.587 V
IO= 1 to 150mA TJ= -40 to 125°C 3.377 3.622 V
VOOutput Voltage VI= 4.6V 3.564 3.6 3.636 V
IO= 1 to 150mA 3.510 3.690 V
IO= 1 to 150mA TJ= -40 to 125°C 3.474 3.726 V
VOOutput Voltage VI= 4.8V 3.762 3.8 3.838 V
IO= 1 to 150mA 3.705 3.895 V
IO= 1 to 150mA TJ= -40 to 125°C 3.667 3.933 V
VOOutput Voltage VI= 5.0V 3.96 4 4.04 V
IO= 1 to 150mA 3.9 4.1 V
IO= 1 to 150mA TJ= -40 to 125°C 3.86 4.14 V
LD2985 SERIES
4/13
VOOutput Voltage VI= 5.7V 4.653 4.7 4.747 V
IO= 1 to 150mA 4.582 4.817 V
IO= 1 to 150mA TJ= -40 to 125°C 4.5355 4.8645 V
VOOutput Voltage VI= 6.0V 4.95 5 5.05 V
IO= 1 to 150mA 4.875 5.125 V
IO= 1 to 150mA TJ= -40 to 125°C 4.825 5.175 V
ISC Short Circuit Current RL= 0 400 mA
∆VO/∆VILine Regulation VI=V
O
+1V to 16V, IO=1mA 0.003 0.014 %/VI
VI=V
O
+1V to 16V, IO=1mA
TJ= -40 to 125°C 0.032 %/VI
VdDropout Voltage IO=0 1 3 mV
I
O=0 T
J
= -40 to 125°C 5mV
I
O
=1mA 7 10 mV
I
O=1mA T
J
= -40 to 125°C 15 mV
IO= 10mA 40 60 mV
IO= 10mA TJ= -40 to 125°C 90 mV
IO= 50mA 120 150 mV
IO= 50mA TJ= -40 to 125°C 225 mV
IO= 150mA 280 350 mV
IO= 150mA TJ= -40 to 125°C 575 mV
IdQuiescent Current IO= 0 80 100 µA
IO=0 T
J
= -40 to 125°C 150 µA
IO= 1mA 100 150 µA
IO=1mA T
J
= -40 to 125°C 200 µA
IO= 10mA 200 300 µA
IO= 10mA TJ= -40 to 125°C 400 µA
IO= 50mA 600 900 µA
IO= 50mA TJ= -40 to 125°C 1200 µA
IO= 150mA 2000 3000 µA
IO= 150mA TJ= -40 to 125°C 4000 µA
OFF MODE VINH<0.18V 0 µA
OFF MODE VINH<0.18V
TJ= -40 to 125°C 2µA
SVR Supply Voltage Rejection CBYP = 0.01µFCO=10µF f = 1KHz 45 dB
VIL Control Input Logic Low TJ= -40 to 125°C 0.15 V
VIH Control Input Logic High TJ= -40 to 125°C 2V
I
iNH Control Input Current TJ= -40 to 125°C VSHDN =5V 515µA
T
J
= -40 to 125°C VSHDN =0V 0-1µA
eN Output Noise Voltage B= 300Hz to 50KHz
CBYP = 0.01µFC
O
=10µF30 µV
Symbol Parameter Test Conditions Min. Typ. Max. Unit
LD2985 SERIES
5/13
ELECTRICAL CHARACTERISTICS FOR LD2985B (TJ= 25°C, VI=VO+1V, IO=1mA, VSHDN=2V,
CI=1µF, CO=1µF, unless otherwise specified)
Symbol Parameter Test Conditions Min. Typ. Max. Unit
VOp Operating Input Voltage 2.5 16 V
VOOutput Voltage VI= 2.5V 1.477 1.5 1.523 V
IO= 1 to 150mA 1.455 1.545 V
IO= 1 to 150mA TJ= -40 to 125°C 1.440 1.560 V
VOOutput Voltage VI= 2.8V 1.773 1.8 1.827 V
IO= 1 to 150mA 1.746 1.854 V
IO= 1 to 150mA TJ= -40 to 125°C 1.728 1.872 V
VOOutput Voltage VI= 3.5V 2.4625 2.5 2.5375 V
IO= 1 to 150mA 2.425 2.575 V
IO= 1 to 150mA TJ= -40 to 125°C 2.4 2.6 V
VOOutput Voltage VI= 3.8V 2.758 2.8 2.842 V
IO= 1 to 150mA 2.716 2.884 V
IO= 1 to 150mA TJ= -40 to 125°C 2.688 2.912 V
VOOutput Voltage VI= 3.85V 2.807 2.85 2.893 V
IO= 1 to 150mA 2.764 2.935 V
IO= 1 to 150mA TJ= -40 to 125°C 2.736 2.964 V
VOOutput Voltage VI= 4.0V 2.955 3.0 3.045 V
IO= 1 to 150mA 2.91 3.09 V
IO= 1 to 150mA TJ= -40 to 125°C 2.88 3.12 V
VOOutput Voltage VI= 4.1V 3.0535 3.1 3.1465 V
IO= 1 to 150mA 3.007 3.193 V
IO= 1 to 150mA TJ= -40 to 125°C 2.976 3.224 V
VOOutput Voltage VI= 4.2V 3.152 3.2 3.248 V
IO= 1 to 150mA 3.104 3.296 V
IO= 1 to 150mA TJ= -40 to 125°C 3.072 3.328 V
VOOutput Voltage VI= 4.3V 3.2505 3.3 3.3495 V
IO= 1 to 150mA 3.201 3.399 V
IO= 1 to 150mA TJ= -40 to 125°C 3.168 3.432 V
VOOutput Voltage VI= 4.5V 3.447 3.5 3.552 V
IO= 1 to 150mA 3.395 3.605 V
IO= 1 to 150mA TJ= -40 to 125°C 3.360 3.640 V
VOOutput Voltage VI= 4.6V 3.546 3.6 3.654 V
IO= 1 to 150mA 3.492 3.708 V
IO= 1 to 150mA TJ= -40 to 125°C 3.456 3.744 V
VOOutput Voltage VI= 4.8V 3.743 3.8 3.857 V
IO= 1 to 150mA 3.686 3.914 V
IO= 1 to 150mA TJ= -40 to 125°C 3.648 3.952 V
VOOutput Voltage VI= 5.0V 3.94 4 4.06 V
IO= 1 to 150mA 3.88 4.12 V
IO= 1 to 150mA TJ= -40 to 125°C 3.84 4.16 V
LD2985 SERIES
6/13
VOOutput Voltage VI= 5.7V 4.6295 4.7 4.7705 V
IO= 1 to 150mA 4.559 4.841 V
IO= 1 to 150mA TJ= -40 to 125°C 4.512 4.888 V
VOOutput Voltage VI= 6.0V 4.925 5 5.075 V
IO= 1 to 150mA 4.85 5.15 V
IO= 1 to 150mA TJ= -40 to 125°C 4.8 5.2 V
ISC Short Circuit Current RL= 0 400 mA
∆VO/∆VILine Regulation VI=V
O
+1V to 16V, IO=1mA 0.003 0.014 %/VI
VI=V
O
+1V to 16V, IO=1mA
TJ= -40 to 125°C 0.032 %/VI
VdDropout Voltage IO=0 1 3 mV
I
O=0 T
J
= -40 to 125°C 5mV
I
O
=1mA 7 10 mV
I
O=1mA T
J
= -40 to 125°C 15 mV
IO= 10mA 40 60 mV
IO= 10mA TJ= -40 to 125°C 90 mV
IO= 50mA 120 150 mV
IO= 50mA TJ= -40 to 125°C 225 mV
IO= 150mA 280 350 mV
IO= 150mA TJ= -40 to 125°C 575 mV
IdQuiescent Current IO= 0 80 100 µA
IO=0 T
J
= -40 to 125°C 150 µA
IO= 1mA 100 150 µA
IO=1mA T
J
= -40 to 125°C 200 µA
IO= 10mA 200 300 µA
IO= 10mA TJ= -40 to 125°C 400 µA
IO= 50mA 600 900 µA
IO= 50mA TJ= -40 to 125°C 1200 µA
IO= 150mA 2000 3000 µA
IO= 150mA TJ= -40 to 125°C 4000 µA
OFF MODE VINH<0.18V 0 µA
OFF MODE VINH<0.18V
TJ= -40 to 125°C 2µA
SVR Supply Voltage Rejection CBYP = 0.01µFCO=10µF f = 1KHz 45 dB
VIL Control Input Logic Low TJ= -40 to 125°C 0.15 V
VIH Control Input Logic High TJ= -40 to 125°C 2V
I
iNH Control Input Current TJ= -40 to 125°C VSHDN =5V 515µA
T
J
= -40 to 125°C VSHDN =0V 0-1µA
eN Output Noise Voltage B= 300Hz to 50KHz
CBYP = 0.01µFC
O
=10µF30 µV
Symbol Parameter Test Conditions Min. Typ. Max. Unit
LD2985 SERIES
7/13
TYPICAL CHARACTERISTICS (unless otherwise specified TJ= 25°C, CI=1µF, CO=2.2µF, CBYP=100nF)
Figure 1 : Output Voltage vs Temperature
Figure 2 : Dropout Voltage vs Temperature
Figure 3 : Dropout Voltage vs Output Current
Figure 4 : Quiescent Current vs Load Current
Figure 5 : Quiescent Current vs Temperature
Figure 6 : Supply Voltage Rejection vs
Temperature
LD2985 SERIES
8/13
Figure 7 : Supply Voltage Rejection vs Output
Current
Figure 8 : Supply Voltage Rejection vs Output
Current
Figure 9 : Supply Voltage Rejection vs
Frequency
Figure 10 : Supply Voltage Rejection vs
Frequency
Figure 11 : Line Transient
Figure 12 : Line Transient
V
O=
2
.
5V
,
I
O=
50
m
A
,no
C
I
,
C
O
=
4
.
7
µ
F
,
t
r
=
t
f
=
2
ns
V
O=
2
.5
V
,
I
O=5
0
m
A
,no
C
I
,
C
O
=
4
.7µ
F
,t
r
=tf=
1
µs
LD2985 SERIES
9/13
Figure 13 : Load Transient Figure 14 : Load Transient
EXTERNAL CAPACITORS
Like any low-dropout regulator, the LD2985 requires external capacitors for regulator stability. This
capacitor must be selected to meet the requirements of minimum capacitance and equivalent series
resistance. We suggest to solder input and output capacitors as close as possible to the relative pins.
INPUT CAPACITOR
An input capacitor whose value is 1µF is required with the LD2985 (amount of capacitance can be
increased without limit). This capacitor must be located a distance of not more than 0.5" from the input pin
of the device and returned to a clean analog ground. Any good quality ceramic, tantalum or film capacitors
can be used for this capacitor.
OUTPUT CAPACITOR
The LD2985 is designedspecifically to work with ceramic output capacitors. It may also be possible to use
Tantalum capacitors, but these are not as attractive for reasons of size and cost. By the way, the output
capacitor must meet both the requirement for minimum amount of capacitance and E.S.R. (equivalent
series resistance) value. Due to the different loop gain, the stability improves for higher output versions
and so the suggested minimum output capacitor value, if low E.S.R. ceramic type is used, is 1µF for
output voltages equal or major than 3.8V, 2.2µF for VOgoing from 1.8 to 3.3V, and 3.3µF for the other
versions. However, if an output capacitor lower than the suggested one is used, it's possible to make
stable the regulator adding a resistor in series to the capacitor.
IMPORTANT:
The output capacitor must maintain its ESR in the stable region over the full operating temperature to
assure stability. Also, capacitor tolerance and variation with temperature must be considered to assure
the minimum amount of capacitance is provided at all times. This capacitor should be located not more
than 0.5" from the output pin of the device and returned to a clean analog ground.
INHIBIT INPUT OPERATION
The inhibit pin can be used to turn OFF the regulator when pulled low, so drastically reducing the current
consumption down to less than 1µA. When the inhibit feature is not used, this pin must be tied to VIto
keep the regulator output ON at all times. To assure proper operation, the signal source used to drive the
inhibit pin must be able to swing above and below the specified thresholds listed in the electrical
characteristics section under VIH VIL.Anyslewratecanbeusedtodrivetheinhibit.
V
O
=
2
.5
V
,
I
O=
0
to 5
0
m
A
,no
C
I
,
C
O
=
10
µ
F
,t
s
=tf=
2
ns
V
O=
2
.5
V
,
I
O=
0
to 5
0
m
A
,no
C
I
,
C
O
=
4
.7µ
F
,t
s
=tf=
2
ns
LD2985 SERIES
10/13
REVERSE CURRENT
The power transistorused in the LD2985 has not an inherentdiode connected between the regulator input
and output. If the output is forced above the input, no current will flow from the output to the input across
the series pass transistor. When a VREV voltage is applied on the output, the reverse current measured
flows to the GND across the two feedback resistors. This current typical value is 160µA. R1and R2
resistors are implanted type; typical values are, respectively, 42.6 KΩand 51.150 KΩ.
Figure 15 : Reverse Current Test Circuit
LD2985 SERIES
11/13
DIM. mm. mils
MIN. TYP MAX. MIN. TYP. MAX.
A 0.90 1.45 35.4 57.1
A1 0.00 0.10 0.0 3.9
A2 0.90 1.30 35.4 51.2
b 0.35 0.50 13.7 19.7
C 0.09 0.20 3.5 7.8
D 2.80 3.00 110.2 118.1
E 1.50 1.75 59.0 68.8
e0.95 37.4
H 2.60 3.00 102.3 118.1
L 0.10 0.60 3.9 23.6
SOT23-5L MECHANICAL DATA
7049676C
.
LD2985 SERIES
12/13
DIM. mm. inch
MIN. TYP MAX. MIN. TYP. MAX.
A 180 7.086
C 12.8 13.0 13.2 0.504 0.512 0.519
D 20.2 0.795
N 60 2.362
T 14.4 0.567
Ao 3.13 3.23 3.33 0.123 0.127 0.131
Bo 3.07 3.17 3.27 0.120 0.124 0.128
Ko 1.27 1.37 1.47 0.050 0.054 0.0.58
Po 3.9 4.0 4.1 0.153 0.157 0.161
P 3.9 4.0 4.1 0.153 0.157 0.161
Tape & Reel SOT23-xL MECHANICAL DATA
LD2985 SERIES
13/13
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the
conseq uences of u se of such inform ation nor for any in fring ement of p atents or o ther ri ghts of th ird p arties which may r esul t f rom
its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications
mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information
previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or
systems without express written approval of STMicroelectronics.
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