Datasheet

UNISONIC TECHNOLOGIES CO., LTD
LD1985
LINEAR INTEGRATED CIRCUIT
VERY LOW DROP AND LOW
NOISE VOLTAGE
REGULATOR LOW ESR CAP.
COMPATIBLE, WITH INHIBIT
FUNCTION

DESCRIPTION
The UTC LD1985 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 pin 3 (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 is in cellular phone, palmtop laptop
computer, personal digital assistant (PDA), personal stereo,
camcorder and camera.

FEATURES
* Very Low Dropout Voltage (280mV at 150mA and 7mV at 1mA
Load)
* Very Low Quiescent Current
* 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
* Low Output Noise Voltage 30μVrms

ORDERING INFORMATION
Ordering Number
LD1985G-xx-AF5-R
Note: xx: Output Voltage, refer to Marking Information.
www.unisonic.com.tw
Copyright © 2015 Unisonic Technologies Co., Ltd
Package
SOT-25
Packing
Tape Reel
1 of 9
QW-R102-021.I
LD1985
LINEAR INTEGRATED CIRCUIT
MARKING INFORMATION

PACKAGE
VOLTAGE CODE
15:1.5V
18:1.8V
25:2.5V
28:2.8V
2J:2.85V
30:3.0V
31:3.1V
32:3.2V
33:3.3V
35:3.5V
36:3.6V
38:3.8V
40:4.0V
47:4.7V
50:5.0V
SOT-25

PIN CONFIGURATION

PIN DESCRIPTION
PIN NO.
1
2
PIN NAME
VIN
GND
3
INHIBIT
4
Bypass
5
VOUT

MARKING
DESCRIPTION
Input port
Ground Pin
Control switches 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
Bypass pin: capacitor to be connected to GND in order to improve the thermal noise
performances.
Output port
BLOCK DIAGRAM
VOUT
VIN
CURRENT
LIMIT
INHIBIT
START-UP
SHUTDOWN
REFERENCE
VOLTAGE
ERROR
AMPLIFIER
DRIVER
BYPASS
TERM. PROTEC.
GND
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
2 of 9
QW-R102-021.I
LD1985

LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATINGS (TA=25°C)
PARAMETER
SYMBOL
RATINGS
UNIT
DC Input Voltage
VIN
7
V
INHIBIT Input Voltage
VINH
7
V
Output Current
IOUT
Internally limited
Power Dissipation
PD
Internally limited
Operating Junction Temperature
TOPR
-40 ~ +85
°C
Storage Temperature
TSTG
-40 ~ +150
°C
Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.

THERMAL DATA
PARAMETER
Junction to Case

SYMBOL
θJC
RATINGS
81
UNIT
°C/W
ELECTRICAL CHARACTRISTICS
(TJ=25°C, VIN=VOUT+1V, IOUT=1mA, VSHDN=2V, CI=1μF, CO=1μF, unless otherwise specified)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
Operating Input Voltage
VI(OPR)
2.5
VIN=2.5V
1.470
1.5
IOUT=1 ~ 150mA
1.455
VIN =2.8V
1.764
1.8
IOUT =1 ~ 150mA
1.746
VIN =3.5V
2.450
2.5
IOUT =1 ~ 150mA
2.425
VIN =3.8V
2.744
2.8
IOUT =1 ~ 150mA
2.716
VIN =3.85V
2.793
2.85
IOUT =1 ~ 150mA
2.764
VIN =4.0V
2.940
3.0
IOUT =1 ~ 150mA
2.910
VIN =4.1V
3.038
3.1
IOUT =1 ~ 150mA
3.007
VIN =4.2V
3.136
3.2
Output Voltage
VOUT
IOUT =1 ~ 150mA
3.104
VIN =4.3V
3.234
3.3
IOUT =1 ~ 150mA
3.201
VIN =4.5V
3.430
3.5
IOUT =1 ~ 150mA
3.395
VIN =4.6V
3.528
3.6
IOUT =1 ~ 150mA
3.492
VIN =4.8V
3.724
3.8
IOUT =1 ~ 150mA
3.686
VIN =5.0V
3.920
4
IOUT =1 ~ 150mA
3.880
VIN =5.7V
4.606
4.7
IOUT =1 ~ 150mA
4.559
VIN =6.0V
4.900
5
IOUT =1 ~ 150mA
4.850
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
MAX
7
1.530
1.545
1.836
1.854
2.550
2.575
2.856
2.884
2.907
2.936
3.060
3.090
3.162
3.193
3.264
3.296
3.366
3.399
3.570
3.605
3.672
3.708
3.876
3.914
4.080
4.120
4.794
4.841
5.100
5.150
UNIT
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
3 of 9
QW-R102-021.I
LD1985

LINEAR INTEGRATED CIRCUIT
ELECTRICAL CHARACTRISTICS(Cont.)
PARAMETER
Short Circuit Current
Line Regulation
SYMBOL
ISC
△VOUT
Dropout Voltage
VD
Quiescent Current
IQ
Supply Voltage Rejection
Control Input Logic Low
Control Input Logic High
SVR
VIL
VIH
Control Input Current
IINH
Output Noise Voltage
eN
TEST CONDITIONS
RL=0
VIN = VOUT +1V ~ 7V, IOUT =1mA
IOUT =0
IOUT =1mA
IOUT =10mA
IOUT =50mA
IOUT =150mA
IOUT =0
IOUT =1mA
IOUT =10mA
IOUT =50mA
IOUT =150mA
OFF MODE VINH<0.18V
CBYP=0.01μF, Co=10μF, f=1KHz
TJ=-20 ~ 125°C
TJ=-20 ~ 125°C
TJ=-20 ~ 125°C, VSHDN=5V
TJ=-20 ~ 125°C, VSHDN=0V
B=300Hz ~ 50KHz
CBYP=0.01μF, Co=10μF
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
MIN
TYP
600
1
7
40
120
280
80
100
280
1050
2900
1.5
45
MAX
30
3
10
60
150
350
100
150
330
1300
3300
0.15
2
5
0
30
15
-1
UNIT
mA
mV
mV
mV
mV
mV
mV
µA
µA
µA
µA
µA
µA
dB
V
V
µA
µA
µV
4 of 9
QW-R102-021.I
LD1985

LINEAR INTEGRATED CIRCUIT
REVERSE CURRENT TEST CIRCUIT
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
5 of 9
QW-R102-021.I
LD1985

LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION
EXTERNAL CAPACITORS
Like any low-dropout regulator, the UTC LD1985 requires external capacitors for regulator stability. This
capacitor must be selected to meet the requirements of minimum capacitance and equivalent series resistance. We
suggest soldering input and outputting capacitors as close as possible to the relative pins.
INPUT CAPACITOR
An input capacitor whose value is 1μF is required with the UTC LD1985 (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 UTC LD1985 is designed specifically 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
VOUT going from 1.8 ~ 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 VIN to 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.
Any slew rate can be used to drive the inhibit.
REVERSE CURRENT
The power transistor used in the UTC LD1985 has not an inherent diode 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. R1 and R2 resistors are implanted type;
typical values are, respectively, 42.6 KΩ and 51.150 KΩ.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
6 of 9
QW-R102-021.I
LD1985
LINEAR INTEGRATED CIRCUIT
TYPICAL CHARACTERISTICS (TJ=25°C, CIN=1μF, COUT=2.2μF, CBYP=100nF)

Output Voltage vs Temperature
2.60
Quiescent Current vs Load Current
3000
VIN=3.5V
IOUT=1mA
2.58
VOUT=2.5V
CBY=10nF
2500
2.56
2000
2.52
IQ (μA)
VOUT (V)
2.54
2.50
1500
2.48
1000
2.46
2.44
500
2.42
2.40
-50
0
-25
50
25
Tc ( )
75
100
0
125
0
50
25
Dropout Voltage vs Temperature
100
75
IOUT (mA)
175
Quiescent Current vs Temperature
0.4
IOUT=150mA
VOUT=2.5V
CBY=10nF
150
125
VOUT=2.5V
CBY=10nF
3.5
IOUT=150mA
3.0
0.3
0.2
IQ (mA)
VD (V)
2.5
IOUT=50mA
2.0
1.5
0.1
1.0
IOUT=10mA
0.5
IOUT=1mA
0
-50
-25
0
50
25
TC ( )
75
100
0
-50
125
-25
0
25
50
TC ( )
75
Supply Voltage Rejection vs Temperature
Dropout Voltage vs Output Current
90
250
fOSC=1KHz
VIN=3.5 ~ 6.5V
IOUT=10mA
80
SVR (dB)
VD (mV)
200
150
COUT=10μF
70
COUT=1μF
60
50
100
40
VOUT=2.5V
50
0
125
100
30
0
25
50
75
100
125
150
175
IOUT (mA)
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
20
-50
-25
0
25
50
75
100
125
TC ( )
7 of 9
QW-R102-021.I
LD1985

LINEAR INTEGRATED CIRCUIT
TYPICAL CHARACTERISTICS(Cont.)
Supply Voltage Rejection vs Output Current
Supply Voltage Rejection vs Frequency
80
100
70
80
50
60
SVR (dB)
SVR (dB)
60
40
40
30
20
20
0
VIN=3.5 ~ 6.5V
COUT=10μF
fOSC=1KHz
0
25
50
10
100
75
IOUT (mA)
125
150
VIN=3.5 ~ 6.5V
IOUT=10mA
VOUT=2.5V
COUT=1μF
0
101
175
102
103
f (KHz)
104
105
Line Transient
Supply Voltage Rejection vs Output Current
100
Tek Run:5.00MS/s
SVR (dB)
80
60
VIN
1
40
1
20
0
VOUT
VIN=3.5 ~ 6.5V
COUT=1μF
fOSC=1KHz
0
25
50
100
75
125
150
Ch1 500mV Ch2 20.0mV M 10.0μs Ch1
3.96V
CH2
VOUT=2.5V, IOUT=50mA, no CIN, COUT=4.7μF, tR=tF=20ns
175
IOUT (mA)
Line Transient
Supply Voltage Rejection vs Frequency
70
Tek Run:5.00MS/s
60
VIN
SVR (dB)
50
1
40
30
VOUT
20
10
2
VIN=2.8 ~ 5.8V
IOUT=10mA
VOUT=1.8V
COUT=10μF
0
101
102
103
104
105
f (KHz)
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
CH220.0mV M 10.0μs Ch1
Ch1 500mV Ch2
3.96V
VOUT=2.5V, IOUT=50mA, no CIN, COUT=4.7μF, tR=tF=1μs
8 of 9
QW-R102-021.I
LD1985

LINEAR INTEGRATED CIRCUIT
TYPICAL CHARACTERISTICS(Cont.)
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
9 of 9
QW-R102-021.I
Similar pages