One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A.
Tel: 617/329-4700 Fax: 617/326-8703
FUNCTIONAL BLOCK DIAGRAMS
50mV
VIN
ADM663
SHDN
GND
VTC
VSET
VOUT1
VOUT2
SENSE
1.3V
REF
C2
0.9V
0.5V
C1
A2
A1
50mV
V
IN
ADM666
SHDN
GND
LBO
V
SET
V
OUT
SENSE
1.3V
REF
C2
0.5V
C1
C3
A1
LBI
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
a
+5 V Fixed, Adjustable
Micropower Linear Voltage Regulators
ADM663/ADM666
FEATURES
5 V Fixed or +1.3 V to +16 V Adjustable
Low Power CMOS: 12 µA max Quiescent Current
40 mA Output Current
Current Limiting
Pin Compatible with MAX663/666
+2 V to +16.5 V Operating Range
Low Battery Detector ADM666
No Overshoot on Power-Up
APPLICATIONS
Handheld Instruments
LCD Display Systems
Pagers
Remote Data Acquisition
GENERAL DESCRIPTION
The ADM663/ADM666 are precision voltage regulators featur-
ing a maximum quiescent current of 12 µA. They can be used to
give a fixed +5 V output with no additional external compo-
nents or can be adjusted from 1.3 V to 16 V using two external
resistors. Fixed or adjustable operation is automatically selected
via the V
SET
input. The low quiescent current makes these de-
vices especially suitable for battery powered systems. The input
voltage range is 2 V to 16.5 V and an output current up to
40 mA is provided. The ADM663 can directly drive an external
pass transistor for currents in excess of 40 mA. Additional fea-
tures include current limiting and low power shutdown. Ther-
mal shutdown circuitry is also included for additional safety.
The ADM666 features additional low battery monitoring
circuitry to detect for low battery voltages.
The ADM663/ADM666 are pin-compatible replacements for
the MAX663/666. Both are available in 8-pin DIP and in nar-
row surface mount (SOIC) packages.
ORDERING GUIDE
Model Temperature Range Package Option
ADM663AN –40°C to +85°C N-8
ADM663AR –40°C to +85°C R-8
ADM666AN –40°C to +85°C N-8
ADM666AR –40°C to +85°C R-8
Parameter Min Typ Max Units Test Conditions/Comments
Input Voltage, V
IN
2.0 16.5 V T
A
= T
MIN
to T
MAX
Quiescent Current, I
Q
No Load, V
IN
= +16.5 V
612µAT
A
= +25°C
15 µAT
A
= T
MIN
to T
MAX
Output Voltage, V
OUT
4.75 5.0 5.25 V T
A
= T
MIN
to T
MAX
, V
SET
= GND
Line Regulation, ∆V
OUT
/∆V
IN
0.03 0.35 %/V +2 V ≤ V
IN
≤ +15 V, V
OUT
= V
REF
Load Regulation, ∆V
OUT
/∆I
OUT
3.0 7.0 ΩADM663, 1 mA ≤ I
OUT2
≤ 20 mA
1.0 5.0 ΩADM663, 50 µA ≤ I
OUT1
≤ 5 mA
3.0 7.0 ΩADM666, 1 mA ≤ I
OUT
≤ 20 mA
Reference Voltage, V
SET
1.27 1.33 V V
OUT
= V
SET
Reference Tempco, ∆V
SET
/∆T±100 ppm/°CT
A
= T
MIN
to T
MAX
V
SET
Internal Threshold, V
F/A
50 mV V
SET
< V
F/A
for +5 V Out;
V
SET
> V
F/A
for Adj. Out
V
SET
Input Current, I
SET
±0.01 ±10 nA T
A
= T
MIN
to T
MAX
Shutdown Input Voltage, V
SHDN
1.4 V V
SHDN
High = Output Off
0.3 V V
SHDN
Low = Output On
Shutdown Input Current, I
SHDN
±0.01 ±10 nA
SENSE Input Threshold, V
OUT
–V
SENSE
0.5 V Current Limit Threshold
SENSE Input Resistance, R
SENSE
3MΩ
Input-Output Saturation Resistance, R
SAT
ADM663 V
OUT1
200 500 ΩV
IN
= +2 V, I
OUT
= 1 mA
70 150 ΩV
IN
= +9 V, I
OUT
= 2 mA
50 150 ΩV
IN
= +15 V, I
OUT
= 5 mA
Output Current from V
OUT(2)
, I
OUT
40 mA +3 V ≤ V
IN
≤ +16.5 V, V
IN
–V
OUT
= +1.5 V
Minimum Load Current, I
L (MIN)
1.0 µAT
A
= +25°C
5.0 µAT
A
= T
MIN
to T
MAX
LBI Input Threshold, V
LBI
1.21 1.28 1.37 V ADM666
LBI Input Current, I
LBI
±0.01 ±10 nA ADM666
LBO Output Saturation Resistance, R
SAT
35 100 ΩADM666, I
SAT
= 2 mA
LBO Output Leakage Current 10 nA ADM666, LBI = 1.4 V
V
TC
Open Circuit Voltage, V
TC
0.9 V ADM663
V
TC
Sink Current, I
TC
2.0 8.0 mA ADM663
V
TC
Temperature Coefficient +2.5 mV/°C ADM663
Specifications subject to change without notice.
ADM663/ADM666–SPECIFICATIONS
REV. 0
–2–
(V
IN
= +9 V, V
OUT
= + 5 V, T
A
= + 25°C unless otherwise noted)
Power Dissipation, N-8 . . . . . . . . . . . . . . . . . . . . . . . .625 mW
(Derate 8.3 mW/°C above +50°C)
θ
JA
, Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 120°C/W
Power Dissipation R-8 . . . . . . . . . . . . . . . . . . . . . . . . .450 mW
(Derate 6 mW/°C above +50°C)
θ
JA
, Thermal Impedance . . . . . . . . . . . . . . . . . . . . . 170°C/W
Operating Temperature Range
Industrial (A Version) . . . . . . . . . . . . . . . . . .–40°C to +85°C
Storage Temperature Range . . . . . . . . . . . .–65°C to +150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . . +300°C
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . . +215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . . +220°C
ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .>5000 V
*This is a stress rating only and functional operation of the device at these or any
other conditions above those indicated in the operation sections of this specifica-
tion is not implied. Exposure to absolute maximum rating conditions for extended
periods of time may affect reliability.
ABSOLUTE MAXIMUM RATINGS*
(
T
A
= +25°C unless otherwise noted)
Input Voltage, V
IN
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . +18 V
Terminal Voltage
(ADM663) Pins 1, 3, 5, 6, 7
. . . . . . . . . . . . . . . . . . . . (GND – 0.3 V) to (V
IN
+ 0.3 V)
(ADM666) Pins 1, 2, 3, 5, 6
. . . . . . . . . . . . . . . . . . . . .(GND – 0.3 V) to (V
IN
+ 0.3 V)
(ADM663) Pin 2 . . . . . . . (GND – 0.3 V) to (V
OUT1
+ 0.3 V)
(ADM666) Pin 7 . . . . . . . . . . . . (GND
– 0.3 V) to +16.5 V
Output Source Current
(ADM663, ADM666) Pin 2 . . . . . . . . . . . . . . . . . . . . 50 mA
(ADM663) Pin 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 mA
Output Sink Current,
(ADM663, ADM666) Pin 7 . . . . . . . . . . . . . . . . . . . .–20 mA
ADM663/ADM666
REV. 0 –3–
DIP & SOIC PIN CONFIGURATIONS
GENERAL INFORMATION
The ADM663/ADM666 contains a micropower bandgap refer-
ence voltage source, an error amplifier A1, two comparators
C1, C2 and a series pass output transistor. A P-channel FET
and an NPN transistor are used on the ADM663 while the
ADM666 uses an NPN output transistor.
CIRCUIT DESCRIPTION
The internal bandgap reference is trimmed to 1.3 V ± 30 mV.
This is used as a reference input to the error amplifier A1. The
feedback signal from the regulator output is supplied to the
other input by an on-chip voltage divider or by two external re-
sistors. When V
SET
is at ground, the internal divider provides
the error amplifier’s feedback signal giving a +5 V output. When
V
SET
is at more than 50 mV above ground, the error amplifier's
input is switched directly to the V
SET
pin, and external resistors
are used to set the output voltage. The external resistors are
selected so that the desired output voltage gives 1.3 V at V
SET
.
Comparator C1 monitors the output current via the SENSE
input. This input, referenced to V
OUT(2)
, monitors the voltage
drop across a load sense resistor. If the voltage drop exceeds
0.5 V, then the error amplifier A
1
is disabled and the output
current is limited.
The ADM663 has an additional amplifier, A2, which provides a
temperature-proportional output, V
TC
. If this is summed into
the inverting input of the error amplifier, a negative temperature
coefficient results at the output. This is useful when powering
liquid crystal displays over wide temperature ranges.
The ADM666 has an additional comparator, C3 which com-
pares the voltage on the Low Battery Input, LBI, pin to the in-
ternal +1.3 V reference. The output from the comparator drives
PIN FUNCTION DESCRIPTION
Mnemonic Function
V
OUT(1) (2)
Voltage Regulator Output(s)
V
IN
Voltage Regulator Input
SENSE Current Limit Sense Input. (Referenced to
V
OUT(2).
) If not used it should be connected to
V
OUT(2)
GND Ground Pin. Must be connected to 0 V
LBI Low Battery Detect Input. Compared with 1.3 V
LBO Low Battery Detect Output. Open Drain Output
SHDN Digital Input. May be used to disable the device
so that the power consumption is minimized
V
SET
Voltage Setting Input. Connect to GND for +5 V
output or connect to resistive divider for adjust
able output
V
TC
Temperature-Proportional Voltage for negative
TC Output
an open drain FET connected to the Low Battery Output pin,
LBO. The Low Battery Threshold may be set using a suitable
voltage divider connected to LBI. When the voltage on LBI falls
below 1.3 V, the open drain output LBO is pulled low.
Both the ADM663 and the ADM666 contain a shutdown
(SHDN) input which can be used to disable the error amplifier
and hence the voltage output. The quiescent current in shut-
down is less than 12 µA.
50mV
VIN
ADM663
SHDN
GND
VTC
VSET
VOUT1
VOUT2
SENSE
1.3V
REF
C2
0.9V
0.5V
C1
A2
A1
Figure 1. ADM663 Functional Block Diagram
SENSE
VOUT2
VOUT1
GND
VIN
VTC
VSET
SHDN
1
2
3
4
8
7
6
5
TOP VIEW
(Not to Scale)
ADM663
SENSE
V
OUT
LBI
GND
1
2
3
4
8
7
6
5
TOP VIEW
(Not to Scale)
ADM666
V
IN
LBO
V
SET
SHDN
ADM663/ADM666
REV. 0
–4–
ADM663
ADM666
SENSE
V
OUT(2)
GND
V
IN
V
SET
SHDN
+5V
OUTPUT
+6V TO +16V
INPUT
ADM663
ADM666
SENSE
V
OUT(2)
GND
V
IN
V
SET
SHDN
+1.3V TO +15V
OUTPUT
+2V TO +16V
INPUT R
CL
R2
R1
Figure 4. ADM663/ADM666 Adjustable Output
Current Limiting
Current limiting may be achieved by using an external current
sense resistor in series with V
OUT(2)
. When the voltage across
the sense resistor exceeds the internal 0.5 V threshold, current
limiting is activated. The sense resistor is therefore chosen such
that the voltage across it will be 0.5 V when the desired current
limit is reached.
R
CL
=0.5
I
CL
where R
CL
is the current sense resistor, I
CL
is the maximum
current limit.
The value chosen for R
CL
should also ensure that the current is
limited to less than the 50 mA absolute maximum rating and
also that the power dissipation will also be within the package
maximum ratings.
If current limiting is employed, there will be an additional volt-
age drop across the sense resistor which must be considered
when determining the regulators dropout voltage.
If current limiting is not used, the SENSE input should be con-
nected to V
OUT(2)
.
Shutdown Input (SHDN)
The SHDN input allows the regulator to be switched off with a
logic level signal. This will disable the output and reduce the
current drain to a low quiescent (12 µA maximum) current.
This is very useful for low power applications. The SHDN input
should be driven with a CMOS logic level signal since the input
threshold is 0.3 V. In TTL systems, an open collector driver
with a pull-up resistor may be used.
If the shutdown function is not being used, then SHDN should
be connected to GND.
Low Supply or Low Battery Detection
The ADM666 contains on-chip circuitry for low power supply
or battery detection. If the voltage on the LBI pin falls below the
internal 1.3 V reference, then the open drain output LBO will
go low. The low threshold voltage may be set to any voltage
above 1.3 V by appropriate resistor divider selection.
R3=R4×V
BATT
1. 30 –1
where R3 and R4 are the resistive divider resistors and V
BATT
is
the desired low voltage threshold.
50mV
V
IN
ADM666
SHDN
GND
LBO
V
SET
V
OUT
SENSE
1.3V
REF
C2
0.5V
C1
C3
A1
LBI
Figure 2. ADM666 Functional Block Diagram
Circuit Configurations
For a fixed +5 V output the V
SET
input is grounded and no ex-
ternal resistors are necessary. This basic configuration is shown
in Figure 3. Current limiting is not being utilized so the SENSE
input is connected to V
OUT(2)
. The input voltage can range from
+6 V to +16 V and output currents up to 40 mA are available
provided that the maximum package power dissipation is not
exceeded.
Figure 3. ADM663/ADM666 Fixed +5 V Output
Output Voltage Setting
If V
SET
is not connected to GND, the output voltage is set ac-
cording to the following equation.
V
OUT
=V
SET
×R1+R2
R1whereV
SET
=1. 30 V
The resistor values may be selected by firstly choosing a
value for R1 and then selecting R2 according to the following
equation.
R2=R1×V
OUT
1. 30 –1
The input leakage current on V
SET
is 10 nA maximum. This al-
lows large resistor values to be chosen for R1 and R2 with little
degradation in accuracy. For example, a 1 MΩ resistor may be
selected for R1 and then R2 may be calculated accordingly.
The tolerance on V
SET
is guaranteed at less than ±30 mV so in
most applications, fixed resistors will be suitable.
ADM663/ADM666
REV. 0 –5–
Since the LBI input leakage current is less than 10 nA, large val-
ues may be selected for R3 and R4 in order to minimize loading.
For example, a 6 V low threshold, may be set using 10 MΩ for
R3 and 2.7 MΩ for R4.
Figure 5. ADM666 Adjustable Output with Low Battery
Detection
High Current Operation
The ADM663 contains an additional output, V
OUT1
, suitable
for directly driving the base of an external NPN transistor. Fig-
ure 6 shows a configuration which can be used to provide +5 V
with boosted current drive. A 1 Ω current sensing resistor limits
the current at 0.5 A.
ADM663
V
OUT1
V
OUT2
GND
V
IN
SHDN
2N4237
V
IN
100Ω
1.0Ω
SENSE
V
SET
+
10µF
+
10µF
SHUTDOWN
+5V, 0. 5A
OUTPUT
Figure 6. ADM663 Boosted Output Current (0.5 A)
Temperature Proportional Output
The ADM663 contains a V
TC
output with a positive tempera-
ture coefficient of +2.5 mV/°C. This may be connected to the
summing junction of the error amplifier (V
SET
) through a resis-
tor resulting in a negative temperature coefficient at the output
of the regulator.
This is especially useful in multiplexed LCD displays to com-
pensate for the inherent negative temperature coefficient of the
LCD threshold. At 25°C the voltage at the VTC output is typi-
cally 0.9 V. The equations for setting both the output voltage
and the tempco are given below. If this function is not being
used, then V
TC
should be left unconnected.
ADM666
SENSE
V
OUT
GND
V
IN
V
SET
LBI
+1.3V TO +15V
OUTPUT
+2V TO +16V
INPUT
R
CL
R2
R1
LBO
SHDN
R3
R4
LOW
BATTERY
OUTPUT
R3 R1
R2
ADM663
VTC
VSET
SENSE
VOUT2 VOUT
Figure 7. ADM663 Temperature Proportional Output
VOUT =VSET ×1+R2
R1
+R2
R3×VSET –VTC
()
TCVOUT =–R2
R3×TVCTC
whereVSET =+1. 3V,VTC =+0.9V,TCVTC =+2.5 mV/°C
APPLICATION HINTS
Input-Output (Dropout Voltage)
A regulator’s minimum input-output differential or dropout
voltage determines the lowest input voltage for a particular out-
put voltage. The ADM663/ADM666 dropout voltage is 0.8 V at
its rated output current. For example when used as a fixed +5 V
regulator the minimum input voltage is +5.8 V. At lower output
currents, (I
OUT
< 5 mA), on the ADM663, V
OUT1
may be used
as the output driver in order to achieve lower dropout voltages.
Please refer to Figure 9. In this case the dropout voltage de-
pends on the voltage drop across the internal FET transistor.
This may be calculated by multiplying the FET’s saturation re-
sistance by the output current. As the current limit circuitry is
referenced to V
OUT2
, V
OUT2
should be connected to V
OUT1
. For
high current operation V
OUT2
should be used alone and V
OUT1
left unconnected.
Bypass Capacitors
The high frequency performance of the ADM663/ADM666
may be improved by decoupling the output using a filter capaci-
tor. A capacitor value of 10 µF is suitable.
An input capacitor helps reduce noise and improves dynamic
performance. A suitable input capacitor of 0.1 µF or greater
may be used.
ADM663/ADM666
REV. 0
–6–
C1907–18–4/94
PRINTED IN U.S.A.
0.01 0.1 100001000100101
80
40
0
20
60
FREQUENCY – Hz
PSRR – dB
V
IN
DC = +9V
V
IN
p-p = +2V
V
OUT
DC = +5V
T
A
= +25°C
Figure 8. Power Supply Rejection Ratio vs. Frequency
2.0
020
0.6
0.2
2
0.4
0
1.2
0.8
1.0
1.4
1.6
1.8
1816141210864
I
OUT1
– mA
(V
IN
– V
OUT
) – Volts
V
IN
= +2V T
A
= +25°C
V
IN
= +9V
V
IN
= +15V
Figure 9. V
OUT1
Input-Output Differential vs. Output
Current
12
016
6
2
4
4
2
10
8
14108612
V
IN
– Volts
I
IN
– µA
T
A
= +25°C
V
OUT
= +5V
V
OUT
= +3.3V
Figure 10. Quiescent Current vs. Input Voltage
5010
0
1.0
0
0.3
0.1
0.2
0.6
0.4
0.5
0.7
0.8
0.9
403020
I
OUT2
– mA
|V
IN
– V
OUT
| – Volts
V
IN
= +2V
T
A
= +25°C
V
IN
= +9V
V
IN
= +15V
Figure 11. V
OUT(2)
Input-Output Differential vs. Output
Current
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead Plastic DIP 8-Lead Narrow-Body
(N-8) (R-8)
PIN 1
4
58
1
0.280 (7.11)
0.240 (6.10)
SEATING
PLANE
0.130
(3.30)
MIN
0.210
(5.33)
MAX
0.070 (1.77)
0.045 (1.15)
0.100
(2.54)
BSC
0.430 (10.92)
0.348 (8.84)
0.160 (4.06)
0.115 (2.93)
0.022 (0.558)
0.014 (0.356)
0.060 (1.52)
0.015 (0.38) 0.195 (4.95)
0.115 (2.93)
0.325 (8.25)
0.300 (7.62)
0.015 (0.381)
0.008 (0.204)
0.0500 (1.27)
0.0160 (0.41)
0.0098 (0.25)
0.0075 (0.19)
x 45
°
0.0196 (0.50)
0.0099 (0.25)
8
°
0
°
0.0500
(1.27)
BSC
0.102 (2.59)
0.094 (2.39)
0.0192 (0.49)
0.0138 (0.35)
0.0098 (0.25)
0.0040 (0.10)
0.1968 (5.00)
0.1890 (4.80)
PIN 1 4
5
1
8
0.1574 (4.00)
0.1497 (3.80)
0.2440 (6.20)
0.2284 (5.80)
–Typical Performance Characteristics
