19-3894; Rev 4; 9/08
+5V/Programmable Low-Dropout
Voltage Regulator
_______________General Description
The MAX667 low-dropout, positive, linear voltage regu-
lator supplies up to 250mA of output current. With no
load, it has a typical quiescent current of 20µA. At
200mA of output current, the input/output voltage differ-
ential is typically 150mV. Other features include a low-
voltage detector to indicate power failure, as well as
early-warning and low-dropout detectors to indicate an
imminent loss of output voltage regulation. A shutdown
control disables the output and puts the circuit into a
low quiescent-current mode.
The MAX667 employs Dual Mode™ operation. One
mode uses internally trimmed feedback resistors to pro-
duce +5V. In the other mode, the output may be varied
from +1.3V to +16V by connecting two external resistors.
The MAX667 is a pin-compatible upgrade to the
MAX666 in most applications where the input voltages
are above +3.5V. Choose the MAX667 when high out-
put currents and/or low dropout voltages are desired,
as well as for improved performance at higher
temperatures.
____________________________Features
♦
350mV Max Dropout at 200mA
♦
250mA Output Current
♦
Normal Mode: 20µA Typ Quiescent Current
Shutdown Mode: 0.2µA Typ Quiescent Current
♦
Low-Battery Detector
♦
Fixed +5V (Min Component Count) or
Adjustable Output
♦
+3.5V to +16.5V Input
♦
Dropout Detector Output
♦
10µF Output Capacitor
MAX667
Ordering Information
PART
MAX667CPA
MAX667CSA
MAX667C/D
MAX667EPA
MAX667ESA
MAX667MJA
MAX667MSA/PR
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
-55°C to +125°C
PIN-PACKAGE
8 Plastic DIP
8 SO
Dice*
8 Plastic DIP
8 SO
8 CERDIP**
8 SO†
________________________Applications
Battery-Powered Devices
Pagers and Radio Control Receivers
Portable Instruments
Solar-Powered Instruments
MAX667MSA/PR-T
-55°C to +125°C
8 SO†
*Contact
factory for dice specifications.
**Contact
factory for availability and processing to MIL-STD-883.
†Contact
factory for availability.
__________Typical Operating Circuit
__________________Pin Configuration
TOP VIEW
IN
+6.3V
BATTERY
OUT
C1
10μF
+5V OUT
MAX667
DD
1
OUT
2
LBI
3
GND
4
8
IN
LBO
SET
SHDN
MAX667
7
6
5
SET
GND
SHDN
DIP/SO
TM
Dual
Mode is a trademark of Maxim Integrated Products.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
+5V/Programmable Low-Dropout
Voltage Regulator
MAX667
ABSOLUTE MAXIMUM RATINGS
Input Supply Voltage ...........................................................+18V
Output Short Circuited to Ground.........................................1sec
LBO Output Sink Current ....................................................50mA
LBO Output Voltage ...............................................GND to V
OUT
SHDN Input Voltage ....................................-0.3V to (V
IN
+ 0.3V)
Input Voltages LBI, SET................................-0.3V to (V
IN
- 1.0V)
Continuous Power Dissipation
Plastic DIP (derate 9.09mW/°C above +70°C) ............727mW
SO (derate 5.88mW/°C above +70°C) .........................471mW
CERDIP (derate 8.00mW/°C above +70°C) .................640mW
Operating Temperature Ranges
MAX667C_A........................................................0°C to +70°C
MAX667E_A .....................................................-40°C to +85°C
MAX667MJA ..................................................-55°C to +125°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
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 in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(GND = 0V, V
IN
= +9V, V
OUT
= +5V, C1 = 10µF, unless otherwise noted.)
PARAMETER
Input Voltage
SYMBOL
V
IN
V
SET
= 0V, V
IN
= 6V, I
OUT
= 10mA,
T
A
= -40°C to +85°C
V
SET
= 0V, V
IN
= 6V, I
OUT
= 10mA,
T
A
= -55°C to +125°C
V
IN
= 6V, 4.5V < V
OUT
< 5.5V
V
SHDN
= 2V
Quiescent Current
I
Q
V
SHDN
= 0V,
V
SET
= 0V
I
OUT
= 0µA
I
OUT
= 100µA
I
OUT
= 200mA
250
0.2
20
20
5
5
150
50
5
1.225
V
SET
= 1.5V
V
SHDN
= 2V
(Note 2)
1.225
V
LBI
= 1.5V
V
IN
= 9V, V
LBI
= 2V, I
LBO
= 10mA
V
IH
V
IL
V
SHDN
= 0V to V
IN
V
SET
= 0V,
V
SHDN
= 0V,
R
DD
= 100kΩ,
I
OUT
= 10mA
V
IN
= 7V
V
IN
= 4.5V
3.5
1.5
0.3
0.01
±10
0.01
±10
0.25
1.5
0.3
±1000
0.25
V
0.01
0.1
400
1.195
±10
1
25
30
15
60
250
100
10
1.20
5
5
CONDITIONS
T
A
= +25°C
T
A
= T
MIN
to T
MAX
MIN
TYP
MAX MIN
TYP MAX
3.5
4.8
4.75
250
2
35
50
20
75
350
250
15
1.25
±1000
1
450
1.255
±1000
0.4
mA
mV
mV
mV
V
nA
µA
mA
V
nA
V
V
nA
µA
16.5
5.2
V
5.25
mA
UNITS
V
Output Voltage
V
OUT
Maximum Output Current
I
OUT
Dropout Voltage (Note1)
Load Regulation
Line Regulation
SET Reference Voltage
SET Input Leakage Current
Output Leakage Current
Short-Circuit Current
Low-Battery Detector
Reference Voltage
Low-Battery Detector
Input Leakage Current
Low-Battery Detector
Output Voltage
SHDN Threshold
SHDN Leakage Current
V
SET
I
SET
I
OUT
I
OUT
V
LBI
I
LBI
V
LBO
V
SHDN
I
SHDN
I
OUT
= 100µA
I
OUT
= 200mA
I
OUT
= 10mA to 200mA
V
IN
= 6V to 10V, I
OUT
= 10mA
Dropout Detector Output
Voltage
V
DD
Note 1:
Dropout Voltage is V
IN
-V
OUT
when V
OUT
falls to 0.1V below its value at V
IN
= V
OUT
+ 2V.
Note 2:
Short-Circuit Current is pulse tested to maintain junction temperature. Short-circuit duration is limited by package dissipation.
2
_______________________________________________________________________________________
+5V/Programmable Low-Dropout
Voltage Regulator
MAX667
__________________________________________Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX667-Fg TOC 1
QUIESCENT CURRENT
vs. LOAD CURRENT
MAX667-Fg TOC 2
DD OUTPUT CURRENT
vs. INPUT-OUTPUT DIFFERENCE
5 10
DD OUTPUT CURRENT (μA)
MAX667-Fg TOC 3
1000
100,000
QUIESCENT CURRENT (μA)
VIN = +6V
1000
20 50 100mA LOAD
100
DROPOUT VOLTAGE (mV)
10,000
100
1000
10
10
100
1
1
1
10
100
1000
LOAD CURRENT (mA)
10
0.01
1
0.1
1
10
100
1000
0
LOAD CURRENT (mA)
2
50
100
150
200
250
INPUT-OUTPUT DIFFERENCE (mV)
_____________________Pin Description
PIN
NAME
FUNCTION
Dropout Detector Output—the collec-
tor of a PNP pass transistor. Normally
an open circuit, it sources current as
dropout is reached.
Regulated Output Voltage. OUT falls
to 0V when SHDN is above 1.5V. SET
determines output voltage when SET
is above 50mV; otherwise, it is 5V.
OUT must be connected to an output
filter capacitor.
Low-Battery Detector. A CMOS input
to an internal 1.255V comparator
whose output is the LBO pin.
Ground
Shutdown Input. Connect to GND for
normal operation (output active). Pull
above 1.5V to disable OUT, LBO, and
DD and to reduce quiescent current to
less than 1µA.
(Output) Voltage Set, CMOS Input.
Connect to GND for 5V output. For
other voltages, connect external resis-
tive divider from OUT.
Low-Battery Output. An open-drain N-
channel transistor that sinks current to
GND when LBI is less than 1.22V.
Positive Input Voltage (unregulated)
_______________Detailed Description
Figure 1 shows a micropower bandgap reference, an
error amplifier, a PNP pass transistor, and two com-
parators as the main elements of the MAX667. One
comparator, C1, selects the fixed 5V or adjustable
operation with an external voltage divider. The other
comparator, C2, is a low-battery detector.
The bandgap reference, which is trimmed to 1.22V,
connects internally to one input of the error amplifier,
A1. The feedback signal from the regulator output sup-
plies the other input of A1 from either an on-chip volt-
age divider or two external resistors. When SET is
grounded, the internal divider provides the error ampli-
fier feedback signal for a fixed 5V output. When SET is
more than 50mV above ground, the error amplifier’s
input switches directly to SET while an external resistor
divider from OUT determines the output voltage.
A second comparator, C2, compares the LBI input to
the internal reference voltage. LBO is an open-drain
FET connected to GND. The low-battery threshold can
also be set with a voltage divider at LBI. In addition, the
MAX667 has a shutdown input (SHDN) that disables
the load and the device while reducing quiescent cur-
rent when it is pulled high.
1
DD
2
OUT
3
4
LBI
GND
5
SHDN
6
SET
+5V Output
Figure 2 shows the connection for a fixed 5V output.
The SET input is grounded, and no external resistors
are required. Figure 3 shows adjustable output opera-
tion. R1 and R2 set the output voltage. SHDN should be
grounded if not used.
3
7
8
LBO
IN
_______________________________________________________________________________________
+5V/Programmable Low-Dropout
Voltage Regulator
MAX667
IN
OUT
DD
SHDN
A1
SET
LBO
C2
C1
1.255V REF
LBI
GND
+50mV
MAX667
Figure 1. MAX667 Block Diagram
8
IN
OUT
2
C1
10μF
+5V OUT
250mA
8
MAX667
IN
OUT
2
VOUT
C1
10μF
7 LBO
VREF
R2
3 LBI
6
MAX667
R3
N
SET
SET
6
GND
4
SHDN
5
R4
SHDN
5
GND
4
R1
Figure 2. Fixed +5V Regulator
Figure 3. Adjustable Output and Low-Battery Detector
4
_______________________________________________________________________________________
+5V/Programmable Low-Dropout
Voltage Regulator
Output-Voltage Selection
If SET is connected to a resistive voltage divider (Figure
3), the output voltage is set by the equation:
V
OUT
= V
SET
x (R1 + R2) / R1,
where V
SET
= 1.22V
To simplify resistor selection:
R2 = R1 x (V
OUT
/ V
SET
- 1)
Since the input bias current at SET has a maximum
value of 10nA, relatively large values can be used for
R1 and R2 with no loss of accuracy. 1MΩ is a typical
value for R1. The V
SET
tolerance is less than ±25mV.
This allows the output to be preset without trim pots,
using only fixed resistors in most cases. However, when
resistor values greater than 1MΩ are used, pay special
attention to printed circuit board leakage that can intro-
duce error at the SET input.
Dropout Detector
The minimum input-output differential, or dropout volt-
age, determines the regulator’s lowest usable input
voltage. In battery-operated systems, this determines
the useful end-of-life battery voltage. The MAX667 fea-
tures very low dropout voltage (see
Electrical
Characteristics).
In addition, the MAX667 has a dropout
detector output, DD, that changes as the dropout volt-
age approaches its limit. DD is an open collector of a
PNP transistor. The dropout voltage and the dropout
detector both depend on the output current and tem-
perature. When the input voltage is more than 300mV
above the output voltage, the dropout detector will not
conduct. As the differential decreases below 300mV,
the DD source current increases abruptly. This current
signals a warning that regulation is about to be lost.
Connecting a resistor (typically 100kΩ) from DD to
ground develops a voltage that can be monitored by
analog circuits or changed to digital levels by a com-
parator. LBI may be used for this purpose.
MAX667
MAX667
Shutdown (Standby) Mode
SHDN puts the device into standby mode to conserve
power. When this pin is held low, the IC operates nor-
mally. If it is driven above 1.5V, the chip shuts down.
Quiescent current of the MAX667 is then reduced to
less than 1µA, and OUT turns off.
Note that the voltage for SHDN must never be more
than 0.3V higher than V
IN
.
__________Applications Information
Output Capacitor
As with all PNP output regulators, an output capacitor
(C1, Figure 2) is required to maintain stability. 10µF is
recommended. To ensure stability, the output-capacitor
ESR must be sufficiently high. Figure 4 shows the mini-
mum required output-capacitor ESR for a given temper-
ature. Alternatively, a resistor may be added in series
with the output capacitor (Figure 5); the sum of the out-
Low-Battery Function
The MAX667 contains circuitry for low-battery detec-
tion. If the voltage at LBI falls below the regulator’s
internal reference (1.22V), LBO, an open-drain output,
sinks current to GND. The threshold can be set to any
level above the reference voltage by connecting a
resistive divider to LBI based on the equation:
R3 = R4 x (V
BATT
/ V
LBI
- 1)
where V
BATT
is the desired threshold of the low-battery
detector, and R3 and R4 are the LBI input divider
resistors.
Since LBI input current is no more than 10nA, high val-
ues for R3 and R4 minimize loading. If V
OUT
is 5V, a
5.5V low-battery threshold can be set using 8.2MΩ for
R3 and 2.4MΩ for R4. When resistor values greater
than 1MΩ are used, pay special attention to PC board
leakage that can introduce error at the LBI input.
When the voltage at LBI is below the internal threshold,
LBO sinks current to GND. A pull-up resistor of 10kΩ or
more connected to OUT can be used with this pin when
driving CMOS circuits. Any pull-up resistor connected
to LBO should
not
be returned to a voltage source
greater than V
OUT
. When LBI is above the threshold or
the MAX667 is in SHDN mode, the LBO output is off.
4
MINIMUM ESR (Ω)
3
2
1
0
-60 -40 -20
0
20
40 60
80 100 120
TEMPERATURE (˚C)
Figure 4. Minimum Required Output-Capacitor ESR vs.
Temperature
_______________________________________________________________________________________
MAX667-Fg 4
5
5
