Maxim MAX667EPA, MAX667ESA, MAX667C-D, MAX667CPA, MAX667CSA Datasheet

...
19-3894; Rev 3; 10/94
+5V/Programmable Low-Dropout
_______________General Description
The MAX667 low-dropout, positive, linear voltage regu­lator 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 differ­ential is typically 150mV. Other features include a low­voltage 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 pro­duce +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 out­put currents and/or low dropout voltages are desired, as well as for improved performance at higher temperatures.
________________________Applications
Battery-Powered Devices Pagers and Radio Control Receivers Portable Instruments Solar-Powered Instruments
Voltage Regulator
____________________________Features
350mV Max Dropout at 200mA250mA Output CurrentNormal Mode: 20µA Typ Quiescent Current
Shutdown Mode: 0.2µA Typ Quiescent Current
Low-Battery DetectorFixed +5V (Min Component Count) or
Adjustable Output
+3.5V to +16.5V InputDropout Detector Output10µF Output Capacitor
______________Ordering Information
PART TEMP. RANGE PIN-PACKAGE
MAX667CPA 0°C to +70°C 8 Plastic DIP MAX667CSA 0°C to +70°C 8 SO MAX667C/D 0°C to +70°C MAX667EPA -40°C to +85°C 8 Plastic DIP MAX667ESA -40°C to +85°C 8 SO MAX667MJA -55°C to +125°C 8 CERDIP
* Contact factory for dice specifications.
Dice
*
MAX667
MAX667
__________Typical Operating Circuit
IN
+6.3V
BATTERY
MAX667
TM
Dual Mode is a trademark of Maxim Integrated Products.
________________________________________________________________
OUT
GND SHDNSET
C1
10µF
+5V OUT
__________________Pin Configuration
TOP VIEW
1
DD
2
OUT
LBI
GND
MAX667
3 4
DIP/SO
Maxim Integrated Products
Call toll free 1-800-998-8800 for free samples or literature.
8
IN
7
LBO
6
SET
5
SHDN
1
+5V/Programmable Low-Dropout Voltage Regulator
ABSOLUTE MAXIMUM RATINGS
Input Supply Voltage ...........................................................+18V
Output Short Circuited to Ground.........................................1sec
LBO Output Sink Current....................................................50mA
LBO Output Voltage...............................................GND to V
SHDN Input Voltage....................................-0.3V to (VIN+ 0.3V)
Input Voltages LBI, SET................................-0.3V to (V
Continuous Power Dissipation
MAX667
Plastic DIP (derate 9.09mW/°C above +70°C) ............727mW
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.
IN
OUT
- 1.0V)
ELECTRICAL CHARACTERISTICS
(GND = 0V, VIN= +9V, V
PARAMETER
Input Voltage
Output Voltage
Maximum Output Current I
Quiescent Current I
Dropout Voltage (Note1) Load Regulation
Line Regulation SET Reference Voltage V SET Input Leakage Current I 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
Dropout Detector Output Voltage
Note 1: Dropout Voltage is V Note 2: Short-Circuit Current is pulse tested to maintain junction temperature. Short-circuit duration is limited by package dissipation.
= +5V, C1 = 10µF, unless otherwise noted.)
OUT
SYMBOL
V
IN
V
OUT
OUT
Q
SET
SET
I
OUT
I
OUT
V
LBI
I
LBI
V
LBO
V
SHDN
I
SHDN
V
DD
IN-VOUT
V TA= -40°C to +85°C
V TA= -55°C to +125°C
VIN= 6V, 4.5V < V V
V V
I I I VIN= 6V to 10V, I
V (Note 2)
VIN= 9V, V V
V V
V RDD= 100k, I
when V
CONDITIONS
= 0V, VIN= 6V, I
SET
= 0V, VIN= 6V, I
SET
LBI
OUT
I I I
OUT
= 2V, I
IN
VIN= 7V
VIN= 4.5V
OUT OUT OUT
= 2V
SHDN
= 0V,
SHDN
= 0V
SET
= 100µA
OUT
= 200mA
OUT
= 10mA to 200mA
OUT
= 1.5V nA
SET
= 2V
SHDN
= 1.5V nA
LBI
IH IL
= 0V to V
SHDN
= 0V,
SET
= 0V,
SHDN
= 10mA
OUT
falls to 0.1V below its value at VIN= V
OUT
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
TA= +25°C
MIN TYP MAX
TA= T
MIN TYP MAX
MIN
to T
3.5 16.5
= 10mA,
OUT
OUT
< 5.5V
= 10mA,
250 250
5 4.8 5.2
5 4.75 5.25
0.2 1 = 0µA = 100µA = 200mA
20 25 35 20 30
515 20 560 75
150 250
50 100 250
= 10mA
510
1.225
1.20 1.25
0.01 ±10 ±1000V
0.1 1
400
1.225 1.195 1.255
0.01 ±10 ±1000V
LBO
= 10mA
1.5
0.25 0.4
1.5
0.3 0.3V
0.01 ±10 ±1000
3.5
+ 2V.
OUT
MAX
2
50
350
15
450
0.25
UNITS
V
V
mA
µA
mA mV mV
mV
V
µA
mA
V
V
V
nA
V
2 _______________________________________________________________________________________
+5V/Programmable Low-Dropout
Voltage Regulator
__________________________________________Typical Operating Characteristics
(TA= +25°C, unless otherwise noted.)
DROPOUT VOLTAGE
1000
100
10
DROPOUT VOLTAGE (mV)
1
vs. LOAD CURRENT
1 10 100 1000
LOAD CURRENT (mA)
MAX667-Fg TOC 1
QUIESCENT CURRENT
100,000
10,000
1000
QUIESCENT CURRENT (µA)
100
10
vs. LOAD CURRENT
VIN = +6V
0.01 0.1 1 10 100 1000 LOAD CURRENT (mA)
1000
MAX667-Fg TOC 2
100
10
DD OUTPUT CURRENT (µA)
1
DD OUTPUT CURRENT
vs. INPUT-OUTPUT DIFFERENCE
5 10
20 50 100mA LOAD
1
2
0 50 150 250
100 200
INPUT-OUTPUT DIFFERENCE (mV)
MAX667-Fg TOC 3
_____________________Pin Description _______________Detailed Description
Figure 1 shows a micropower bandgap reference, an
PIN
FUNCTIONNAME
Dropout Detector Output—the collec-
DD1
OUT2
LBI3
SHDN5
SET6
LBO7
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.
GroundGND4 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 resis­tive divider from OUT.
Low-Battery Output. An open-drain N­channel transistor that sinks current to GND when LBI is less than 1.22V.
Positive Input Voltage (unregulated)IN8
error amplifier, a PNP pass transistor, and two com­parators 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 sup­plies the other input of A1 from either an on-chip volt­age divider or two external resistors. When SET is grounded, the internal divider provides the error ampli­fier 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 cur­rent when it is pulled high.
+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 opera­tion. R1 and R2 set the output voltage. SHDN should be grounded if not used.
MAX667
_______________________________________________________________________________________ 3
+5V/Programmable Low-Dropout Voltage Regulator
MAX667
Figure 1. MAX667 Block Diagram
8
IN
IN
SHDN
LBO
LBI
GND
MAX667
A1
C2 C1
1.255V REF
OUT
2
C1 10µF
+5V OUT 250mA
OUT DD
SET
+50mV
MAX667
8
IN LBO
7
N
R3
MAX667
OUT
VREF
2
V
OUT
C1 10µF
R2
LBI
3
GND SHDNSET
645
Figure 2. Fixed +5V Regulator
R4
GNDSHDN
54
Figure 3. Adjustable Output and Low-Battery Detector
4 _______________________________________________________________________________________
SET
6
R1
+5V/Programmable Low-Dropout
If SET is connected to a resistive voltage divider (Figure
3), the output voltage is set by the equation: V
where V To simplify resistor selection:
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. 1Mis a typical value for R1. The V This allows the output to be preset without trim pots, using only fixed resistors in most cases. However, when resistor values greater than 1Mare used, pay special attention to printed circuit board leakage that can introduce error at the SET input.
SHDN puts the device into standby mode to conserve power. When this pin is held low, the IC operates nor­mally. 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 VIN.
The MAX667 contains circuitry for low-battery detec­tion. 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:
where V detector, and R3 and R4 are the LBI input divider resistors.
Since LBI input current is no more than 10nA, high val­ues for R3 and R4 minimize loading. If V
5.5V low-battery threshold can be set using 8.2Mfor
R3 and 2.4Mfor R4. When resistor values greater than 1Mare 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 10kor 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 the MAX667 is in SHDN mode, the LBO output is off.
OUT
= 1.22V
SET
R2 = R1 x (V
R3 = R4 x (V
is the desired threshold of the low-battery
BATT
OUT
Output-Voltage Selection
= V
x (R1 + R2) / R1,
SET
/ V
SET
- 1)
OUT
tolerance is less than ±25mV.
SET
Shutdown (Standby) Mode
Low-Battery Function
/ V
LBI
- 1)
OUT
is 5V, a
BATT
. When LBI is above the threshold or
Voltage Regulator
The minimum input-output differential, or dropout volt­age, determines the regulator’s lowest usable input voltage. In battery-operated systems, this determines the useful end-of-life battery voltage. The MAX667 fea­tures very low dropout voltage (see
Characteristics
detector output, DD, that changes as the dropout volt­age 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 tem­perature. 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 100k) from DD to ground develops a voltage that can be monitored by analog circuits or changed to digital levels by a com­parator. LBI may be used for this purpose.
). In addition, the MAX667 has a dropout
__________Applications Information
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 mini­mum required output-capacitor ESR for a given temper­ature. Alternatively, a resistor may be added in series with the output capacitor (Figure 5); the sum of the out-
5
4
3
2
MINIMUM ESR ()
1
0
-60 -40 -20 0 20 40 60 80 100 120
Figure 4. Minimum Required Output-Capacitor ESR vs. Temperature
TEMPERATURE (˚C)
Dropout Detector
Electrical
Output Capacitor
MAX667-Fg 4
MAX667
MAX667
_______________________________________________________________________________________ 5
+5V/Programmable Low-Dropout Voltage Regulator
82
OUT
+5V OUTIN
8
OUT
2
C1 10µF
+5V OUTIN
R
10µF
MAX667
MAX667
SHDNSET GND
645
Figure 5. Alternative Stability Scheme Using Resistor R
8
OUT
2
C1 10µF
+5V OUTIN
MAX667
1
DD
GND SHDNSET
645
R1
47k
C2
0.1µF
Figure 6. Quiescent-Current Reduction Below Dropout
put-capacitor ESR and this series resistance should, at minimum, meet the requirements shown in Figure 4.
An upper limit to the output-capacitor ESR is important only if step changes to the load are anticipated. Higher ESR results in higher-amplitude output-voltage tran­sients when the output current is varied. A Sanyo OS-CON capacitor, whose ESR is nearly flat over tem­perature (and is low to begin with), in series with the appropriate resistor ensures the best load-transient performance. A less expensive alternative is to use a tantalum capacitor in series with the resistor.
MAX667
5
SHDN
41
SET
DDGND
R3 1M
6
R2 1M
R1 332k
Figure 7. Connection for Minimum Quiescent Current Near Dropout
10
V
SHDN = 0V
8
6
4
QUIESCENT CURRENT (mA)
2
0
0123456
INPUT VOLTAGE (V)
MAX667-Fg 8
Figure 8. Quiescent Current Below Dropout for Circuit of Figure 2
In most cases, inexpensive aluminum-electrolytic capacitors work well with the MAX667 over their entire temperature range, having sufficient ESR to ensure sta­bility without the need for a series resistor. The ESR of aluminium electrolytics rises, often dramatically, as temperature decreases. For surface-mount applica­tions, certain tantalum capacitors have sufficient ESR; an example is the TAJB106K016 chip capacitor made by AVX (phone: (803) 448-9411, fax: (803) 448-1943).
Battery Drain
The MAX667 uses a PNP output transistor. When the input voltage falls below the desired output voltage, the
6 _______________________________________________________________________________________
800
600
(µA)
400
GND
I
200
0
12 4 6
CIRCUIT OF
FIGURE 7
CIRCUIT OF
FIGURE 6
35
VIN (V)
+5V/Programmable Low-Dropout
+5V/Programmable Low-Dropout
Voltage Regulator
Voltage Regulator
400
= +50˚C
T
MAX667-Fg 9
LOAD CURRENT (mA)
A
300
200
100
SO PACKAGE
DISSIPATION LIMIT
0
015
GUARANTEED 250mA
DIP PACKAGE DISSIPATION LIMIT
5
V
IN-VOUT
10
(V)
MAX667-Fg 10
MAX667
MAX667
Figure 9. Quiescent Current Below Dropout with Connections of Figures 6 and 7
PNP transistor is turned on fully as regulation is lost. Even with a load current of a few microamperes, the base current will be driven above 5mA. Figure 8 shows how this base current may be significant. Consequently, a mostly discharged battery can be fur­ther discharged at end-of-life.
Figure 6 shows how this condition can be modified by connecting DD to SHDN with a 47kresistor, R1, par­alleled with a 0.1µF capacitor to GND. This modifica­tion reduces the no-load quiescent current to approximately 160µA when dropout is reached (Figure
9), but increases the dropout voltage by about 0.1V. The output voltage drops to approximately 3V once DD begins to activate SHDN, but it does not fall to zero because SHDN is only partially activated.
A second alternate connection (Figure 7) further reduces quiescent current near the dropout voltage, compared to the circuit in Figure 6. The output must be set with external resistors (R1, R2), so DD lowers the output voltage as the input voltage falls by sourcing current into SET via R3. Quiescent current remains low for inputs down to 3.5V, and peaks before falling to 0 at low input voltages. Although the current peak is higher than with the connection in Figure 6, this may be more useful because the quiescent current peaks at an input voltage well below the useful range of most batteries (Figure 9). Also, as IN falls below 5V, OUT tracks IN minus the dropout voltage. This connection still allows separate use of the SHDN input.
Power Dissipation
The MAX667 can regulate currents as high as 250mA and withstand input-output differential voltages as high
_______________________________________________________________________________________ 7
Figure 10. MAX667 Load Current vs. Input-Output Differential Voltage
+10V
INPUT
+2V/div
+6V
+5V OUTPUT
+0.2V/div
1ms/div
Figure 11. Output Response to +4V/100µs Input Step
as 15.2V, but not simultaneously. The maximum power dissipation is dependent on the package and the tem­perature (see
Absolute Maximum Ratings
). Figure 10 shows the maximum output current at various input­output differential voltages for the plastic DIP and SO packages. The MAX667 can withstand short-circuit loads up to 1 second.
Operation from AC Sources
The MAX667 is a micropower CMOS regulator intend­ed principally for battery operation. When operating from AC sources, consider power-supply ripple rejec­tion. The MAX667’s error amplifier produces very low gain bandwidth, and the input power-supply rejection
+5V/Programmable Low-Dropout Voltage Regulator
___________________Chip Topography
+5V OUTPUT
0.1V/div
MAX667
100mA
OUTPUT
CURRENT
10mA
200µs/div
Figure 12. Output Response to 10mA/100mA Load Step with 10µF Output Capacitor (1.5ESR)
ratio (PSRR) is therefore not specified. Since the output must be connected to a 10µF or larger filter capacitor, the capacitor characteristics dominate the PSRR. Large values of input and output capacitors reduce the ripple.
In addition, both DD and LBI/LBO can trigger on the lowest DC component of the ripple, particularly at high load currents. In the case of the low-battery detector, the ripple can be effectively filtered out by placing a capacitor to ground in parallel with the LBI input pin. The high resistance values that can be used for the voltage divider allow relatively small capacitance val­ues to form an effective lowpass filter at 120Hz. When power is first applied, however, this filter tends to hold LBO low longer than normal.
The low operating current and gain-bandwidth product of the internal reference and amplifier result in limited rejection of fast-step input changes. Negative-going steps, which occur in under 100µs, may turn off the out­put for several milliseconds. An input filter (nominally 10µF) is recommended if input changes greater than 1V and faster than 100µs (other than turn-on or turn-off) are anticipated. Figure 12 shows the output response to a 10mA/100mA instantaneous load step. The rela­tionship between output-capacitor ESR and load-tran­sient response is explained in the section.
Transient Considerations
Output Capacitor
OUT
DD
LBI
GND
IN
0.107"
(2.71mm)
LBO SET
SHDN
0.070"
(1.78mm)
TRANSISTOR COUNT: 65 SUBSTRATE MUST BE LEFT UNCONNECTED
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8
___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
© 1994 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Loading...