View MAX667_15749.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-3894; Rev 3; 10/94
+5V/Programmable Low-Dropout Voltage Regulator
_______________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 20A. 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 ModeTM 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.
____________________________Features
o 350mV Max Dropout at 200mA o 250mA Output Current o Normal Mode: 20A Typ Quiescent Current Shutdown Mode: 0.2A Typ Quiescent Current o Low-Battery Detector o Fixed +5V (Min Component Count) or Adjustable Output o +3.5V to +16.5V Input o Dropout Detector Output o 10F Output Capacitor
MAX667
______________Ordering Information
PART MAX667CPA MAX667CSA MAX667C/D MAX667EPA MAX667ESA MAX667MJA TEMP. RANGE 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C -55C to +125C PIN-PACKAGE 8 Plastic DIP 8 SO Dice* 8 Plastic DIP 8 SO 8 CERDIP
________________________Applications
Battery-Powered Devices Pagers and Radio Control Receivers Portable Instruments Solar-Powered Instruments
* Contact factory for dice specifications.
__________Typical Operating Circuit
__________________Pin Configuration
TOP VIEW
IN +6.3V BATTERY
OUT C1 10F
+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
Call toll free 1-800-998-8800 for free samples or literature.
+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 VOUT SHDN Input Voltage ....................................-0.3V to (VIN + 0.3V) Input Voltages LBI, SET................................-0.3V to (VIN - 1.0V) Continuous Power Dissipation Plastic DIP (derate 9.09mW/C above +70C) ............727mW SO (derate 5.88mW/C above +70C) .........................471mW CERDIP (derate 8.00mW/C above +70C) .................640mW Operating Temperature Ranges MAX667C_A........................................................0C to +70C MAX667E_A .....................................................-40C to +85C MAX667MJA ..................................................-55C to +125C Storage Temperature Range .............................-65C to +160C Lead Temperature (soldering, 10sec) .............................+300C
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, VIN = +9V, VOUT = +5V, C1 = 10F, unless otherwise noted.) PARAMETER Input Voltage SYMBOL VIN VSET = 0V, VIN = 6V, IOUT = 10mA, TA = -40C to +85C VSET = 0V, VIN = 6V, IOUT = 10mA, TA = -55C to +125C VIN = 6V, 4.5V < VOUT < 5.5V VSHDN = 2V Quiescent Current IQ VSHDN = 0V, VSET = 0V IOUT = 0A IOUT = 100A 250 0.2 20 20 5 5 150 50 5 1.225 VSET = 1.5V VSHDN = 2V (Note 2) 1.225 VLBI = 1.5V VIN = 9V, VLBI = 2V, ILBO = 10mA VIH VIL VSHDN = 0V to VIN VSET = 0V, VSHDN = 0V, RDD = 100k, IOUT = 10mA VIN = 7V VIN = 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 MIN TA = +25C TA = TMIN to TMAX 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 A mA V nA V V nA A 16.5 5.2 V 5.25 mA UNITS V
Output Voltage
VOUT
Maximum Output Current
IOUT
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 VSET ISET IOUT IOUT VLBI ILBI VLBO VSHDN ISHDN
IOUT = 200mA IOUT = 100A IOUT = 200mA IOUT = 10mA to 200mA VIN = 6V to 10V, IOUT = 10mA
Dropout Detector Output Voltage
VDD
Note 1: Dropout Voltage is VIN-VOUT when VOUT falls to 0.1V below its value at VIN = VOUT + 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
__________________________________________Typical Operating Characteristics
(TA = +25C, unless otherwise noted.)
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX667-Fg TOC 1
MAX667
QUIESCENT CURRENT vs. LOAD CURRENT
MAX667-Fg TOC 2
DD OUTPUT CURRENT vs. INPUT-OUTPUT DIFFERENCE
5 10 DD OUTPUT CURRENT (A) 20 50 100mA LOAD 100
MAX667-Fg TOC 3
1000
100,000 QUIESCENT CURRENT (A)
VIN = +6V
1000
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 collector 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 1A. (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)
_______________Detailed Description
Figure 1 shows a micropower bandgap reference, an 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.
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 operation. 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 10F
+5V OUT 250mA
8
MAX667
IN OUT
2
VOUT C1 10F
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: VOUT = VSET x (R1 + R2) / R1, where VSET = 1.22V To simplify resistor selection: R2 = R1 x (VOUT / VSET - 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. 1M is a typical value for R1. The VSET 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 1M are used, pay special attention to printed circuit board leakage that can introduce error at the SET input.
Dropout Detector
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 Electrical Characteristics). In addition, the MAX667 has a dropout 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.
MAX667
Shutdown (Standby) Mode
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 1A, and OUT turns off. Note that the voltage for SHDN must never be more than 0.3V higher than VIN.
__________Applications Information
Output Capacitor
As with all PNP output regulators, an output capacitor (C1, Figure 2) is required to maintain stability. 10F 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-
Low-Battery Function
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: R3 = R4 x (VBATT / VLBI - 1) where VBATT 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 values for R3 and R4 minimize loading. If VOUT is 5V, a 5.5V low-battery threshold can be set using 8.2M for R3 and 2.4M for R4. When resistor values greater than 1M 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 10k 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 VOUT. When LBI is above the threshold or the MAX667 is in SHDN mode, the LBO output is off.
4 MINIMUM ESR ()
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
+5V/Programmable Low-Dropout Voltage Regulator MAX667
8 +5V OUT 2 C1 10F +5V OUT
8
IN
OUT
2
IN
OUT
MAX667
R 10F 5 SHDN
MAX667
R2 1M
SET DD 1
6
GND SET 6 GND 4 SHDN 5 4
R1 332k
R3 1M
Figure 5. Alternative Stability Scheme Using Resistor R
Figure 7. Connection for Minimum Quiescent Current Near Dropout
8
IN
OUT
2 C1 10F
+5V OUT QUIESCENT CURRENT (mA) 8
VSHDN = 0V
MAX667
6
DD SET 6 GND 4 SHDN 5
1
4
2
R1 47k
C2 0.1F
0 0 1 2 3 4 5 6 INPUT VOLTAGE (V)
Figure 6. Quiescent-Current Reduction Below Dropout
Figure 8. Quiescent Current Below Dropout for Circuit of Figure 2
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.
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
_______________________________________________________________________________________
MAX667-Fg 8
10
+5V/Programmable Low-Dropout Voltage Regulator MAX667
MAX667-Fg 9
TA = +50C LOAD CURRENT (mA) 300 GUARANTEED 250mA
600 IGND (A)
CIRCUIT OF FIGURE 7
400 CIRCUIT OF FIGURE 6 200
200 DIP PACKAGE DISSIPATION LIMIT 100 SO PACKAGE DISSIPATION LIMIT 0 5 10 15
0 1 2 3 4 VIN (V) 5 6
0
VIN-VOUT (V)
Figure 9. Quiescent Current Below Dropout with Connections of Figures 6 and 7
Figure 10. MAX667 Load Current vs. Input-Output Differential Voltage
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 47k resistor, R1, paralleled with a 0.1F capacitor to GND. This modification reduces the no-load quiescent current to approximately 160A 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.
+10V INPUT +2V/div +6V
+5V OUTPUT +0.2V/div
1ms/div
Figure 11. Output Response to +4V/100s 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
7
Power Dissipation
The MAX667 can regulate currents as high as 250mA and withstand input-output differential voltages as high
_______________________________________________________________________________________
MAX667-Fg 10
800
400
+5V/Programmable Low-Dropout Voltage Regulator MAX667
___________________Chip Topography
+5V OUTPUT 0.1V/div
DD IN
OUT
100mA OUTPUT CURRENT 10mA
LBI
0.107" (2.71mm)
200s/div
LBO
Figure 12. Output Response to 10mA/100mA Load Step with 10F Output Capacitor (1.5 ESR)
SET
ratio (PSRR) is therefore not specified. Since the output must be connected to a 10F 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.
GND 0.070" (1.78mm)
SHDN
TRANSISTOR COUNT: 65 SUBSTRATE MUST BE LEFT UNCONNECTED
Transient Considerations
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 100s, may turn off the output for several milliseconds. An input filter (nominally 10F) is recommended if input changes greater than 1V and faster than 100s (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 Output Capacitor section.
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 (c) 1994 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

▲Up To Search▲

Price & Availability of MAX667

	To Download MAX667 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .