View MAX8880_30333.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-1679; Rev 0; 4/00
12V, Ultra-Low-IQ, Low-Dropout Linear Regulators with POK
General Description
The MAX8880/MAX8881 are ultra-low supply current, low-dropout linear regulators, capable of delivering up to 200mA. They are designed for battery-powered applications where reverse battery protection and long battery life are critical. These regulators' low 3.5A supply current extends battery life in applications with long standby periods. Unlike PNP-based designs, a 2 PMOS device maintains ultra-low supply current throughout the entire operating range and in dropout. The parts are internally protected from output short circuits, reverse battery connection, and thermal overload. An internal powerOK (POK) comparator indicates when the output is out of regulation. The MAX8880 output is adjustable from 1.25V to 5V using an external resistor-divider. The MAX8881 provides only factory-preset output voltages of 1.8V, 2.5V, 3.3V, or 5V (see Ordering Information). Both devices are available in miniature 6-pin SOT23 packages. o 3.5A Supply Current at 12V o Reverse Battery Protection o 2.5V to 12V Input Voltage Range o 1.5% Output Voltage Accuracy o 200mA max Output Current o 2 PMOS Output Device o Short-Circuit and Thermal Overload Protection o POK Output for Out-of-Regulation Indicator o Fixed 1.8V, 2.5V, 3.3V, and 5V (MAX8881) Adjustable from 1.25V to 5V (MAX8880) o Tiny 6-Pin SOT23 Package
Features
MAX8880/MAX8881
________________________Applications
Smoke Detectors Battery-Powered Alarms Remote Transmitters Smart Battery Packs PDAs Handy Terminals CMOS Backup Power Real-Time Clocks
Typical Operating Circuit
Pin Configuration
TOP VIEW
IN 1 6 POK
VIN 2.5V TO 12V 1F IN OUT FB VOUT 1.25V TO 5V UP TO 200mA 4.7F
MAX8881
ON OFF REGULATION OK SHDN GND POK
GND 2
MAX8880 MAX8881
5
SHDN
OUT 3
4
FB
SOT23-6
Ordering Information
PART MAX8880EUT-T MAX8881EUT18-T MAX8881EUT25-T MAX8881EUT33-T MAX8881EUT50-T OUTPUT Adjustable 1.8V 2.5V 3.3V 5.0V TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 6 SOT23-6 6 SOT23-6 6 SOT23-6 6 SOT23-6 6 SOT23-6 TOP MARK AAHR AAHS AAHT AAHU AAHV
________________________________________________________________ Maxim Integrated Products
1
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.
12V, Ultra-Low-IQ, Low-Dropout Linear Regulators with POK MAX8880/MAX8881
ABSOLUTE MAXIMUM RATINGS
IN to GND ................................................................-14V to +14V SHDN to GND .............................................-0.3V to (VIN + 0.3V), -0.3V to +0.3V when VIN < 0V OUT, FB to GND...............................-0.3V to +6V when VIN > 5.7V, -0.3V to (VIN + 0.3V) when 0V VIN 5.7V, -0.3V to +0.3V when VIN < 0V POK to GND ...........................................................-0.3V to +14V OUT Continuous Current...................................................200mA OUT Short Circuit...........................................................Indefinite Continuous Power Dissipation (TA = +70C) 6-Pin SOT23 (derate 8.7mW/C above +70C)...........696mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature.........................................-65C to +165C Lead Temperature (soldering, 10s) .................................+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
(VIN = VOUT + 1V, SHDN = IN, COUT = 4.7F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Input Voltage Range Supply Current Shutdown Supply Current Input Undervoltage Lockout FB Voltage, Adjustable Mode SYMBOL VIN IIN IIN(SHDN) VUVLO VFB MAX8880, IOUT = 20mA TA = +25C TA = 0C to +85C TA = -40C to +85C TA = +25C TA = 0C to +85C TA = -40C to +85C OUT Voltage Range OUT Line Regulation OUT Load Regulation (Note 3) Current Limit (Note 3) Dropout Voltage (Notes 3, 4) IN Reverse Leakage Current Foldback Current Limit SHDN Input Threshold SHDN Input Bias Current FB Input Bias Current POK Trip Threshold Hysteresis POK Off-Current POK Low Voltage IPOK VPOK VPOK = 12V, TA = +25C IPOK = 1mA 50 IFB IOUT VDO IIN(REV) IOUT(SC) VIH VIL IOUT = 50mA VIN = -12V, V SHDN = 0 VIN = 5V, VOUT = 0 VIN = 2.5V to 12V V SHDN = 0 to 12V, TA = +25C FB = 1.25V, TA = +25C, MAX8880 only Falling TA = +25C TA = -40C to +85C 2 0.5 -100 0 87.5 86 1.5 100 200 2 90.5 100 20 93.5 95 250 VOUT MAX8880 VIN = VOUT + 1V to 12V IOUT = 10A to 100mA 200 1.238 1.232 1.219 -1.5 -2 -3 1.25 0.01 0.006 400 100 200 1 VIN = 12V V SHDN = 0, VIN = 12V, VOUT = 0, TA = +25C CONDITIONS MIN 2.5 3.5 1.5 2.1 1.257 TYP MAX 12 10 3 2.4 1.276 1.282 1.295 1.5 2 3 5.5 0.05 0.015 V %/V %/mA mA mV mA mA V nA nA % of VOUT nA mV % V UNITS V A A V
OUT Voltage Accuracy (Note 2)
MAX8881, IOUT = 20mA
2
_______________________________________________________________________________________
12V, Ultra-Low-IQ, Low-Dropout Linear Regulators with POK
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VOUT + 1V, SHDN = IN, COUT = 4.7F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Thermal Shutdown Threshold OUT Noise SYMBOL TTSD CONDITIONS (Hysteresis = 15C) MIN TYP 160 300 MAX UNITS C VRMS
MAX8880/MAX8881
VOUT(NOISE) f = 10Hz to 100kHz, IOUT = 1mA
Note 1: Note 2: Note 3: Note 4:
All devices are 100% production tested at TA = +25C. All temperature limits are guaranteed by design. Output accuracy with respect to nominal preset voltages. FB = OUT. This specification is valid for VIN > 3V. The dropout voltage is defined as VIN - VOUT , when VOUT is 100mV below the value of VOUT for VIN = VOUT + 1V.
Typical Operating Characteristics
(VIN = 5V, VOUT = 3.3V, IOUT = 30mA, COUT = 4.7F, TA = +25C, unless otherwise noted. See Figure 1.)
SUPPLY CURRENT vs. INPUT VOLTAGE
MAX8880/1-01
SUPPLY CURRENT vs. TEMPERATURE
4.5 4.0 SUPPLY CURRENT (A) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 VOUT = 1.8V
MAX8880/1-02
DROPOUT VOLTAGE vs. LOAD CURRENT
450 400 DROPOUT VOLTAGE (mV) 350 300 250 200 150 100 50 0 TA = -40C 0 50 100 150 200 TA = +25C TA = +85C
MAX8880/1-03
4.5 4.0 SUPPLY CURRENT (A) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 2 4 6 8 10 NO LOAD IOUT = 30 mA
5.0
500
12
-40
-15
10
35
60
85
INPUT VOLTAGE (V)
TEMPERATURE (C)
LOAD CURRENT (mA)
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX8880/1-04
OUTPUT NOISE SPECTRAL DENSITY vs. FREQUENCY
MAX186-14A
OUTPUT NOISE vs. LOAD CURRENT
350 OUTPUT NOISE (VRMS) 300 250 200 150 100 50 VOUT = 1.8V 0 20 40 60 80 100 COUT = 4.7F COUT = 1.0F
MAX8880/1-06
70 60 50 40 30 20 10 0 0.1 1 10 100 1k
10
400
NOISE (V/Hz)
1
PSRR (dB)
0.10
0.01 10k 10 100 1k FREQUENCY (Hz) 10k 100k FREQUENCY (Hz)
0
LOAD CURRENT (mA)
_______________________________________________________________________________________
3
12V, Ultra-Low-IQ, Low-Dropout Linear Regulators with POK MAX8880/MAX8881
Typical Operating Characteristics (continued)
(VIN = 5V, VOUT = 3.3V, IOUT = 30mA, COUT = 4.7F, TA = +25C, unless otherwise noted. See Figure 1.)
OUTPUT VOLTAGE ERROR vs. LOAD CURRENT
0.1 OUTPUT VOLTAGE ERROR (%) 0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 0 50 100 150 200 LOAD CURRENT (mA) 3.3 0 50 100 LOAD CURRENT (mA) 150 200
MAX8880/1-07
SUPPLY CURRENT vs. LOAD CURRENT
MAX8880/1-08
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX8880/1-09
0.2
3.8
3.50 3.00 OUTPUT VOTLAGE (V) 2.50 2.00 1.50 1.00 0.50 0 0 2 4 6 8 10 12
3.7 SUPPLY CURRENT (A)
3.6
3.5
3.4
14
INPUT VOLTAGE (V)
CHANGE FROM NOMINAL OUTPUT VOLTAGE vs. TEMPERATURE
0.15 CHANGE FROM NOMINALOUTPUT VOLTAGE (%) 0.10 0.05 0 -0.05 -0.10 -0.15 -0.20 -40 -15 10 35 60 85 TEMPERATURE (C) 0.1 0 COUT ESR () 10
MAX8880/1-10
REGION OF STABLE COUT ESR vs. OUTPUT CURRENT
MAX8880/1-11
LINE-TRANSIENT RESPONSE
MAX8880/1-12
0.20
100
COUT = 10F
9.75V 9V
1
COUT = 4.7F
STABLE REGION 50 100 150 200 200s/div CH1 = VIN, 500mV/div, AC COUPLED CH2 = VOUT, 20mV/div, AC COUPLED VOUT = 5V, IOUT = 5mA
OUTPUT CURRENT (mA)
LOAD-TRANSIENT RESPONSE
MAX8880/1-13
LOAD-TRANSIENT RESPONSE NEAR DROPOUT
MAX8880/1-14
TURN-ON RESPONSE
MAX8880/1-15
32.5mA
32.5mA 4V
1.25mA
1.25mA
1.8V
400s/div CH1 = IOUT, 12.5mA/div CH2 = VOUT, 100mV/div, AC COUPLED VOUT(NOMINAL) = 5V, VIN = 9V
400s/div CH1 = IOUT, 12.5mA/div CH2 = VOUT, 100mV/div, AC COUPLED VIN = 5.2V, VOUT(NOMINAL) = 5V CH1 = SHDN, 2V/div CH2 = VOUT, 1V/div VIN = 4.0V
100s/div
4
_______________________________________________________________________________________
12V, Ultra-Low-IQ, Low-Dropout Linear Regulators with POK
Pin Description
PIN 1 2 3 4 5 6 NAME IN GND OUT FB SHDN POK FUNCTION Input Voltage. Bypass with a 1F capacitor to GND. Ground Output Voltage. Bypass with a 4.7F capacitor (<0.5 ESR) to GND for load currents up to 200mA. For load currents up to 40mA, 1F is acceptable. Feedback Set Point, 1.25V (MAX8880 only). Output sense, connect to OUT externally (MAX8881EUT_ _ only). ON/OFF Control. Regulator is ON when V SHDN > 2V. If unused, connect to IN. If reverse battery protection of the SHDN input is desired, connect a 100k resistor in series with SHDN. POK Output, Open Drain. Low when OUT is out of regulation or in shutdown. Connect POK to IN through a high-value resistor for a simple error indicator.
MAX8880/MAX8881
Detailed Description
The MAX8880/MAX8881 are low-dropout, low-quiescent current linear regulators designed primarily for battery-powered applications (Figure 1). The MAX8880 provides an adjustable output voltage from 1.25V to 5V using an external resistor-divider. The MAX8881 is available in factory preset output voltages of 1.8V, 2.5V, 3.3V, and 5V. Both devices have a +1.25V reference, error amplifier, MOSFET driver, and P-channel pass transistor (Figure 2).
Low-Dropout Regulator
The 1.25V reference is connected to the error amplifier's inverting input. The error amplifier compares this reference with the selected feedback voltage and amplifies the difference. The MOSFET driver reads the error signal and applies the appropriate drive to the Pchannel pass transistor. If the feedback voltage is lower
than the reference voltage, the pass-transistor gate is pulled lower, allowing more current to pass, increasing the output voltage. If the feedback voltage is higher than the reference voltage, the pass-transistor gate is driven higher, allowing less current to pass to the output. The output voltage is fed back through either an internal resistor voltage divider by externally connecting FB to OUT (MAX8881EUT_ _), or an external resistor network connected to FB (MAX8880). Additional blocks include an output current limiter, reverse battery protection, a thermal sensor, shutdown logic, and a POK comparator to indicate when the output is out of regulation (Figure 2).
Internal P-Channel Pass Transistor
The MAX8880/MAX8881 feature a 2 P-channel MOSFET pass transistor. This provides advantages over similar designs using PNP pass transistors, including longer battery life. The P-channel MOSFET requires no base drive, which reduces quiescent current considerably. PNP-based regulators waste considerable current in dropout when the pass transistor saturates. They also use high base-drive currents under large loads. The MAX8880/MAX8881 do not suffer from these problems and consume only 3.5A of supply current (see Typical Operating Characteristics).
VIN 2.5V TO 12V C1 1F
VOUT IN R2* 100k OUT FB C2 4.7F
MAX8881
REGULATION OK SHDN GND POK
Dropout Voltage
A regulator's minimum input-output differential (or dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this determines the useful end-of-life battery voltage. Because the MAX8880/MAX8881 use a P-channel MOSFET pass transistor, their dropout voltage is RDS(ON) (2) multiplied by the load current (see Electrical Characteristics).
*OPTIONAL
Figure 1. Standard Application Circuit _______________________________________________________________________________________ 5
12V, Ultra-Low-IQ, Low-Dropout Linear Regulators with POK MAX8880/MAX8881
IN SHDN REVERSE BATTERY PROTECTION
ERROR AMP SHUTDOWN LOGIC
MOS DRIVER WITH ILIMIT
P OUT FB
MAX8881
POK THERMAL SENSOR 1.25V REF 91% REF POK
GND
Figure 2. Functional Diagram
Current Limiting
VIN 2.5V TO 12V IN C1 1F OUT C2 4.7F VOUT 1.25V TO 5.5V UP TO 200mA R3
The MAX8880/MAX8881 include a current limiter. When the output is shorted to ground, drive to the output PMOS is limited. The output can be shorted to ground without damage to the part.
MAX8880
FB SHDN GND REGULATION OK R4
Thermal Overload Protection
Thermal overload protection limits total power dissipation in the MAX8880/MAX8881. When the internal junction temperature exceeds TJ = +160C, the thermal sensor signals the shutdown logic, turning off the pass transistor and allowing the IC to cool. The thermal sensor turns the pass transistor on again after the IC's junction temperature cools by 15C, resulting in a pulsed output during continuous thermal-overload conditions. Thermal-overload protection is designed to protect the MAX8880/MAX8881 in the event of fault conditions. For continuous operation, do not exceed the absolute maximum junction temperature rating of TJ(MAX) = +150C.
POK
Figure 3. Adjustable Output Using External Feedback Resistors
Reverse Battery Protection
The MAX8880/MAX8881 have a unique protection scheme that limits the reverse supply current to less than 1mA when VIN is forced below ground. The circuit monitors the polarity of IN, disconnecting the internal circuitry and parasitic diodes when the battery is reversed. This feature prevents the device from electrical stress and damage when the battery is connected backwards. If reverse battery protection is needed, drive SHDN through a 100k resistor.
Operating Region and Power Dissipation
The MAX8880/MAX8881's maximum power dissipation depends on the thermal resistance of the case and circuit board, the temperature difference between the die junction and ambient air, and the rate of airflow. The power dissipation in the device is P = I OUT (V IN VOUT). The maximum power dissipation allowed is:
6
_______________________________________________________________________________________
12V, Ultra-Low-IQ, Low-Dropout Linear Regulators with POK MAX8880/MAX8881
PMAX =
(TJ - TA ) (JC + CA )
(MAX )
where TJ(MAX) = +150C, TA is the ambient temperature, JC is the thermal resistance from the junction to the case (115C/W), and CA is the thermal resistance from the case through the PC board, copper traces, and other materials to the surrounding air.
output to 5V. Connect the MAX8881's FB to OUT for proper operation. The MAX8880 features an adjustable output voltage from 1.25V to 5.5V, using two external resistors connected as a voltage-divider to FB (Figure 3). The output voltage is set by the following equation: R3 VOUT = VFB 1 + R4 where typically VFB = 1.257V. Choose R4 = 1.2M to optimize quiescent current, accuracy, and high-frequency power-supply rejection. To simplify resistor selection: V R3 = R4 OUT - 1 VFB The total current through the external resistive feedback and load resistors should be greater than 1A. Since the VFB tolerance is typically less than 1.5%, the output can be set using fixed resistors instead of trim pots.
POK Output
The open-drain POK output is useful as a simple error flag, as well as a delayed reset output. POK sinks current when the output voltage is 10% below the regulation point. Connect POK to OUT through a high-value resistor for a simple error flag indicator. Connect a capacitor in parallel with the resistor to produce a delayed POK signal (delay set by the RC time constant). POK is low during out of regulation or in shutdown and is high impedance during normal operation.
Applications Information
Capacitor Selection and Regulator Stability
The MAX8880/MAX8881 are designed to be stable with an output filter capacitor as low as 1F and an ESR as high as 1. For general purposes, use a 1F capacitor on the device's input and a 4.7F capacitor on the output. Larger input capacitor values and lower ESR provide better supply-noise rejection and transient response. Use a higher value input capacitor (10F may be necessary) if large, fast transients are anticipated and the device is located several inches from the power source. Use large output capacitors to improve loadtransient response, stability, and power-supply rejection. Note that some ceramic dielectric materials (e.g., Z5U and Y5V) exhibit a large temperature coefficient for both capacitance and ESR, and a larger output capacitance may be needed to ensure stability at low temperatures. A 4.7F output capacitor with X7R or X5R dielectrics should be sufficient for stable operation over the full temperature range, with load currents up to 200mA. For load currents up to 40mA, 1F is acceptable. A graph of the Region of Stable C out ESR vs. Output Current is shown in the Typical Operating Characteristics.
Power-Supply Rejection and Operation from Sources Other than Batteries
The MAX8880/MAX8881 are designed to deliver lowdropout voltages and low quiescent currents in batterypowered systems. Power-supply rejection is -66dB at low frequencies and rolls off with frequencies above 100Hz. At high frequencies, the output capacitor is the major contributor to the rejection of power-supply noise (see Power-Supply Rejection Ratio vs. Frequency in the Typical Operating Characteristics). When operating from sources other than batteries, improve supply-noise rejection and transient response by increasing the value of the input and output capacitors and by using passive filtering techniques. The MAX8880/MAX8881 load-transient response graphs (see Typical Operating Characteristics) show the output response due to changing load current. Reduce overshoot by increasing the output capacitor's value up to 10F and by reducing its ESR.
Chip Information
TRANSISTOR COUNT: 134
Output Voltage Selection
The MAX8881 features a preset output voltage. Internal precision feedback resistors set the MAX8881EUT18 output to 1.8V, the MAX8881EUT25 output to 2.5V, the MAX8881EUT33 output to 3.3V, and the MAX8881EUT50
_______________________________________________________________________________________
7
12V, Ultra-Low-IQ, Low-Dropout Linear Regulators with POK MAX8880/MAX8881
Package Information
6LSOT.EPS
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) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

▲Up To Search▲

Price & Availability of MAX8880

	To Download MAX8880 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .