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19-1301; Rev 1; 3/98
Low-Noise, Low-Dropout, 150mA Linear Regulators with `2982 Pinout
__________________General Description
The MAX8877/MAX8878 low-noise, low-dropout linear regulators operate from a 2.5V to 6.5V input and deliver up to 150mA. These devices are pin-compatible with the industry-standard `2982 and offer an improved dropout voltage. Typical output noise is 30VRMS, and typical dropout is only 165mV at 150mA. The output voltage is preset to voltages in the range of 2.5V to 5.0V, in 100mV increments. Designed with an internal P-channel MOSFET pass transistor, the MAX8877/MAX8878 maintain a low 100A supply current, independent of the load current and dropout voltage. Other features include a 10nA logic-controlled shutdown mode, short-circuit and thermal-shutdown protection, and reverse battery protection. The MAX8878 also includes an auto-discharge function, which actively discharges the output voltage to ground when the device is placed in shutdown. Both devices come in a miniature 5-pin SOT23 package.
____________________________Features
o Pin-Compatible with the Industry-Standard `2982 o Low Output Noise: 30VRMS o Low 55mV Dropout at 50mA Output (165mV at 150mA output) o Low 85A No-Load Supply Current o Low 100A Operating Supply Current (even in dropout) o Thermal-Overload and Short-Circuit Protection o Reverse Battery Protection o Output Current Limit o Preset Output Voltages (1.4% Accuracy) o 10nA Logic-Controlled Shutdown
MAX8877/MAX8878
________________________Applications
Cellular Telephones Cordless Telephones PCS Telephones PCMCIA Cards Modems Hand-Held Instruments Palmtop Computers Electronic Planners
_________________Ordering Information
PART** MAX8877C/Dxy MAX8877EUKxy-T MAX8878C/Dxy MAX8878EUKxy-T TEMP. RANGE 0C to +70C -40C to +85C 0C to +70C -40C to +85C PIN-PACKAGE Dice* 5 SOT23-5 Dice* 5 SOT23-5
*Dice are tested at TA = +25C only. **xy is the output voltage code (see Expanded Ordering Information table at end of data sheet).
____________Typical Operating Circuit
_____________________Pin Configuration
TOP VIEW
INPUT 2.5V TO 6.5V IN CIN 1F ON OFF CBP 0.01F OUT COUT 1F
OUTPUT PRESET 2.5V TO 5.0V 150mA
IN 1
5
OUT
MAX8877 MAX8878
SHDN BP GND
GND 2
MAX8877 MAX8878
4 BP
SHDN 3
SOT23-5
________________________________________________________________ Maxim Integrated Products
1
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Low-Noise, Low-Dropout, 150mA Linear Regulators with `2982 Pinout MAX8877/MAX8878
ABSOLUTE MAXIMUM RATINGS
IN to GND ....................................................................-7V to +7V Output Short-Circuit Duration ............................................Infinite SHDN to GND..............................................................-7V to +7V SHDN to IN ...............................................................-7V to +0.3V OUT, BP to GND ..........................................-0.3V to (VIN + 0.3V) Continuous Power Dissipation (TA = +70C) SOT23-5 (derate 7.1mW/C above +70C)..................571mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C JB ..................................................................................140C/W Storage Temperature.........................................-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
(VIN = VOUT(NOMINAL) + 0.5V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER Input Voltage Output Voltage Accuracy Maximum Output Current Current Limit Ground Pin Current ILIM IQ No load IOUT = 150mA IOUT = 1mA Dropout Voltage (Note 2) Line Regulation Load Regulation Output Voltage Noise SHUTDOWN SHDN Input Threshold SHDN Input Bias Current Shutdown Supply Current Shutdown Exit Delay (Note 3) Resistance Shutdown Discharge THERMAL PROTECTION Thermal Shutdown Temperature Thermal Shutdown Hysteresis TSHDN TSHDN 155 15 C C VIH VIL ISHDN IQ(SHDN) VIN = 2.5V to 5.5V VIN = 2.5V to 5.5V VSHDN = VIN VOUT = 0V CBP = 0.1F COUT = 1F, no load MAX8878 only TA = +25C TA = +85C TA = +25C TA = +85C TA = +25C TA = -40C to +85C 300 0.01 0.5 0.01 0.2 30 150 300 1 2.0 0.4 100 V nA A s VLNR VLDR en IOUT = 50mA IOUT = 150mA VIN = (VOUT + 0.1V) to 6.5V, IOUT = 1mA IOUT = 0mA to 120mA, COUT = 1F f = 10Hz to 100kHz, CBP = 0.01F COUT = 10F COUT = 100F -0.15 SYMBOL VIN IOUT = 0mA, TA = +25C IOUT = 0mA to 120mA, TA = -40C to +85C CONDITIONS MIN 2.5 -1.4 -3 150 160 390 85 100 1.1 55 165 0 0.01 30 20 0.15 0.04 %/V %/mA VRMS 120 mV 180 TYP MAX 6.5 1.4 2 UNITS V % mA mA A
Note 1: Limits are 100% production tested at TA = +25C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control (SQC) Methods. Note 2: The dropout voltage is defined as VIN - VOUT, when VOUT is 100mV below the value of VOUT for VIN = VOUT + 0.5V. Note 3: Time needed for VOUT to reach 95% of final value. 2 _______________________________________________________________________________________
Low-Noise, Low-Dropout, 150mA Linear Regulators with `2982 Pinout
__________________________________________Typical Operating Characteristics
(VIN = VOUT(NOMINAL) + 0.5V, CIN = 1F, COUT = 1F, CBP = 0.01F, TA = +25C, unless otherwise noted.)
MAX8877/MAX8878
OUTPUT VOLTAGE vs. LOAD CURRENT (MAX887_EUK25)
MAX8877-01
OUTPUT VOLTAGE vs. LOAD CURRENT (MAX887_EUK50)
MAX8877-02
GROUND PIN CURRENT vs. LOAD CURRENT
105 GROUND PIN CURRENT (A) 100 95 90 85 80 75 70 65 MAX887_EUK25 MAX887_EUK50
MAX8877-03
2.60
5.2
110
OUTPUT VOLTAGE (V)
2.50
OUTPUT VOLTAGE (V)
2.55
5.1
5.0
2.45
4.9
2.40 0 50 100 150 LOAD CURRENT (mA)
4.8 0 50 100 150 LOAD CURRENT (mA)
60 0 50 100 150 LOAD CURRENT (mA)
GROUND PIN CURRENT vs. INPUT VOLTAGE (MAX887_EUK25)
MAX8877-04
GROUND PIN CURRENT vs. INPUT VOLTAGE (MAX887_EUK50)
MAX8877-05
OUTPUT VOLTAGE vs. INPUT VOLTAGE
NO LOAD 5 OUTPUT VOLTAGE (V) MAX887_EUK50 4 3 2 1 0 MAX887_EUK25
MAX8877-06
120 ILOAD = 50mA GROUND PIN CURRENT (A) 100 80 NO LOAD 60 40 20 0 0 1 2 3 4 5 6 INPUT VOLTAGE (V)
120 100 80
ILOAD = 50mA
6
GROUND PIN CURRENT (A)
NO LOAD 60 40 20 0 0 1 2 3 4 5 6 INPUT VOLTAGE (V)
0
1
2
3
4
5
6
INPUT VOLTAGE (V)
OUTPUT VOLTAGE vs. TEMPERATURE (MAX887_EUK25)
MAX8877-07
OUTPUT VOLTAGE vs. TEMPERATURE (MAX887_EUK50)
MAX8877-08
GROUND PIN CURRENT vs. TEMPERATURE
180 GROUND PIN CURRENT (A) 160 140 120 100 80 60 40 20 MAX887_EUK25 MAX887_EUK50 ILOAD = 50mA
MAX8877-09
2.60 ILOAD = 50mA 2.55
5.2 ILOAD = 50mA 5.1
200
OUTPUT VOLTAGE (V)
2.50
OUTPUT VOLTAGE (V)
5.0
2.45
4.9
2.40 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
4.8 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
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3
Low-Noise, Low-Dropout, 150mA Linear Regulators with `2982 Pinout MAX8877/MAX8878
____________________________Typical Operating Characteristics (continued)
(VIN = VOUT(NOMINAL) + 0.5V, CIN = 1F, COUT = 1F, CBP = 0.01F, TA = +25C, unless otherwise noted.)
DROPOUT VOLTAGE vs. LOAD CURRENT (MAX887_EUK25)
MAX8877-10
DROPOUT VOLTAGE vs. LOAD CURRENT (MAX887_EUK50)
MAX8877-11
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX8877-12
250 TA = +85C TA = +25C TA = -40C 100
200
70 60 50 PSRR (dB) 40 30 20 10 ILOAD = 50mA CBP = 0.1F 0.01 0.1 1 10 100 COUT = 1F
DROPOUT VOLTAGE (mV)
DROPOUT VOLTAGE (mV)
200
150
TA = +85C TA = +25C
COUT = 10F
150
100 TA = -40C 50
50
0 0 20 40 60 80 100 120 140 160 LOAD CURRENT (mA)
0 0 20 40 60 80 100 120 140 160 LOAD CURRENT (mA)
0 1000 FREQUENCY (kHz)
OUTPUT NOISE SPECTRAL DENSITY vs. FREQUENCY
MAX8877-13
OUTPUT NOISE vs. BP CAPACITANCE
70 OUTPUT NOISE (VRMS) 60 50 MAX887_EUK50 40 30 20 MAX887_EUK25 10 0 10 0 0.001 0.01 BP CAPACITANCE (F) 0.1 1 MAX887_EUK30 COUT = 10F ILOAD = 10mA f = 10Hz to 100kHz
MAX8877-14
OUTPUT NOISE vs. LOAD CURRENT
MAX8877-15
OUTPUT NOISE SPECTRAL DENSITY (V/Hz)
10 CBP = 0.01F ILOAD = 10mA
80
60 50 OUTPUT NOISE (VRMS) 40 MAX887_EUK30 30 20 COUT = 10F CBP = 0.01F f = 10Hz to 100kHz 10 100 MAX887_EUK25 MAX887_EUK50
1
COUT = 1F 0.1 COUT = 10F 0.01 0 1 10 FREQUENCY (kHz) 100 1000
1000
LOAD CURRENT (mA)
OUTPUT NOISE 10Hz TO 100kHz
MAX8877-16
REGION OF STABLE COUT ESR vs. LOAD CURRENT
MAX8877-17
100
10 COUT ESR ()
COUT = 10F
VOUT 50V/div
1 STABLE REGION 0.1
COUT = 1F
0.01 1ms/div MAX887_EUK25, COUT = 10F, ILOAD = 10mA, CBP = 0.1F 0 100 LOAD CURRENT (mA) 150
4
_______________________________________________________________________________________
Low-Noise, Low-Dropout, 150mA Linear Regulators with `2982 Pinout
____________________________Typical Operating Characteristics (continued)
(VIN = VOUT(NOMINAL) + 0.5V, CIN = 1F, COUT = 1F, CBP = 0.01F, TA = +25C, unless otherwise noted.)
LINE-TRANSIENT RESPONSE
MAX8877-18
MAX8877/MAX8878
LOAD-TRANSIENT RESPONSE
MAX8877-19
LOAD-TRANSIENT RESPONSE NEAR DROPOUT
MAX8877-20
4V 3V
VIN
3.01V 3.00V 2.99V VOUT
3.01V 3.00V 2.99V VOUT
3.001V 3.000V 2.999V VOUT
50mA ILOAD 50mA ILOAD
100s/div MAX887_EUK30, ILOAD = 50mA
10s/div MAX887_EUK30, VIN = VOUT + 0.5V, CIN = 10F, ILOAD = 0mA TO 50mA
10s/div MAX887_EUK30, VIN = VOUT + 0.1V, CIN = 10F, ILOAD = 0mA TO 50mA
MAX887_EUK25 SHUTDOWN EXIT DELAY
MAX8877-21
MAX887_EUK50 SHUTDOWN EXIT DELAY
MAX8877-22
ENTERING SHUTDOWN
MAX8877-23
2V 0V CBP = 0.01F
VSHDN
2V 0V CBP = 0.01F
VSHDN
2V 0V 5V
V SHDN
2V CBP = 0.1F
VOUT
4V
CBP = 0.1F
VOUT VOUT
1V
2V 0V 0V 5s/div MAX887_EUK50, ILOAD = 50mA 500s/div MAX8878, NO LOAD
0V 5s/div MAX887_EUK25, ILOAD = 50mA
______________________________________________________________Pin Description
PIN 1 2 3 4 5 NAME IN GND SHDN BP OUT FUNCTION Regulator Input. Supply voltage can range from 2.5V to 6.5V. Bypass with a 1F capacitor to GND (see Capacitor Selection and Regulator Stability section). Ground. This pin also functions as a heatsink. Solder to a large pad or the circuit-board ground plane to maximize power dissipation. Active-Low Shutdown Input. A logic low reduces the supply current to 10nA. On the MAX8878, a logic low also causes the output voltage to discharge to GND. Connect to IN for normal operation. Reference-Noise Bypass. Bypass with a low-leakage, 0.01F ceramic capacitor for reduced noise at the output. Regulator Output. Sources up to 150mA. Bypass with a 1F (<0.2 typical ESR) capacitor to GND.
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5
Low-Noise, Low-Dropout, 150mA Linear Regulators with `2982 Pinout MAX8877/MAX8878
_______________Detailed Description
The MAX8877/MAX8878 are low-noise, low-dropout, low-quiescent-current linear regulators designed primarily for battery-powered applications. The parts are available with preset output voltages ranging from 2.5V to 5V, in 100mV increments. These devices can supply loads up to 150mA. As illustrated in Figure 1, the MAX8877/MAX8878 consist of a 1.25V reference, error amplifier, P-channel pass transistor, and internal feedback voltage divider. The 1.25V bandgap reference is connected to the error amplifier's inverting input. The error amplifier compares this reference with the feedback voltage and amplifies the difference. If the feedback voltage is lower than the reference voltage, the pass-transistor gate is pulled lower, which allows more current to pass to the output and increases the output voltage. If the feedback voltage is too high, the pass-transistor gate is pulled up, allowing less current to pass to the output. The output voltage is fed back through an internal resistor voltage divider connected to the OUT pin. An external bypass capacitor connected to the BP pin reduces noise at the output. Additional blocks include a current limiter, reverse battery protection, thermal sensor, and shutdown logic. The MAX8878 also includes an auto-discharge function, which actively discharges the output voltage to ground when the device is placed in shutdown mode.
Output Voltage
The MAX8877/MAX8878 are supplied with factory-set output voltages from 2.5V to 5.0V, in 100mV increments. Except for the MAX887_EUK29 and the MAX887_EUK32 (which have an output voltage preset at 2.84V and 3.15V, respectively), the two-digit suffix allows the customer to choose the output voltage in 100mV increments. For example, the MAX8877EUK33 has a preset output voltage of 3.3V (see Expanded Ordering Information).
Internal P-Channel Pass Transistor
The MAX8877/MAX8878 feature a 1.1 typical P-channel MOSFET pass transistor. This provides several 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 MAX8877/MAX8878 do not suffer from these problems and consume only 100A of quiescent current whether in dropout, light-load, or heavy-load applications (see the Typical Operating Characteristics).
Current Limit
The MAX8877/MAX8878 include a current limiter, which monitors and controls the pass transistor's gate voltage, limiting the output current to 390mA. For design purposes, consider the current limit to be 160mA minimum to 500mA maximum. The output can be shorted to ground for an indefinite amount of time without damaging the part.
IN SHDN
REVERSE BATTERY PROTECTION
MAX8877 MAX8878
SHUTDOWN AND POWER-ON CONTROL
ERROR AMP
MOS DRIVER WITH ILIMIT
P
*
THERMAL SENSOR 1.25V REF
OUT N
GND BP * AUTO-DISCHARGE, MAX8878 ONLY
Figure 1. Functional Diagram
6 _______________________________________________________________________________________
Low-Noise, Low-Dropout, 150mA Linear Regulators with `2982 Pinout
Thermal-Overload Protection
Thermal-overload protection limits total power dissipation in the MAX8877/MAX8878. When the junction temperature exceeds T J = +155C, the thermal sensor signals the shutdown logic, turning off the pass transistor and allowing the IC to cool. The thermal sensor will turn 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 MAX8877/MAX8878 in the event of fault conditions. For continual operation, do not exceed the absolute maximum junction-temperature rating of TJ = +150C.
____________Applications Information
Capacitor Selection and Regulator Stability
Normally, use a 1F capacitor on the MAX8877/ MAX8878's input and a 1F to 10F capacitor on the output. Larger input capacitor values and lower ESRs provide better supply-noise rejection and line-transient response. Reduce noise and improve load-transient response, stability, and power-supply rejection by using large output capacitors. For stable operation over the full temperature range and with load currents up to 150mA, a minimum of 1F is recommended. Note that some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. With dielectrics such as Z5U and Y5V, it may be necessary to use 2.2F or more to ensure stability at temperatures below -10C. With X7R or X5R dielectrics, 1F should be sufficient at all operating temperatures. Also, for high-ESR tantalum capacitors, 2.2F or more may be needed to maintain ESR in the stable region. A graph of the Region of Stable COUT ESR vs. Load Current is shown in the Typical Operating Characteristics. Use a 0.01F bypass capacitor at BP for low output voltage noise. Increasing the capacitance will slightly decrease the output noise, but increase the start-up time. Values above 0.1F provide no performance advantage and are not recommended (see Shutdown Exit Delay graphs in the Typical Operating Characteristics).
MAX8877/MAX8878
Operating Region and Power Dissipation
The MAX8877/MAX8878'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 air flow. The power dissipation across the device is P = IOUT (VIN - VOUT). The maximum power dissipation is: PMAX = (TJ - TA) / (JB + BA) where TJ - TA is the temperature difference between the MAX8877/MAX8878 die junction and the surrounding air, JB (or JC) is the thermal resistance of the package, and BA is the thermal resistance through the printed circuit board, copper traces, and other materials to the surrounding air. The GND pin of the MAX8877/MAX8878 performs the dual function of providing an electrical connection to ground and channeling heat away. Connect the GND pin to ground using a large pad or ground plane.
PSRR and Operation from Sources Other than Batteries
The MAX8877/MAX8878 are designed to deliver low dropout voltages and low quiescent currents in batterypowered systems. Power-supply rejection is 63dB at low frequencies and rolls off above 10kHz. See the Power-Supply Rejection Ratio Frequency graph in the Typical Operating Characteristics. When operating from sources other than batteries, improved supply-noise rejection and transient response can be achieved by increasing the values of the input and output bypass capacitors, and through passive filtering techniques. The Typical Operating Characteristics show the MAX8877/MAX8878's line- and loadtransient responses.
Reverse Battery Protection
The MAX8877/MAX8878 have a unique protection scheme that limits the reverse supply current to 1mA when either VIN or V SHDN falls below ground. Their circuitry monitors the polarity of these two pins and disconnects the internal circuitry and parasitic diodes when the battery is reversed. This feature prevents device damage.
Noise Reduction
An external 0.01F bypass capacitor at BP, in conjunction with an internal 200k resistor, creates a 80Hz lowpass filter for noise reduction. The MAX8877/MAX8878 exhibit 30VRMS of output voltage noise with C BP = 0.01F and COUT = 10F. This is negligible in most applications. Start-up time is minimized by a power-on circuit that pre-charges the bypass capacitor. The Typical Operating Characteristics section shows graphs of Noise vs. BP Capacitance, Noise vs. Load Current, and Output Noise Spectral Density.
Load-Transient Considerations
The MAX8877/MAX8878 load-transient response graphs (see Typical Operating Characteristics) show two components of the output response: a DC shift from the output impedance due to the load current change, and the transient response. Typical transient
_______________________________________________________________________________________
7
Low-Noise, Low-Dropout, 150mA Linear Regulators with `2982 Pinout MAX8877/MAX8878
for a step change in the load current from 0mA to 50mA is 12mV. Increasing the output capacitor's value and decreasing the ESR attenuates the overshoot. ply voltage. In battery-powered systems, this will determine the useful end-of-life battery voltage. Because the MAX8877/MAX8878 use a P-channel MOSFET pass transistor, their dropout voltage is a function of drain-tosource on-resistance (RDS(ON)) multiplied by the load current (see Typical Operating Characteristics).
Input-Output (Dropout) Voltage
A regulator's minimum input-output voltage differential (or dropout voltage) determines the lowest usable sup-
_ __________________Chip Information
TRANSISTOR COUNT: 247 SUBSTRATE CONNECTED TO GND
____________________________________________Expanded Ordering Information
OUTPUT VOLTAGE (xy) CODE MAX887_EUK25-T MAX887_EUK28-T MAX887_EUK29-T MAX887_EUK30-T MAX887_EUK32-T MAX887_EUK33-T MAX887_EUK36-T MAX887_EUK50-T Other xy*** PRESET OUTPUT VOLTAGE (V) 2.50 2.80 2.84 3.00 3.15 3.30 3.60 5.00 x.y0 SOT TOP MARK MAX8877 ACBM ACBN ACBO ACBP ACBQ ACBR ACDB ACBS -- MAX8878 ACBT ACBU ACBV ACBW ACBX ACBY ACDC ACBZ --
***Other xy between 2.5V and 5.0V are available in 100mV increments. Contact factory for other versions. Minimum order quantity is 25,000 units.
________________________________________________________Package Information
SOT5L.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) 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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