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19-0466; Rev 2; 11/98
Low-Dropout, 120mA Linear Regulators
_______________General Description
The MAX8863T/S/R and MAX8864T/S/R low-dropout linear regulators operate from a +2.5V to +6.5V input range and deliver up to 120mA. A PMOS pass transistor allows the low, 80A supply current to remain independent of load, making these devices ideal for battery-operated portable equipment such as cellular phones, cordless phones, and modems. The devices feature Dual ModeTM operation: their output voltage is preset (at 3.15V for the T versions, 2.84V for the S versions, or 2.80V for the R versions) or can be adjusted with an external resistor divider. Other features include low-power shutdown, short-circuit protection, thermal shutdown protection, and reverse battery protection. The MAX8864 also includes an auto-discharge function, which actively discharges the output voltage to ground when the device is placed in shutdown mode. Both devices come in a miniature 5-pin SOT23-5 package.
____________________________Features
o Low Cost o Low, 55mV Dropout Voltage @ 50mA IOUT o Low, 68A No-Load Supply Current Low, 80A Operating Supply Current (even in dropout) o Low, 350VRMS Output Noise o Miniature External Components o Thermal Overload Protection o Output Current Limit o Reverse Battery Protection o Dual ModeTM Operation: Fixed or Adjustable (1.25V to 6.5V) Output o Low-Power Shutdown
MAX8863T/S/R, MAX8864T/S/R
______________Ordering Information ________________________Applications
Cordless Telephones PCS Telephones Cellular Telephones PCMCIA Cards Modems Hand-Held Instruments Palmtop Computers Electronic Planners
PART TEMP. RANGE PINPACKAGE 5 SOT23-5 5 SOT23-5 5 SOT23-5 5 SOT23-5 5 SOT23-5 5 SOT23-5 SOT TOP MARK* AABE AABF AABV AABG AABH AABW
MAX8863TEUK-T -40C to +85C MAX8863SEUK-T -40C to +85C MAX8863REUK-T -40C to +85C MAX8864TEUK-T -40C to +85C MAX8864SEUK-T -40C to +85C MAX8864REUK-T -40C to +85C
*Alternate marking information: CY_ _ = MAX8863T, CZ_ _ = MAX8863S, DA_ _ = MAX8864T, DB_ _ = MAX8864S
__________Typical Operating Circuit
__________________Pin Configuration
TOP VIEW
SHDN 1 5 SET
IN
OUT
OUTPUT VOLTAGE COUT 1F GND 2
BATTERY
CIN 1F
MAX8863 MAX8864
SHDN GND SET
MAX8863 MAX8864
OUT
IN 3
4
SOT23-5
Dual Mode is a trademark of Maxim Integrated Products.
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.
Low-Dropout, 120mA Linear Regulators MAX8863T/S/R, MAX8864T/S/R
ABSOLUTE MAXIMUM RATINGS
VIN to GND ..................................................................-7V to +7V Output Short-Circuit Duration ............................................Infinite SET to GND ..............................................................-0.3V to +7V SHDN to GND..............................................................-7V to +7V SHDN to IN ...............................................................-7V to +0.3V OUT 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 JA ..............................................................................140C/Watt 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
(VIN = +3.6V, GND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER Input Voltage (Note 2) Output Voltage Adjustable Output Voltage Range (Note 3) Maximum Output Current Current Limit (Note 4) Ground Pin Current Dropout Voltage (Note 5) Line Regulation Load Regulation Output Voltage Noise SHUTDOWN SHDN Input Threshold SHDN Input Bias Current Shutdown Supply Current Shutdown Discharge Resistance (MAX8864) VIH VIL ISHDN IQSHDN V SHDN = VIN VOUT = 0V TA = +25C TA = TMAX TA = +25C TA = TMAX 0 0.05 0.0001 0.02 300 1 2.0 0.4 100 V nA A VLNR VLDR ILIM IQ SET = GND IOUT = 1mA IOUT = 50mA VIN = 2.5V to 6.5V, SET tied to OUT, IOUT = 1mA IOUT = 0mA to 50mA 10Hz to 1MHz SET = GND SET tied to OUT COUT = 1F COUT = 100F -0.15 ILOAD = 0mA ILOAD = 50mA SYMBOL VIN VOUT 0mA IOUT 50mA, SET = GND MAX886_T MAX886_S MAX886_R VOUT CONDITIONS MIN 2.5 3.05 2.75 2.70 VSET 120 280 68 80 1.1 55 0 0.011 0.006 350 220 120 0.15 0.040 150 3.15 2.84 2.80 TYP MAX 6.5 3.25 2.93 2.88 6.5 V mA mA A mV %/V %/mA VRMS V UNITS V
2
_______________________________________________________________________________________
Low-Dropout, 120mA Linear Regulators
ELECTRICAL CHARACTERISTICS (continued)
(VIN = +3.6V, GND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER SET INPUT SET Reference Voltage (Note 3) SET Input Leakage Current (Note 3) THERMAL PROTECTION Thermal Shutdown Temperature Thermal Shutdown Hysteresis TSHDN TSHDN 170 20 C C VSET ISET VIN = 2.5V to 6.5V, IOUT = 1mA VSET = 1.3V TA = +25C TA = TMIN to TMAX TA = +25C TA = TMAX 1.225 1.215 1.25 1.25 0.015 0.5 1.275 1.285 2.5 V nA SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX8863T/S/R, MAX8864T/S/R
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: Guaranteed by line regulation test. Note 3: Adjustable mode only. Note 4: Not tested. For design purposes, the current limit should be considered 120mA minimum to 420mA maximum. Note 5: The dropout voltage is defined as (VIN - VOUT) when VOUT is 100mV below the value of VOUT for VIN = VOUT +2V.
__________________________________________Typical Operating Characteristics
(VIN = +3.6V, CIN = 1F, COUT = 1F, TA = +25C, MAX886_T, unless otherwise noted.)
OUTPUT VOLTAGE vs. LOAD CURRENT
MAX8863/4-01
SUPPLY CURRENT vs. LOAD CURRENT
MAX8863/4-02
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX8863/4-03
3.30 3.25 OUTPUT VOLTAGE (V) 3.20 3.15 3.10 3.05 3.00 0
100 95 SUPPLY CURRENT (A) 90
3.5 3.0 OUTPUT VOLTAGE (V) 2.5 2.0 NO LOAD 1.5 1.0 0.5 0
85 80 75 70 65 60 55 50
10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA)
0
10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA)
0
1
2
3
4
5
6
INPUT VOLTAGE (V)
_______________________________________________________________________________________
3
Low-Dropout, 120mA Linear Regulators MAX8863T/S/R, MAX8864T/S/R
____________________________Typical Operating Characteristics (continued)
(VIN = +3.6V, CIN = 1F, COUT = 1F, MAX886_T, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. INPUT VOLTAGE
MAX8863/4-04
OUTPUT VOLTAGE vs. TEMPERATURE
MAX8863/4-05
SUPPLY CURRENT vs. TEMPERATURE
90 SUPPLY CURRENT (A) 80 70 60 50 40 30 20 10 ILOAD = 50mA
MAX8863/4-06
90 80 SUPPLY CURRENT (A) 70 60 50 40 30 20 ILOAD = 0mA ILOAD = 50mA
3.30 ILOAD = 50mA 3.25 OUTPUT VOLTAGE (V) 3.20 3.15 3.10 3.05
100
10 0 0 1 2 3 4 5 6 INPUT VOLTAGE (V) 3.00 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX8863/4-07
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
OUTPUT SPECTRAL NOISE DENSITY (V/Hz) VOUT = 3.15V RL = 100
MAX8863/4-08
OUTPUT SPECTRAL NOISE DENSITY vs. FREQUENCY
RL = 50 COUT = 1F 1
MAX8863/64-8A
140 120 DROPOUT VOLTAGE (mV) 100 80 60 40 20 0 0 TA = -40C TA = +85C
70 60 50 PSRR (dB) 40 30 20 10 0
10
TA = +25C
COUT = 10F
COUT = 100F 0.10
COUT = 1F
0.01 0.1 1 10 FREQUENCY (kHz) 100 1000
10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA)
0.01
0.1
100 1 10 FREQUENCY (kHz)
1000
REGION OF STABLE COUT ESR vs. LOAD CURRENT
COUT = 1F 100 COUT ESR () INTERNAL FEEDBACK
MAX8863/64-8B
OUTPUT NOISE DC TO 1MHz
1000
10
VOUT
EXTERNAL FEEDBACK STABLE REGION
1
0.1
0.01 0 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA)
1ms/div ILOAD = 50mA, VOUT IS AC COUPLED
4
_______________________________________________________________________________________
Low-Dropout, 120mA Linear Regulators
____________________________Typical Operating Characteristics (continued)
(VIN = +3.6V, CIN = 1F, COUT = 1F, MAX886_T, TA = +25C, unless otherwise noted.) LINE TRANSIENT
3.16V VOUT 3.15V 3.14V 3.16V VOUT 3.15V 3.14V
MAX8863T/S/R, MAX8864T/S/R
LOAD TRANSIENT
VIN
4.6V 3.6V 50s/div ILOAD = 50mA, VOUT IS AC COUPLED
ILOAD
10s/div ILOAD = 0mA to 50mA, CIN = 10F, VOUT IS AC COUPLED
LOAD TRANSIENT
3.16V VOUT 3.15V 3.14V 3.16V VOUT 3.15V 3.14V
LOAD TRANSIENT
ILOAD
50mA ILOAD 0mA 10s/div VIN = VOUT + 0.2V, ILOAD = 0mA to 50mA, CIN = 10F, VOUT IS AC COUPLED 10s/div VIN = VOUT + 0.1V, ILOAD = 0mA to 50mA, CIN = 10F, VOUT IS AC COUPLED
MAX8864 SHUTDOWN (NO LOAD)
4V VOUT 2V 0V VOUT 4V 2V 0V
MAX8864 SHUTDOWN
VSHDN
2V VSHDN 0V
2V 0V
500s/div NO LOAD ILOAD = 50mA
200s/div
_______________________________________________________________________________________
5
Low-Dropout, 120mA Linear Regulators MAX8863T/S/R, MAX8864T/S/R
______________________________________________________________Pin Description
PIN 1 2 3 4 NAME SHDN GND IN OUT FUNCTION Active-Low Shutdown Input. A logic low reduces the supply current to 0.1nA. On the MAX8864, a logic low also causes the output voltage to discharge to GND. Connect to IN for normal operation. Ground. This pin also functions as a heatsink. Solder to large pads or the circuit board ground plane to maximize thermal dissipation. Regulator Input. Supply voltage can range from +2.5V to +6.5V. Bypass with 1F to GND (see Capacitor Selection and Regulator Stability). Regulator Output. Fixed or adjustable from 1.25V to +6.5V. Sources up to 120mA. Bypass with a 1F, <0.2 typical ESR capacitor to GND. Feedback Input for Setting the Output Voltage. Connect to GND to set the output voltage to the preset 2.80V (MAX886_R), 2.84V (MAX886_S), or 3.15V (MAX886_T). Connect to an external resistor divider for adjustable-output operation.
5
SET
_______________Detailed Description
The MAX8863/MAX8864 are low-dropout, low-quiescentcurrent linear regulators designed primarily for batterypowered applications. They supply an adjustable 1.25V to 6.5V output or a preselected 2.80V (MAX886_R), 2.84V (MAX886_S), or 3.15V (MAX886_T) output for load currents up to 120mA. As illustrated in Figure 1, these devices consist of a 1.25V reference, error amplifier, MOSFET driver, Pchannel pass transistor, Dual ModeTM comparator, 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 selected feedback voltage and amplifies the difference. The MOSFET driver reads the error signal
and applies the appropriate drive to the P-channel pass transistor. If the feedback voltage is lower than the reference, the pass-transistor gate is pulled lower, allowing more current to pass and increasing 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 either an internal resistor voltage divider connected to the OUT pin, or an external resistor network connected to the SET pin. The Dual Mode comparator examines the SET voltage and selects the feedback path. If SET is below 60mV, internal feedback is used and the output voltage is regulated to the preset output voltage. Additional blocks include a current limiter, reverse battery protection, thermal sensor, and shutdown logic.
IN SHDN
REVERSE BATTERY PROTECTION
ERROR AMP
MOS DRIVER WITH ILIMIT N
P
MAX8863 MAX8864
SHUTDOWN LOGIC
OUT SET
*
THERMAL SENSOR 1.25V REF DUAL-MODE COMPARATOR 60mV
GND * AUTO-DISCHARGE, MAX8864 ONLY
Figure 1. Functional Diagram
6 _______________________________________________________________________________________
Low-Dropout, 120mA Linear Regulators
Choose R2 = 100k to optimize power consumption, accuracy, and high-frequency power-supply rejection. The total current through the external resistive feedback and load resistors should not be less than 10A. Since the VSET tolerance is typically less than 25mV, the output can be set using fixed resistors instead of trim pots. Connect a 10pF to 25pF capacitor across R1 to compensate for layout-induced parasitic capacitances. In preset voltage mode, impedances between SET and ground should be less than 100k. Otherwise, spurious conditions could cause the voltage at SET to exceed the 60mV Dual Mode threshold.
MAX8863T/S/R, MAX8864T/S/R
IN
OUT
OUTPUT VOLTAGE
MAX8863 MAX8864
CIN BATTERY 1F SHDN GND SET
R1 20pF COUT 1F RL
R2
Shutdown
Figure 2. Adjustable Output Using External Feedback Resistors
Internal P-Channel Pass Transistor
The MAX8863/MAX8864 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 current, which reduces quiescent current considerably. PNPbased regulators waste considerable amounts of current in dropout when the pass transistor saturates. They also use high base-drive currents under large loads. The MAX8863/MAX8864 do not suffer from these problems, and consume only 80A of quiescent current, whether in dropout, light load, or heavy load applications (see Typical Operating Characteristics).
A low input on the SHDN pin shuts down the MAX8863/MAX8864. In shutdown mode, the pass transistor, control circuit, reference, and all biases are turned off, reducing the supply current to typically 0.1nA. Connect SHDN to IN for normal operation. The MAX8864 output voltage is actively discharged to ground when the part is placed in shutdown (see Typical Operating Characteristics).
Current Limit
The MAX8863/MAX8864 include a current limiter that monitors and controls the pass transistor's gate voltage, estimating the output current and limiting it to about 280mA. For design purposes, the current limit should be considered 120mA (min) to 420mA (max). The output can be shorted to ground for an indefinite time period without damaging the part.
Thermal Overload Protection
Thermal overload protection limits total power dissipation in the MAX8863/MAX8864. When the junction temperature exceeds T J = +170C, the thermal sensor sends a signal to 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 typically cools by 20C, resulting in a pulsed output during continuous thermal overload conditions. Thermal overload protection is designed to protect the MAX8863/MAX8864 in the event of fault conditions. Stressing the device with high load currents and high input-output differential voltages (which result in die temperatures above +125C) may cause a momentary overshoot (2% to 8% for 200ms) when the load is completely removed. This can be remedied by raising the minimum load current from 0A (+125C) to 100A (+150C). For continuous operation, do not exceed the absolute maximum junction temperature rating of TJ = +150C.
Output Voltage Selection
The MAX8863/MAX8864 feature Dual Mode operation: they operate in either a preset voltage mode or an adjustable mode. In preset voltage mode, internal, trimmed feedback resistors set the MAX886_R output to 2.80V, the MAX886_S output to 2.84V, and the MAX886_T output to 3.15V. Select this mode by connecting SET to ground. In adjustable mode, select an output between 1.25V and 6.5V using two external resistors connected as a voltage divider to SET (Figure 2). The output voltage is set by the following equation: VOUT = VSET (1 + R1 / R2) where VSET = 1.25V. To simplify resistor selection: V R1 = R2 OUT VSET - 1
_______________________________________________________________________________________
7
Low-Dropout, 120mA Linear Regulators MAX8863T/S/R, MAX8864T/S/R
Operating Region and Power Dissipation
Maximum power dissipation of the MAX8863/MAX8864 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 resulting maximum power dissipation is: PMAX = (TJ - TA) / JA where (TJ - TA) is the temperature difference between the MAX8863/MAX8864 die junction and the surrounding air, and JA is the thermal resistance of the chosen package to the surrounding air. The GND pin of the MAX8863/MAX8864 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.
Noise
The MAX8863/MAX8864 exhibit 350VRMS noise during normal operation. When using the MAX8863/MAX8864 in applications that include analog-to-digital converters of greater than 12 bits, consider the ADC's power-supply rejection specifications (see the Output Noise DC to 1MHz photo in the Typical Operating Characteristics).
Power-Supply Rejection and Operation from Sources Other than Batteries
The MAX8863/MAX8864 are designed to deliver low dropout voltages and low quiescent currents in batterypowered systems. Power-supply rejection is 62dB at low frequencies and rolls off above 300Hz. As the frequency increases above 20kHz, the output capacitor is the major contributor to the rejection of power-supply noise (see the Power-Supply Rejection Ratio vs. Ripple Frequency graph in the Typical Operating Characteristics). When operating from sources other than batteries, improve supply-noise rejection and transient response by increasing the values of the input and output capacitors, and using passive filtering techniques (see the supply and load-transient responses in the Typical Operating Characteristics).
Reverse Battery Protection
The MAX8863/MAX8864 have a unique protection scheme that limits the reverse supply current to less than 1mA when either VIN or V SHDN falls below ground. The circuitry monitors the polarity of these two pins, disconnecting the internal circuitry and parasitic diodes when the battery is reversed. This feature prevents the device from overheating and damaging the battery.
VIN > 5.5V Minimum Load Current
When operating the MAX8863/MAX8864 with an input voltage above 5.5V, a minimum load current of 20A is required to maintain regulation in preset voltage mode. When setting the output with external resistors, the minimum current through the external feedback resistors and load must be 30A.
Load Transient Considerations
The MAX8863/MAX8864 load-transient response graphs (see Typical Operating Characteristics) show two components of the output response: a DC shift of the output voltage due to the different load currents, and the transient response. Typical overshoot for step changes in the load current from 0mA to 50mA is 12mV. Increasing the output capacitor's value and decreasing its ESR attenuates transient spikes.
__________Applications Information
Capacitor Selection and Regulator Stability
Normally, use a 1F capacitor on the input and a 1F capacitor on the output of the MAX8863/MAX8864. Larger input capacitor values and lower ESR provide better supply-noise rejection and transient response. 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. Improve load-transient response, stability, and power-supply rejection by using large output capacitors. For stable operation over the full temperature range, with load currents up to 120mA, a minimum of 1F is recommended.
Input-Output (Dropout) Voltage
A regulator's minimum input-output voltage differential (or dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this will determine the useful end-of-life battery voltage. Because the MAX8863/MAX8864 use a P-channel MOSFET pass transistor, their dropout voltage is a function of RDS(ON) multiplied by the load current (see Electrical Characteristics).
___________________Chip Information
TRANSISTOR COUNT: 148
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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