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_______________General Description
The MAX8865 and MAX8866 dual, low-dropout linear
regulators operate from a +2.5V to +5.5V input range
and deliver up to 100mA. At 200mA total load, the
PMOS pass transistors keep the supply current at
145µA, making these devices ideal for battery-operated
portable equipment such as cellular phones, cordless
phones, and modems.
The devices feature Dual Mode™ operation: their out-
put voltages are 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 external resistor dividers. Other
features include independent low-power shutdown,
short-circuit protection, thermal shutdown protection,
and reverse battery protection. The MAX8866 also
includes an auto-discharge function, which actively dis-
charges the selected output voltage to ground when
the device is placed in shutdown mode. Both devices
come in a miniature 8-pin µMAX package.
________________________Applications
Cordless Telephones Modems
PCS Telephones Hand-Held Instruments
Cellular Telephones Palmtop Computers
PCMCIA Cards Electronic Planners
____________________________Features
♦Low Cost
♦Low, 55mV Dropout Voltage @ 50mA IOUT
♦Low, 105µA No-Load Supply Current
♦Low, 145µA Operating Supply Current (even in
dropout)
♦Low, 350µVRMS Output Noise
♦Independent, Low-Current Shutdown Control
♦Thermal Overload Protection
♦Output Current Limit
♦Reverse Battery Protection
♦Dual Mode Operation: Fixed or Adjustable (1.25V
to 5.5V) Outputs
MAX8865T/S/R, MAX8866T/S/R
Dual, Low-Dropout, 100mA Linear Regulators
________________________________________________________________
Maxim Integrated Products
1
TOP VIEW
1
2
3
4
8
7
6
5
SET1
SHDN1
SHDN2
SET2
OUT2
GND
IN
OUT1
MAX8865
MAX8866
µMAX
__________________Pin Configuration
MAX8865
MAX8866
OUT1
OUT2
GND SET2SET1
IN
SHDN1 COUT2
1µF
COUT1
1µF
CIN
2µF
BATTERY
OUTPUT
VOLTAGE 2
OUTPUT
VOLTAGE 1
SHDN2
SHDN2
__________Typical Operating Circuit
19-0485; Rev 0; 4/96
PART
MAX8865TEUA
MAX8865SEUA
MAX8866TEUA -40°C to +85°C
-40°C to +85°C
-40°C to +85°C
TEMP. RANGE PIN-
PACKAGE
8 µMAX
8 µMAX
8 µMAX
______________Ordering Information
PRESET
VOUT (V)
3.15
2.84
3.15
MAX8866SEUA -40°C to +85°C 8 µMAX 2.84
Dual Mode is a trademark of Maxim Integrated Products.
MAX8865REUA -40°C to +85°C 8 µMAX 2.80
MAX8866REUA -40°C to +85°C 8 µMAX 2.80
MAX8865T/S/R, MAX8866T/S/R
Dual, Low-Dropout, 100mA Linear Regulators
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN = +3.6V, GND = 0V, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
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.
VIN to GND ..................................................................-6V to +6V
Output Short-Circuit Duration ............................................Infinite
SET_ to GND ............................................................-0.3V to +6V
SHDN_ _ to GND............................................................-6V to +6V
SHDN_ _ to IN .............................................................-6V to +0.3V
OUT_ to GND...............................................-0.3V to (VIN + 0.3V)
Continuous Power Dissipation (TA= +70°C)
µMAX (derate 4.1mW/°C above +70°C)......................330mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Thermal Resistance (θJA)...............................................244°C/W
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10sec).............................+300°C
ms1
Shutdown to Output
Discharge Delay (MAX8866)
0 1000ISHDN_ _
SHDN Input Bias Current
V
0.4VIL
SHDN Input Threshold 2.0VIH
µVRMS
220
Output Voltage Noise 350
0.012 0.03
%/V-0.10 0 0.10∆VLNR
Line Regulation
mV
55 120
Dropout Voltage (Note 4)
V2.5 5.5VIN
Input Voltage (Note 1)
1.1
3.08 3.15 3.24
VVSET_ 5.5VOUT_
Adjustable Output Voltage
Range (Note 2) mA100Maximum Output Current
UNITSMIN TYP MAXSYMBOLPARAMETER
COUT = 1µF, no load
VSHDN_ _ = VIN
VIN = 2.5V to 5.5V, SET_ tied to OUT_,
IOUT_ = 1mA
IOUT = 50mA
CONDITIONS
mA220ILIM
Current Limit (Note 3)
MAX886_T
10Hz to 1MHz
IOUT = 1mA
MAX886_S 2.77 2.84 2.91
105 270
0.16 3000 nAIQ SHDN
Shutdown Supply Current VOUT_ = 0V nA
1.222 1.25 1.276VSET_ VIN = 2.5V to 5.5V, IOUT_ = 1mASET Reference Voltage (Note 2) V
0.015 50ISET_ VSET_ = 1.3V
SET Input Leakage Current
(Note 2) nA
170TSHDN
Thermal Shutdown Temperature °C
20∆TSHDN
Thermal Shutdown Hysteresis °C
145
SET_ = GND µAIQ
Ground Pin Current
IOUT_ = 0mA to 50mA %/mA
0.006
∆VLDR
Load Regulation
IOUT_ = 50mA
IOUT_ = 0mA
MAX886_R V
2.73 2.80 2.87
VOUT_
Output Voltage 0mA ≤IOUT ≤50mA,
SET_ = GND
SHUTDOWN
THERMAL PROTECTION
SET INPUT
SET_ = GND
SET_ tied to OUT_
COUT = 1µF
COUT = 100µF
MAX8865T/S/R, MAX8866T/S/R
Dual, Low-Dropout, 100mA Linear Regulators
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS
(VIN = +3.6V, GND = 0V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 5)
Note 1: Guaranteed by line regulation test.
Note 2: Adjustable mode only.
Note 3: Not tested. For design purposes, the current limit should be considered 120mA minimum to 320mA maximum.
Note 4: The dropout voltage is defined as (VIN_ - VOUT_) when VOUT_ is 100mV below the value of VOUT_ for VIN_ = VOUT_ +2V.
Note 5: Specifications to -40°C are guaranteed by design and not production tested.
MAX886_S 2.74 2.84 2.93
1.207 1.25 1.288
105 270
nA
MAX886_T
0.16 3000
IOUT = 1mA
nAIQ SHDN
mA
Shutdown Supply Current
220
VSET_
VOUT_ = 0V
ILIM
ms1
Shutdown to Output
Discharge Delay (MAX8866)
VIN = 2.5V to 5.5V, IOUT_ = 1mASET Reference Voltage (Note 2)
0 1000
V
0.015 50
20
ISHDN_ _
SHDN Input Bias Current
µVRMS
220
Output Voltage Noise
∆TSHDN
350
ISET_ VSET_ = 1.3V
SET Input Leakage Current
(Note 2)
Thermal Shutdown Hysteresis °C
nA
0.012 0.03
%/V-0.11 0 0.11∆VLNR
Line Regulation
170TSHDN
mV
55 120
Dropout Voltage (Note 4)
Thermal Shutdown Temperature °C
V2.5 5.5VIN
Input Voltage (Note 1)
1.1
µA
3.05 3.15 3.26
VVSET_ 5.5VOUT_
Adjustable Output Voltage
Range (Note 2)
mA80Maximum Output Current
UNITSMIN TYP MAXSYMBOLPARAMETER
COUT = 1µF
VSHDN_ _ = VIN
10Hz to 1MHz
VIN = 2.5V to 5.5V,
SET_ tied to OUT_, IOUT_ = 1mA
IOUT = 50mA
CONDITIONS
Current Limit (Note 3)
145
SET_ = GNDIQ
Ground Pin Current
%/mA
0.006
∆VLDR
Load Regulation
IOUT_ = 50mA
IOUT_ = 0mA
IOUT_ = 0mA to 50mA SET_ = GND
SET_ tied to OUT_
V
0.4VIL
SHDN Input Threshold 2.0VIH
COUT = 1µF
COUT = 100µF
MAX886_R V
2.70 2.80 2.89
VOUT_
Output Voltage 0mA ≤IOUT ≤50mA,
SET_ = GND
SHUTDOWN
SET INPUT
THERMAL PROTECTION
MAX8865T/S/R, MAX8866T/S/R
Dual, Low-Dropout, 100mA Linear Regulators
4 _______________________________________________________________________________________
__________________________________________Typical Operating Characteristics
(VIN = +3.6V, CIN = 2µF, COUT = 1µF, SHDN2 = GND, MAX886_S, TA= +25°C, unless otherwise noted.)
3.00
2.70 0203010 60 70 100
OUTPUT VOLTAGE
vs. LOAD CURRENT
2.75
2.95
2.90
MAX8865/66-01
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
40 50 80 90
2.85
2.80
VOUT1
180
02010 60 70 100
SUPPLY CURRENT
vs. LOAD CURRENT
140
160
120
MAX8865/66-02
LOAD CURRENT (mA)
SUPPLY CURRENT (µA)
30 40 50 80 90
100
60
80
SHDN2 = VIN, ILOAD2 = 50mA
SHDN2 = GND
3.5
001 4 6
OUTPUT VOLTAGE
vs. INPUT VOLTAGE
1.0
0.5
3.0
2.5
MAX8865/66-03
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
23 5
2.0
1.5
VOUT1
NO LOAD
100
001 4 6
SUPPLY CURRENT
vs. INPUT VOLTAGE
30
20
10
80
90
70
MAX8865/66-04
INPUT VOLTAGE (V)
SUPPLY CURRENT (µA)
23 5
60
40
50
ILOAD1 = 50mA
ILOAD1 = 0mA
ONE REGULATOR ENABLED, NO LOAD
180
60 -40 -20 40 80
SUPPLY CURRENT
vs. TEMPERATURE
100
80
160
140
MAX8865/66-07
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
020 60
120
SHDN2 = VIN
ILOAD1 = ILOAD2 = 50mA
SHDN2 = GND
ILOAD1 = 50mA
200
001 4 6
TOTAL SUPPLY CURRENT
vs. INPUT VOLTAGE
60
40
20
160
180
140
MAX8865/66-05
INPUT VOLTAGE (V)
SUPPLY CURRENT (µA)
23 5
120
80
100
ILOAD1 = ILOAD2 = 50mA
ILOAD1 = ILOAD2 = 0mA
SHDN1 = SHDN2 = VIN 3.0
2.7 -40 -20 40 80
OUTPUT VOLTAGE
vs. TEMPERATURE
2.8
MAX8865/66-06
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
020 60
2.9
0
60
40
20
80
100
120
140
0 20 60 100
DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX8865/66-08
LOAD CURRENT (mA)
DROPOUT VOLTAGE (mV)
40 8010 30 7050 90
TA = +85°C
TA = +25°C
TA = -40°C
110
MAX8865/66-09
FREQUENCY (kHz)
PSRR (dB)
80
70
60
50
40
30
10
20
0100 1000
0.100.01
VOUT = 2.84V
RL = 55Ω
COUT = 10µF
COUT = 1µF
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX8865T/S/R, MAX8866T/S/R
Dual, Low-Dropout, 100mA Linear Regulators
_______________________________________________________________________________________
5
10
0.01 0.1 10 1001 1000
OUTPUT SPECTRAL NOISE DENSITY
vs. FREQUENCY
0.1
MAX8865/66-10
FREQUENCY (kHz)
OUTPUT SPECTRAL NOISE DENSITY (µV/Hz)
1
RL = 55Ω
COUT = 1µF
COUT = 100µF
1000
0.01 0506070809010 20 30 40 100
REGION OF STABLE COUT ESR
vs. LOAD CURRENT
0.1
MAX8865/66-11
LOAD CURRENT (mA)
COUT ESR (Ω)
1
10
100
INTERNAL FEEDBACK
STABLE REGION
COUT = 1µF
EXTERNAL FEEDBACK
ILOAD = 50mA, VOUT IS AC COUPLED
LINE-TRANSIENT RESPONSE
4.6V
3.6V
2.84V
2.82V
2.83V
50µs/div
VIN
VOUT
ILOAD = 50mA, VOUT IS AC COUPLED
OUTPUT NOISE DC TO 1MHz
VOUT
1ms/div
VIN = 3.60V, ILOAD = 0mA to 50mA, CIN = 10µF, VOUT IS AC COUPLED
LOAD-TRANSIENT RESPONSE
ILOAD
10µs/div
VOUT
50mA
0mA
2.85V
2.84V
2.83V
____________________________Typical Operating Characteristics (continued)
(VIN = +3.6V, CIN = 2µF, COUT = 1µF, SHDN2 = GND, MAX886_S, TA= +25°C, unless otherwise noted.)
MAX8865T/S/R, MAX8866T/S/R
Dual, Low-Dropout, 100mA Linear Regulators
6 _______________________________________________________________________________________
____________________________Typical Operating Characteristics (continued)
(VIN = +3.6V, CIN = 2µF, COUT = 1µF, SHDN2 = GND, MAX886_S, TA= +25°C, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE
10µs/div
VIN = VOUT + 0.2V, ILOAD = 0mA to 50mA, CIN = 10µF,
VOUT IS AC COUPLED
VOUT
ILOAD 50mA
0mA
2.85V
2.84V
2.83V
LOAD-TRANSIENT RESPONSE
10µs/div
VIN = VOUT + 0.1V, ILOAD = 0mA to 50mA, CIN = 10µF,
VOUT IS AC COUPLED
VOUT
ILOAD 50mA
0mA
2.85V
2.84V
2.83V
NO LOAD
MAX8866 SHUTDOWN (NO LOAD)
VOUT
2V
0V
4V
2V
0V
VSHDN
500µs/div
CIN = 10µF, IOUT1 = 100mA, SHDN2 = VIN
CROSSTALK DUE TO LOAD TRANSIENT
VOUT2
AC COUPLED
(50mV/div)
100mA
0mA
ILOAD2
VOUT1
AC COUPLED
(10mV/div)
20µs/div
ILOAD = 50mA
MAX8866 SHUTDOWN (50mA LOAD)
500µs/div
VOUT
2V
0V
4V
2V
0V
VSHDN
MAX8865T/S/R, MAX8866T/S/R
Dual, Low-Dropout, 100mA Linear Regulators
_______________________________________________________________________________________ 7
_______________Detailed Description
The MAX8865/MAX8866 are dual, low-dropout, low-qui-
escent-current linear regulators designed primarily for
battery-powered applications. They supply adjustable
1.25V to 5.5V outputs or preselected 2.80V
(MAX886_R), 2.84V (MAX886_S), or 3.15V (MAX886_T)
outputs for load currents up to 100mA. As illustrated in
Figure 1, these devices have a 1.25V reference and two
independent linear regulators. Each linear regulator
consists of an error amplifier, MOSFET driver, P-channel
pass transistor, Dual Mode™ comparator, and internal
feedback voltage divider.
The 1.25V bandgap reference is connected to the error
amplifiers’ inverting inputs. Each error amplifier com-
pares 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 inter-
nal 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 2.80V for the MAX886_R, 2.84V for the
MAX886_S, or 3.15V for the MAX886_T. Both regulators
are preset for the same voltage. The reference and the
thermal sensor are shared between the regulators.
Duplicate blocks exist for current limiters, reverse bat-
tery protection, and shutdown logic.
Internal P-Channel Pass Transistor
The MAX8865/MAX8866 feature 1.1Ωtypical P-channel
MOSFET pass transistors. This provides several advan-
tages over similar designs using PNP pass transistors,
including longer battery life.
The P-channel MOSFET requires no base-drive current,
which reduces quiescent current significantly. PNP-
based regulators waste considerable amounts of cur-
rent in dropout when the pass transistor saturates. They
also use high base-drive currents under large loads.
The MAX8865/MAX8866 do not suffer from these prob-
lems, and consume only 145µA of quiescent current,
whether in dropout, light load, or heavy load applica-
tions (see
Typical Operating Characteristics
).
Output Voltage Selection
The MAX8865/MAX8866 feature Dual Mode operation:
they operate in either a preset voltage mode or an
adjustable mode.
______________________________________________________________Pin Description
Regulator 1 Output. Fixed or adjustable from 1.25V to 5.5V. Sources up to 100mA. Bypass with a 1µF
capacitor to GND.
OUT11
PIN FUNCTIONNAME
IN2 Regulator Input. Supply voltage can range from +2.5V to +5.5V. Bypass with 2µF to GND.
3Ground. Solder to large pads or the circuit board ground plane to maximize thermal dissipation.
OUT24 Regulator 2 Output. Fixed or adjustable from 1.25V to 5.5V. Sources up to 100mA. Bypass with a 1µF
capacitor to GND.
GND
SET25 Feedback Input for Setting the Output 2 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.
SET1
6Active-Low Shutdown 2 Input. A logic low turns off regulator 2. On the MAX8866, a logic low also causes the
output voltage to discharge to GND. Connect to IN for normal operation.
SHDN1
7Active-Low Shutdown 1 Input. A logic low turns off regulator 1. On the MAX8866, a logic low also causes the
output voltage to discharge to GND. Connect to IN for normal operation.
8Feedback Input for Setting the Output 1 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.
SHDN2
MAX8865T/S/R, MAX8866T/S/R
Dual, Low-Dropout, 100mA Linear Regulators
8 _______________________________________________________________________________________
SHUTDOWN
LOGIC
ERROR
AMP
1.25V
REF
P
N
*OUT1
SET1
DUAL-MODE
COMPARATOR 60mV
IN
SHDN1
MAX8865
MAX8866
MOS DRIVER
WITH ILIMIT
THERMAL
SENSOR
REVERSE
BATTERY
PROTECTION
SHUTDOWN
LOGIC
ERROR
AMP P
N
*OUT2
SET2
DUAL-MODE
COMPARATOR 60mV
* AUTO-DISCHARGE, MAX8866 ONLY
GND
SHDN2
MOS DRIVER
WITH ILIMIT
REVERSE
BATTERY
PROTECTION
Figure 1. Functional Diagram
MAX8865T/S/R, MAX8866T/S/R
Dual, Low-Dropout, 100mA Linear Regulators
_______________________________________________________________________________________ 9
In preset voltage mode, internal, trimmed feedback
resistors set the MAX886_R outputs to 2.80V, the
MAX886_S outputs to 2.84V, and the MAX886_T out-
puts to 3.15V. Select this mode by connecting SET_ to
ground. If SET_ can’t be grounded in preset voltage
mode, limit impedances between SET_ and ground to
less than 100kΩ. Otherwise, spurious conditions could
cause the voltage at SET_ to exceed the 60mV Dual
Mode threshold.
In adjustable mode, select an output between 1.25V
and 5.5V 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:
Choose R2 = 100kΩto 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 10µA. 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.
Shutdown
A low input on a SHDN_ _ pin individually shuts down one
of the two outputs. In shutdown mode, the selected
pass transistor, control circuit, and all biases are turned
off. When both sections are turned off, the reference
and thermal shutdown are also turned off and the sup-
ply current is typically reduced to 0.16nA. Connect
SHDN_ _ to IN for normal operation. The MAX8866 output
voltages are actively discharged to ground when indi-
vidual regulators are shut down (see
Typical Operating
Characteristics
).
Current Limit
The MAX8865/MAX8866 include a current limiter for
each output section that monitors and controls the pass
transistor’s gate voltage, estimating the output current
and limiting it to about 220mA. For design purposes,
the current limit should be considered 120mA (min) to
320mA (max). The outputs can be shorted to ground for
an indefinite time period without damaging the part.
Thermal Overload Protection
Thermal overload protection limits total power dissipa-
tion in the MAX8865/MAX8866. When the junction tem-
perature exceeds TJ= +170°C, the thermal sensor
sends a signal to the shutdown logic, turning off the
pass transistors and allowing the IC to cool. The ther-
mal sensor will turn the pass transistors on again after
the IC’s junction temperature typically cools by 20°C,
resulting in a pulsed output during continuous thermal
overload conditions.
Thermal overload protection is designed to protect the
MAX8865/MAX8866 in the event of fault conditions.
Stressing the device with high load currents and high
input-output differential voltages (which result in elevat-
ed die temperatures above +125°C) 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 0µA (+125°C) to
100µA (+150°C). For continuous operation, do not
exceed the absolute maximum junction temperature
rating of TJ= +150°C.
Operating Region and Power Dissipation
Maximum power dissipation of the MAX8865/MAX8866
depends on the thermal resistance of the case and cir-
cuit 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) / θJA
where (TJ- TA) is the temperature difference between
the MAX8865/MAX8866 die junction and the surround-
ing air, and θJA is the thermal resistance of the pack-
age to the surrounding air (244°C/W).
R1 = R2 V
V
OUT
SET
_
_ −
1
MAX8865
MAX8866
OUT_
SET_
GND
IN
SHDN_ COUT
1µF
CIN
2µF
BATTERY
OUTPUT
VOLTAGE
R1 20pF
R2
RL
Figure 2. Adjustable Output Using External Feedback
Resistors
MAX8865T/S/R, MAX8866T/S/R
Dual, Low-Dropout, 100mA Linear Regulators
10 ______________________________________________________________________________________
Reverse Battery Protection
The MAX8865/MAX8866 have a unique protection
scheme that limits the reverse supply current to less
than 1mA when either VIN or VSHDN_ _ falls below
ground. The circuitry monitors the polarity of these
pins, disconnecting the internal circuitry and parasitic
diodes when the battery is reversed. This feature pre-
vents the device from overheating and damaging the
battery.
__________Applications Information
Capacitor Selection and
Regulator Stability
Normally, use two 1µF surface-mount ceramic capaci-
tors on the input and a 1µF surface-mount ceramic
capacitor on each output of the MAX8865/MAX8866.
Larger input capacitor values and lower ESR provide
better supply-noise rejection and transient response. A
higher-value input capacitor (10µF) 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 cur-
rents of 100mA, a minimum of 1µF is recommended
(see the Region of Stable COUT ESR vs. Load Current
graph in the
Typical Operating Characteristics
).
Noise
The MAX8865/MAX8866 exhibit 350µVRMS noise during
normal operation. When using the MAX8865/MAX8866
in applications that include analog-to-digital converters
of greater than 12 bits, consider the ADC’s power-sup-
ply 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 MAX8865/MAX8866 are designed to deliver low
dropout voltages and low quiescent currents in battery-
powered systems. Power-supply rejection is 60dB at low
frequencies and rolls off above 400Hz. As the frequency
increases above 100kHz, the output capacitor is the
major contributor to the rejection of power-supply noise
(see the Power-Supply Rejection Ratio vs. 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 capac-
itors, and using passive filtering techniques (see the
supply and load-transient responses in the
Typical
Operating Characteristics
).
Load-Transient Considerations
The MAX8865/MAX8866 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.
Cross-Regulation
Cross-regulation refers to the change in one output
voltage when the load changes on the other output. For
the MAX8865/MAX8866, cross-regulation for a 0mA to
50mA load change on one side results in less than 1mV
change of output voltage. If the power dissipation on
one output causes the junction temperature to exceed
125°C, ensure regulation of the other output with a mini-
mum load current of 100µA.
Input-Output (Dropout) Voltage
A regulator’s minimum input-output voltage differential (or
dropout voltage) determines the lowest usable supply volt-
age. In battery-powered systems, this will determine the
useful end-of-life battery voltage. Because the
MAX8865/MAX8866 use P-channel MOSFET pass transis-
tors, their dropout voltages are a function of RDS(ON) multi-
plied by the load currents (see
Electrical Characteristics
).
___________________Chip Information
TRANSISTOR COUNT: 259
MAX8865T/S/R, MAX8866T/S/R
Dual, Low-Dropout, 100mA Linear Regulators
______________________________________________________________________________________ 11
________________________________________________________Package Information
L
α
C
A1B
DIM
A
A1
B
C
D
E
e
H
L
α
MIN
0.036
0.004
0.010
0.005
0.116
0.116
0.188
0.016
0°
MAX
0.044
0.008
0.014
0.007
0.120
0.120
0.198
0.026
6°
MIN
0.91
0.10
0.25
0.13
2.95
2.95
4.78
0.41
0°
MAX
1.11
0.20
0.36
0.18
3.05
3.05
5.03
0.66
6°
INCHES MILLIMETERS
8-PIN µMAX
MICROMAX SMALL-OUTLINE
PACKAGE
0.650.0256
A
e
E H
D
0.101mm
0.004 in
21-0036D
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.
12
__________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
© 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
MAX8865T/S/R, MAX8866T/S/R
Dual, Low-Dropout, 100mA Linear Regulators
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.
12
__________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
© 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
