MAX8902 [MAXIM]
Low-Noise 500mA LDO Regulators in a 2mm x 2mm TDFN Package;
| 型号： | MAX8902 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Low-Noise 500mA LDO Regulators in a 2mm x 2mm TDFN Package |
| 文件： | 总9页 (文件大小：355K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
EVALUATION KIT AVAILABLE
Low-Noise 500mA LDO Regulators
in a 2mm x 2mm TDFN Package
MAX8902A/MAX8902B
General Description
Features
The MAX8902A/MAX8902B low-noise linear regulators
deliver up to 500mA of output current with only
• 1.7V to 5.5V Input Voltage Range
• 0.6V to 5.3V Output Voltage Range
16µV
of output noise in a 100kHz bandwidth. These
RMS
• 16µV
Output Noise, 10Hz to 100kHz
RMS
regulators maintain their output voltage over a wide
input range, requiring only 100mV of input-to-output
headroom at full load.
• 80µA Operating Supply Current
• 92dB PSRR at 5kHz
These LDOs maintain a low 80µA typical supply cur-
rent, independent of the load current and dropout volt-
age. The regulator control circuitry includes a
programmable soft-start circuit and short circuit,
reverse current, and thermal-overload protection. Other
features include an enable input and a power-OK out-
put (MAX8902B only).
• Guaranteed 500mA Output Current
•
1.5ꢀ Output Aꢁꢁuraꢁy Oꢂer ꢃoad, ꢃine, and
Temperature
• 100mV (max) Dropout at 500mA ꢃoad
• < 1µA Shutdown Supply Current
• 700mA Short-Cirꢁuit Proteꢁtion
The MAX8902A output voltage can be set to 1.5V, 1.8V,
2.0V, 2.5V, 3.0V, 3.1V, 3.3V, 4.6V, or 4.7V using the
SELA and SELB inputs. The MAX8902B output voltage
can be set between 0.6V and 5.3V with an external
resistor voltage-divider.
• Thermal-Oꢂerload Proteꢁtion
• Output-to-Input Reꢂerse Current Proteꢁtion
• 2mm x 2mm x 0.8mm TDFN Paꢁkage
Ordering Information
Applications
TOP
MARK
PART
FEATURES
Notebook Computers
MP3 and Portable Media Players
Wireless Headphones
Pin-selectable output
voltage
MAX8902AATA+
MAX8902AATA/V+
ABG
BRP
Pin-selectable output
voltage
GPS Portable Navigation Devices
Smartphones
MAX8902BATA+
Adjustable output voltage
Adjustable output voltage
ABH
ADL
MAX8902BATA/V+
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
Note: All devices are in an 8-pin, 2mm x 2mm TDFN package
with an exposed paddle and operate over the -40°C to +125°C
automotive temperature range.
Typical Operating Circuits
INPUT
4.7V TO 5.5V
INPUT
1.7V TO 5.5V
OUTPUT
4.6V
OUTPUT ADJUSTABLE
0.6V TO 5.3V
IN
OUT
BYP
IN
OUT
10μF
10μF
MAX8902A
MAX8902B
0.01μF
0.01μF
10μF
10μF
R1
R2
BYP
FB
ON
EN
EN
OFF
ON
LOGIC
SUPPLY
OFF
OUTS
R3
100kΩ
SELA
EP
SELB
GND
GS
POK
TO μC
GND
EP
Pin Configurations appear at end of data sheet.
19-0990; Rev 6; 1/15
ꢃow-Noise 500mA ꢃDO Regulators
in a 2mm x 2mm TDFN Paꢁkage
MAX8902A/MAX8902B
Absolute Maximum Ratings
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature Range............................-40°C to +150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
BYP, EN, IN, OUT, SELA, SELB, POK to GND, GS to GND, FB,
OUTS to GND.....................................................-0.3V to +6.0V
Output Short-Circuit Duration.....................................Continuous
Continuous Power Dissipation (T = +70°C)
A
TDFN (derate 11.9mW/°C above +70°C)...................953.5mW
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
(V = V = 5V, OUTS = OUT, circuit of Figure 2 (MAX8902A) and Figure 3 (MAX8902B), T = -40°C to +125°C, unless otherwise
IN
EN
A
noted.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
IN
Input Voltage Range
Input Undervoltage Lockout
OUT
1.7
1.5
5.5
1.7
V
V
V
V
rising, 100mV typical hysteresis
1.6
IN
IN
Output Voltage Range
ꢀ V
+ 0.1V
0.6
5.3
V
OUT
V
V
= 1.7V to 5.5V for V
ꢁ 1.4V,
OUT
IN
IN
Output Voltage Accuracy
Load Regulation
= (V
+ 0.3V) to 5.5V for V
> 1.4V,
> 1.4V,
-1.5
+1.5
%
%
%
OUT
OUT
I
= 0.1mA to 500mA
OUT
I
= 0.1mA to 500mA
0.02
0.04
50
OUT
V
V
= 1.7V to 5.5V for V
ꢁ 1.4V,
IN
IN
OUT
Line Regulation
= (V
+ 0.3V) to 5.5V for V
OUT
OUT
I
= 200mA
OUT
V
V
V
ꢀ 3.6V, T ꢁ +85°C
100
120
IN
IN
IN
A
Dropout Voltage
(Note 2)
I
= 500mA
mV
mA
OUT
ꢀ 3.6V, T ꢁ +125°C
= 1.7V
A
150
700
16
Current Limit
Output Noise
V
= 95% of regulation, V = V + 0.5V
OUT
600
800
OUT
IN
I
= 100mA, f = 10Hz to 100kHz, C
f = 5kHz
= 0.01μF
μV
RMS
OUT
BYP
92
Power-Supply Rejection Ratio
I
= 10mA
dB
μA
f = 10kHz
85
OUT
f = 100kHz
62
OUTS (MAX8902A only)
OUTS Input Bias Current
FB (MAX8902B only)
In regulation
0.5
7.0
FB Threshold Accuracy
V
V
= 1.7V to 5.5V, I
= 0.6V
= 0.1mA to 500mA
OUT
0.591
-0.1
0.600
0.02
0.03
0.609
+0.1
V
IN
T
A
A
= +25°C
= -40°C
FB Input Bias Current
μA
FB
T
BYP
BYP Capacitor Range
BYP Startup Current
Regulator remains stable
From BYP to GND during startup
1
100
nF
50
μA
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Maxim Integrated | 2
ꢃow-Noise 500mA ꢃDO Regulators
in a 2mm x 2mm TDFN Paꢁkage
MAX8902A/MAX8902B
Electrical Characteristics (continued)
(V = V = 5V, OUTS = OUT, circuit of Figure 2 (MAX8902A) and Figure 3 (MAX8902B), T = -40°C to +125°C, unless otherwise
IN
EN
A
noted.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
GND
T
T
T
< +85°C
< +125°C
= +25°C
80
120
160
+1
A
GND Supply Current
I
= 0mA
μA
μA
OUT
A
0.001
0.01
A
A
GND Shutdown Current
V
= 5.5V, EN = 0V
IN
T
= +85°C
SELA/SELB (MAX8902A only)
Select Input Resistance
When shorted to GND or V
When open
500
10
ꢂ
IN
1
Mꢂ
pF
Select Input Capacitance
When open
EN
EN rising
EN falling, T < +85°C
0.8
0.7
0.7
1.2
Enable Input Threshold
V
V
= 1.7V to 5.5V
= 0V to 5.5V
0.4
0.38
-1
V
IN
A
EN falling, T < +125°C
A
T
A
T
A
= +25°C
= +85°C
0.001
0.01
+1
94
Enable Input Bias Current
POK (MAX8902B only)
POK Threshold
μA
EN
OUT rising
OUT falling
88
-1
91
88
%
%
OUT voltage when POK
switches
POK Voltage, Low
I
= 1mA
10
100
+1
mV
POK
T
T
= +25°C
= +85°C
0.001
0.01
A
POK Leakage Current
THERMAL SHUTDOWN
Thermal Shutdown Threshold
POK = 5.5V, V = 0V
μA
°C
EN
A
T rising
J
165
150
T falling
J
OUTPUT TRANSIENT
Load Transient
mV/
P-P
I
= 50mA to 500mA to 50mA, t
= t
= 1μs
25
3
OUT
RISE
FALL
mV/
P-P
Line Transient
V
= 4V to 5V to 4V, t
= t = 5μs, I
FALL
= 500mA
IN
RISE
OUT
IN-to-OUT Reverse Voltage
Turnoff Threshold
IN falling below OUT
10
mV
Note 1: All devices are production tested at T = +25°C. Specifications over the operating temperature range are guaranteed by
A
design and characterization.
Note 2: The dropout voltage is defined V - V
, when V
is 5% lower than the value of V
when V = V
+ 0.5V.
OUT
IN
OUT
OUT
OUT
IN
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Maxim Integrated | 3
ꢃow-Noise 500mA ꢃDO Regulators
in a 2mm x 2mm TDFN Paꢁkage
MAX8902A/MAX8902B
Typical Operating Characteristics
(MAX8902A, V = 3.6V, V
= 2.5V, T = +25°C, unless otherwise noted.)
A
IN
OUT
QUIESCENT CURRENT
EN = HIGH, NO LOAD
LOAD REGULATION
LINE REGULATION
2.510
2.508
2.506
2.504
2.502
2.500
2.498
2.496
2.494
2.492
2.490
140
120
100
80
2.506
2.505
2.504
2.503
2.502
2.501
2.500
200mA LOAD
3.6V INPUT
60
40
20
0
0
100
200
300
400
500
1.5
2.5
3.5
4.5
5.5
0
1
2
3
4
5
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
LOAD TRANSIENT RESPONSE
50mA TO 500mA TO 50mA
LINE TRANSIENT RESPONSE
STARTUP WAVEFORM
MAX8902A/02B toc06
MAX8902A/02B toc05
MAX8902A/02B toc04
2V/div
5V
5V
V
EN
2V/div
500mV/div
100mV/div
V
V
IN
OUT
4V
200mA/div
2mV/div
V
OUT
V
OUT
200mA/div
I
IN
I
OUT
2.5V OUTPUT
5Ω LOAD
5Ω LOAD
C = 0.01μF
BYP
t
= t
= 1μs
RISE FALL
10μs/div
100μs/div
40ms/div
MAX8902A LDO OUTPUT-NOISE SPECTRAL
DENSITY vs. FREQUENCY
10E+3
PSRR vs. FREQUENCY
DROPOUT VOLTAGE vs. LOAD CURRENT
0
80
70
60
50
40
30
20
10
0
3.6V INPUT, 4.6V OUTPUT PRESET
THE SLOPE OF THE LINE INDICATES
A 129mΩ ON-RESISTANCE IN
DROPOUT
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
1E+3
100E+0
10E+0
10
100
1k
10k
100k
0
100
200
300
400
500
10
100
1k
10k
100k
1M
LOAD CURRENT (mA)
FREQUENCY (Hz)
FREQUENCY (Hz)
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ꢃow-Noise 500mA ꢃDO Regulators
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MAX8902A/MAX8902B
Pin Description
NAME
PIN
FUNCTION
MAX8902A MAX8902B
Regulator Power Input. Connect IN to a supply from 1.7V to 5.5V. Bypass IN with a 10μF
ceramic capacitor to GND.
1
2
3
IN
GND
EN
IN
GND
EN
Ground
Enable Input. A logic-low drives the output low through a 3k resistor and reduces the supply
current to less than 1μA. Drive logic-high or connect to IN for normal operation.
Output Voltage Select Input. Connect SELA to GND, IN, or leave unconnected. The states of
SELA and SELB are sampled when the regulator turns on and the output voltage is set as
shown in Table 2.
SELA
—
—
GS
—
4
5
Internally Used. Connect GS to GND.
Output Voltage Select Input. Connect SELB to GND, IN, or leave unconnected. The states of
SELA and SELB are sampled when the regulator turns on and the output voltage is set as
shown in Table 2.
SELB
Power-OK Output. Open-drain output that goes low when the output is above 91% of the
nominal regulation voltage. POK is high impedance in shutdown or when the output is below
the regulation voltage.
—
POK
Output Sense Input. Connect OUTS to the load at a point where accurate regulation is
required, or connect OUTS directly to OUT.
OUTS
—
—
6
7
Feedback Input. Connect FB to the center of a resistor voltage-divider connected between
OUT and GND to set the output voltage. V regulates to 0.6V.
FB
FB
Bypass Input. Connect a 0.01μF ceramic capacitor from BYP to OUT to achieve 16μV
RMS
output noise. Adjust the value of this capacitor to control the output slew rate during startup.
BYP
BYP
Slew Rate = (5V / ms) x (0.01μF / C
)
BYP
Regulator Output. Sources up to 500mA at the output regulation voltage. Bypass with a 10μF
(< 0.03 ESR) capacitor to GND.
8
OUT
EP
OUT
EP
—
Exposed Paddle. Connect the exposed paddle to a ground plane to provide heat sinking.
(POK) output (MAX8902B only). A simplified functional
Detailed Description
diagram is shown in Figure 1.
The MAX8902A/MAX8902B low-noise, low-dropout lin-
ear regulators deliver up to 500mA of output current
The MAX8902A output voltage can be set to 1.5V, 1.8V,
2.0V, 2.5V, 3.0V, 3.1V, 3.3V, 4.6V, or 4.7V using the
SELA and SELB inputs. The MAX8902B output voltage
can be set between 0.6V and 5.3V with an external
resistor voltage-divider.
with only 16µV
of output noise in a 100kHz band-
RMS
width. These regulators maintain their output voltage
over a wide input range, requiring only 100mV of input-
to-output headroom at full load.
The MAX8902 maintains a low 80µA typical supply cur-
rent, independent of the load current and dropout volt-
age. The regulator control circuitry includes a
programmable soft-start circuit and short circuit,
reverse current, and thermal-overload protection. Other
features include an enable input and a power-OK
Enable (EN)
The MAX8902A/MAX8902B include an enable input,
EN. Pull EN low to shut down the output, or drive EN
high to enable the output. If shutdown is not needed,
connect EN to IN.
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Maxim Integrated | 5
ꢃow-Noise 500mA ꢃDO Regulators
in a 2mm x 2mm TDFN Paꢁkage
MAX8902A/MAX8902B
THERMAL
PROTECTION
IN
CURRENT
LIMIT
REVERSE
CURRENT
EN
CONTROL
PROTECTION
OUT
GND
BYP
BYP
REF
0.6V
EA
POK
MAX8902A
MAX8902B
0.54V
FB
MAX8902B ONLY
OUTS
MAX8902A ONLY
990kΩ
SELA
SELB
VOLTAGE
SELECT
Figure 1. Simplified Functional Diagram
The slew rate of the output voltage during startup is
also determined by the BYP capacitor. A 0.01µF
capacitor sets the slew rate to 5V / ms. This startup rate
results in a 50mA slew current drawn from the input at
startup to charge the 10µF output capacitance.
Bypass (BYP)
The capacitor connected from BYP to OUT filters the
noise of the reference, feedback resistors, and regula-
tor input stage and provides a high-speed feedback
path for improved transient response. A 0.01µF capaci-
tor rolls off input noise at approximately 32Hz.
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ꢃow-Noise 500mA ꢃDO Regulators
in a 2mm x 2mm TDFN Paꢁkage
MAX8902A/MAX8902B
The BYP capacitor value can be adjusted from 0.001µF
to 0.1µF to change the startup slew rate according to
the following formula:
Table 1. 2mm x 2mm TDFN Package
Thermal Characteristics
Startup slew rate = (5V / ms) x (0.01µF / C
)
BYP
CONTINUOUS POWER
DISSIPATION
953.5mW DERATE 11.9mW/°C
ABOVE +70°C
Note that this slew rate applies only at startup, and that
recovery from a short circuit occurs at a slew rate
approximately 500 times slower.
ꢀ
JA
*
83.9°C/W
10.8°C/W
ꢀ
JC
Also note that, being a low-frequency filter node, BYP is
sensitive to leakage. BYP leakage currents above 10nA
cause measurable inaccuracy at the output and should
be avoided.
*θ is specified according to the JESD51 standard with the
JA
part mounted on a multilayer PCB.
Table 2. MAX8902A Output Voltages
Protection Features
OUTPUT VOLTAGE
The MAX8902A/MAX8902B are fully protected from an
output short circuit by a current-limiting and thermal-
overload circuit. If the output is shorted to GND, the
output current is limited to 700mA (typ). Under these
conditions, the part quickly heats up. When the junction
temperature reaches +165°C, a thermal-limit circuit
shuts off the output device. When the junction cools to
+150°C, the output turns back on in an attempt to
reestablish regulation. While the fault persists, the out-
put current cycles on and off, as the junction tempera-
ture slews between +150°C and +165°C.
SELA STATE
SELB STATE
(V)
1.5
1.8
2.0
2.5
3.0
3.1
3.3
4.6
4.7
IN
Unconnected
Unconnected
Unconnected
GND
Unconnected
GND
IN
Unconnected
GND
GND
IN
GND
Unconnected
GND
IN
The MAX8902A/MAX8902B are also protected against
reverse current when the output voltage is higher than
the input. In the event that extra output capacitance is
used at the output, a power-down transient at the input
would normally cause a large reverse current through a
conventional regulator. The MAX8902A/MAX8902B
include a reverse voltage detector that trips when IN
drops 10mV below OUT, shutting off the regulator and
opening the pMOS body diode connection, preventing
any reverse current.
IN
IN
are sampled only at startup. The regulation voltage can
be set to a different level by cycling EN or IN momen-
tarily to GND.
Setting the Output Voltage (MAX8902B)
The MAX8902B uses external feedback resistors to set
the output regulation voltage as shown in Figure 3. The
output can be set from 0.6V to 5.3V. Set the lower feed-
back resistor (R2) to 120kΩ or less to minimize FB input
bias current error. Then calculate the value of the upper
feedback resistor (R1) as follows:
Thermal Considerations
The MAX8902A/MAX8902B are packaged in an 8-pin,
2mm x 2mm TDFN package with an exposed paddle.
The exposed paddle is the main path for heat to leave
the IC, and therefore, must be connected to a ground
plane with thermal vias to allow heat to dissipate from
the device. Thermal properties of the IC package are
given in Table 1.
⎛
⎞
V
V
OUT
R1= R2 ×
−1
⎟
⎜
⎝
⎠
FB
where V is the feedback regulation voltage of 0.6V.
FB
Selecting the Output Voltage (MAX8902A)
The MAX8902A output can be set to one of nine volt-
ages by shorting or opening the SELA and SELB
inputs, as shown in Table 2. SELA and SELB should be
connected to GND, IN, or left unconnected.
Alternatively, they may be driven high, low, or open with
external logic; however, the states of SELA and SELB
Power-OK (MAX8902B)
The MAX8902B includes an additional open-drain out-
put, POK, that pulls low to indicate the output voltage is
in regulation. During startup, POK is high impedance
until the output voltage rises to 91% of its regulation
level. If an overload occurs at the output, or the output
is shut down, POK is high impedance.
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Maxim Integrated | 7
ꢃow-Noise 500mA ꢃDO Regulators
in a 2mm x 2mm TDFN Paꢁkage
MAX8902A/MAX8902B
INPUT
4.7V TO 5.5V
INPUT
1.7V TO 5.5V
OUTPUT
4.6V
OUTPUT ADJUSTABLE
0.6V TO 5.3V
IN
OUT
BYP
IN
OUT
10μF
10μF
MAX8902A
MAX8902B
0.01μF
0.01μF
10μF
10μF
R1
R2
BYP
FB
ON
EN
EN
OFF
ON
LOGIC
SUPPLY
OFF
OUTS
R3
100kΩ
SELA
EP
SELB
GND
GS
POK
TO μC
GND
EP
Figure 2. MAX8902A Fixed-Output Application Circuit
Figure 3. MAX8902B Adjustable-Output Application Circuit
Pin Configurations
TOP VIEW
Input Capacitor
A 10µF ceramic capacitor is recommended for the
input. Select a capacitor that maintains its capacitance
over temperature and DC bias. Capacitors with X5R or
X7R temperature characteristics generally perform well.
+
+
Output Capacitor
1
2
3
4
8
7
6
5
OUT
1
2
3
4
8
7
6
5
OUT
BYP
FB
IN
GND
EN
IN
GND
EN
A minimum of 10µF of capacitance is required at OUT
to ensure stability. Select a ceramic capacitor that
maintains its capacitance over temperature and DC
bias. Capacitors with X5R or X7R temperature charac-
teristics generally perform well.
BYP
MAX8902A
MAX8902B
OUTS
SELB
EP
EP
POK
SELA
GS
TDFN
TDFN
(2mm x 2mm)
(2mm x 2mm)
EP = EXPOSED PADDLE.
Package Information
Chip Information
For the latest package outline information and land patterns (foot-
prints), go to www.maximintegrated.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but the
drawing pertains to the package regardless of RoHS status.
PROCESS: BiCMOS
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
8 TDFN-EP
T822+1
21-0168
90-0064
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ꢃow-Noise 500mA ꢃDO Regulators
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MAX8902A/MAX8902B
Revision History
REVISION
REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
0
1
2
3
4
5
6
9/07
1/08
2/08
5/08
4/11
10/12
1/15
Initial release
—
Changed input capacitor value from 4.7µF to 10µF
Changed BP to BYP
1, 5, 8
2, 4–8
Updated TOC 5 title
4
1
7
1
Added the MAX8902BATA/V+ part to the Ordering Information table
Updated θ specification in Table 1
JC
Added MAX8902AATA/V+ to Ordering Information
For priꢁing, deliꢂery, and ordering information, please ꢁontaꢁt Maxim Direꢁt at 1-888-629-4642, or ꢂisit Maxim Integrated’s website at www.maximintegrated.ꢁom.
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相关型号：
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Fixed Positive LDO Regulator, 1.5V, 0.12V Dropout, BICMOS, PDSO8, 2 X 2 MM, 0.80 MM HEIGHT, ROHS COMPLIANT, TDFN-8
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