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19-0990; Rev 0; 9/07
Low-Noise 500mA LDO Regulators in a 2mm x 2mm TDFN Package
General Description
The MAX8902A/MAX8902B low-noise linear regulators deliver up to 500mA of output current with only 16VRMS of output noise in a 100kHz bandwidth. These regulators maintain their output voltage over a wide input range, requiring only 100mV of input-to-output headroom at full load. These LDOs maintain a low 80A typical supply current, independent of the load current and dropout voltage. The regulator control circuitry includes a programmable soft-start circuit and short circuit, reverse current, and thermal overload protection. Other features include a shutdown input and a power-OK output (MAX8902B only). 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. 1.7V to 5.5V Input Voltage Range 0.6V to 5.3V Output Voltage Range 16VRMS Output Noise, 10Hz to 100kHz 80A Operating Supply Current 92dB PSRR at 5kHz Guaranteed 500mA Output Current 1.5% Output Accuracy Over Load, Line, and Temperature 100mV (max) Dropout at 500mA Load < 1A Shutdown Supply Current 700mA Short-Circuit Protection Thermal-Overload Protection Output-to-Input Reverse Current Protection 2mm x 2mm x 0.8mm TDFN Package
Features
MAX8902A/MAX8902B
Applications
Notebook Computers MP3 and Portable Media Players Wireless Headphones GPS Portable Navigation Devices Smartphones
MAX8902AATA+ MAX8902BATA+ PART
Ordering Information
FEATURES Pin-selectable output voltage Adjustable output voltage TOP MARK ABG ABH PKG CODE T822-1 T822-1
+Denotes a lead-free, RoHS-compliant package.
Note: All devices are in an 8-pin, 2mm x 2mm TDFN package with an exposed paddle and operate over the -40C to +125C automotive temperature range.
Typical Operating Circuits
INPUT 4.7V TO 5.5V IN 4.7F MAX8902A ON OFF EN BYP OUTS OUT 4.7F 0.01F 10F ON OFF LOGIC SUPPLY R3 100k TO C EP GND POK EP GND EN FB R2 SELA SELB GS MAX8902B BYP OUTPUT 4.6V INPUT 1.7V TO 5.5V IN OUT 0.01F R1 10F OUTPUT ADJUSTABLE 0.6V TO 5.3V
Pin Configurations appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
Low-Noise 500mA LDO Regulators in a 2mm x 2mm TDFN Package MAX8902A/MAX8902B
ABSOLUTE MAXIMUM RATINGS
BP, 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 (TA = +70C) 8-Pin, 2mm x 2mm TDFN (derate 11.9mW/C above +70C) .............................953.5mW Operating Temperature Range .........................-40C to +125C Junction Temperature........................................-40C to +150C Storage Temperature.........................................-65C to +150C 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 = VEN = 5V, OUTS = OUT, circuit of Figure 2 (MAX8902A) and Figure 3 (MAX8902B), TA = -40C to +125C, unless otherwise noted.) (Note 1)
PARAMETER IN Input Voltage Range Input Undervoltage Lockout OUT Output Voltage Range Output Voltage Accuracy Load Regulation Line Regulation VIN VOUT + 0.1V VIN = 1.7V to 5.5V for VOUT 1.4V VIN = (VOUT + 0.3V) to 5.5V for VOUT > 1.4V IOUT = 0.1mA to 500mA IOUT = 0.1mA to 500mA VIN = 1.7V to 5.5V for VOUT 1.4V VIN = (VOUT + 0.3V) to 5.5V for VOUT > 1.4V IOUT = 200mA VIN 3.6V, TA +85C IOUT = 500mA VIN 3.6V, TA +125C VIN = 1.7V 600 0.6 -1.5 0.02 0.04 50 150 700 16 92 85 62 0.5 0.591 -0.1 0.600 0.02 0.03 1 50 100 7.0 0.609 +0.1 A V A dB 800 mA VRMS 100 120 mV 5.3 +1.5 V % % % VIN rising, 100mV typical hysteresis 1.7 1.5 1.6 5.5 1.7 V V CONDITIONS MIN TYP MAX UNITS
Dropout Voltage (Note 2) Current Limit Output Noise Power-Supply Rejection Ratio OUTS (MAX8902A Only) OUTS Input Bias Current FB (MAX8902B Only) FB Threshold Accuracy FB Input Bias Current BP BP Capacitor Range BP Startup Current
VOUT = 95% of regulation, VIN = VOUT + 0.5V IOUT = 100mA, f = 10Hz to 100kHz, CBP = 0.01F f = 5kHz IOUT = 10mA f = 10kHz f = 100kHz In regulation VIN = 1.7V to 5.5V, IOUT = 0.1mA to 500mA VFB = 0.6V TA = +25C TA = -40C
Regulator remains stable From BP to GND during startup
nF A
2
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Low-Noise 500mA LDO Regulators in a 2mm x 2mm TDFN Package
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VEN = 5V, OUTS = OUT, circuit of Figure 2 (MAX8902A) and Figure 3 (MAX8902B), TA = -40C to +125C, unless otherwise noted.) (Note 1)
PARAMETER GND GND Supply Current GND Shutdown Current SELA/SELB (MAX8902A Only) Select Input Resistance Select Input Capacitance EN EN rising Enable Input Threshold VIN = 1.7V to 5.5V EN falling, TA < +85C EN falling, TA < +125C TA = +25C TA = +85C OUT rising OUT falling TA = +25C TA = +85C -1 88 0.4 0.38 -1 0.8 0.7 0.7 0.001 0.01 91 88 10 0.001 0.01 165 150 25 3 10 100 +1 94 +1 1.2 V When shorted to GND or VIN When open When open 1 10 500 M pF IOUT = 0mA VIN = 5.5V, EN = 0V TA < +85C TA < +125C TA = +25C TA = +85C 80 0.001 0.01 120 160 +1 A A CONDITIONS MIN TYP MAX UNITS
MAX8902A/MAX8902B
Enable Input Bias Current POK (MAX8902B Only) POK Threshold POK Voltage, Low POK Leakage Current THERMAL SHUTDOWN Thermal Shutdown Threshold OUTPUT TRANSIENT Load Transient Line Transient IN-to-OUT Reverse Voltage Turnoff Threshold
VEN = 0V to 5.5V
A
OUT voltage when POK switches IPOK = 1mA POK = 5.5V, VEN = 0V
% % mV A
TJ rising TJ falling IOUT = 50mA to 500mA to 50mA, tRISE = tFALL= 1s VIN = 4V to 5V to 4V, tRISE = tFALL = 5s, IOUT = 500mA IN falling below OUT
C
mV/p-p mV/p-p mV
Note 1: All devices are production tested at TA = +25C. Specifications over the operating temperature range are guaranteed by design and characterization. Note 2: The dropout voltage is defined VIN - VOUT, when VOUT is 5% lower than the value of VOUT when VIN = VOUT + 0.5V.
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Low-Noise 500mA LDO Regulators in a 2mm x 2mm TDFN Package MAX8902A/MAX8902B
Typical Operating Characteristics
(MAX8902A, VIN = 3.6V, VOUT = 2.5V, TA = +25C, unless otherwise noted.)
QUIESCENT CURRENT EN = HIGH, NO LOAD
MAX8902A/02B toc01
LOAD REGULATION
MAX8902A/02B toc02
LINE REGULATION
2.508 2.506 OUTPUT VOLTAGE (V) 2.504 2.502 2.500 2.498 2.496 2.494 2.492 200mA LOAD
MAX8902A/02B toc03
140 120 INPUT CURRENT (A) 100 80 60 40 20 0 0 1 2 3 4 5 INPUT VOLTAGE (V)
2.506 2.505 OUTPUT VOLTAGE (V) 2.504 2.503 2.502 2.501 2.500 0 100 200 300
2.510
3.6V INPUT
2.490 400 500 1.5 2.5 3.5 INPUT VOLTAGE (V) 4.5 5.5 LOAD CURRENT (mA)
LOAD TRANSIENT RESPONSE 50mA TO 500mA TO 50mA
MAX8902A/02B toc04
LOAD TRANSIENT RESPONSE
MAX8902A/02B toc05
STARTUP WAVEFORM
MAX8902A/02B toc06
2V/div 5V VOUT 100mV/div VIN 5V 2V/div 4V VEN 500mV/div
200mA/div VOUT 2mV/div VOUT IOUT tRISE = tFALL = 1s 40ms/div 10s/div 200mA/div 2.5V OUTPUT 5 LOAD IIN 5 LOAD CBP = 0.01F 100s/div
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX8902A/02B toc07
PSRR vs. FREQUENCY
MAX8902A/02B toc08
MAX8902A LDO OUTPUT-NOISE SPECTRAL DENSITY vs. FREQUENCY
MAX8902A/02B toc09
80 70 DROPOUT VOLTAGE (mV) 60 50 40 30 20 10 0 0
0 -10 -20 -30 PSRR (dB) -40 -50 -60 -70 -80 -90 -100
NOISE DENSITY (nV Hz)
3.6V INPUT, 4.6V OUTPUT PRESET THE SLOPE OF THE LINE INDICATES A 129m ON-RESISTANCE IN DROPOUT
10E+3
1E+3
100E+0
10E+0 10 100 1k FREQUENCY (Hz) 10k 100k 10 100 1000 10,000 100,000 1,000,000 FREQUENCY (Hz)
100
200
300
400
500
LOAD CURRENT (mA)
4
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Low-Noise 500mA LDO Regulators in a 2mm x 2mm TDFN Package
Pin Description
PIN 1 2 3 NAME MAX8902A IN GND EN MAX8902B IN GND EN FUNCTION Regulator Power Input. Connect IN to a supply from 1.7V to 5.5V. Bypass IN with a 4.7F ceramic capacitor to GND. Ground Enable Input. A logic-low drives the output low through a 3k resistor and reduces the supply current to less than 1A. 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. 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. 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. Output Sense Input. Connect OUTS to the load at a point where accurate regulation is required, or connect OUTS directly to OUT. Feedback Input. Connect FB to the center of a resistor voltage divider connected between OUT and GND to set the output voltage. VFB regulates to 0.6V. Bypass Input. Connect a 0.01F ceramic capacitor from BP to OUT to achieve 16VRMS output noise. Adjust the value of this capacitor to control the output slew rate during startup. Slew Rate = (5V / ms) x (0.01F / CBP) 8 -- OUT EP OUT EP Regulator Output. Sources up to 500mA at the output regulation voltage. Bypass with a 10F (< 0.03 ESR) capacitor to GND. Exposed Paddle. Connect the exposed paddle to a ground plane to provide heat sinking.
MAX8902A/MAX8902B
4
SELA -- SELB
-- GS --
5 -- POK
OUTS 6 --
-- FB
7
BP
BP
Detailed Description
The MAX8902A/MAX8902B low-noise, low-dropout linear regulators deliver up to 500mA of output current with only 16VRMS of output noise in a 100kHz bandwidth. These regulators maintain their output voltage over a wide input range, requiring only 100mV of inputto-output headroom at full load. The MAX8902 maintains a low 80A typical supply current, independent of the load current and dropout voltage. The regulator control circuitry includes a programmable soft-start circuit and short circuit, reverse input, and thermal overload protection. Other features include an enable input and a power-OK
(POK) output (MAX8902B only). A simplified functional diagram is shown in Figure 1. 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.
Enable (EN)
The MAX8902A/MAX8902B include an enable input, EN. Pull EN low to shutdown the output, or drive EN high to enable the output. If shutdown is not needed, connect EN to IN.
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Low-Noise 500mA LDO Regulators in a 2mm x 2mm TDFN Package MAX8902A/MAX8902B
THERMAL PROTECTION CURRENT LIMIT IN
EN
CONTROL
REVERSE CURRENT PROTECTION
OUT
BP
BP REF 0.6V
GND
EA POK
MAX8902A MAX8902B
0.54V FB MAX8902B ONLY OUTS MAX8902A ONLY SELA 990k
VOLTAGE SELECT
SELB
Figure 1. Simplified Functional Diagram
Bypass (BP)
The capacitor connected from BP to OUT filters the noise of the reference, feedback resistors, and regulator input stage and provides a high-speed feedback path for improved transient response. A 0.01F capacitor rolls off input noise at approximately 32Hz.
6
The slew rate of the output voltage during startup is also determined by the BP capacitor. A 0.01F 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 10F output capacitance.
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Low-Noise 500mA LDO Regulators in a 2mm x 2mm TDFN Package
The BP capacitor value can be adjusted from 0.001F to 0.1F, to change the startup slew rate according to the following formula: Startup slew rate = (5V / ms) x (0.01F / CBP) 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. Also note that, being a low-frequency filter node, BP is sensitive to leakage. BP leakage currents above 10nA cause measurable inaccuracy at the output and should be avoided.
MAX8902A/MAX8902B
Table 1. 2mm x 2mm TDFN Package Thermal Characteristics
CONTINUOUS POWER DISSIPATION JA* JC 953.5mW DERATE 11.9mW/C ABOVE +70C 83.9C/W 36.6C/W
*JA is specified according to the JESD51 standard with the part mounted on a multilayer PCB.
Protection Features
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 +165C, a thermal limit circuit shuts off the output device. When the junction cools to +150C, the output turns back on in an attempt to reestablish regulation. While the fault persists, the output current cycles on and off, as the junction temperature slews between +150C and +165C. 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.
Table 2. MAX8902A Output Voltages
OUTPUT VOLTAGE 1.5V 1.8V 2.0V 2.5V 3.0V 3.1V 3.3V 4.6V 4.7V SELA STATE IN Unconnected Unconnected Unconnected GND GND GND IN IN SELB STATE Unconnected GND IN Unconnected GND IN Unconnected GND IN
are sampled only at startup. The regulation voltage can be set to a different level by cycling EN or IN momentarily 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 feedback resistor (R2) to 120k or less to minimize FB input bias current error. Then calculate the value of the upper feedback resistor (R1) as follows: V R1 = R2 x OUT - 1 , VFB where VFB is the feedback regulation voltage of 0.6V.
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.
Selecting the Output Voltage (MAX8902A)
The MAX8902A output can be set to one of nine voltages 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 output, 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 shutdown, POK is high impedance.
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Low-Noise 500mA LDO Regulators in a 2mm x 2mm TDFN Package MAX8902A/MAX8902B
INPUT 4.7V TO 5.5V IN 4.7F MAX8902A ON OFF EN BYP OUTS OUT 4.7F 0.01F 10F ON OFF LOGIC SUPPLY R3 100k TO C EP GND POK EP GND EN FB R2 SELA SELB GS MAX8902B BYP OUTPUT 4.6V INPUT 1.7V TO 5.5V IN OUT 0.01F R1 10F OUTPUT ADJUSTABLE 0.6V TO 5.3V
Figure 2. MAX8902A Fixed Output Application Circuit
Figure 3. MAX8902B Adjustable Output Application Circuit
Input Capacitor
A 4.7F 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.
TOP VIEW
MAX8902A
IN 1 GND 2 EN 3 SELA 4 EP + 8 OUT 7 BP 6 OUTS 5 SELB
Pin Configurations
MAX8902B
IN 1 GND 2 EN 3 GS 4 EP + 8 OUT 7 BP 6 FB 5 POK
Output Capacitor
A minimum of 10F 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 characteristics generally perform well.
TDFN-EP 2mm x 2mm
EP = EXPOSED PADDLE.
TDFN-EP 2mm x 2mm
Chip Information
PROCESS: BiCMOS
8
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Low-Noise 500mA LDO Regulators in a 2mm x 2mm TDFN Package
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
8L TDFN EXPOSED PADS.EPS
MAX8902A/MAX8902B
PACKAGE OUTLINE 6 & 8L TDFN EXPOSED PAD, 2x2x0.80mm
21-0168
D
1 2
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Low-Noise 500mA LDO Regulators in a 2mm x 2mm TDFN Package MAX8902A/MAX8902B
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
COMMON DIMENSIONS SYMBOL A D E A1 L k A2 MIN. 0.70 1.90 1.90 0.00 0.20 MAX. 0.80 2.10 2.10 0.05 0.40
0.25 MIN. 0.20 REF.
PACKAGE VARIATIONS PKG. CODE T622-1 T822-1 T822-2 N 6 8 8 D2 0.900.10 0.700.10 0.800.10 E2 1.600.10 1.300.10 1.200.10 e 0.65 TYP. 0.50 TYP. 0.50 TYP. b 0.300.05 0.250.05 0.250.05 r 0.150 0.125 0.125 [(N/2)-1] x e 1.30 REF 1.50 REF 1.50 REF
PACKAGE OUTLINE 6 & 8L TDFN EXPOSED PAD, 2x2x0.80mm
21-0168
D
2 2
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 10
(c) 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
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