MAX881REUB ,Low-Noise Bias Supply in MAX with Power-OK for GaAsFET PAfeatures include a power-OK (POK) output that sig-nals when the negative voltage is within 7.5% of ..
MAX881REUB+ ,Low-Noise Bias Supply in µMAX with Power OK for GaAsFET PAApplications Ordering InformationCell Phones Wireless ModemsPART TEMP RANGE PIN-PACKAGEPCS Phones T ..
MAX881REUB-T ,Low-Noise Bias Supply in µMAX with Power OK for GaAsFET PAfeatures include a power-OK (POK) output that sig-nals when the negative voltage is within 7.5% of ..
MAX882 ,5V/3.3V or Adjustable, Low-Dropout, Low-IApplicationsOrdering Information continued at end of data sheet.*Dice are tested at T = +25°C, DC p ..
MAX8821ETI+ ,White LED Charge Pump with Mono Class D Audio Amp and Dual LDOApplicationsINDIVIDUALLED3AGND MAX88210.1mA TOCell Phones and Smartphones25.6mAREF LED4DIMMINGPDAs, ..
MAX8822ETE+ ,Ultra-Efficient Negative Charge-Pump LED Driver with Dual LDOs in 3mm x 3mm Thin QFNApplicationsWhite LED BacklightingPKGPART PIN-PACKAGE TOP MARKCODECell Phones and Smartphones16 Thi ..
MB86391 ,MPEG2 1chip Audio/Video EncoderMPEG2 1chip Audio/Video Encoder MB86391 Product Specification Revision 1.1 12, November 2001 Copy ..
MB86434 ,5V Single Power Supply Audio Interface Unit (AIU)FUJITSU SEMICONDUCTORDS04-23003-1EDATA SHEETASSPCMOS5V Single Power Supply Audio Interface Unit (AI ..
MB86437PFV ,3 V Single Power Supply Audio Interface Unit (AIU)FUJITSU SEMICONDUCTORDS04-23005-3EDATA SHEETASSPCMOS3 V Single Power Supply Audio Interface Unit (A ..
MB86604L ,SCSI-II Protocol Controller (with single-ended driver/receiver)FUJITSU SEMICONDUCTORDS04-22415-1EDATA SHEETASSP Communication ControlCMOSSCSI-II Protocol Contr ..
MB86604LPFV ,SCSI-II Protocol Controller (with single-ended driver/receiver)FUJITSU SEMICONDUCTORDS04-22415-1EDATA SHEETASSP Communication ControlCMOSSCSI-II Protocol Contr ..
MB86606A ,FAST-20 SCSI Protocol ControllerFEATURESSCSI Protocol Controller Block:• Operable as initiator and target• WIDE and FAST-20 data tr ..
MAX881REUB
Low-Noise Bias Supply in MAX with Power-OK for GaAsFET PA
General DescriptionThe MAX881R low-noise, inverting power supply is
designed for biasing GaAsFET power amplifiers in
portable wireless applications. This device is a charge-
pump inverter followed by a negative linear regulator.
The input voltage range is 2.5V to 5.5V. The output is
preset at -2.0V or can be set, using two resistors, to any
voltage from -0.5V to (-VIN+ 0.6V). It can deliver up to
4mA. The internal linear regulator also filters the output
to 1mVp-p ripple and noise.
Other features include a power-OK (POK) output that sig-
nals when the negative voltage is within 7.5% of its set
point. It protects the GaAsFET by not allowing power to
be applied to the GaAsFET’s drain until it is properly
biased. The signal can be routed either to a microcon-
troller or directly to a switch at the GaAsFET drain. The
MAX881R is available in a space-saving 10-pin µMAX
package.
ApplicationsCell Phones
PCS Phones
PHS Phones
Wireless Handsets
Wireless Modems
Two-Way Pagers
Mobile Radios
Wireless Computers
FeaturesSmall µMAX Package1mVp-p Output Voltage Ripple and NoisePower-OK Signal to Control GaAsFET Drain
Switch0.05µA Logic-Controlled Shutdown1ms Guaranteed Start-Up2.5V to 5.5V Input-0.5V to (-VIN+ 0.6V) Output at up to 4mAOperates with One 4.7µF and Three 0.22µF
Capacitors (no inductors needed)
MAX881R
Low-Noise Bias Supply in µMAX
with Power-OK for GaAsFET PA
Typical Operating Circuit
Pin Configuration
Ordering Information
MAX881R
Low-Noise Bias Supply in µMAX
with Power-OK for GaAsFET PA
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(Circuit of Figure 3, VIN= +3.6V, FB = GND, RL= ∞, SHDN= IN, TA
= -40°C to +85°C, unless otherwise noted. Typical values are at= +25°C.) (Note 2)
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.
IN to GND.................................................................-0.3V to +6VSHDNto GND...........................................................-0.3V to +6V
POKto GND...........................................................-0.3V to +12V
C1+ to GND.................................................-0.3V to (VIN+ 0.3V)
C1-, NEGOUT, OUT, FB to GND....................-6V to (VIN+ 0.3V)
Continuous Power Dissipation (TA= +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C)...........444mW
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +165°C
Lead Temperature (soldering, 10sec).............................+300°C
Note 1:The output may be shorted to NEGOUT or GND if the package power dissipation is not exceeded. Typical short-circuit
current is 35mA.
Note 2:Specifications to -40°C are guaranteed by design, not production tested.
MAX881R
Low-Noise Bias Supply in µMAX
with Power-OK for GaAsFET PA
Typical Operating Characteristics(Circuit of Figure 3, VIN= 3.6V, TA= +25°C, unless otherwise noted.)
MAX881R
Low-Noise Bias Supply in µMAX
with Power-OK for GaAsFET PA
Typical Operating Characteristics (continued)(Circuit of Figure 3, VIN= 3.6V, TA= +25°C, unless otherwise noted.)
MAX881R
Low-Noise Bias Supply in µMAX
with Power-OK for GaAsFET PA
Pin DescriptionFigure 1. Functional Diagram
Dual-Mode is a trademark of Maxim Integrated Products.
MAX881R
Low-Noise Bias Supply in µMAX
with Power-OK for GaAsFET PA
________________Detailed DescriptionThe MAX881R, a low-noise, inverting, regulated charge-
pump power supply, is designed for biasing GaAsFET
devices such as power-amplifier modules in cellular
handsets.
The applied input voltage (VIN) is inverted to a negative
voltage at NEGOUT by a capacitive charge pump. This
voltage is regulated by an internal linear regulator at
OUT (Figure 1). With FB connected to GND, VOUTis
regulated at -2V. Alternatively, use a voltage-divider at
FB to adjust the output voltage between -0.5V and -(VIN
- 0.6V) (see the section Setting the Output Voltage).
The internal linear regulator reduces the ripple noise
induced by the charge-pump inverter to 1mVp-p at
OUT (circuit of Figure 3b). In addition, the excellent AC
rejection of the linear regulator attenuates noise from
the incoming supply.
Power-OK SignalThe MAX881R has an active-low, open-drain, power-OK
(POK) output. This output goes low when OUT reaches
92.5% of the regulated output voltage. POKcan be
used to drive the gate of a P-MOSFET that switches
power to the GaAsFET power amplifier (Figure 2), there-
by ensuring that the power amplifier is not powered
before the required negative bias voltage is present.
Use a 50kΩor larger pull-up resistor to signal a logic
high when POKgoes high impedance.
Shutdown ModeThe MAX881R features a shutdown mode that reduces
supply current to less than 1µA over temperature. SHDN
is an active-low, logic-level input. Start-up time coming
out of shutdown mode is typically 0.5ms. OUT and
NEGOUT are switched to GND in shutdown mode.
Applications Information
Setting the Output VoltageSelect either a fixed or adjustable output for the
MAX881R. Connect FB to GND for a fixed -2V output
(Figure 3). Select an alternative output voltage by con-
necting FB to the midpoint of a resistor-divider from
OUT to GND (Figure 4). When operating under full load
(4mA), the voltage at IN should be at least 0.6V higher
than the absolute voltage required at OUT. Note that
the minimum input voltage required for operation is
2.5V, regardless of the desired output voltage.
Choose R1 to be between 100kΩand 400kΩand cal-
culate R2. For greater accuracy, use resistors with 1%
or better tolerance.
R2 = R1 (2 x |VOUT|- 1)
