MAX1958 Datasheet, PDF (1/24 Pages) Maxim Integrated Products – W-CDMA/N-CDMA Cellular Phone HBT PA Management ICs

19-2659; Rev 0; 10/02
W-CDMA/N-CDMA ^{EVAALVUAAILTAIOBNLEKIT} Cellular Phone HBT PA
Management ICs
General Description
The MAX1958/MAX1959 power amplifier (PA) power-
management ICs (PMICs) integrate an 800mA, dynami-
cally adjustable step-down converter, a 5mA Rail-to-
Rail^® operational amplifier (op amp), and a precision
temperature sensor to power a heterojunction bipolar
transistor (HBT) PA in W-CDMA and N-CDMA cell
phones.
The high-efficiency, pulse-width modulated (PWM), DC-
to-DC buck converter is optimized to provide a guaran-
teed output current of 800mA. The output voltage is
dynamically controlled to produce any fixed-output volt-
age in the range of 0.75V to 3.4V (MAX1958) or 1V to
3.6V (MAX1959), with settling time less than 30µs for a
full-scale change in voltage and current. The 1MHz PWM
switching frequency allows the use of small external
components while pulse-skip mode reduces quiescent
current to 190µA with light loads. The converter utilizes a
low on-resistance internal MOSFET switch and synchro-
nous rectifier to maximize efficiency and minimize
external component count. The 100% duty-cycle opera-
tion allows for an IC dropout voltage of only 130mV (typ)
at 600mA load.
The micropower op amp is used to provide bias to the
HBT PA to maximize efficiency. The amplifier features
active discharge in shutdown for full PA bias control. It
has 5mA rail-to-rail drive capability, 800kHz gain-band-
width product, and 120dB open-loop voltage gain.
The precision temperature sensor measures tempera-
tures between -40°C to +125°C, with linear tempera-
ture-to-voltage analog output characteristics.
The MAX1958/MAX1959 are available in a 20-pin 5mm ✕
5mm thin QFN package (0.8mm max height).
Features
o Step-Down Converter
Dynamically Adjustable Output Voltage from
0.75V to 3.4V (MAX1958)
Dynamically Adjustable Output Voltage from
1V to 3.6V (MAX1959)
800mA Guaranteed Output Current
130mV IC Dropout at 600mA Load
Low Quiescent Current
190µA (typ) in Skip Mode (MAX1958)
3mA (typ) in PWM Mode
0.1µA (typ) in Shutdown Mode
1MHz Fixed-Frequency PWM operation
16% to 100% Duty-Cycle Operation
No External Schottky Diode Required
Soft-Start
o Operational Amplifier
5mA Rail-to-Rail Output
Active Discharge in Shutdown
800kHz Gain-Bandwidth Product
120dB Open-Loop Voltage Gain (R_L = 100kΩ)
o Temperature Sensor
Accurate Sensor -11.7mV/°C Slope
-40°C to +125°C-Rated Temperature Range
o 20-Pin Thin QFN (5mm ✕ 5mm), 0.8mm Height (max)
Ordering Information
PART
TEMP RANGE
MAX1958ETP
-40°C to +85°C
MAX1959ETP
-40°C to +85°C
*EP = Exposed paddle.
PIN-PACKAGE
20 Thin QFN-EP*
20 Thin QFN-EP
Pin Configuration
Applications
W-CDMA and N-CDMA Cellular Phones
Wireless PDAs and Modems
TOP VIEW
AOUT 1
SHDN2 2
AGND 3
TOUT 4
REF 5
MAX1958/
MAX1959
15 PWM
14 INP
13 IN
12 LX
11 PGND
Typical Operating Circuit and Functional Diagram appear at
end of data sheet.
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
THIN QFN
5mm x 5mm
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