MAX8500 Datasheet, PDF (1/14 Pages) Maxim Integrated Products – PWM Buck Converters with Bypass FET for N-CDMA/W-CDMA Handsets

19-2641; Rev 0; 10/02
PWM ^{EVAALVUAAILTAIOBNLEKIT} Buck Converters with Bypass FET
for N-CDMA/W-CDMA Handsets
General Description
The MAX8500–MAX8504 PWM DC-to-DC buck converters
are optimized with integrated bypass FET (0.25Ω typ)
to provide power to the PA in N-CDMA and W-CDMA
cell phones. The devices have a low on-resistance FET
to bypass the external inductor for low dropout of only
150mV at 600mA load, regardless of inductor series
resistance. The supply voltage range is from 2.6V to
5.5V and the guaranteed converter output current is
600mA. The 1MHz PWM switching frequency allows for
small external components.
The MAX8500–MAX8503 are dynamically controlled to
provide varying output voltages from 0.4V to V_BATT.
The LDO regulation point is slightly lower than the PWM
converter such that the transition into and out of dropout
is smooth, regardless of the inductor resistance. The
MAX8504 is programmed for fixed 1.25V to 2.5V output
with external resistors. It features a high-power bypass
mode that connects the output directly to the battery. All
devices are designed to achieve an output settling time
of less than 30µs for a full-scale change in output volt-
age and load current.
The MAX8500–MAX8504 are available in a 12-lead
4mm x 4mm thin QFN package (0.8mm max height).
Applications
N-CDMA/W-CDMA Cellular Phones
Wireless PDAs and Modems
Typical Operating Circuit
INPUT 2.6V TO 5.5V
10µF
BATT
SKIP
SHDN
REF
PWM
1MHz
OSC
4.7µH
OUTPUT 0.4V TO VBATT
LX
OUT
4.7µF
LDO
REFIN
DAC
gm
COMP
PGND
RC
8.2kΩ
CC
1000pF
MAX8500-
MAX8503 _GND
Features
o Integrated Bypass PFET
o 150mV Dropout at 600mA Load (Regardless of
External Inductor)
o Dynamically Adjustable Output from 0.4V to
V_BATT
o Externally Fixed Output from 1.25V to 2.5V with
Digitally Controlled High-Power Bypass Mode
(MAX8504)
o 1MHz Fixed-Frequency PWM Switching
o 600mA Guaranteed Output Current
o 10% to 100% Duty-Cycle Operation
o Low Quiescent Current
280µA (typ) in Normal Mode
3.3mA (typ) in PWM Mode
0.1µA (typ) in Shutdown Mode
o 12-Pin Thin QFN (4mm x 4mm, 0.8mm max Height)
Ordering Information
PART
TEMP RANGE
PIN-
PACKAGE
MAX8500ETC
MAX8501ETC*
MAX8502ETC*
MAX8503ETC
MAX8504ETC
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
12 Thin QFN
12 Thin QFN
12 Thin QFN
12 Thin QFN
12 Thin QFN
*Future product—contact factory for availability.
TOP
MARK
AABQ
—
—
AABU
AABS
Pin Configuration
SHDN SKIP OUT
12 11 10
GND 1
9 BATT
REF 2
REFIN
(FB)
3
MAX8500–
MAX8504
8 BATTP
7 LX
4
5
6
COMP BATT PGND
(HP)
Thin QFN 4mm x 4mm
( ) MAX8504 ONLY
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.