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.
General Description
The MAX1798/MAX1798A/MAX1799/MAX1799A system
power supplies are designed specifically for CDMA cel-
lular/PCS handsets. Each device contains five low-
dropout linear regulators (LDOs), a 140ms (min) reset
timer, a serial interface, push-on/push-off control logic,
and two general-purpose open-drain outputs. Only the
serial interface is different between the MAX1798/
MAX1798A/MAX1799/MAX1799A: the MAX1798/
MAX1798A feature an SPI-compatible serial interface,
and the MAX1799/MAX1799A feature an I
2
C-compati-
ble interface. The “A” parts have a -13% reset thresh-
old, the non-A parts have a 9.5% threshold. The “A”
parts have a 175 delay on a reset-triggered shutdown,
the non-A shutdown instantly.
Each linear regulator features extremely low dropout
voltage, specified at two-thirds of the maximum output
current. LDO1 is rated for 300mA, while LDOs 2–5 are
each rated for 150mA. All LDOs are optimized for low
noise and isolation. Each LDO can be individually
enabled and disabled through the serial port, as well as
individually programmed to any of 32 voltages from
1.8V to 3.3V.
The MAX1798/MAX1798A/MAX1799/MAX1799As’ wide
2.5V to 5.5V input voltage range makes them compati-
ble with a wide range of input supplies, including a sin-
gle lithium-ion (Li+) cell battery. Both devices are
available in thermally-enhanced 20-pin TSSOP and QFN
exposed pad (EP) packages. Evaluation kits in TSSOP
(MAX1798EVKIT and MAX1799EVKIT) are available to
facilitate designs.
Typical Operating Circuit
Features
o
One 300mA Low-Noise LDO
o
Four 150mA Low-Noise LDOs
o
45μV
RMS
Noise from 10Hz to 100kHz
o
>60dB Crosstalk Isolation Below 10kHz
o
>60dB PSRR Below 10kHz
o
125mV (max) Dropout (OUT1 at 200mA)
o
100mV (max) Dropout (OUT2–5 at 100mA)
o
Programmable Output Voltages
1.8V to 3.3V in 32 Steps
o
140ms (min) Reset Timer
o
SPI- or I
2
C-Compatible Serial Interface
o
Push-On/Push-Off Control Logic
o
Two 150mA General Purpose Open-Drain Outputs
o
Overcurrent and Thermal Protection (all LDOs)
o
1μA Shutdown Current
o
20-Pin Thermally-Enhanced TSSOP or QFN
Packages
Applications
CDMA Cellular/PCS Handsets
PDAs, Palmtops, and Handy-Terminals
Single-Cell Li+ Systems
2- or 3-Cell NiMH, NiCd, or Alkaline Systems
M
CDMA Cellular/PCS System
Power Supplies
________________________________________________________________
Maxim Integrated Products
1
19-1655; Rev 1; 2/01
EVALUAVAILABLE
SPI is a trademark of Motorola, Inc.
I
2
C is a trademark of Philips Corp.
Ordering Information continued and Pin Configurations
appear at end of data sheet.
( ) ARE FOR MAX1799/MAX1799A.
*-13% RESET THRESHOLD AND SHUTDOWN RESET TIMER ADDED.
BACKLIGHT
GND
PGND
MAX1798
MAX1798A*
MAX1799
MAX1799A*
CS (AS)
0.01
μ
F
DR2
OUT3
RX
OUT4
BBA
OUT5
AUDIO OR
PLL + VCO
OUT2
TX
BP
IN1
IN2/3
SPI OR I
2
C
DIN (SDA)
SCLK (SCK)
ON
DR1
V
IN1
VIBRATOR
OUT1
OFF
ONO
RSO
RESET
V
CC
WDOUT
IRQ
M
2.5V
TO 5.5V
IN4/5
Ordering Information
PA RT
TEMP
RANGE
PIN-
PA CKA GE
INTER-
FACE
M A X17 98
E GP
M AX1798E U P
M A X17 98A
EGP
M AX1798AE UP
-40
°
C to +85
°
C
-40
°
C to +85
°
C
-40
°
C to +85
°
C
-40
°
C to +85
°
C
20 QFN
20 TS SOP EP
20 QFN
20 TS SOP EP
SPI
SPI
SPI
SPI