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PDF MAX781 Data sheet ( Hoja de datos )
| Número de pieza | MAX781 | |
| Descripción | PDA/Hand-Held Computer Power Controller | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-0205; Rev 0; 7/94
EVAALVUAAILTAIOBNLEKIT
PDA/Hand-Held Computer Power Controller
_______________General Description
The MAX781 is a system-engineered power-supply con-
troller for subnotebook computers, PDAs, or similar bat-
tery-powered equipment. It provides high-performance,
step-down (buck), pulse-width modulated (PWM) control
for generating +3.3V and constant-current battery charg-
ing. Dual PCMCIA VPP outputs are powered by a regulat-
ed flyback winding. Five high-side gate drivers and a
buffered analog multiplexer are also included. All func-
tions are controlled by an SPI/Microwire™ compatible
four-wire serial interface.
The MAX781 generates +3.3V with high efficiency through
synchronous rectification and PWM operation at heavy
loads. It uses Idle Mode™ operation at light loads. Only
small external components are required because of the
device’s high switching frequency (300kHz) and advanced
current-mode PWM architecture that allows for output
capacitance as low as 50µF per ampere of load.
The MAX781 is configured by 32 bits of serial data. These
bits select the operating mode, set the switch-mode bat-
tery charger current level, select one of eight analog multi-
plexer channels, and turn on/off the five high-side gate
drivers. A status byte read from the serial interface indi-
cates if the battery has been removed, if the DC charging
source has been connected, or if there is a fault condition
on the +3.3V output. An interrupt output signals the CPU if
a status signal changes.
____________________________Features
o +3.3V Step-Down Controller
o Dual PCMCIA 2.0 Compatible VPP Outputs
(0V/3.3V/5V/12V)
o Digitally Adjustable Switching Current Source for
Battery Charging
o 5 High-Side Switch Gate-Driver Outputs
o SPI Serial Interface
o 300kHz Switching Frequency
o Oscillator SYNC Input
o 2.5V ±1.5% Reference Output
o 36-Pin SSOP Package
________________________Applications
Subnotebook Computers
PDAs
Communicating Computers
Handy-Terminals
______________Ordering Information
PART
MAX781CBX
MAX781EBX
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
36 SSOP
36 SSOP
________________________________________________Typical Application Diagram
DCIN
(up to 18V)
5 to 8
NiCd/NiMH
CELLS
or
2 LION
CELLS
DIGITALLY
ADJUSTABLE
SWITCHING
CURRENT
SOURCE
MAX781
HIGH-SIDE GATE DRIVERS
5
+3.3V AT 1A OR MORE
SERIAL INTERFACE
4
INTERRUPT
VPPA
VPPB
ANALOG MULTIPLEXER OUTPUT
SUBSYSTEMS
LOAD
SWITCHES
SELF REFRESH
DRAM
CPU
PCMCIA
SLOT A
PCMCIA
SLOT B
ADC
Pin Configuration on last page.
™SPI is a trademark of Motorola Inc. Microwire is a trademark of National Semiconductor Corp.
Idle Mode is a trademark of Maxim Integrated Porducts.
________________________________________________________________ Maxim Integrated Products 1
Call toll free 1-800-998-8800 for free samples or literature.
1 page  
PDA/Hand-Held Computer Power Controller
TIMING CHARACTERISTICS (Note 1)
PARAMETER
DIN to SCLK Data Setup Time
DIN to SCLK Data Hold Time
SCLK to DOUT Valid Propagation Delay
SCLK Clock Period
SCLK High Pulse Width
SCLK Low Pulse Width
CE Assertion to DOUT Enable
CE Deassertion to DOUT Disable
CE Assertion to SCLK Rising-Edge
Setup Time
SCLK Rising Edge to CE Deassertion
CE High Pulse Width
SCLK Rising Edge to CE Assertion
CE Deassertion to SCLK Rising Edge
Note 1: Guaranteed by design.
SYMBOL
tDS
tDH
tDO
tCP
tCH
tCL
tDV
tTR
tCSS
tCSH
tCSW
tCS0
tCS1
MIN TYP MAX
125
0
30 200
400
125
125
120
120
200
200
300
200
200
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
__________________________________________Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
NO LOAD SUPPLY CURRENT
10
OPERATE MODE (IDLE = 0)
1 OPERATE MODE (IDLE = 1)
0.1
0.01
STANDBY MODE
(I3OUT=0mA)
LOW-POWER MODE
SYNC=UVLO=AGND,
CHARGE=0
GDSEL_=0
MUX_=0
5ON=1
SHUTDOWN MODE
VPP_=0
0.001
2 4 6 8 10 12 14 16
BATT INPUT VOLTAGE (V)
18
CHARGER OUTPUT CURRENT
1000
%
100
90
80
70
100
10
1
60
50
mA
40
R4 = 0.2Ω
SYNC = AGND
30
BATT = 7V TO 8V 20
VCHG = 12V
10
3 7 15 31 63 127
CHARGER CODE (CHG6–CHG0 VALUE)
_______________________________________________________________________________________ 5
5 Page 
PDA/Hand-Held Computer Power Controller
Table 3. Configuration Data-Bit Assignments
BIT R/W *
NAME
DESCRIPTION
31 R/W 0 BATTINT 1 = TEMP pin voltage crossed 0.82* 3OUT
30 R 0 BATTSTAT 1 = TEMP > 0.82*3OUT, 0 = TEMP < 0.82*3OUT
29 R/W 0
3VINT
1 = 3OUT fault detected
28
R
0
3VSTAT
1 = 3OUT out of regulation, 0 = in regulation
27 R/W 0 CHGINT 1 = VCHG > BATT detected
26 R 0 CHGSTAT 1 = VCHG > BATT, 0 = VCHG < BATT
25 Unused
24 W 0 GDSEL5 1 = GD5 sources from VHI, 0 = GD5 sinks to AGND
23 W 0 GDSEL4 1 = GD4 sources from VHI, 0 = GD4 sinks to AGND
22 W 0 GDSEL3 1 = GD3 sources from VHI, 0 = GD3 sinks to AGND
21 W 0 GDSEL2 1 = GD2 sources from VHI, 0 = GD2 sinks to AGND
20 W 1 GDSEL1 1 = GD1 sources from VHI, 0 = GD1 sinks to AGND
19
W
0
MUX2
Analog multiplexer bit 2
18
W
1
MUX1
Analog multiplexer bit 1
17
W
0
MUX0
Analog multiplexer bit 0
16
W
0
CHG6
Charger current setting DAC bit 6
15
W
0
CHG5
Charger current setting DAC bit 5
14
W
0
CHG4
Charger current setting DAC bit 4
13
W
0
CHG3
Charger current setting DAC bit 3
12
W
0
CHG2
Charger current setting DAC bit 2
11
W
1
CHG1
Charger current setting DAC bit 1
10
W
0
CHG0
Charger current setting DAC bit 0
9 W 1 50N 1 = 5OUT linear regulator on, 0 = off
8 W 0 FASTON 1 = FAST sinks current, 0 = FAST open drain
7 W 1 CHARGE 1 = DCHG switching current source on, 0 = off
6
W1
IDLE
1 = Idle regulation, 0 = PWM regulation
5
W
1
MODE1
Operating mode select bit, 1, see Table 2
4
W
1
MODE0
Operating mode select bit, 0, see Table 2
3
W
0
VPPB1
VPPB voltage select bit 1, see Table 5
2
W
0
VPPB0
VPPB voltage select bit 0, see Table 5
1
W
0
VPPA1
VPPA voltage select bit 1, see Table 5
0
W
0
VPPA0
VPPA voltage select bit 0, see Table 5
* = Power-on reset default state
nal, causing the battery pack to need at least three ter-
minals: BATT+, BATT,- and THERM. The MAX781’s
TEMP pin connects to the battery pack’s thermistor
(Figure 6). Without the battery pack installed, R8 pulls
the MAX781’s TEMP pin up to 3OUT, and BATTSTAT =
1. When the battery pack is inserted, the resistive
divider formed by the thermistor and R8 pulls the TEMP
pin below 3OUT, forcing BATTSTAT = 0. Any transition
of BATTSTAT sets BATTINT. Clear BATTINT by writting
a logic 1 in bit 31 of the serial-configuration data. The
BATTSTAT comparator is disabled in low-power and
shutdown modes, and outputs a logic zero regardless
of the state of its inputs.
3VINT and 3VSTAT indicate the status of the 3OUT
output (+3.3V ±4%). 3OUT is out of regulation when
its output voltage falls below +3.1V. 3VSTAT = 0 when
3OUT is in regulation, and 3VSTAT = 1 when 3OUT is
out of regulation. A rising edge on 3VSTAT sets
3VINT; thus, 3OUT going out of regulation sets 3VINT.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet MAX781.PDF ] | |
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