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PDF MAX1534 Data sheet ( Hoja de datos )
| Número de pieza | MAX1534 | |
| Descripción | High-Efficiency / Triple-Output / Keep-Alive Power Supply for Notebook Computers | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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19-2662; Rev 0; 10/02
High-Efficiency, Triple-Output, Keep-Alive
Power Supply for Notebook Computers
General Description
The MAX1534 is a high-efficiency, triple-output power
supply for keep-alive (always on) voltage rails. The
500mA buck regulator with an internal current-limited
0.5Ω PMOS steps down the battery or wall adapter
supply rail to a fixed 5V or an adjustable output voltage.
Two integrated low-voltage linear regulators follow this
output and provide two independent preset output volt-
ages of 3.3V and 1.8V, or adjustable output voltages.
The buck regulator utilizes a peak current-limit, pulse-
frequency modulation (PFM) architecture for highest
light-load efficiency to conserve battery life. High
switching frequencies (up to 200kHz) allow the use of
tiny surface-mount inductors and output capacitors.
Operation to 100% duty cycle minimizes dropout volt-
age (250mV at 500mA).
The low-dropout linear regulators use an internal
P-channel metal-oxide (PMOS) pass transistor to mini-
mize supply current and deliver up to 160mA each of
continuous current.
The MAX1534 includes a power-OK (POK) signal that
indicates all outputs are in regulation. The 4% accurate
threshold of the SHDN input permits its use as a low-
battery detector.
The MAX1534 is available in a small 16-pin thin QFN
(4mm ✕ 4mm) package, occupying 33% less board
space than discrete solutions.
Applications
Notebook and Sub-
Notebook Computers
Wake-On LAN
2 to 4 Li+ Cells Battery-
Powered Devices
Hand-Held Devices
Keep-Alive Supplies
Standby Supplies
Features
o One Switching and Two Linear Regulators
o Switching Regulator
+4.5V to +24V Input Voltage Range
Over 95% Efficiency
Up to 500mA Output Current
Up to 200kHz Switching Frequency
Fixed 5V or Adjustable Output Voltage
Internal 0.5Ω PMOS Switch
100% Maximum Duty Cycle for Low-Dropout
Operation
o Two Low-Dropout Linear Regulators
Up to 160mA Output Current (Each)
3.3V/Adj Output Voltage for OUT1
1.8V/Adj Output Voltage for OUT2
o ±1.5% Accurate Output Voltage
o ±4% Accurate Shutdown for Low Battery
Detection
o Thermal Shutdown Protection
o POK Output
o 1mW Typical Standby Power
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX1534ETE -40°C to +85°C 16 Thin QFN (4mm × 4mm)
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
VOUT1 = +3.3V ALWAYS
VOUT2 = +1.8V ALWAYS
POK SHDN
BP
IN
FB3
PRESET
ILIM
FB1
MAX1534
FB2
LX
OUT1
OUT2
LDOIN
GND
VIN = +7V TO +24V
VOUT3 = +5V ALWAYS
________________________________________________________________ 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.
1 page  
High-Efficiency, Triple-Output, Keep-Alive
Power Supply for Notebook Computers
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, VIN = 12V, ILIM = GND, PRESET = GND, TA = -40°C to +85°C, unless otherwise noted.) (Note 4)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
INPUTS AND OUTPUTS
SHDN Input Trip Level
Rising trip level, 100mV hysteresis
0.96
1.04
PRESET, ILIM Logic Levels
Low
High
0.5
2.2
UNITS
V
V
V
Note 1: The output voltage at light loads has a DC regulation level higher than the error comparator threshold by half the ripple volt-
age.
Note 2: The dropout voltage is defined as VLDOIN - VOUT_ when VLDOIN = VOUT_(NOM). Specification only applies when VOUT_ ≥
2.5V.
Note 3: OUT1, OUT2 DC set point, FB3 set point at the DC trip threshold of buck regulator.
Note 4: Specifications to -40°C are guaranteed by design, not production tested.
Typical Operating Characteristics
(Circuit of Figure 1, VIN = +12V, PRESET = GND, TA = +25°C, unless otherwise noted.)
BUCK OUTPUT VOLTAGE
vs. LOAD CURRENT, CIRCUIT 1
5.20
5.15
5.10 VIN = 12V
5.05
5.00
4.95 VIN = 20V
4.90
4.85
ILIM = IN
VIN = 6V
(tON LIMITED)
4.80
0 50 100 150 200 250 300 350 400 450 500
IOUT3 (mA)
BUCK EFFICIENCY
vs. LOAD CURRENT, CIRCUIT 1
100
VIN = 6V
95
90
85
80 VIN = 12V
75
70 VIN = 20V
65
60
55
50
0.1
ILIM = IN
1 10 100
IOUT3 (mA)
1000
100
95
90
85
80
75
70
65
60
55
50
0.1
BUCK EFFICIENCY
vs. LOAD CURRENT, CIRCUIT 2
VIN = 7V
VIN = 12V
VIN = 20V
ILIM = GND
1 10 100
IOUT3 (mA)
1000
BUCK EFFICIENCY vs. LOAD CURRENT
CIRCUIT 1, VIN = 12V
89 L = 22µH
87
85
83
L = 15µH
81
L = 10µH
79
77
75
0.1
ILIM = IN
1 10 100
IOUT3 (mA)
1000
200
180
160
140
120
100
80
60
40
20
0
6
SWITCHING FREQUENCY
vs. VIN, CIRCUIT 1, ILIM = IN
IOUT3 = 500mA
IOUT3 = 250mA
IOUT3 = 100mA
IOUT3 = 50mA
IOUT3 = 10mA
10 14 18 22 26
VIN (V)
_______________________________________________________________________________________ 5
5 Page 
High-Efficiency, Triple-Output, Keep-Alive
Power Supply for Notebook Computers
0.01µF
IN
1V MAX1534
BP
REF
GND
1V VL
TSDN
STARTUP
SHDN
VL
REG
ENABLE
PMOS
DRIVER
IPEAK
VL
VL
ZX
1V
POK OUT3_OK LDOIN
OUT2_OK
PRESET
OUT1_OK
0.9V
OUT1
PMOS
DRIVER
1V
OUT2_OK
1V
PMOS
DRIVER
LX
FB3
PRESET
LDOIN
OUT2
LDOIN 0.9V
FB1 OUT1_OK
0.9V
PRESET PRESET
PRESET PRESET
FB2
Figure 2. MAX1534 Functional Block Diagram
down, the supply current drops to 3.5µA, maximizing
battery life. The internal P-channel MOSFET in the buck
converter and linear regulators turn off to isolate each
input from its output. The output capacitance and load
current determine the rate at which the output voltage
decays. For automatic shutdown and startup, connect
SHDN to IN. Connect SHDN to IN through a resistive
voltage-divider to implement a programmable under-
voltage lockout. Do not leave SHDN floating.
Power-OK (POK)
The open-drain POK output is useful as a simple error
flag, as well as a delayed reset output. POK sinks cur-
rent when any of the three regulated output voltages is
11% below its regulation point. Connect POK to OUT_
through a high-value resistor for a simple error flag indi-
cator. Connect a capacitor from POK to GND to pro-
duce a delayed POK signal (delay set by the RC time
constant). POK is low in shutdown and is high imped-
ance when all three outputs are in regulation.
Thermal-Overload Protection
Thermal-overload protection limits total power dissipation
in the MAX1534. When the junction temperature exceeds
TJ = +160°C, a thermal sensor turns off the pass transis-
tor, allowing the IC to cool. The thermal sensor turns the
IC on again after the IC’s junction temperature cools by
15°C, resulting in a pulsed output during continuous
thermal-overload conditions.
Thermal-overload protection is designed to protect the
MAX1534 in the event of fault conditions. For continu-
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet MAX1534.PDF ] | |
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