MAX1534 Datasheet, PDF (10/16 Pages) Maxim Integrated Products – High-Efficiency, Triple-Output, Keep-Alive Power Supply for Notebook Computers

High-Efficiency, Triple-Output, Keep-Alive
Power Supply for Notebook Computers
Table 1. Recommended Components
Input voltage
Max frequency
On-time
Buck output
ILIM connection
L1
D1
C_OUT3
7V
73kHz
8.8µs
CIRCUIT 1
5V, 500mA
IN
24V
175kHz
1µs
15µH, 57mΩ, 1.60A
Sumida CDRH6D38R-150
1A, 30V Schottky
Nihon EP10QY03
47µF, 6.3V, ceramic
TDK C3225X5R0J476M
7V
71kHz
9µs
CIRCUIT 2
5V, 250mA
GND
24V
160kHz
1µs
33µH, 124mΩ, 1.10A
Sumida CDRH6D38R-330
0.5A, 30V Schottky
Nihon EP05Q03L
33µF, 6.3V, ceramic
TDK C3225X5R0J336M
Table 2. Component Suppliers
SUPPLIER
DIODES
Central Semiconductor
Fairchild Semiconductor
General Semiconductor
International Rectifier
Nihon
ON Semiconductor
Vishay-Siliconix
Zetex
CAPACITORS
AVX
Kemet
Nichicon
Sanyo
TDK
Taiyo Yuden
INDUCTORS
Coilcraft
Coiltronics
Pulse Engineering
Sumida USA
Toko
WEBSITE
www.centralsemi.com
www.fairchildsemi.com
www.gensemi.com
www.irf.com
www.niec.co.jp
www.onsemi.com
www.vishay.com
www.zetex.com
www.avxcorp.com
www.kemet.com
www.nichicon-us.com
www.sanyo.com
www.components.tdk.com
www.t-yuden.com
www.coilcraft.com
www.cooperet.com
www.pulseeng.com
www.sumida.com
www.tokoam.com
base drive, which reduces quiescent current signifi-
cantly. PNP-based regulators waste considerable cur-
rent in dropout when the pass transistor saturates, and
they also use high base-drive currents under large
Table 3. Current-Limit Configuration
ILIM
IN
GND
PEAK LX
MAXIMUM BUCK
CURRENT LIMIT (mA) OUTPUT CURRENT (mA)
1000
500
500
250
loads. The MAX1534 does not suffer from these prob-
lems. While a PNP-based regulator has dropout voltage
that is independent of the load, a P-channel MOSFET’s
dropout voltage is proportional to load current, provid-
ing for low dropout voltage at heavy loads and
extremely low dropout voltage at lighter loads.
Current Limit
The MAX1534 contain two independent current limiters,
one for each linear regulator, which monitor and control
the pass transistor’s gate voltage, limiting the guaran-
teed maximum output current to 160mA minimum. The
output can be shorted to ground for an indefinite time
without damaging the part.
Low-Noise Operation
An external 0.01µF bypass capacitor at BP, in conjunc-
tion with an internal resistor, creates a lowpass filter,
reducing the LDO output voltage noise.
Shutdown (SHDN)
The MAX1534’s accurate SHDN input can be used as a
low-battery voltage detector. Drive SHDN above the 1V
input rising-edge trip level to start up the MAX1534.
The 100mV SHDN input hysteresis prevents the
MAX1534 from oscillating between startup and shut-
down. Drive SHDN low to shut down the MAX1534’s
buck converter and linear regulators. When in shut-
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