Datasheet

MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
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Pin Description (continued)
PIN
MAX1533A
MAX1537A
NAME FUNCTION
25 27 CSL5
Negative Current-Sense Input for 5V SMPS. Connect to the negative terminal of the
current-sense element. Figure 9 describes two different current-sensing options.
CSL5 also serves as the bootstrap input for LDO5.
26 28 CSH5
Positive Current-Sense Input for 5V SMPS. Connect to the positive terminal of the
current-sense element. Figure 9 describes two different current-sensing options.
27 29 IN
Input of the Startup Circuitry and the LDO5 Internal 5V Linear Regulator. Bypass to
PGND with 0.22µF close to the IC.
28 30 LX5
Inductor Connection for 5V SMPS. Connect LX5 to the switched side of the inductor.
LX5 serves as the lower supply rail for the DH5 high-side gate driver.
29 31 BST5
Boost Flying-Capacitor Connection for 5V SMPS. Connect to an external capacitor
and diode as shown in Figure 6. An optional resistor in series with BST5 allows the
DH5 pullup current to be adjusted.
30 32 DH5 High-Side Gate-Driver Output for 5V SMPS. DH5 swings from LX5 to BST5.
31 33 SKIP
Pulse-Skipping Control Input. Connect to V
CC
for low-noise forced-PWM mode.
Connect to GND for high-efficiency pulse-skipping mode at light loads.
32 34 SHDN
Shutdown Control Input. The device enters its 5µA supply-current shutdown mode if
V
SHDN
is less than the SHDN input falling-edge trip level and does not restart until
V
SHDN
is greater than the SHDN input rising-edge trip level. Connect SHDN to V
IN
for
automatic startup. SHDN can be connected to V
IN
through a resistive voltage-divider
to implement a programmable undervoltage lockout.
— 35 INA
Supply Voltage Input for the Auxiliary LDOA Linear Regulator. INA is clamped with an
internal shunt to 26V.
— 36 LDOA
Adjustable (12V Nominal) 150mA Auxiliary Linear-Regulator Output. Input supply
comes from INA. Bypass LDOA to GND with 2.2µF (min) (1µF/20mA). Secondary
feedback threshold is set at INA - LDOA = 0.8V, and triggers the DL5 on the 5V
SMPS only. ONA high enables regulator output and secondary regulation. PGOOD is
not affected by the state of LDOA.