Datasheet

PIN
NAME FUNCTION
MAX1530 MAX1531
23 23 DH
High-Side Gate Driver Output. DH drives the main switch of the step-down regulator.
DH swings from LX to BST.
24 24 BST
Step-Down Regulator Boostrap Capacitor Connection for High-Side Gate Driver.
Connect a 0.1µF ceramic capacitor from BST to LX.
25 25 SEQ
Sequence Control Input for LR2, LR3, LR4, and LR5. Controls the current sources and
switches that charge and discharge the capacitors connected to the ONL_ pins.
26 26 FREQ
Oscillator Frequency Select Input. Connect FREQ to VL for 500kHz operation. Connect
FREQ to AGND for 250kHz operation.
27 27 IN
Main Input Voltage (+4.5V to 28V). Bypass IN to AGND with a 1µF ceramic capacitor
close to the pins. IN powers the VL linear regulator. Connect IN to the drain of the high-
side MOSFET (for current sense) through a 1Ω resistor.
28 28 VL
Internal 5V Linear Regulator Output. Connect a minimum 1µF ceramic capacitor from
VL to AGND. Place the capacitor close to the pins. VL can supply up to 30mA for gate
drive and external loads. VL remains active when EN is low.
29 29 AGND Analog Ground
30 30 EN
Enable Input. This general-purpose on/off control input has an accurate 1.238V (typ)
rising threshold with 5% hysteresis. This allows EN to monitor an input voltage level or
other analog parameter. If EN is less than its threshold, then the main step-down and
all linear regulators are turned off. VL and the internal reference remain active when EN
is low. The rising edge of EN clears any latched faults except for a thermal fault, which
is cleared only by cycling the input power. An internal lter with a 10µs time constant
prevents short glitches from accidentally clearing the fault latch.
31 31 FBL1
Low-Voltage Logic Linear Regulator (LR1) Feedback Input. FBL1 regulates at 1.245V
nominal. Connect FBL1 to the center tap of a resistive voltage-divider between LR1
output AGND to set the output voltage. Place the divider close to the FBL1 pin. LR1
starts automatically after the step-down converter soft-start ends.
32 32 DRV1
Low-Voltage Logic Linear Regulator (LR1) Base Drive. Open drain of an internal
N-channel MOSFET. Connect DRV1 to the base of an external PNP pass transistor.
(See the Pass Transistor Selection section.)
— 5 CSH
Overcurrent Protection Positive Input. CSH is also the supply input for the overcurrent
sense block. CSH and CSL can be used to sense any current in the application circuit
and to shut the device down in an overcurrent condition. This feature is typically used
to protect the main input or the input to one of the linear regulators since they do not
have their own current limits. Insert an appropriate sense resistor in series with the
protected input and connect CSH and CSL to its positive and negative terminals. The
controller sets the fault latch when V
CSH
- V
CSL
exceeds the 300mV (typ) overcurrent
threshold. An internal lowpass lter prevents large currents of short duration (less than
50µs) or noise glitches from setting the latch. If the overcurrent protection is not used,
connect CSH and CSL to VL.
— 6 CSL Overcurrent Protection Negative Input. See CSH above.
MAX1530/MAX1531 Multiple-Output Power-Supply
Controllers for LCD Monitors
www.maximintegrated.com
Maxim Integrated │ 12
Pin Description (continued)