Pin description (continued) – Rainbow Electronics MAX17031 User Manual

Page 11

MAX17031

Dual Quick-PWM Step-Down Controller with Low-

Power LDO and RTC Regulator for MAIN Supplies

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Pin Description (continued)

PIN

NAME

FUNCTION

9 PGOOD

Open-Drain Power-Good Output for SMPS1 and SMPS2. PGOOD is low when either output voltage is
more than 15% (typ) below the nominal regulation threshold, during soft-start, in shutdown, when
either SMPS is disabled, and after the fault latch has been tripped. After the soft-start circuit has
terminated, PGOOD becomes high impedance if both outputs are in regulation.

ON1

Enable Input for SMPS1. Drive ON1 high to enable SMPS1. Drive ON1 low to shut down SMPS1.

DH1

High-Side Gate-Driver Output for SMPS1. DH1 swings from LX1 to BST1.

12 LX1

Inductor Connection for SMPS1. Connect LX1 to the switched side of the inductor. LX1 is the lower
supply rail for the DH1 high-side gate driver.

13 BST1

Boost Flying Capacitor Connection for SMPS1. Connect to an external capacitor as shown in
Figure 1. An optional resistor in series with BST1 allows the DH1 turn-on current to be adjusted.

DL1

Low-Side Gate-Driver Output for SMPS1. DL1 swings from power GND to V

DD.

15 V

Supply Voltage Input for the DL_ Gate Drivers. V

is internally connected to the drain of the HVPV

BST diode switch. Connect to a 5V supply, and bypass V

to power GND with a 1µF or greater

ceramic capacitor.

16 GND

Analog

and

Power

Ground

DL2

Low-Side Gate-Driver Output for SMPS2. DL2 swings from power GND to V

DD.

18 BST2

Boost Flying Capacitor Connection for SMPS2. Connect to an external capacitor as shown in
Figure 1. An optional resistor in series with BST2 allows the DH2 turn-on current to be adjusted.

19 LX2

Inductor Connection for SMPS2. Connect LX2 to the switched side of the inductor. LX2 is the lower
supply rail for the DH2 high-side gate driver.

DH2

High-Side Gate-Driver Output for SMPS2. DH2 swings from LX2 to BST2.

ON2

Enable Input for SMPS2. Drive ON2 high to enable SMPS2. Drive ON2 low to shut down SMPS2.

22 SKIP

Pulse-Skipping Control Input. This three-level input determines the operating mode for the
switching regulators:

High (> 2V) = pulse-skipping mode
Middle (1.8V) = forced-PWM mode
GND = ultrasonic mode

23 OUT2

Output-Voltage Sense Input for SMPS2. OUT2 is an input to the Quick-PWM on-time one-shot timer.
OUT2 also serves as the feedback input for the preset 3.3V.

24 ILIM2

Valley Current-Limit Adjustment for SMPS2. The GND - LX2 current-limit threshold is 1/10 the
voltage present on ILIM2 over a 0.2V to 2V range. An internal 5µA current source allows this
voltage to be set with a single resistor between ILIM2 and analog ground.

—

Exposed Pad. Connect backside exposed pad to analog GND and power GND.