40V, 600mA Buck Converters with Low-

Quiescent-Current Linear Regulator Mode

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9

Pin Description

PIN

TQFN

TSSOP

NAME

FUNCTION

14

PGND

Power Ground. Return path for p-channel power MOSFET driver. Connect the input

capacitor return, freewheeling diode anode, and output capacitor return terminals to

PGND.

25

SGND

Signal Ground. Connect SGND to PGND near the input bypass capacitor return terminal.

36

RESET

Open-Drain, Active-Low Reset Output. RESET asserts low when OUT drops below the

reset threshold. When output rises above 92% of the programmed level, RESET

becomes high impedance after the reset timeout period. Connect a pullup resistor from

RESET to the converter output to create a logic output.

47

BP

4V Internal Regulator Output. Bypass BP to SGND with a 1µF or greater ceramic

capacitor.

59

SYNC

Synchronization Input. Connect SYNC to an external clock for synchronization. Connect

SYNC to SGND when not used.

610

SS

Soft-Start Timer Input. Connect an external capacitor from SS to SGND to adjust the soft-

start timeout period (see the Soft-Start (SS) section).

711

CT

Reset Timeout Period. Connect a capacitor from CT to SGND to set the reset timeout

period (see the Power-On Reset Output RESET section).

812

COMP

Buck Converter (Buck Mode) Control Loop Compensation. See the Compensation

Network section for compensation network design. LDO mode does not need external

compensation.

913

LDO/BUCK

LDO Mode/Buck Mode Select. Drive LDO/BUCK low to select the Buck Mode. The Buck

Mode activates after 32 internal/external clock cycles. Force the LDO/BUCK high (> 2V),

to select LDO Mode. The Buck Mode stops and LDO Mode is activated with a 100µs

delay.

10

15

ADJ

Regulator Output Feedback Point. Connect ADJ to SGND for a fixed 3.3V

(MAX5096A/MAX5097A) or 5V (MAX5096B/MAX5097B). For adjustable output voltage,

11

16

OUT

Converter Output. OUT must always be connected to the regulator output. Connect at

least a 22µF low-ESR (equivalent series resistance) capacitor from OUT to PGND for

stable operation.

12

17

EN

Enable Input. EN is internally pulled to ground. Drive EN high to turn on the regulator.

Force EN low or leave unconnected to place the device in shutdown mode.

13, 14

19, 20

LX

Drain Connection of Internal p-Channel High-Side Switch

15, 16

1, 2, 3

IN

Regulator Input. Bypass IN to PGND with a parallel combination of low-ESR ceramic and

aluminum capacitor to handle the input ripple current.

—8, 14, 18

N. C.

No Connection. Not internally connected.

EP

EP

EP

Exposed Pad. Connect externally to a large ground plane (SGND) for improved heat

dissipation. Do not use EP as an electrical ground connection.