_______________________________________________________________________________________ 9

76V, 300mW Boost Converter and Current

Monitor for APD Bias Applications

Pin Description

Pin Configuration

15

16

14

13

6

5

7

EP

1

2

LX

4

12

11

9

LX

PGND

SGND

ILIM

CNTRL

FB

MAX15059

3

10

BIAS

TQFN

+

TOP VIEW

8

PIN

NAME

FUNCTION

1, 16

PGND

Power Ground. Connect the negative terminals of the input and output capacitors to PGND. Connect

PGND externally to SGND at a single point, typically at the return terminal of the output capacitor.

2

IN

Input-Supply Voltage. Bypass IN to PGND with a ceramic capacitor of 1FF minimum value.

3

SHDN

Active-Low Shutdown Control Input. Apply a logic-low voltage to SHDN to shut down the device.

Connect SHDN to IN for normal operation. Ensure that VSHDN is not greater than the input voltage, VIN.

SHDN is internally pulled low. The converter is disabled when SHDN is left unconnected.

4, 8

SGND

Signal Ground. Connect directly to the local ground plane. Connect SGND to PGND at a single point,

typically near the return terminal of the output capacitor.

5

FB

Feedback Regulation Input. Connect FB to the center tap of a resistive voltage-divider from the boost

output to SGND to set the output voltage. The FB voltage regulates to 1.23V (typ) when VCNTRL is

above 1.3V (typ) and to VCNTRL when VCNTRL is below 1.2V (typ).

6

CNTRL

Control Input for Boost Converter Output-Voltage Programmability. CNTRL allows the feedback set-point

voltage to be set externally by CNTRL when CNTRL is less than 1.2V. Pull CNTRL above 1.3V (typ) to

use the internal 1.23V (typ) feedback set-point voltage.

7

ILIM

Open-Drain Current-Limit Indicator. ILIM asserts low when the APD current limit has been exceeded.

9

RLIM

Current-Limit Resistor Connection. Connect a resistor from RLIM to SGND to program the APD current-

limit threshold. When RLIM is connected to SGND, the current limit is set to 4.6mA.

10

MOUT

Current-Monitor Output. For the MAX15059A, MOUT sources a current equal to IAPD. For the

MAX15059B, MOUT sources a current equal to 1/5 of IAPD.

11

CLAMP

Clamp Voltage Input. CLAMP is the external potential used for voltage clamping of MOUT.