Select preset voltage mode by connecting SET to

ground. In adjustable mode, select an output between

+2.5V and +11V using two external resistors connected

as a voltage-divider to SET (Figure 4). Set the output

voltage using the following equation:

≅ 100kΩ.

Available Output Current Calculation

The MAX5023/MAX5024 high-voltage regulator pro-

vides up to 150mA of output current. The input voltage

extends to +65V. Package power dissipation limits the

amount of output current available for a given input/

output voltage and ambient temperature. Figure 5

depicts the maximum power dissipation curve for these

devices. The graph assumes that the exposed metal

pad of the MAX5023/MAX5024 package is soldered to

Use Figure 5 to determine the allowable package dissi-

pation for a given ambient temperature. Alternately, use

the following formula to calculate the allowable pack-

age dissipation:

After determining the allowable package dissipation,

calculate the maximum output current using the follow-

ing formula:

The above equations do not include the negligible

power dissipation from self-heating due to the IC

ground current.

I

P

V

mA

OUT MAX

D

IN

150

P

W for T

C

C for

C

C

D

A

=

≤+ °

°

















1 538

70

1 538

70

70

125

.

.

- 0.01923 T -

T

AA

65V, Low-Quiescent-Current, High-Voltage Linear

Regulators with µP Reset and Watchdog Timer

10

______________________________________________________________________________________

IN

EN

GND

HOLD

R2 = 1k

Ω TO 500kΩ

SET

OUT

RESET

TO

µP

15

µF

R1

+6.5V TO +65V

+2.5V TO +11V

ON

OFF

R2

MAX5024

10

µF

Figure 4. Setting the MAX5024 Adjustable Output Voltage

10 20

30 40 50

60 70

80 90 100 110 120 130 140 150

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

°C)

DERATE

19.23mW/

°C

1.538W

Figure 5. Maximum Power Dissipation vs. Temperature

Table 1. Truth Table for Regulator Output

State

X = Don’t care.

ORDER

EN

HOLD OUT

COMMENTS

1

Low

X

Off

Initial state. EN has 5M

Ω

internal resistor to ground.

HOLD has internal current

source to OUT.

2

High

X

On

Regulator output is active

when EN is pulled high.

3

High

Low

On

Hold is asserted forcing the

regulator output on even if

EN goes low.

4X

Low

On

Self-holding state. Regulator

output stays on regardless of

the state of EN.

5

Low

High

Off

Regulator output is

shutdown by releasing

HOLD while EN remains low.