10

For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824

978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com

Application Support: apps@hittite.com

HMC976LP3E

400mA LOW NOISE, HIGH PSRR

LINEAR VOLTAGE REGULATOR

v02.1112

Thermal dissipation should be taken into account at all times especially with large dropout voltages VDD-VR, i.e.

if 1.8V output is required from 5.5V input voltage, then the output current must be restricted to <210mA , or VDD

restricted to <3.75V for a 400mA load.

The exact maximum operating temperature before the thermal protection circuit activates is largely dependent on

the customer PCB design. Below is an example for maximum ambient temperature calculation for the standard

HMC976LP3E evaluation PCB with no heat sink and no air flow (fans). Customers should perform this calculation for

their PCB layout and operating conditions.

VIN=5.5V, Vout=5.0V, Iout=400mA

Vdropout=VIN-VOUT=0.5V

Dissipated power on regulator Pd=0.5Vx0.4A=0.2W

=51.5°C/W

Junction temperature increase using standard HMC976 board: DTj=Pd x

=10.3°C. Thermal shutdown

junction temperature of regulator (absolute min) Tsdwn=+115°C. Maximum corresponding ambient temperature

Ta_max = Tsdwn - DTj = +104.7°C

The plots below show how the PCB ground copper area affects the HMC976LP3E junction temperature for different

HMC976LP3E power dissipation conditions. The following cases are included in the plots:

The typical corresponding

is shown in Table 8:

25

50

75

100

125

150

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

POWER DISSIPATION (W)

Tjmax

JEDEC no HS

2580mm

2580mm

1000mm

100mm

115°C WORST CASE

THERMAL SHUTDOWN

25

50

75

100

125

150

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

POWER DISSIPATION (W)

100mm

2580mm

2580mm

1000mm

Tjmax

JEDEC no HS

115°C WORST CASE

THERMAL SHUTDOWN

Table 8. Typical

for specified PCB Copper Sizes

(

100

173.5

1000

57.3

2580 no HS

51.5

2580 with HS

44

Figure 14. HMC976LP3E JUNCTION TEMPERATURE

°C vs. TOTAL POWER DISSIPATION 25°C AMBIENT

Figure 15. HMC976LP3E JUNCTION TEMPERATURE

°C vs. TOTAL POWER DISSIPATION 50°C AMBIENT

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other

rights of third parties that may result from its use. Specifications subject to change without notice. No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarks and registered trademarks are the property of their respective owners.

For price, delivery, and to place orders: Analog Devices, Inc.,

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106

Phone: 781-329-4700 • Order online at www.analog.com

Application Support: Phone: 1-800-ANALOG-D