amc7140 ADD Microtech Inc., amc7140 Datasheet - Page 7

• Manufacturer Part Number: amc7140
• Description: 700ma High Voltage Adjustable Current Regulator With Enable Control
• Manufacturer: ADD Microtech Inc.

The Maximum Power Dissipation on Current Regulator:
Thermal Consideration:
conditions. However, maximum junction temperature ratings should not be exceeded under continuous normal load
conditions. The thermal protection circuit of AMC7140 prevents the device from damage due to excessive power
dissipation. When the device junction temperature rises to approximately 150°C, the regulator will be turned off. When
power consumption is over about 1000mW (TO-252 package, at T
the junction temperature below 125°C.
of copper foil required. For multi-layered PCB, these layers can also be used as a heat sink. They can be connected with
several through-hole vias.
Copyright © 2008 ADDtek Corp.
PCB heat sink size (mm
PCB θ
P
The AMC7140 has internal power and thermal limiting circuitry designed to protect the device under overload
The junction temperature is:
T
If PC Board copper is going to be used as a heat sink, below table can be used to determine the appropriate size
D(MAX)
J
= P
V
I
I
V
P
θ
θ
θ
D
OUT(NOM)
DD
D
= V
OUT(MAX)
IN(MAX)
(θ
SA
JT
CS
SA
= the quiescent current the regulator consumes at I
:  T hermal resistance from the junction to the mounting tab of the package.
: Dissipated power.
:  T hermal resistance through the interface between the IC and the surface on which it is mounted.
:  T hermal resistance from the mounting surface to ambient (thermal resistance of the heat sink).
(°C /W)
JT
OUT(MAX)
For TO-252 package, θ
(typically, θ
+θ
= the maximum input voltage.
= the nominal output current;
= the maximum voltage on output pin;
CS
+θ
Through hole vias
2
× I
)
SA
OUT(NOM)
CS
) + T
500
< 1.0°C /W)
59
A
+ V
THERMAL CONSIDERATION
JT
IN(MAX)
= 7.0 oC /W.
1000
45
Recommended figure of PCB area used as a heat sink.
× I
DD
1500
38
7
OUT(NOM)
5
4
3
2
1
A
Heat-pad of TO-252
=70°C), additional heat sink is required to control
2000
33
OUT
OE
GND
ISET
VDD
;
3000
27
DD032_D -- AUGUST 2008
4000
24
AMC7140
5000
21