HDP01-0512N
April 1999 - Ed: 6A
HARD DISK DRIVE
POWER SUPPLY PROTECTION
SOT223
PROTECTION FOR THE +5V AND +12V
POWER LINES OF:
- Hard disk drives
- Floppy disk drives
- CD-ROMs, CD-R, CD-RW
- DVDs
APPLICATIONS
This device is dedicated to the protection of the
+5V power supply line against transient overvol-
tages due to surge of power rails up to the activa-
tion of the serial thermal protection element. It is
also dedicated to the protection of the +12V rail
against transient overvoltages.
DESCRIPTION
Application Specific Discretes
A.S.D.
TM
GND
PL5
PL5
PL12
BASIC APPLICATION DIAGRAM
Unprotected 5V
Unprotected 12V
HDP01-0512N
Protected 5V
Protected 12V
PL12
PL5
Gnd
OVERVOLTAGE
CLAMPING
PL12
PL5
OVERVOLTAGE
DETECTION
note: The element in series with the 5V line is a resettable device, like Raychem Polyswitch MiniSMD075.
TM : ASD is trademark of STMicroelectronics.
COMPONENT COUNT REDUCTION
PCB SURFACE REDUCTION
SIMPLIFIED SYSTEM PROTECTION DESIGN
BENEFITS
PROTECTION OF BOTH 5V AND 12V SUPPLY
RAILS.
MAXIMUM CURRENT ON THE 5V LINE 3A
DURING 1s.
MONOLITHIC INTEGRATION IN PLANAR
TECHNOLOGY.
FEATURES
1/6
Symbol
Parameter
Value
Unit
t
on
Conduction time with I-
PL5
= 3A DC (note1)
1
s
T
op
Operating temperature range
0 to + 75
C
T
j
Maximum junction temperature
125
C
T
stg
Storage temperature range
- 55 to + 150
C
T
L
Lead solder temperature (10s duration)
260
C
note 1 : I-PL5 is the current going through the 5V line (PL5)
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
Unit
Rth (j-t)
Junction to tab
30
C/W
Rth (j-a)
Junction to ambient (note 2)
60
C/W
note 2 : With 5cm
2
copper (e=35
m) surface under tab.
THERMAL RESISTANCE
Symbol
Parameter
Value
Unit
Min.
Typ.
Max.
V
NA
-PL5
Non activation voltage between PL5 and Gnd at I
RM
=100
A
6.0
V
V
A
-PL5
Activation voltage between PL5 and Gnd
7.0
7.4
V
I
RM
-PL5
Leakage current between PL5 and Gnd at V
RM
=5V
1
A
IA-PL5
Activation current between PL5 and Gnd
10
mA
V
ON
-PL5
Voltage drop on active state at I
ON
=3A
1.3
V
ELECTRICAL CHARACTERISTICS (T
amb
= 25C)
PROTECTION OF 5 V LINE (PL5)
Symbol
Parameter
Value
Unit
Min.
Typ.
Max.
V
BR
-PL12
Breakdown voltage at I
R
=1mA
14
16
V
I
RM
-PL12
Leakage current between PL12 and Gnd at V
RM
=12V
1
A
Rd
Dynamic resistance. Square pulse Ipp=3A, tp = 2.5
s
2.5
PROTECTION OF 12 V LINE (PL12)
ELECTRICAL CHARACTERISTICS (Tamb=25C)
I
VNA-PL5
IRM-PL5
VA-PL5
IA-PL5
VON-PL5
VRM-PL5
ION
+5V PROTECTION
VRM-PL12
VBR-PL12
I
IRM-PL12
Slope = 1 / Rd
+12V PROTECTION
HDP01-0512N
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1
10
100
1000
1
10
50
ITSM(A)
Pl5 vs GND
Tj initial=25C
tp(ms)
Fig. 1: Non repetitive surge peak on-state current
versus pulse duration (rectangular waveform).
0.01
0.1
1
10
100
300
1
10
100
500
Ppp(W)
Tj initial=25C
Pl12 vs GND
tp(ms)
Fig. 2: Peak pulse power dissipation versus
exponential pulse duration (Tj initial = 25C).
15
16
17
18
19
20
21
22
0.1
0.5
1
2
3
Ipp(A)
PL12 vs GND
Vcl(V)
Fig. 3: Typical clamping voltage versus peak pulse
current (rectangular waveform, tp=2.5
s).
0
1
2
3
4
5
0
10
20
30
40
50
60
70
80
90
100
110
120
130
Rth(j-a) (C/W)
S(Cu) (cm)
Fig. 4: Thermal resistance junction to ambient
versus copper surface under tab (Epoxy printed
circuit board FR4, copper thickness: 35
m).
1E-4
1E-3
1E-2
1E-1
1E+0
1E+1
1E+2
1E-2
1E-1
1E+0
1E+1
1E+2
2E+2
Zth(C/W)
Zth(j-a)
Zth(j-t)
tp(s)
Fig. 5: Thermal impedance junction to ambient
and junction to tab versus pulse duration.
Note: Rth(j-a) = (TjMax - Tamb) / PMax
HDP01-0512N
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The HDP01-0512N has been specially designed to protect equipment supplied by both +5 and +12 Volt
power rails such as hard disk drives, CD-ROMs, DVDs, floppy disk drives with the topology indicated in
figure A.1.
This protection device is able to protect both +5 and
+12 Volts power rails against transients and rails in-
version.
The internal +5V protection is achieved with a crowbar
structure whereas the +12V one is secured by a
clamping structure.
ABOUT THE +5V PROTECTION
In normal conditions, (region
of figure A.2) the +5V protection (PL5 termination) of the HDP01-0512N
connected to the +5V rail, is in idle state and its leakage current is 1
A max at +5V @ 25C. Upon occur-
rence of transients, the HDP01-0512N eliminates the overvoltage by clamping up to a maximum of +7.4V
(region
) since the current induced by the transient does not exceed the activation current I
A
min (10mA).
If the I
A
min current value is passed, the internal +5V protection trips in crowbar mode (region
) and then
a short circuit appears on the +5V rail .
The arrows indicate the way the device is activated
from point
to point
, and the way it goes back in
idle state, point
to point
Thanks to this behavior the electronic module (i.e.
disk drive) connected to the +5V rail is safe.
As soon as the transient disappears and assuming that the current in the +5V power supply rail is under the
holding current I
H
min value (10mA) of the +5V protection, the HDP01-0512N gets back in idle state and the
protected electronic module turns back on. As in many cases the current delivered by the +5V power supply
is higher than the I
H
min current value of the HDP01-0512N, it is necessary to use a serial protection on the
+5V rail (i.e. resettable fuse), connected before the HDP protection. This will prevent the HDP01-0512N
from being damaged by an over-rated dissipated power. The choice of the serial protector is led by both
peak current and current duration the HDP01-0512N is able to support. The serial protection shall fulfill the
next condition :
i
2
t serial protection < I
TSM
@ tp of +5V HDP protection.
APPLICATION INFORMATION
DESCRIPTION
Fig. A.1: typical application schematic.
+5V supply rail
+12V supply rail
ELECTRONIC
MODULE
(i.e. Disk drive)
H
D
P01
-
51
2N
O
VER
V
O
L
T
A
GE
E
L
IM
IN
A
T
O
R
O
VER
V
O
L
T
A
GE
DETECT
OR
Fig. A.2: Current and voltage characteristic of the
+5V protection.
I
V
I
H
I
A
V
A
3
1
2
HDP01-0512N
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The I
TSM
value as a function of the pulse duration tp for the HDP01 device is given on the figure 1 of this
datasheet.
In the case the supply cables of the +12V and +5V are reversed, the +5V (PL5) internal protection of the
HDP01-512N immediately shorts circuits +5V rail and ensures on efficient protection of the electronic mod-
ule.
ABOUT THE +12V PROTECTION
The +12V internal protection (PL12 termination) eliminates all transients appearing on the +12V supply rail.
In normal conditions (region 4 of figure A.3) its leakage current is 1
A maximum at 12V @ 25C. When a
surge occurs on the +12V rail, the overvoltage is clamped (region 5) and the electronic module connected
to this rail is protected.
The clamping voltage (Vcl) is depending on several
parameters which are :
- current induced by the transient (Ipp)
- ambient temperature effect (
T)
- breakdown voltage of the protection (V
BR
)
- dynamic resistance of the protection (Rd)
To evaluate the clamping voltage appearing on the +12V rail when a transient occurs, the next formula is
needed :
Vcl = V
BR
max + Rd*I
PP
with a typical Rd equals to 2.5
I
PP
is the peak current given by the transient which is :
I
PP
= (Vtransient - Vcl)/Rs
Vtransient = peak voltage of the transient
Rs is the series resistance of the surge generator.
If, for example, we consider a 50V combined surge 1.2/50
s - 8/20
s, as defined by the standard
IEC1000-4-5, the Vcl is calculated as:
Vcl = 16 + 2.5*I
PP
and I
PP
= (50 - Vcl) / 42 R
S
= 42
(generator impedance)
then it comes up with Vcl = 17.9V and I
PP
= 0.7A
The impact of the temperature on the clamping voltage can be considered as to be :
Vcl(TC) = Vcl(25C) * (1 +
T(TC-25C)) where TC is the ambient temperature for which the module shall
run.
The HDP01-0512N +12V protection has a power dissipation capability that is given in the figure 2 of this
datasheet named "Peak pulse power versus exponential pulse duration". This figure is necessary to deter-
mine if the power involved in the +12V protection does not exceed the maximum power the HDP01 +12V
protection can support. For example, considering the last calculation where Vcl=17.9 and I
PP
=0.7A, the
peak power is in that case 12.5W (Vcl*I
PP
) for a 20
s exponential surge duration. If we compare this value
to the curve of figure 2, then we see the dissipated power is much lower than the +12V protection limit
(200W @ 20
s) this tells us the +12V protection of the HDP01-0512N can easily withstand such a 12.5W
surge.
Fig. A.3: Current and voltage characteristic of the
+12V protection.
I
V
V
CL
5
4
HDP01-0512N
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