![](http://datasheet.mmic.net.cn/280000/HIP5600IS_datasheet_16070840/HIP5600IS_5.png)
5
of HIP5600 and the zener diode (
V
REF
and
V
z
), load reg-
ulation of the HIP5600 (V
REF LOAD REG
), and the effects of
temperature on the HIP5600 and the zener diode (V
REF
TC,
V
Z
TC).
Example:
Given:
V
IN
= 200V, V
OUT
= 14.18V (V
REF
=
1.18V, V
Z
= 13V),
V
Z
= 5%, V
Z
TC
= +
0.079%
/°
C
(
assumes
1N5243BPH)
,
I
OUT
equal 10mA and
Temp equal +60
o
C.
The worst case
V
OUT
is 0.4956V. The shift in V
OUT
is
attributed to the following: -0.2 (HIP5600) and 0.69 (zener
diode).
The regulator/zener diode configuration gives a 3.5%
(0.49/14.18) worst case output voltage error where, for the
same conditions, the regulator/resistor configuration results
in an 7.5% (1.129/15) worst case output voltage error.
External Capacitors
A minimum10
μ
F output capacitor (C2) is required for stability
of the output stage. Any increase of the load capacitance
greater than 10
μ
F will merely improve the loop stability and
output impedance.
A 0.02
μ
F input decoupling capacitor (C1) between V
IN
and
ground may be required if the power source impedance is
not sufficiently low for the 1MHz - 10MHz band. Without this
capacitor, the HIP5600 can oscillate at 2.5MHz when driven
by a power source with a high impedance for the 1MHz -
10MHz band.
An optional bypass capacitor (C3) from V
ADJ
to ground
improves the ripple rejection by preventing the ripple at the
Adjust pin from being amplified. Bypass capacitors larger
than 10
μ
F do not appreciably improve the ripple rejection of
the part (see Figure 20 through Figure 25).
Load Regulation
For improved load regulation, resistor RF1 (connected
between the adjustment terminal and V
OUT
) should be tied
directly to the output of the regulator (Figure 4A) rather than
near the load Figure 4B. This eliminates line drops (R
S
) from
appearing effectively in series with RF1 and degrading regu-
lation. For example, a 15V regulator with a 0.05
resistance
between the regulator and the load will have a load regula-
tion due to line resistance of 0.05
x
I
L
. If RF1 is con-
nected near the load the effective load regulation will be 11.9
times worse (1+R2/R1, where R2 = 12k, R1 = 1.1k).
FIGURE 4.
Protection Diodes
The HIP5600, unlike other voltage regulators, is internally
protected by input diodes in the event the input becomes
shorted to ground. Therefore,
no
external protection diode is
required between the input pin and the output pin to protect
against the output capacitor (C2) discharging through the
input to ground.
If the output is shorted in the absence of D1 (Figure 5), the
bypass capacitor voltage (C3) could exceed the absolute
maximum voltage rating of
±
5V between V
OUT
and V
IN
.
Note; No protection diode (D1) is needed for output voltages
less than 6V or if C3 is not used.
FIGURE 5. REGULATOR WITH PROTECTION DIODE
Selecting the Right Heat Sink
Linear power supplies can dissipate a lot of power. This
power or heat must be safely dissipated to permit continuous
operation. This section will discuss thermal resistance and
show how to calculate heat sink requirements.
Electronic heat sinks are generally rated by their thermal
resistance. Thermal resistance is defined as the temperature
rise per unit of heat transfer or power dissipated, and is
expressed in units of degrees centigrade per watt. For a par-
ticular application determine the thermal resistance (
θ
SA
)
which the heat sink must have in order to maintain a junction
temperature below the thermal shut down limit (T
TS
).
V
OUT
VREF
VZ
+
=
(EQ. 3)
VOUT
VTREF
VT
Z
+
=
(EQ. 4A)
VTREF
VREF
VREFLOADREG
I
OUT
(
)
VREFTC
Temp
(
)
+
+
≡
(EQ. 4B)
VTZ
VZtolerance VZ
)
VZTC
Temp
(
)
+
≡
(EQ. 4C)
Error Budget
+VREFTC
θ
SA
(
)
IOUT
VIN
(
)
V
+
REFLINEREG
AC/DC
AC/DC
I
ADJ
R
S
(A)
(B)
V
REF
V
OUT
A
V
O
V
I
RF1
RF2
HIP5600
I
1
AC/DC
I
ADJ
R
S
V
REF
V
OUT
A
V
O
V
I
RF1
RF2
HIP5600
I
1
AC/DC
V
IN
A
V
O
V
I
+ V
OUT
RF1
RF2
C1
0.02
μ
F
C2
10
μ
F
C3
10
μ
F
D1
D1 PROTECTS AGAINST C3
DISCHARGING WHEN THE
OUTPUT IS SHORTED.
HIP5600
HIP5600