KH232
DATA SHEET
T
case
100°C/W
T
j(pnp)
P
pnp
100°C/W
T
j(npn)
P
npn
48
°
C/W
T
j(circuit)
P
circuit
+
-
T
ambient
θ
ca
Other methods of heat sinking may be used, but for
best results, make contact with the base of the KH232
package, use a large thermal capacity heat sink and use
forced air convection.
Low V
CC
Operation: Supply Current Adjustment
The KH232 is designed to operate on supplies as low
as ±5V. In order to improve full bandwidth at reduced
supply voltages, the supply current (I
CC
) must be
increased. The plot of Bandwidth vs. V
CC
, shows the
effect of shorting pins 1 and 2 and pins 8 and 9; this
will increase both bandwidth and supply current. Care
should be taken to not exceed the maximum junction
temperatures; for this reason this technique should not
be used with supplies exceeding ±10V. For intermediate
values of V
CC
, external resistors between pins 1 and 2
and pins 8 and 9 can be used.
P
(circuit)
= (I
CC
)((+V
CC
) – (V
CC
)) where I
CC
= 14mA at ±15V
P
(xxx)
= [(±V
CC
) – V
out
– (I
col
) (R
col
+ 4)] (I
col
) (%Duty)
For positive V
o
and V
CC
, this is the power in the npn
device. For negative V
o
and V
CC
, this is the power in the
pnp device.
I
col
= V
o
/R
L
or 12mA, whichever is greater. (Include feed-
back R in R
L
.)
R
col
is a resistor (33Ω recommended) between the xxx
collector and ±V
CC
.
The limiting factor for output current and voltage is junction
temperature. Of secondary importance is I
(out)
, which
should not exceed 150mA.
T
j(pnp)
= P
(pnp)
(100 +
θ
ca
) + (P
(cir)
+ P
(npn)
)(θ
ca
) + T
a
,
similar for T
j(npn)
.
T
j(cir)
= P
(cir)
(48 +
θ
ca
) + (P
(pnp)
+ P
(npn)
)(θ
ca
) + T
a
.
θ
ca
= 65°C/W for the KH232 without heat sink in still air.
35°C/W for the KH232 with a Thermalloy 2268A
heat sink in still air.
15°C/W for the KH232 with a Thermalloy 2268A
heat sink at 300 ft/min air.
(Thermalloy 2240A works equally as well.)
For example, with the KH232 operating at ±15V while
driving a 100Ω load at 15V
pp
output (50% duty cycle
pulse waveform, DC = 0), P
(npn)
= P
(pnp)
= 190mW (R
col
= 33) and P
(cir)
= 0.42W. Then with the Thermalloy
2268 heat sink and air flow of 300 ft/min the output
transistors’ T
j
is 31°C above ambient and worst case T
j
in
the rest of the circuit is 32°C above ambient. In still air,
however, the rise in T
j
is 47°C and 48°C, respectively.
With no heat sink, the rise in T
j
is 71°C and 72°C,
respectively! Under most conditions,
HEAT SINKING IS
REQUIRED.
REV. 1A January 2004
5
CADEKA [ CADEKA MICROCIRCUITS LLC. ]
