
Board Mountable
DC-DC Converters
G Series
Edition 5/5.2000
9/16
Temperature Monitor
TMON, referenced to Vi–
The TMON output warns the user of possible overheating of
the converter prior to shutting down the outputs should the
maximum operating temperature be exceeded. This feature
allows for instance a connected microprocessor system to
take measures (for example to save data or to activate a
cooling fan).
The TMON signal will become high (
UTMON >2.4 V) if the in-
ternal temperature of the converter is above 110
°C. The
TMON signal does not disable the converter.
The converter protects itself from overheating by shutting
down at an internal temperature of 115
°C and will auto-
matically restart at an internal temperature of 110
°C.
The TMON pin is connected to an internal open collector
with a pull-up current source of typ. 50
A
Table 6: Temperature monitor
Internal Temperature
UTMON
<110
°C
≤0.5 V at I
TMON sink <1 mA
>110
°C
>2.4 V at
ITMON source ≤30 A
Important: An additional external pull-up resistor at
TMON needs to be connected to a supply voltage less
than 8 V and referenced to Vi–, otherwise the unit may
be damaged.
R Control for Output Voltage Adjustment
R input, referenced to Go
As a standard feature, the G converters offer adjustable
output voltages in the range 60% to 110% of
Uo nom by us-
ing the R input. If the R pin is left open circuit the output volt-
age is set to
Uo nom. The voltages at outputs 2 and 3 are al-
tered in the same ratio as the main output (
Uo1). An internal
limitation will not admit to adjust the output voltages below
60%
±2% of U
o nom or above 110 %
±2% of U
o nom. In spite
of this limitation the current into or out of the R pin must be
limited to
±0.5 mA in order to prevent damage of the inter-
nal circuits.
The R control pin is referenced to the secondary side of the
converter (Go). Adjustment of the output voltages is possi-
ble by means of either an external resistor or a voltage
source.
a) Adjustment by means of an external resistor
Rext
Depending upon the value of the required output voltage,
the resistor shall be connected
either: Between the R pin and Go to achieve an output
voltage adjustment range of approximately
Uo = 60...100% Uo nom.
Uo
Rext 1
≈ ––––––––– 4 k
Uo nom – Uo
or: Between the R pin and Vo1+ to achieve an output
voltage range of approximately
Uo = 100...110% Uo nom.
Uo – 2.5 V
R'ext 2 ≈ –––––––––––––––––– 4 k
2.5 V (
Uo /Uo nom – 1)
b) Adjustment by means of an external voltage
Uext be-
tween the R pin and Go pins.
The control voltage range is 1.5...2.75 V and allows for
an adjustment in the range of approximately 60...110%
of
Uo nom.
2.5 V
Uext
≈ –––––– U
o
Uo nom
+
Uext
R
Vo1+
Go
Rext 1
Rext 2
–
2.5 V
Limiter
and
control
circuit
4 k
06012
Inhibit Function
Inhibit, referenced to Vi–
The outputs of the converter may be enabled or disabled by
means of a logic signal applied to the inhibit pin. If the inhibit
input is low (
Uinh ≤0.8 V) the outputs are enabled. If the in-
hibit input is high (
Uinh ≥2.4 V) or floating the outputs are
disabled. (Input current see table:
Electrical input data.)
Table 7: Inhibit function
Uinh min...Uinh max
Outputs
–0.3...0.8 V
Enabled
2.4...8 V
Disabled
The inhibit input has an internal pull-up resistor of >50 k
connected to an internal 8 V source.
Important:
– If the inhibit function is not required, the i pin must be
connected to Vi– to enable the outputs.
– Voltages higher than 8 V or lower than –0.3 V at the
inhibit input may damage the unit.
Fig. 18
Output voltage control by means of R input.