IMX15, IMY15, IMS15 Series Data Sheet
15 Watt DC-DC Converters
a) Adjustment by means of an external resistor Rext
.
Auxiliary Functions
Depending upon the value of the required output voltage,
the resistor shall be connected:
Shutdown Function
The outputs of the converters may be enabled or disabled by
means of a logic signal (TTL, CMOS, etc.) applied to the shut-
down pin. If this function is not required, the shut-down pin
should be left open-circuit.
either: Between the R pin and Vo– to achieve an output
voltage adjustment range of Vo ≈ 80 to 100% of Vo nom
.
Vo
R
ext1 ≈ 4 kΩ • –––––––––
V
o nom – Vo
or: Between the R pin and Vo+ to achieve an output voltage
range of Vo ≈ 100 to 105% of Vo nom
• Converter operating:
• Converter disabled:
2.0 to 20 V
.
–10 to +0.7 V
(Vo – 2.5V)
ext2 ≈ 4 kΩ • ––––––––––––––––––
2.5 V • (Vo/Vo nom – 1)
Adjustable Output Voltage
R
• R input for single-output models and -0503-models
• Trim input for double-output models
b) Adjustment by means of an external voltage Vext
between Vo– and R pin.
• R input as option R for most double-output models.
The control voltage range is 1.96 to 2.62 V and allows for
adjustment in the range of Vo ≈ 80 to 105% of Vo nom
As a standard feature, the single- and double-output models
offer adjustable output voltage(s) by using the control input R
or Trim. If the control input is left open-circuit, the output
voltage is set to Vo nom. For output voltages Vo > Vo nom, the
.
Vo • 2.5 V
Vo nom
V
ext ≈ ––––––––
minimum input voltage Vi
increases proportionally to Vo/Vo nom
(see Electrical Input Data)
min
Attempting to adjust the output below this range will cause
the converter to shut down (hiccup mode).
.
Single-output models with synchronous rectifier (G):
Note: Applying an external control voltage >2.75 V may damage
the converter.
The R input is referenced to the secondary side of the
converter. Adjustment of the output voltage is possible by
means of an external resistor connected between the R pin
and either Vo+ or Vo–.
06029e
Vi+
Vo+
Note: For models with synchronous rectifier the logic for Vo
adjustment differs from other models with R input.
Rext2
4 kΩ
Vref = 2.5 V
R
06131
+
+
–
Vo+
Vi+
Control
logic
Vext
Rext1
Rext1
Vo–
Vi–
R
Rext2
Vi–
Fig. 15
Output voltage control for single-output models, -0503-
models, and double-output models fitted with option R by
means of the R input.
Vo–
Fig. 14
Output voltage control for single-output models with
synchronous rectifier.
Double-output models with Trim input:
The Trim input is referenced to the primary side. The figure
below shows the topology. Adjustment is possible trough either
Table 8: Vo versus Vext approximate values
an external resistor or an external voltage source Vext
.
Vonom
Typ. values of Rext1
Typ. values of Rext2
[V]
Vo [% of Vo nom
]
Rext1 [kΩ] Vo [% of Vo nom Rext2 [kΩ]
]
06089a
3.3
90
95
100
0.47
2.7
∞
100
105
110
∞
15
6.8
Vi+
Vo1+
Vo1–
Vo2+
Trim
+
5.1
90
95
100
3.3
8.2
∞
100
105
110
∞
9.1
3.9
Control
circuit
Vref 2.5 V
Vext
Rext
Vi–
–
Vo2–
All other models fitted with R-input:
The R input is referenced to the secondary side of the
converter. Adjustment of the output voltage is possible by
means of either an external resistor or a voltage source.
Fig. 16
Output voltage control for double-output models (without
option R) by means of the Trim input.
MELCHER
The Power Partners.
BCD20008-G Rev AD, 10-Aug-2015
Page 13 of 19