STMicroelectronics 12 V, 150 mA non-isolated buck converter using VIPer™ Plus - VIPER06XS STEVAL-ISA115V1 STEVAL-ISA115V1 Hoja De Datos
Los códigos de productos
STEVAL-ISA115V1
Adapter features
AN4260
4/29
DocID024275 Rev 2
1 Adapter
features
2 Circuit
description
. The input section includes a resistor R1 for
inrush current limiting, a diode D1 and a Pi filter (C1, L1, C2) for rectification and EMC
suppression.
suppression.
The FB pin is the inverting input of the internal transconductance error amplifier, internally
referenced to 3.3 V. This allows the output voltage value to be set in a simple way through
the R4-R5 voltage divider between the output terminal and the FB pin, according to the
following equation:
referenced to 3.3 V. This allows the output voltage value to be set in a simple way through
the R4-R5 voltage divider between the output terminal and the FB pin, according to the
following equation:
Equation 1
where R4 has been split into R4a and R4b; and R5 into R5a and R5b so to allow a better
tuning of the output voltage value.
tuning of the output voltage value.
The compensation network is connected between the COMP pin (which is the output of the
error amplifier) and the GND pin and is made up of Cc, R3 and C7.
error amplifier) and the GND pin and is made up of Cc, R3 and C7.
The bleeder resistor Rbl provides about 1 mA minimum load, in order to avoid overvoltage
when the output load is disconnected. Its value is a trade-off between output voltage
increase and power consumption rise in no load.
when the output load is disconnected. Its value is a trade-off between output voltage
increase and power consumption rise in no load.
At power-up the DRAIN pin supplies the internal HV startup current generator which
charges the C3 capacitor up to V
charges the C3 capacitor up to V
DDon
(13 V typical). At this point, the power MOSFET starts
switching, the generator is turned off and the IC is powered by the energy stored in C3,
waiting for V
waiting for V
OUT
reaches its steady-state value. After that, the IC is supplied from the output
through the diode Daux. This allows the system to reach very low values of standby
consumption because, keeping the V
consumption because, keeping the V
DD
voltage always above the V
DDCSon
threshold,
prevents the HV startup generator from being turned on.
Table 1. Electrical specifications
Parameter
Symbol
Value
Input voltage range
V
IN
[90 V
AC
; 265 V
AC
]
Output voltage
V
OUT
12 V
Max. output current
I
OUT
0.15 A
Precision of output regulation
Δ
V
OUT_LF
±5%
High frequency output voltage ripple
Δ
V
OUT_HF
50 mV
Max. ambient operating temperature
T
AMB
60
°
C
V
O UT
3.3V
1
R5
R4
R4
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