Basic thermostat control board for cooling applications
Features
■ Capacitive power supply providing
approximately 30 mA at 220 VAC 50 Hz
■ Temperature level regulation (potentiometer)
■ Temperature measurement input (external
NTC 5k)
■ Zero voltage switching (ZVS) to synchronize
the gate pulses with the mains
■ Stall rotor detection via AC switch temperature
monitoring
■ ST7Ultralite 8-bit, 8-pin MCU running at 1 MHz
(internal clock)
■ ICC programming connector
Description
STEVAL-IHT002V1
based on ST7LITEUS5
Data Brief
STEVAL-IHT002V1
The STEVAL-IHT002V1 is a low-cost evaluation
board designed to replace existing mechanical
thermostats. While driving a compressor, the
evaluation board is also capable of driving the
RUN winding, replacing the PTC and directly
driving the START winding. Stall rotor detection is
also implemented. These functions are oriented
towards reducing total power consumption. The
evaluation board is based on the new low-cost, 8pin, 8-bit ST7Ultralite microcontroller (MCU),
which controls the entire process. The MCU is
equipped with programmable Flash memory, a 1
MHz internal clock source and runs 1 KB C-based
software. Although the evaluation board is
specially designed to drive small to mid-size
compressors, it is fully customizable and
adaptable to any other application where
thermostat or temperature control is required.
October 2007 Rev 1 1/4
For further information contact your local STMicroelectronics sales office.
www.st.com
4
Board schematic STEVAL-IHT002V1
R14
10K
1%
R5
10K
R9
300
ICC Programmer
MAINS
+VDD
C3
100nF
VDD
1
PA5/AIN 4/CLKIN/ei4
2
PA4/AIN3/MC0/ei3
3
PA3/RESET
4
ei2/LTIC/AIN2/PA2
5
ei1/ICCCLK/AIN1/PA1
6
ei0/ICCDATA/ATPWM/ AIN0/PA0
7
VSS
8
U1
ST7ULTRA LITE
C4
10nF
+VDD
+
C2
1000uF
16V
105˚C
1
2
3
4
5
6
7
8
9
10
J2
CON10A
+VDD
C1
1uF
275~ X2
C5
1nF
R3
5K
+VDD
R4
12K
1%
RUN
D2
1N4007
DZ1
5V6
1/2W
+VDD
1
2
3
J1
CON3
+VDD
R8
300
TR2
ACST67S
COM
G
OUT
P1
50K
+VDD
R2
12K
1%
OUTGCOM
START
NEUTRAL
LINE
+VDD
Q1
BC337
LINE
R13
100K
R12
100K 1%
L1
6.8uH
+VD D
*
R1
47
1W
TR1
ACST67S
C6
47nF
275~ X2
1
2
3
J3
CON3
Neutral
Line
D1
1N4007
R10
47
3W
R11
560K
R6
10K
+VDD
R7
10K
1 Board schematic
Figure 1. Schematic
2/4
STEVAL-IHT002V1 Revision history
2 Revision history
Table 1. Document revision history
Date Revision Changes
26-Oct-2007 1 Initial release
3/4
STEVAL-IHT002V1
y
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