Flash program memory
ST7L34, ST7L35, ST7L38, ST7L39
Doc ID 11928 Rev 7
Figure 5.
Typical ICC interface
1.
If the ICCCLK or ICCDATA pins are only used as outputs in the application, no signal isolation is necessary. As soon as the
programming tool is plugged to the board, even if an ICC session is not in progress, the ICCCLK and ICCDATA pins are
not available for the application. If they are used as inputs by the application, isolation such as a serial resistor must be
implemented in case another device forces the signal. Refer to the Programming Tool documentation for recommended
resistor values.
2.
During the ICP session, the programming tool must control the RESET pin. This can lead to conflicts between the
programming tool and the application reset circuit if it drives more than 5 mA at high level (push-pull output or pull-up
resistor < 1K). A schottky diode can be used to isolate the application reset circuit in this case. When using a classical RC
network with R > 1K or a reset management IC with open drain output and pull-up resistor > 1K, no additional components
are needed. In all cases the user must ensure that no external reset is generated by the application during the ICC session.
3.
The use of pin 7 of the ICC connector depends on the programming tool architecture. This pin must be connected when
using most ST programming tools (it is used to monitor the application power supply). Please refer to the programming tool
manual.
4.
Pin 9 must be connected to the PB4 pin of the ST7 when the clock is not available in the application or if the selected clock
option is not programmed in the option byte. ST7 devices with multi-oscillator capability must have OSC2 grounded in this
case.
5.
With any programming tool, while the ICP option is disabled, the external clock must be provided on PB4.
6.
In ICC mode, the internal RC oscillator is forced as a clock source, regardless of the selection in the option byte.
Caution:
During normal operation the ICCCLK pin must be pulled up, internally or externally (external
pull-up of 10k mandatory in noisy environment). This is to avoid entering ICC mode
unexpectedly during a reset. In the application, even if the pin is configured as output, any
reset puts it back in input pull-up.
ICC connector
ICCDATA
ICCCLK
RESET
V
DD
HE10 connector type
Application
power supply
1
2
4
6
8
10
97
5
3
Programming tool
ICC connector
Application board
ICC cable
(See note 3)
ST7
CLK
IN/PB4
Optional
See note 1
See note 1 and caution
See note 2
Application reset source
Application I/O
(see note 4)
(see
no
te
5
)