L9823 STMicroelectronics, L9823 Datasheet - Page 8

• Manufacturer Part Number: L9823
• Manufacturer: STMicroelectronics

Specifications of L9823

• Switch Type: Low Side
• Power Switch Family: L9823
• Input Voltage: -0.3 to 7V
• Power Switch On Resistance: 800mOhm
• Output Current: 500mA
• Number Of Outputs: 8
• Mounting: Surface Mount
• Supply Current: 6mA
• Package Type: SO
• Propagation Delay Time: 100ns
• Pin Count: 24
• Lead Free Status / Rohs Status: Compliant

L9823
Output Stages Control
Each output is controlled with its latch and with a common Reset line, which enables all outputs.
The control data are transmitted via the SI input, the timing of the serial interface is shown in Fig. 1.
The device is selected with low CSB signal and the input data are transferred into the 8 bit shift register at every
falling SCLK edge. The rising edge of the CSB latches the new data from the shift register to the drivers.
Figure 1. Timing of the Serial Interface
The SPI register data are transferred to the output latch at rising CSB edge. The digital filter between CSB and
the output latch ensures that the data are transferred only after 8 SCLK cycles or multiple of 8 SCLK cycles
since the last CSB falling edge. The CSB changes only at low SCLK.
Diagnostics
The output voltage at all outputs is compared with the diagnostic threshold, typ 0,55 V
Diagnostic Table for outputs:
Fault condition 1) "output short circuit to Vbat" : For SFPD = Low the output was switched on and the voltage at
the output exceeded the diagnostics threshold due to overcurrent, the output overload latch was set and the
output has been switched off. The diagnostic bit is high.
: For SFPD = High the output was switched on and the voltage at the output exceeds the diagnostics threshold.
The output operates in current regulation mode or has been switched off due to thermal shutdown. The status
bit is high.
Fault condition 2) "open load" or "output short circuit to GND" : the output is switched off and the voltage at the
output drops below the diagnostics threshold, because the load current is lower than the output diagnostic cur-
rent source, the load is interrupted. The diagnostic bit is low.
At the falling edge of CSB the output status data are transferred to the shift register. When SCB is low, data bits
contained in the shift register are transferred to SO output at every rising SCLK edge.
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SCLK
CSB
SO
SI
Output
off
off
on
on
tsclch
tcsdv
thclcl
not defined
tpcld
Output-voltage
> DG-threshold
< DG-threshold
< DG-threshold
> DG-threshold
tscld
tclh
D7
D7
thcld
tcll
Status-bit
D6
high
high
low
low
D0
tsclcl
D0
tpchdz
correct operation
correct operation
DD
fault condition 2)
fault condition 1)
Output-mode
= V
DG
thclch
.