MAX14900E Datasheet, PDF (15/31 Pages) Maxim Integrated Products – Global and Per-Channel Diagnostics

MAX14900E
Octal, High-Speed, Industrial, High-Side Switch
Configuration
The global configuration inputs affect all eight O_ channels
while serial configuration is per channel. See Table 3.
The serial interface can be used to configure each output
individually to be in push-pull or high-side mode and to
enable open-load detection for that channel if it is in high-
side mode. The PUSHPL and OL/IN1 inputs override the
per-channel serial configuration when they are set high.
Output Drivers
The drivers can be configured for high-side or push-pull
operation. When configured in high-side mode, each driver
can safely source 850mA (max) load current continuously.
The high-side switches have active current limiting in the
range between 1.4A (min) and 2.0A (max).
When a driver is in push-pull mode, the output drives
resistive/capacitive loads at high switching rates with load
currents up to 100mA to ground. The R_ON is 4Ω (max) for
the high-side and 10Ω (max) for the low-side drivers in
push-pull mode.
Monitoring the Output Logic State
The voltage state of each O_ driver/switch can be read
out via SPI. If the voltage on an O_ output is higher than
the 7V (typ) threshold, then the corresponding S_ bit is
logic 1 in the status byte. If the voltage on an O_ output
is below the threshold, then the corresponding S_ bit is
logic 0. Status monitoring can be read out via 16-bit serial
mode. This is possible on all modes and states of the
outputs: on/off/high/low.
Open-Load Detection
When configured in high-side mode, the device can detect
when no load is connected to the O_ outputs or when a
wire to a load is open circuit. Open-load detection can be
globally enabled in serial mode via the OL/IN1 input, or
on a per-channel basis via the serial interface in parallel
and serial modes. The detection circuitry applies an 80µA
current to the load and monitors the O_ voltage. Open-
load detection occurs when the outputs are configured
in high-side mode and is active while the high-side driver
is off.
When an open-load condition is detected on a high-side
switch, the corresponding switch’s fault bit is set and the
global FAULT output is asserted. Turning off a high-side
driver that has a large capacitive load and low bleed
resistance triggers a temporary detection of an open-load
condition and assert FAULT until the O_ voltage decays
to below the 7V (typ) threshold.
Table 3. Global Configuration Inputs
INPUT
FLTR
SRIAL
X
CONFIGURATION FUNCTION
Enables anti-glitch filtering on all logic input pins except SDI and CLK
0 = Glitch filtering disabled
1 = Glitch filtering enabled
PUSHPL
Configures all O_ outputs as push-pull or high-side
X
0 = All drivers high-side mode unless configured as push-pull by serial interface
1 = All drivers push-pull mode
Enables normal operation of all O_ outputs
EN
X
0 = All O_ outputs high impedance
1 = Normal operation
OL/IN1
Enables global open-load detection in serial mode
1
0 = Open-load detection disabled unless enabled by serial interface
1 = Open-load detection enabled for all high-side mode switches
CRC/IN3
Enables CRC generation and error detection of SPI data
1
0 = CRC disabled
1 = CRC enabled
X = Don’t care
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