HV257

HV257 is a 32-channel, high voltage, sample and hold amplifier array integrated circuit. It operates on a single high voltage supply, up to 300V, and two low voltage supplies, VDD and VNN.

All 32 sample and hold circuits share a common analog input, VSIG. The individual sample and hold circuits are selected by a 5 to 32 logic decoder. The sampled voltage on the holding capacitor is buffered by a low voltage amplifier and amplified by a high voltage amplifier with a closed loop gain of 72V/V. The internal closed loop gain is set for an input voltage range of 0 to 4.096V. The input voltage can be up to 5.0V, but the output will saturate. The maximum output voltage swing is 5.0V below the VPP high voltage supply. The outputs can drive capacitive loads of up to 3000pF.

The maximum output source and sink current can be adjusted by using two external resistors. An external RSOURCE resistor controls the maximum sourcing current, and an external RSINK resistor controls the maximum sinking current. The current limit is approximately 12.5V divided by the external resistor value. The setting is common for all 32 outputs. A low voltage silicon junction diode is made available to help monitor the die temperature.