Datasheet LT6654BX (Analog Devices) - 7

link to page 8 LT6654BX
APPLICATIONS INFORMATION Bypass and Load Capacitors
the turn-on time for the LT6654BX, 2.5V output volt- The LT6654BXMS8 operates between –40°C to 175°C, age with a 0.1μF input bypass and 1μF load capacitor and performs similarly to LT6654BHS6 within –40°C to at 25°C and 175°C, respectively. Figures 3 and 4 show 125°C specified temperature range. The LT6654BX refer- the output response to a 0.5V transient on VIN with the ence is offered in an MS8, 8-lead MSOP package. same capacitors, at 25°C and 175°C, respectively. The test circuit of Figure 5 is used to measure the stability The LT6654BX voltage reference should have an input by- with various load currents. With RL = 1k, the 1V step pass capacitor of 0.1μF or larger. However, for light load- produces a current step of 1mA. Figures 6 and 7 show ing, the bypassing on other components nearby is suf- the response to a ±0.5mA load at 25°C and 175°C, ficient. In high voltage applications, VIN > 30V, a transient respectively. Figures 8 and 9 are the output response output short-circuit to ground can create an input voltage to a sourcing step at 25°C and 175°C, respectively, and transient that could exceed the maximum input voltage Figures 10 and 11 are the output response of a sinking rating. To prevent this worst-case condition, an RC input step at 25°C and 175°C, respectively. line filter of 10μs (i.e. 10Ω and 1μF) is recommended. This reference also requires an output capacitor for sta- bility. The optimum output capacitance for most applica- COUT = 1µF 3.5V tions is 1μF, although larger values work as well. This VIN/DC capacitor affects the turn-on and settling time for the 3V output to reach its final value. Figures 1 and 2 show COUT = 1µF +2V VOUT/AC VIN –2V 1V/DIV 6654BX F03 GND 50µs/DIV
Figure 3. 25°C Output Response to 0.5V Ripple on VIN
VOUT 1V/DIV GND TA = 175°C 20µs/DIV 6654BX F01 COUT = 1µF 3.5V
Figure 1. 25°C Turn-On Characteristics of LT6654BX-2.5
VIN/DC 3V +5mV VOUT/AC –5mV VIN 1V/DIV 100µs/DIV 6654BX F04 GND
Figure 4. 175°C Output Response to 0.5V Ripple on VIN
VOUT 1V/DIV GND TA = 175°C COUT = 1µF 50µs/DIV 6654BX F02
Figure 2. 175°C Turn-On Characteristics of LT6654BX-2.5
Rev. 0 For more information www.analog.com 7 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Applications Information Package Description Typical Application Related Parts