7/23

BD63521EFV

TSZ02201-0P2P0B701180-1-2

© 2016 ROHM Co., Ltd. All rights reserved.

17.Aug.2016 Rev.001

www.rohm.com

TSZ22111・15・001

○CR／Connection terminal of CR for setting chopping frequency

This is the terminal to set the chopping frequency of output. Please connect the external C(470p～1500pF) and R(10k～

200kΩ) between this terminal and GND. Please refer to P9. Please interconnect from external components to GND in such

a way that the interconnection does not have impedance in common with other GND patterns. In addition, please carry out

the pattern design in such ways as keeps such steep pulses as square wave etc. away and that there is no noise plunging.

Please mount the two components of C and R if being used by PWM constant current control because normal PWM

constant current control becomes impossible if CR terminal is open or it is biased externally.

○MTH/ Current decay mode-setting terminal

This is the terminal to set the current decay mode. Current decay mode can be optionally set according to input voltage.

MTH terminal input voltage [V]

Current decay mode

0~0.3

SLOW DECAY

0.4~1.0

MIX DECAY

1.5~3.5

FAST DECAY

Please connect to GND if using at SLOW DECAY mode.

Please avoid using with MTH terminal open because if MTH terminal is open, the input is unsettled, and then there is the

danger that PWM operation becomes unstable. Besides, please take into consideration the outflow current (max.2µA) if

inputted by resistance division when selecting the resistance value.

○NC terminal

This terminal is unconnected electrically with IC internal circuit.

○IC back metal

For HTSSOP-B28 package, the heat-radiating metal is mounted on IC’s back side, and on the metal the heat-radiating

treatment is performed when in use, which becomes the precondition to use, so please secure sufficiently the

heat-radiating area by surely connecting by solder with the GND plane on the board and getting as wide GND pattern as

possible. Please be careful because the allowable loss as shown in P.20 cannot be secured if not connected by solder.

Moreover, the back side metal is shorted with IC chip’s back side and becomes the GND potential, so there is the danger

of malfunction and destruction if shorted with potentials other than GND, therefore please absolutely do not design

patterns other than GND through the IC’s back side.