RH5RH

BLOCK DIAGRAM

Lx

VLX limiter

Slow start

Vref

 

 

OUT

 

 

 

Vss

Buffer

Phase Comp.

 

 

 

 

 

LxSW

 

 

 

PWM control

 

EXT

 

+

 

OSC

Error Amp.

 

 

 

 

Chip Enable

 

 

CE

Error Amp. (Error Amplifier) has a DC gain of 80dB, and Phase Comp. (Phase Compensation Circuit) provides the frequency characteristics including the 1st pole (fp=0.25Hz) and the zero point (fz=2.5kHz). Furthermore, another zero point (fz=1.0kHz) is also obtained by the resistors and a capacitor connected to the OUT pin.

(Note) Lx Pin

............

only for RH5RH⋅⋅1A and RH5RH⋅⋅3B

 

 

.........

EXT Pin

only for RH5RH⋅⋅2B and RH5RH⋅⋅3B

 

 

 

 

 

...........

only for RH5RH⋅⋅3B

CE Pin

 

 

SELECTION GUIDE

In RH5RH Series, the output voltage, the driver, and the taping type for the ICs can be selected at the user's request. The selection can be made by designating the part number as shown below :

 

RH5RH⋅⋅⋅⋅ ⋅⋅ ← Part Number

 

} } }

 

 

 

 

 

 

a

b

c

 

 

 

 

 

 

 

Code

 

 

 

 

Description

 

 

 

a

 

Setting Output Voltage (VOUT):

 

Stepwise setting with a step of 0.1V in the range of 2.7V to 7.5V is possible.

 

 

 

 

 

 

 

Designation of Driver:

 

 

1A: Internal Lx Tr. Driver (Oscillator Frequency 50kHz)

b

 

2B:

External Tr. Driver (Oscillator Frequency 100kHz)

 

 

3B: Internal Tr./External Tr. (selectively available) (Oscillator Frequency 100kHz, with chip

 

 

enable function)

 

 

 

 

 

Designation of Taping Type :

 

 

Ex.

SOT-89

: T1, T2

c

 

 

SOT-89-5

: T1, T2

 

 

(refer to Taping Specifications)

 

 

“T1” is prescribed as a standard.

 

 

 

 

 

 

For example, the product with Output Voltage 5.0V, the External Driver (the Oscillator Frequency 100kHz) and Taping Type T1, is designated by Part Number RH5RH502B-T1.

2