LA1136N, LA1137N Pin Specifications (Pins connected to an external microcontroller)

(1) IF Band Switching : Pin 12

Narrowband :

3.5 V or greater

Wideband :

2.1 V or lower

(2) Seek Detection : Pin 14

Station seek :

3.5 V or greater

Receive mode : 1.5 V or lower

(3) IF Count Buffer : Pin 17

IF count buffer enabled : 2.5 V or greater

IF count buffer disabled : 1.2 V or lower

(4) SD output, tweet prevention control pin: Pin 22

The function of pin 22 is determined by the control voltage on pin 14 as follows:

[Pin 14]

[Pin 22]

HIGH (3.5 V or higher)

→

SD output pin (active high)

LOW (1.5 V or lower)

→

Tweet prevention input pin

Microcontroller control voltage, Tweet prevention

HIGH (3.5 V or higher)

off

LOW (1.5 V or lower)

on

Note: It is necessary to modify the microcontroller specifications in order to implement tweet prevention. When a

conventional microcontroller is used with the LA1136N or the LA1137N, the tweet prevention circuit does not operate,

but all other functions operate independently.

Device Comparison

Comparison between LA1135, LA1136N and LA1137N

Parameter

LA1135

LA1136N

LA1137N

Packages

DIP20S, MFP20

DIP24S, MFP24

DIP20S, MFP20

Double-balanced mixer

Yes

Yes

Yes

Oscillator

LW to SW

Supports AM stereo in LW

and MW, low-band noise reduction

LW to SW

Local-oscillator buffer

Yes

Yes

Yes

IF amplifier

Yes

Yes

Yes

Detector

External capacitor

Internal capacitor

Internal capacitor

IF-band switching

No

Yes

No

S-meter linearity

Approximately 80 dBµ

Approximately 100 dBµ

Approximately 100 dBµ

Active-HIGH stop detector output

No (requires 2 transistors)

Yes

Yes

Stop detector sensitivity

S-meter load dependent

Set by external resistor (Pin 10)

Set by external resistor (Pin 9)

IF count buffer

No (requires 2 transistors)

Yes

Yes

AM stereo buffer

No

Yes

No

IF AGC

Yes

Yes

Yes

IF AGC time-constant switching

No (requires 1 transistor)

Yes

Yes

IF AGC reset

No

Yes

Yes

Wideband RF AGC

Yes

Yes

Yes

RF AGC time-constant switching

No

Yes

Yes

Antenna dumping

Transistor

Pin-diode

Pin-diode

Tweet prevention

No

Yes

Yes

LA1136N, 1136NM, 1137N, 1137NM

No. 3507-11/28