MICRF008(2008) Просмотр технического описания (PDF) - Micrel

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Компоненты Описание

производитель

MICRF008
(Rev.:2008)

QwikRadio® Sweep-Mode Receiver

Micrel 

Micrel, Inc.

Compa-

rator

VDDBB

10µA

DO

10µA

VSSBB

Figure 4. DO Pin

REFOSC Pin

The REFOSC input circuit is shown in Figure 5. Input

impedance is quite high (200kΩ). This is a Colpitts

oscillator, with internal 30pF capacitors. This input is

intended to work with standard ceramic resonators,

connected from this pin to VSSBB. The resonators

should not contain integral capacitors, since these

capacitors are contained inside the IC. Externally applied

signals should be AC-coupled, amplitude limited to

approximately 0.5VPP. The nominal DC bias voltage on

this pin is 1.4V.

REFOSC

30pF

Active

Bias

VDDBB

200k

250

30pF

15µA

VSSBB

VSSBB

Figure 5. REFOSC Pin

MICRF008

Control Input (SEL0)

Control input circuitry is shown in Figure 6. The standard

input is a logic inverter constructed with minimum

geometry MOSFETs (Q2, Q3). P-Channel MOSFET Q1

is a large channel length device which functions

essentially as a “weak” pullup to VDDBB. Typical pullup

current is 5μA, leading to an impedance to the VDDBB

supply of typically 1MΩ.

VDDBB

Q1

VSSBB

Logic

Input

Q2

to Interna

Circuits

Q3

VSSBB

Figure 6. SEL0

August 2008

8

M9999-080108

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