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After Sales Technical Documentation
COMPACT HANDSFREE
UNIT
PHF–2
Original, 11/94
NMP Part No. 0275013
Compact Handsfree Unit PHF–2
AMENDMENT RECORD SHEET
After Sales
Technical Documentation
Amendment
Number
Date Inserted By Comments
Page 2 Original, 11/94
After Sales
Technical Documentation
Compact Handsfree Unit PHF–2
COMPACT HANDSFREE UNIT PHF–2
CONTENTS
Page No
Introduction 5
Technical Summary 5
List of Modules 5
Technical Specifications 6
Modes of Operation 6
Maximum Ratings 7
DC Characteristics 7
Control Signals 8
AC Characteristics 8
External Signals and Connections 9
Mechanical Characteristics 9
Functional Description 10
Circuit Description 10
Input Circuit 10
Power Control Logic 12
Switched Mode Power Supply 12
Audio Circuit 12
Assembly 14
Assembly Parts 15
Parts List 15
List of Figures
Figure 1 Block Diagram 10
Figure 2 Component Layout Diagram 11
Figure 3 Cable Interconnection Diagram 13
Figure 4 Exploded View 14
Figure 5 Circuit Diagram 19
Page 3Original, 11/94
Compact Handsfree Unit PHF–2
After Sales
Technical Documentation
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Page 4 Original, 11/94
After Sales
Technical Documentation
Introduction
The PHF–2 Compact Handsfree Unit forms a major part of the Compact
Handsfree Car Kit; the kit provides a simple–to–install, low cost handsfree
facility for in–car use.
The BABT approved version of PHF–2 is known as PHF–2X. Since both
units are technically identical, all references to PHF–2 equally apply to
PHF–2X.
Technical Summary
PHF–2 allows both handsfree (hf) and normal handset (hs) use of the
phone. Handset use is possible with the curly system cable which
includes an antenna cable. Detection of hf and hs operation is achieved
by a reed–switch located in the PHF–2 plug which detects the presence of
a magnet inside the MBH–9 holder.
Compact Handsfree Unit PHF–2
The phone is connected to the unit via a system connector (fitted to the
end of the curly system cable). There are also connectors for an external
power source, for a standard hf–microphone and for an external antenna
which must be used with this configuration.
The Compact Handsfree Unit consists of speaker and microphone
amplifiers, power on/off –logic, hf–speaker muting and a constant current
switching regulator for charging the phone battery. The unit has an inbuilt
hf–speaker and an external hf–microphone but the actual handsfree
function is generated in the phone.
MPHF2 mechanics comprise the front and rear covers, speaker
The
clamp, the holder cover, screws, type label, and system cable with
rf–cable.
PHF–2 is installed inside the vehicle using a separate mounting plate
(MKE–1). Depending upon the version of car kit being installed, the
PHF–2 unit is supplied with/without the MBH–9 holder already fitted to the
front of the PHF–2 unit.
List of Modules
Table 1. List of Modules
NAME OF MODULE TYPE
CODE
HF Speaker Module DH3N 0200599
Assembly Parts
PHF–2
Installation Kit PHF–1/M 0260254
MPHF2 0260340
MATERIAL
CODE
NOTES
Page 5Original, 11/94
Compact Handsfree Unit PHF–2
After Sales
Technical Documentation
Technical Specifications
Modes of Operation
Power Off : The DH3–module does not receive a supply volt-
age at the DC–connector (X100), hence no
voltages are present on the module.
Standby : The module receives a supply voltage at the DC–
connector but the M2BUS–line (X400) is low (logic
”0” state) because the phone is off and the battery
is fully charged. The switching regulator is off and
there is no supply voltage for the audio.
Power On / Speaker Off : The M2BUS–line is high (logic ”1” state) so the
switching regulator supplies charging current to the
phone. The supply voltage for the audio is on but
the PHFS–line (X400) is low (”0” state) so the HF–
speaker is muted.
Power On / Speaker On : The switching regulator supplies a charging
current to the phone. The supply voltage for the
audio is on and the PHFS–line is high (logic ”1”
state) so the HF–speaker is on.
Table 2. List of Connectors
CONNECTOR NAME CODE NOTES POLES
DC–Supply Connector X100 Power Supply Input Vdc 2–pole
HF–Microphone Connector X200 Microphone Input HFMIC 2–pole
HF–Speaker Connector X300 Speaker Output HFSP 2–pole
System Connector X400 Phone Cable Connector HHP 8–pole
Page 6 Original, 11/94
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