March 2012
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN3850T • Rev. 3.0.2
FAN3850T — Microphone Pre-Amplifier with Temperature Compensation and Digital Output
FAN3850T
Microphone Pre-Amplifier with Temperature
Compensation and Digital Output
Features
Optimized for Mobile Handset and Notebook PC
Microphone Applications
Accepts Input from Electret Condenser Microphones
Pulse Density Modulation (PDM) Output
Standard 5-Wire Digital Interface
Amplifier Gain: 15.7dB or 13.7dB
Negative Temperature Coefficient to Compensate for
ECM Positive Temperature Coefficient
Low Input Capacitance, High PSR, 20kHz
Pre-Amplifier
Low-Power, 1.5µA Sleep Mode
Typical 420µA Supply Current
Signal to Noise Ratio of 62.4dB(A)
Total Harmonic Distortion: 0.01%
Input Clock Frequency Range of 1-4MHz
Integrated Low Drop-Out Regulator (LDO)
Small 1.26mm x 0.86mm 6-Ball WLCSP
Applications
Electret Condenser Microphones with Digital Output
Mobile Handsets
Headset Accessories
Personal Computers (PC)
Description
The FAN3850T integrates a pre-amplifier, LDO, and
Analog-to-Digital Converter (ADC) to convert Electret
Condenser Microphone (ECM) outputs to digital Pulse
Density Modulation (PDM) data streams. The pre-
amplifier accepts analog signals from the ECM and drives
an over-sampled sigma delta ADC and outputs PDM
data. The PDM digital audio has the advantage of noise
rejection and interface-to-mobile handset processors.
The FAN3850T is powered from the system supply rails
up to 3.63V, with a low power consumption of only
0.85mW, and less than 20μW in Power-Down Mode.
The device compensates for the temperature variation
of the microphone element to achieve a flat sensitivity
response over-temperature.
Figure 1. Block Diagram
Ordering Information
Part Number Gain
Option Operating
Temperature Range Package Packing
Method
FAN3850TUC15X35 15.7dB
-30°C to +85°C 6-Ball, Wafer-Level Chip-Scale
Package (WLCSP) 3000 Unit
Tape & Reel
FAN3850TUC13X35 13.7dB
Note:
1. Alternate gain options and temperature coefficient slopes are possible. Please contact a Fairchild representative.
LDO
Pre-Amp

ADC
INPUT
Sleep
Mode Ctrl
DATA
SELECT
CLOCK
GND
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN3850T • Rev. 3.0.2 2
FAN3850T — Microphone Pre-Amplifier with Temperature Compensation and Digital Output
Pin Configuration
Figure 2. Pin Configuration (Top View)
Pin Definitions
Pin# Name Type Description
A1 CLOCK Input Clock Input
B1 GND Input Ground Pin
C1 DATA Output PDM Output – 1-Bit ADC
A2 SELECT Input Rising or Falling Clock-Edge Select
B2 INPUT Input Microphone Input
C2 VDD Input Device Power Pin
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN3850T • Rev. 3.0.2 3
FAN3850T — Microphone Pre-Amplifier with Temperature Compensation and Digital Output
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be
operable above the recommended operating conditions and stressing the parts to these levels is not recommended.
In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability.
The absolute maximum ratings are stress ratings only.
Symbol Parameter Min. Max. Unit
VDD DC Supply Voltage -0.3 4.0 V
VIO Analog and Digital I/O -0.3 VCC+0.3 V
ESD
Human Body Model, JESD22-A114(2),
All Pins Except Microphone Input ±7 kV
Human Body Model, JESD22-A114(2),
Microphone Input ±300 V
Note:
2. This device is fabricated using CMOS technology and is therefore susceptible to damage from electrostatic
discharges. Appropriate precautions must be taken during handling and storage of this device to prevent
exposure to ESD.
Reliability Information
Symbol Parameter Min. Typ. Max. Unit
TJ Junction Temperature +150 °C
TSTG Storage Temperature Range -65 +125 °C
TREFLOW Peak Reflow Temperature +260 °C
JA Thermal Resistance, JEDEC Standard,
Multilayer Test Boards, Still Air 90 °C/W
Recommended Operating Conditions
The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended
operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not
recommend exceeding them or designing to Absolute Maximum Ratings.
Symbol Parameter Min. Typ. Max. Unit
TA Operating Temperature Range -30 +85 °C
VDD Supply Voltage Range 1.64 1.80 3.63 V
tRF-CLK Clock Rise and Fall Time 10 ns
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN3850T • Rev. 3.0.2 4
FAN3850T — Microphone Pre-Amplifier with Temperature Compensation and Digital Output
Electrical Characteristics
Unless otherwise specified, all limits are guaranteed for TA=25°C, VDD=1.8V, VIN=94dB (SPL), fCLK=2.4MHz,
duty cycle = 50%, and CMIC=15pF.
Symbol Parameter Condition Min. Typ. Max. Unit
VDD Supply Voltage Range 1.64 1.80 3.63 V
IDD Supply Current INPUT=AC Coupled to GND,
CLOCK=On, No Load 420 μA
ISLEEP Sleep Mode Current fCLK=GND 1.4 8.0 μA
PSR Power Supply Rejection(7)
INPUT=AC Coupled to GND, Test
Signal on VDD=217Hz Square
Wave and Broad Band Noise(3)
both 100mVP-P
-80 dBFS
INNOM Nominal Sensitivity(4) INPUT=94dBSPL
-26 dBFS
SNR Signal-to-Noise Ratio fIN=1kHz 1Pa, A-Weighted 62.4 dB(A)
eN Input Referred Noise(7) 20Hz to 20kHz, A-Weighted
15.7dB Gain 5.3 8.6 µVRMS
THD Total Harmonic Distortion(5) f
IN=1kHz, INPUT=-26dBFS 0.01 0.10 %
THD+N THD and Noise(7)
50Hz ≤ fIN ≤ 1kHz, INPUT=-20dBFS 0.2 1.0
%
fIN=1kHz, INPUT=-5dBFS 1.0 5.0
fIN=1kHz, INPUT=0dBFS 5.0 10.0
tc Temperature Coefficient(7,11) Gain Measured at 50˚C and -10˚C -0.035 dB/˚C
CIN Input Capacitance(7,11) INPUT 0.2 pF
RIN Input Resistance(7,11) INPUT >100
GΩ
VIL CLOCK & SELECT Input,
Logic LOW Level
0.3 V
VIH CLOCK & SELECT Input,
Logic HIGH Level 1.5 V
DD+0.3 V
VOL Data Output, Logic LOW
Level
0.35×VDD V
VOH Data Output, Logic HIGH
Level 0.65×VDD
V
VIN15dB Maximum Input Signal for
15.7dB of Gain(5)
fIN=1 kHz, THD+N < 10%;
DC Level=0V 503 mVPP
VOUT Acoustic Overload Point(11) THD < 10% 120
dBSPL
Continued on the following page…
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN3850T • Rev. 3.0.2 5
FAN3850T — Microphone Pre-Amplifier with Temperature Compensation and Digital Output
Electrical Characteristics (Continued)
Unless otherwise specified, all limits are guaranteed for TA=25°C, VDD=1.8V, VIN=94dB (SPL), fCLK=2.4MHz,
duty cycle = 50%, and CMIC=15pF.
Symbol Parameter Condition Min. Typ. Max. Unit
tA Time from CLOCK Transition
to Data Becoming Valid
On Falling Edge of CLOCK,
SELECT=GND, CLOAD=15pF 18 43 ns
tB Time from CLOCK Transition
to Data Becoming Hi-Z
On Rising Edge of CLOCK,
SELECT=GND, CLOAD=15pF 0 5 16 ns
tA Time from CLOCK Transition
to Data Becoming Valid
On Rising Edge of CLOCK,
SELECT=VDD, CLOAD=15pF 18 56 ns
tB Time from CLOCK Transition
to Data Becoming Hi-Z
On Falling Edge of CLOCK,
SELECT=VDD, CLOAD=15pF 0 5 16 ns
fCLK Input CLOCK Frequency(8) Active Mode 1.0 2.4 4.0 MHz
CLKdc CLOCK Duty Cycle(7) 40 50 60 %
tWAKEUP Wake-Up Time(9) fCLK=2.4MHz 0.35 2.00 ms
tFALLASLEEP Fall-Asleep Time(10) f
CLK=2.4MHz 0 0.01 1.00 ms
CLOAD Load Capacitance on Data 100 pF
Notes:
3. Pseudo-random noise with triangular probability density function. Bandwidth up to 10MHz.
4. Assumes 120dB(SPL) is mapped to 0dBFS.
5. Assumes an input -41, or -38dBV, depending on the part-specific gain.
6. Verified by design simulation, showing idle tones and low noise level modulation to be typical 96dB.
7. Guaranteed by characterization.
8. All parameters are tested at 2.4MHz. Frequency range guaranteed by characterization.
9. Device wakes up when fCLK ≥ 300kHz.
10. Device falls asleep when fCLK ≤ 70kHz.
11. Guaranteed by design.
12. Temperature coefficient is calculated by measuring gain in db at 50˚C and -10°C and dividing by 60 (Gain(50°C)
– Gain(-10°C)/60).
Figure 3. Interface Timing
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN3850T • Rev. 3.0.2 6
FAN3850T — Microphone Pre-Amplifier with Temperature Compensation and Digital Output
Typical Performance Characteristics
Unless otherwise specified, all limits are guaranteed for TA=25°C, VDD=1.8V, VIN=94dB(SPL), fCLK=2.4MHz, and
duty cycle=50%.
Figure 4. THD, SINAD, and SNR vs. Input Amplitude
Figure 5. THD, SINAD, and SNR vs. Output Level
‐20.00
‐10.00
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
0.001 0.010 0.100 1.000 10.000 100.000 1000.000
SNR(dBa),THD(dB),SINAD(dB)
InputSignal(mVpp)
SNR(dBa) THD(dB) SINAD(dB)
‐100.0
‐90.0
‐80.0
‐70.0
‐60.0
‐50.0
‐40.0
‐30.0
‐20.0
‐10.0
0.0‐20.0
0.0
20.0
40.0
60.0
80.0
100.0
‐95.77
‐89.50
‐83.76
‐77.62
‐71.59
‐65.57
‐61.57
‐55.56
‐49.57
‐43.57
‐37.57
‐31.58
‐25.55
‐19.55
‐17.56
‐15.55
‐13.55
‐11.54
‐9.54
‐7.53
‐5.54
‐3.55
‐1.63
0.00
SNR(dBa),THD(dB),SINAD(dB),Noise(dBFs)
SignalOutputLevel(dBFs)
SNR(dBa) THD(dB) SINAD(dB) Noise(dBFS)
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN3850T • Rev. 3.0.2 7
FAN3850T — Microphone Pre-Amplifier with Temperature Compensation and Digital Output
Figure 6. Gain vs. Temperature (~.035db/˚C)(1)
Note:
13. Alternate temperature coefficient slopes are possible. Please contact a Fairchild representative.
14.8
15.0
15.2
15.4
15.6
15.8
16.0
16.2
16.4
16.6
16.8
0
10
20
30
40
50
AveragGain(dB)
Temperature˚C
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN3850T • Rev. 3.0.2 8
FAN3850T — Microphone Pre-Amplifier with Temperature Compensation and Digital Output
Applications Information
Figure 7. Mono Microphone Application Circuit
Figure 8. Stereo Microphone Application Circuit
L/R
DecimationVDD Interpolation
SELECT
SPEAKER
Applications Software
ADC
SELECT
Clk
Pre-
Amp
SDI
ADC
INPUT
SDO
Pre-
Amp DATA
INPUT
CLOCK
VDD
Serial Port
CLOCK
Audio
Output
DATA
Low Pass Filter Noise Shaper
Decimation
Noise Shaper
Low Pass Filter
INPUT
Serial Port
Clk
Pre-
Amp.
Applications Software
ADC
Interpolation
CLOCK
SDI
DATA
SPEAKER
VDD
SELECT
SDO
Audio
Output
L/R
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN3850T • Rev. 3.0.2 9
FAN3850T — Microphone Pre-Amplifier with Temperature Compensation and Digital Output
Figure 9. MIC Element Drawin g
Applications Information
A 0.1µF decoupling capacitor is required for VDD. It can
be located either inside the microphone or on the PCB
very close to the VDD pin.
Due to high input impedance, careful consideration
should be taken to remove all flux used during the
reflow soldering process.
A 100Ω resistance is recommended on the clock output
of the device driving the FAN3850T to minimize ringing
and improve signal integrity.
For optimal PSR, route a trace to the VDD pin. Do not
place a VDD plane under the device.
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN3850T • Rev. 3.0.2 10
FAN3850T — Microphone Pre-Amplifier with Temperature Compensation and Digital Output
Physical Dimensions
Figure 10. 6-Ball, Wafer-Level Chip-Scale Package (WLCSP)
Table 1. Product-Specific Dimensions
D E X Y
1.260mm 0.860mm 0.145mm 0.145mm
Ball Composition: SN97.5-Ag2.5
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner
without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or
obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the
warranty therein, which covers Fairchild products.
Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings:
http://www.fairchildsemi.com/packaging/.
BOTTOM VIEW
TOP VIEW
12
A
B
C
6X
0.005 CAB
(X) +/-0.018
(Y) +/-0.018
Ø0.120±0.010
F
E
D
B
A
PIN A1
AREA
F
2X
2X
(Ø0.120)
CU PAD
SIDE VIEWS
0.06 C
D
CSEATING
PLANE
0.03 C
0.03 C
NOTES:
A. NO JEDEC REGISTRATION APPLIES.
B. DIMENSIONS ARE IN MILLIMETERS.
C. DIMENSIONS AND TOLERANCES PER
ASME Y14.5M, 1994.
D. DATUM C, THE SEATING PLANE IS DEFINED
BY THE SPHERICAL CROWNS OF THE BALLS.
E. PACKAGE TYPICAL HEIGHT IS 273 MICRONS
±23 MICRONS (254-300 MICRONS).
F. FOR DIMENSIONS D, E, X, AND Y SEE
PRODUCT DATASHEET.
G. DRAWING FILENAME: UC006AHrev3.
E0.080±0.010
0.570
0.485
0.197±0.013
0.300
0.254
0.570
0.485
RECOMMENDED LAND
PATTERN (NSMD)
(Ø0.220)
SOLDER MASK
A1
0.01 C
© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN3850T • Rev. 3.0.2 11
FAN3850T — Microphone Pre-Amplifier with Temperature Compensation and Digital Output
Mouser Electronics
Authorized Distributor
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