ADM1022ARQ-REEL ON Semiconductor, ADM1022ARQ-REEL Datasheet - Page 11

• Manufacturer Part Number: ADM1022ARQ-REEL
• Description: IC SENSOR TEMP/DET 3/5.5V 16QSOP
• Manufacturer: ON Semiconductor
• Type: Temperature Sensorr

Specifications of ADM1022ARQ-REEL

• Rohs Status: RoHS non-compliant
• Input Type: Logic
• Output Type: Analog
• Interface: Serial
• Current - Supply: 2.6mA
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP

ANALOG OUTPUT
The ADM1022 has a single analog output (FAN_SPD) from an
unsigned 8-bit DAC that produces 0 V–2.5 V. The analog out-
put register defaults to 00 during power-on reset, which produces
minimum fan speed. The analog output may be amplified and
buffered with external circuitry such as an op amp and transistor
to provide fan speed control.
Suitable fan drive circuits are given in Figures 14a to 14e. When
using any of these circuits, the following points should be noted:
1. All of these circuits will provide an output range from zero to
2. To amplify the 2.5 V range of the analog output up to +V
3. Care must be taken when choosing the op amp to ensure that
4. The op amp may be powered from the +V rail alone. If it
5. In all these circuits, the output transistor must have an I
6. If the fan motor produces a large back ElectroMotive Force
7. Pulling FAN_SPD/NTEST_IN high externally on power-up
Figure 14c shows how the FAN_OFF signal may be used (with
any of the control circuits) to gate the fan on and off indepen-
dent of the value on the FAN_SPD/NTEST_IN pin.
almost +V
the gain of these circuits needs to be set as shown.
its input common-mode range and output voltage swing are
suitable.
is powered from +V then the input common-mode range
should include ground to accommodate the minimum output
voltage of the DAC, and the output voltage should swing below
0.6 V to ensure that the transistor can be turned fully off.
greater than the maximum fan current, and be capable of dis-
sipating power due to the voltage dropped across it when the
fan is not operating at full speed.
(EMF) when switched off, it may be necessary to add clamp
diodes to protect the output transistors in the event that the
output goes from full-scale to zero very quickly.
causes NAND Test Mode to be invoked on the ADM1022.
Therefore, a 4.7 kΩ pull-down resistor should be added
externally to the FAN_SPD pin to prevent ADM1022 inad-
vertently entering the NAND Tree Test Mode.
FAN_SPD
FAN
.
R1
10k
AD8541
+
15k
R2
5V
Q1
NDT452 P
5V
FAN
FAN
CMAX
,
FAN_SPD
FAN_SPD
FAN_SPD
FAN_SPD
5k
R6
5k
R5
100k
R1
10k
100k
MBT3904
R1
10k
R5
Q1/Q2
DUAL
MBT3904
R3
AD8519
Q1/Q2
+
DUAL
FAN_OFF
AD8519
+
39k
R2
39k
R2
R4
100k
100
100k
R4
100k
R3
1k
3.9k
1k
R4
R3
R3
1k
3.3V
R2
R1
Q3
BC556
2N3906
3.9k
1k
1k
R4
R2
R1
12V
ADM1022
12V
12V
Q1
NDT452 P
Q2
NDT3055L
Q3
NDT452 P
Q1
BD136
2SA968
12V
Q4
BD132
TIP32A