HA17008RFP データシートの表示（PDF） - Hitachi -> Renesas Electronics
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HA17008RFP Datasheet PDF : 11 Pages
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HA17008RP/RFP
Functions
Reference differential amplifier and phase compensation
The reference amplifier is a circuit which converts the reference voltage applied to pin 14 through the
external resistor R14 from a voltage to a current. The converted current is supplied to each bit by a current
mirror and the ladder resistor. Note that this should be used with the polarity of the current flowing in to
pin 14. The reference voltage source provides all of the current flowing into pin 14.
Also, even removing the resistor R15 will have a minimal influence on precision and temperature drift.
To preserve an appropriate value of the phase margin, it is necessary to increase the value of the phase
compensation capacitance as R14 is increased. For example, if R14 is 1 k , 2.5 k , or
5 k , the minimum capacitances should be 15 pF, 37 pF, and 75 pF, respectively. The capacitor is
connected to V EE. If high impedance is required in the reference current source, connect R14 to ground and
connect R15 to the negative reference voltage. (Refer figure 2.) If a DC reference voltage is used, a bypass
capacitor should be inserted in the reference voltage source to reduce compounded hum and noise. We
cannot recommend the use of noisy 5 V logic power supplies. When a logic control 5 V power supply of
good stability is used for the reference supply, connect a resistor to the reference supply and connect a 0.1
µF capacitor between the reference supply and the resistor contact.
When pin 14 is controlled by a high impedance such as a fixed current supply, phase compensation will not
be possible with the above method. Therefore, provide adequate phase compensation in the frequency band
of the fixed current supply.
A1
A2
A3
A4
A5
A6
A7
A8
5
6
7
8
9
10
11
12
VCC
13
HA17008R
3
R14 = R15
14 R14
15
2
R15
4
IO
16
C
(+) VREF
RL
VEE
Figure 1 Positive Reference Potential Application Example
3
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