参数资料
| 型号： | AD5737ACPZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 31/44页 |
| 文件大小： | 0K |
| 描述： | IC DAC QUAD 12BIT CUR 64-LFCSP |
| 标准包装： | 1 |
| 设置时间： | 15µs |
| 位数： | 12 |
| 数据接口： | DSP，MICROWIRE?，QSPI?，串行，SPI? |
| 转换器数目： | 4 |
| 电压电源： | 模拟和数字 |
| 工作温度： | -40°C ~ 105°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 64-VFQFN 裸露焊盘，CSP |
| 供应商设备封装： | 64-LFCSP-VQ（9x9） |
| 包装： | 托盘 |
| 输出数目和类型： | 4 电流，单极 |
| 采样率（每秒）： | * |
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Data Sheet
AD5737
Rev. C | Page 37 of 44
DC-to-DC Converter On-Board Switch
The AD5737 contains a 0.425 internal switch. The switch
current is monitored on a pulse-by-pulse basis and is limited
to 0.8 A peak current.
DC-to-DC Converter Switching Frequency and Phase
The AD5737 dc-to-dc converter switching frequency can be
selected from the dc-to-dc control register (see Table 27). The
phasing of the channels can also be adjusted so that the dc-to-dc
converters can clock on different edges. For typical applications,
a 410 kHz frequency is recommended. At light loads (low output
current and small load resistor), the dc-to-dc converter enters a
pulse-skipping mode to minimize switching power dissipation.
DC-to-DC Converter Inductor Selection
For typical 4 mA to 20 mA applications, a 10 H inductor (such
as the XAL4040-103 from Coilcraft), combined with a switching
frequency of 410 kHz, allows up to 24 mA to be driven into a
load resistance of up to 1 k with an AVCC supply of 4.5 V to
5.5 V. It is important to ensure that the inductor can handle the
peak current without saturating, especially at the maximum
ambient temperature. If the inductor enters saturation mode,
efficiency decreases. The inductance value also drops during
saturation and may result in the dc-to-dc converter circuit not
being able to supply the required output power.
DC-to-DC Converter External Schottky Diode Selection
The AD5737 requires an external Schottky diode for correct
operation. Ensure that the Schottky diode is rated to handle the
maximum reverse breakdown voltage expected in operation
and that the maximum junction temperature of the diode is not
exceeded. The average current of the diode is approximately
equal to the ILOAD current. Diodes with larger forward voltage
drops result in a decrease in efficiency.
DC-to-DC Converter Compensation Capacitors
Because the dc-to-dc converter operates in discontinuous conduc-
tion mode, the uncompensated transfer function is essentially a
single-pole transfer function. The pole frequency of the transfer
function is determined by the output capacitance, input and output
voltage, and output load of the dc-to-dc converter. The AD5737
uses an external capacitor in conjunction with an internal 150 k
resistor to compensate the regulator loop.
Alternatively, an external compensation resistor can be used in
series with the compensation capacitor by setting the DC-DC
comp bit in the dc-to-dc control register (see Table 27). In this
case, a resistor of ~50 k is recommended. The advantages of this
configuration are described in the AICC Supply Requirements—
Slewing section. For typical applications, a 10 nF dc-to-dc com-
pensation capacitor is recommended.
DC-to-DC Converter Input and Output Capacitor
Selection
The output capacitor affects the ripple voltage of the dc-to-dc
converter and indirectly limits the maximum slew rate at which
the channel output current can rise. The ripple voltage is caused
by a combination of the capacitance and the equivalent series
resistance (ESR) of the capacitor. For typical applications, a
ceramic capacitor of 4.7 F is recommended. Larger capacitors
or parallel capacitors improve the ripple at the expense of
reduced slew rate. Larger capacitors also affect the current
Supply Requirements—Slewing section). The capacitance at
the output of the dc-to-dc converter should be >3 F under all
operating conditions.
The input capacitor provides much of the dynamic current
required for the dc-to-dc converter and should be a low ESR
component. For the AD5737, a low ESR tantalum or ceramic
capacitor of 10 F is recommended for typical applications.
Ceramic capacitors must be chosen carefully because they can
exhibit a large sensitivity to dc bias voltages and temperature.
X5R or X7R dielectrics are preferred because these capacitors
remain stable over wider operating voltage and temperature
ranges. Care must be taken if selecting a tantalum capacitor to
ensure a low ESR value.
AICC SUPPLY REQUIREMENTS—STATIC
The dc-to-dc converter is designed to supply a VBOOST_x voltage of
VBOOST_x = IOUT × RLOAD + Headroom
(2)
See Figure 30 for a plot of headroom supplied vs. output
current. Therefore, for a fixed load and output voltage, the
output current of the dc-to-dc converter can be calculated
by the following formula:
CC
V
BOOST
OUT
CC
AV
η
V
I
AV
Efficiency
Out
Power
AI
BOOST
×
=
×
=
(3)
where:
IOUT is the output current from IOUT_x in amperes.
ηV
BOOST
and Figure 33).
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| AD573JD | 功能描述:IC ADC 10BIT SAR REG 20-CDIP RoHS:否 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 位数:12 采样率（每秒）:3M 数据接口:- 转换器数目:- 功率耗散（最大）:- 电压电源:- 工作温度:- 安装类型:表面贴装 封装/外壳:SOT-23-6 供应商设备封装:SOT-23-6 包装:带卷 (TR) 输入数目和类型:- |
| AD573JN | 功能描述:IC ADC 10BIT SAR REGISTER 20-DIP RoHS:否 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1 系列:- 位数:14 采样率（每秒）:83k 数据接口:串行，并联 转换器数目:1 功率耗散（最大）:95mW 电压电源:双 ± 工作温度:0°C ~ 70°C 安装类型:通孔 封装/外壳:28-DIP（0.600"，15.24mm） 供应商设备封装:28-PDIP 包装:管件 输入数目和类型:1 个单端，双极 |
| AD573JNZ | 功能描述:IC ADC 10BIT SAR REGISTER 20-DIP RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1 系列:microPOWER™ 位数:8 采样率（每秒）:1M 数据接口:串行，SPI? 转换器数目:1 功率耗散（最大）:- 电压电源:模拟和数字 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:24-VFQFN 裸露焊盘 供应商设备封装:24-VQFN 裸露焊盘（4x4） 包装:Digi-Reel® 输入数目和类型:8 个单端，单极 产品目录页面:892 (CN2011-ZH PDF) 其它名称:296-25851-6 |
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