- 您现在的位置：买卖IC网 > PDF目录1841 > MAX1932ETC+T (Maxim Integrated Products)IC SUPPLY BIAS APD 12-TQFN PDF资料下载
参数资料
| 型号： | MAX1932ETC+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 7/16页 |
| 文件大小： | 0K |
| 描述： | IC SUPPLY BIAS APD 12-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 应用： | 控制器，光纤网络 |
| 输入电压： | 2.7 V ~ 5.5 V |
| 输出数： | 1 |
| 输出电压： | 4.5 V ~ 90 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 12-WQFN 裸露焊盘 |
| 供应商设备封装： | 12-TQFN-EP（4x4） |
| 包装： | 带卷 (TR) |
Digitally Controlled, 0.5% Accurate,
Safest APD Bias Supply
Output and DAC Adjustments Range
The inductance value is given by:
Many biasing applications require an adjustable output
voltage, which is easily obtained using the MAX1932’s
DAC output (Figure 2).
The DAC output voltage is given by the following equation:
L =
( V IN ) 2 × D 2 × T × η
2 I OUT ( MAX ) × V OUT
? + ?
V DACOUT = CODE × ?
? 1 . 25 V ? ? 1 . 25 V ?
? 256 ? ? 256 ?
R 6 ≥
I PK = IN
?
On power-up, DACOUT defaults to FF hex or 1.25V,
which corresponds to the minimum V OUT output voltage.
The voltage generated at DACOUT is coupled to FB
through R6. DACOUT can sink only 50μA so:
1.25V
50 μ A
Select the minimum output voltage (V OUTFF ), and the
maximum output voltage (V OUT01 ) for the desired
adjustment range. R5 sets the adjustment span using
the following equation:
R5 = (V OUTFF - V OUT01 ) (R6/1.25V)
R8 sets the minimum output of the adjustment range
with the following equation:
R8 = (1.25V ? R5)/(V OUTFF )
Setting the Output Voltage without
the DAC
Adjust the output voltage by connecting a voltage-
divider from the output (V OUT ) to FB (Figure 2 with R6
omitted). Select R8 between 10k Ω to 50k Ω . Calculate
R5 with the following equation:
where V IN is the input voltage, I OUT(MAX) is the maxi-
mum output current delivered, V OUT is the output volt-
age, and T is the switching period (3.3μs), η is the
estimated power conversion efficiency, and D is the
maximum duty cycle:
D < (V OUT - V IN )/V OUT up to a maximum of 0.9
Since the L equation factors in efficiency, for inductor cal-
culation purposes, an η of 0.5 to 0.75 is usually suitable.
For example, with a maximum DC load current of 2.5mA,
a 90V output, V IN = 5V, D = 0.9, T = 3.3μs, and η esti-
mated at 0.75, the above equation yields an L of 111μH,
so 100μH would be a suitable value.
The peak inductor current is given by:
V × D × T
L
These are typical calculations. For worst case, refer to
the article titled “Choosing the MAX1932 External
Indicator, Diode, Current Sense Resistor, and Output
Filter Capacitor for Worst Case Conditions” located on
the Maxim website in the Application Notes section (visit
www.maxim-ic.com/an1805).
External Power-Transistor Selection
An N-FET power switch is required for the MAX1932. The
N-FET switch should be selected to have adequate on-
resistance with the MOSFET V GS = V IN(MIN) . The break-
down voltage of the N-FET must be greater than V OUT .
For higher-current output applications (such as 5mA at
90V), SOT23 high-voltage low-gate-threshold N-FETs
R 5 = R 8 ?
? 1 ?
? VOUT
? 1 . 25 V
?
?
may not have adequate current capability. For example,
with a 5V input, a 90V, 5mA output requires an inductor
peak of 240mA. For such cases it may be necessary to
simply parallel two N-FETs to achieve the required cur-
Inductor Selection
Optimum inductor selection depends on input voltage,
output voltage, maximum output current, switching fre-
quency, and inductor size. Inductors are typically spec-
ified by their inductance (L), peak current (I PK ), and
resistance (L R ).
rent rating. With SOT23 devices this often results in
smaller and lower cost than using a larger N-FET device.
Diode Selection
The output diode should be rated to handle the output
voltage and the peak switch current. Make sure that the
diode’s peak current rating is at least I PK and that its
breakdown voltage exceeds V OUT . Fast reverse recov-
ery time (t rr < 10ns) and low junction capacitance
_______________________________________________________________________________________
7
相关PDF资料 |
PDF描述 |
|---|---|
| MAX1935ETA+T | IC REG LDO ADJ .5A 8TDFN |
| MAX1937EEI+T | IC REG CTRLR PWM HYBRID 28-QSOP |
| MAX1940EEE+ | IC SW USB TRPL 16-QSOP |
| MAX1945REUI+T | IC REG BUCK 6A 28TSSOP |
| MAX1946ETA+T | IC USB SW SGL AUTORESET 8TDFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1932EVKIT | 制造商:Maxim Integrated Products 功能描述:DIGITALLY-CONTROLLED, 0.5% ACCURATE, SAFEST A - Bulk |
| MAX1935ETA | 制造商:Maxim Integrated Products 功能描述:500MA LOW VOLTAGE LINEAR REGULATOR IN TINY QF - Bulk |
| MAX1935ETA+ | 制造商:Maxim Integrated Products 功能描述:LDO REG 0.8V TO 4.5V 0.5A 8TDFN EP - Rail/Tube |
| MAX1935ETA+T | 功能描述:低压差稳压器 - LDO 500mA RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| MAX1935ETA15 | 制造商:Maxim Integrated Products 功能描述:500MA LOW VOLTAGE LINEAR REGULATOR IN TINY QF - Rail/Tube |
发布紧急采购，3分钟左右您将得到回复。